Evolution On a Smaller Scale

[pegase]

If there are any evolutionary biologists here, I have a question.

We separate a fictional mammalian species geographically. There is no contact between any of the new groups. What's the likelihood that the species, when reintroduced to one another, can still successfully reproduce after:

1,000 years?
10,000 years?
100,000 years?
1,000,000 years?

Assuming no artificial evolution.

[Asta Kask]

Depends hugely on circumstances. I don't know the answer, but I do know that.

[Icewalker]

I expect you are talking solely about genetic drift and mutation, which is to say, the selection pressures on both species are identical.

I wouldn't know the timing. But that's just a note worth establishing, and it also suggests that it would be a very very long time before any significant change occurs.

[Knaight]

We need way more information. The difference in conditions that the two are in and the length of a generation for this fictional species alone determine huge differences, and there are a great many other factors as well.

[Brother Oni]

As Icewalker said, it depends entirely on the differences in their environments.

Assuming no differences and hence no selection pressures, the two groups would still be pretty much identical after even a million years (subject to generation length).

As soon as you start introducing differences and other variables, that's when things get interesting.
For a more detailed answer, you'll have to say what the two environments are, any differences in native species, along with any predators and whether you're allowing them to adapt as well, the life expectancy and/or generational length for the species of interest, along with an estimate of their intelligence/ability to affect the environment, and this is just to start.

Edit: As Knaight said, we need way more information.



I wouldn't know the timing. But that's just a note worth establishing, and it also suggests that it would be a very very long time before any significant change occurs.

It depends on how dramatic the selection pressure is. Suppose the population was equally divided among those who could fly and those who couldn't. You then throw the entire species out of the back of an airplane at 30,000 feet into their new environment - obviously the next generation will consist almost exclusively of those who can fly.

[Mx.Silver]

As has been mentioned, there really are an awful lot of variables involved in determining the speed of speciation. In addition to the myriad of natural selection pressures (climate, predators, food availability etc.) the life span of the creatures is also important, since evolution is measured in terms of generations rather than strait years.

The main factor is always going to be selection pressures though. If there's little real difference, or if the pressures are quite weak, then it's entirely possible you won't even begin to see speciation after 10k years. On the other hand, if there's major differences in selection pressure then you could just as feasably end-up with two seperate species who couldn't even create hybrids (sterile or fertile) after the same amount of time.

I mean, the longer the time you allow for the more likely that there's going to be a change in selection pressures, so you'd be less likely to see speciation after 1k years than after 100k or 1 million. But this is far from a cast-iron rule, given the importance of natural selection.


Admittedly, I'm not an evolutionary biologist, but I'd still say there are far too many variables involved to give be able to make any real prediction of the scenario you outlined. Just ruling-out selective breeding by humans (which is what I assume you mean by 'artificial evolution'?) isn't going to be enough.


EDIT: Wow. That's a lot of ninjas.

[Quietus]

Admittedly, I'm not an evolutionary biologist, but I'd still say there are far too many variables involved to give be able to make any real prediction of the scenario you outlined. Just ruling-out selective breeding by humans (which is what I assume you mean by 'artificial evolution'?) isn't going to be enough.

Pretty much this. There isn't nearly enough information to look at things even 1,000 years down the line. The only information I'm aware of is that related to the Lenski affair; The science aspect of that basically boils down to Richard Lenski growing e. coli in a low-glucose solution, which is what e. coli normally uses for food. Over the course of twenty years - roughly 31,500 generations - the e. coli developed the ability to process citrate, which was present in the solution in much greater quantities. Just the science aspect of it is a fascinating read, though the whole "Lenski Affair" deal also contains an equally interesting discussion, of sorts. Unfortunately, that part is pretty heavily charged with religious issues, so I won't really comment on that.

[Eldan]

Depends also on the kind of separation you want. I could see a behavioural reproductive isolation evolving relatively quickly.
As in, there's some kind of mating ritual that needs to be performed before mating occurs, that has some natural variation. That could change relatively quickly, especially if it's learned instead of inherited. There are cases like that, though I must admit that most I can remember right now are from birds.

[Quietus]

Depends also on the kind of separation you want. I could see a behavioural reproductive isolation evolving relatively quickly.
As in, there's some kind of mating ritual that needs to be performed before mating occurs, that has some natural variation. That could change relatively quickly, especially if it's learned instead of inherited. There are cases like that, though I must admit that most I can remember right now are from birds.

This is a good point. Even between human cultures today on earth, there's some pretty vast differences in courting. Just look at our typical western methods of dating versus a country where arranged marriages are the norm. We might be capable of mating with those people, but it would be unlikely to occur naturally due to our vastly different social cues. But that doesn't qualify us as different species, which I think is what the OP is getting at.

[Brother Oni]

Pretty much this. There isn't nearly enough information to look at things even 1,000 years down the line. The only information I'm aware of is that related to the Lenski affair

That's a very interesting paper - thanks for linking it.

This would be a good example of a spontaneous mutation, where genetic drift just happens to find something useful.
Presumably the OP's prohibition of 'no artificial evolution' is intended to mean intentional modification, rather than accidental (as above) or something like the E.coli population encountering a bacteriophage carrying a citrate processing gene.

That 31500 generation number is a good starting point for the OP though - assuming a generational lifespan of 1 year, that's 31,500 years before they show a significant difference in the population. That still doesn't help with the 'can still successfully reproduce' part though and E.Coli is significantly less complex than a mammal.


This is a good point. Even between human cultures today on earth, there's some pretty vast differences in courting. Just look at our typical western methods of dating versus a country where arranged marriages are the norm. We might be capable of mating with those people, but it would be unlikely to occur naturally due to our vastly different social cues. But that doesn't qualify us as different species, which I think is what the OP is getting at.

Depends on how intelligent the species is, but even being a different species isn't a guarantee of non-compatibility - take a look at ligers (http://en.wikipedia.org/wiki/Liger) and wolfdogs (http://en.wikipedia.org/wiki/Wolfdog).

[Asta Kask]

There are cases like that, though I must admit that most I can remember right now are from birds.

Fiddler crabs?

[Quietus]

That's a very interesting paper - thanks for linking it.

This would be a good example of a spontaneous mutation, where genetic drift just happens to find something useful.
Presumably the OP's prohibition of 'no artificial evolution' is intended to mean intentional modification, rather than accidental (as above) or something like the E.coli population encountering a bacteriophage carrying a citrate processing gene.

That 31500 generation number is a good starting point for the OP though - assuming a generational lifespan of 1 year, that's 31,500 years before they show a significant difference in the population. That still doesn't help with the 'can still successfully reproduce' part though and E.Coli is significantly less complex than a mammal.

Yeah, I found it fascinating. I'm no expert, but I like to read things I know nothing about, and that paper lead to a day-long wiki walk that left me for the better. I'm not sure if the OP's prohibition of "No artificial evolution" would include intentionally putting pressures on the population or not; These E. coli were put in a low-food environment, mostly to see what they would do, and they ended up evolving to eat something different. Does that count as artificial evolution? I'm not sure. It's neat, though.

And yeah, that 31,500 generation thing was what I thought would be most relevant. The differences between bacteria and higher organisms is vast, but it really serves to put an exclamation point on just how much time is required for significant changes to occur. Would creatures capable of thinking for themselves, and acting on those thoughts, evolve at a different pace as they sought to avoid some particular issue? Who knows. But it'd take a LONG time for that to show up in their physical makeup, and would most likely be unpredictable at best. Hell, even Lenski didn't know what would happen with his E. coli, from what I understand. He was doing this twenty year experiment just to see what would happen. And that's a big part of why I love science.

[Icewalker]

Actually, one other important thing hasn't been mentioned: population size. It's actually highly relevant. If both groups are very small, there will be a much larger influence due to genetic drift, which will be present even if there are no differences in selection pressures. So if you had two very small populations, you'd be more likely to find significant changes show up.

[Don Julio Anejo]

A thing that hasn't been addressed before: often, due to random chance or whatnot, at least a few individuals will carry the gene that gives it a significant advantage under a specific selection pressure. A common technique in microbiology when you need bacteria with a certain characteristic, like resistance to streptomycin (an antibiotic) or the ability to use galactose as a food source, is to simply take a large colony of bacteria and expose it to that pressure.

So, for example, dump a load of streptomycin in the dish or take away any food other than galactose. Most bacteria will die, except for a select few. These will have the required trait (such as streptomycin resistance). And therefore will survive.

Of course, in humans it would be the equivalent of introducing a zombie virus to find maybe 20 people immune to it. Aka not very ethical, practical or even possible (because unlike most other living things, we can compensate for most pressures with complex behaviour, such as finding a zombie virus cure).

Another point: evolution only works with something an organism already has, since the trait has to be selected for. So something like running ability can go from low to moderate to high if there is selection pressure for fast runners (i.e. a fast predator). However, a human will never spontaneously sprout wings, no matter how many times you chuck him out of an airplane. He simply doesn't have the capacity for them.

[pegase]

You guys pretty much guessed what I wanted, although I should've been more clear.

Large populations, at least, enough for that equation for determining dominant/recessive frequency (x^2+2xy+y^2=1) to be fairly accurate. Whatever that was called.

Random mating. Eliminates new selective pressures.

No natural pressures that didn't exist previously in both spots.

Geographic isolation, but still the exact same scenario in both locales for both groups of the same species.

Random mutation, but at mammalian speeds. Complex eukaryotes mutate much slower than do prokaryotes.

Then if we forced a breeding between the two reintroduced species, would the resulting offspring (assuming there is one) be fertile itself?

In any case, that bacteria study was very interesting to read up on.

Edit. Sorry, took me a while to respond. I tried posting this, but my internet died, so I thought it didn't get through. When I established connection again, I noticed this thread by accident.

[Quietus]

Random mating? The entire point of evolution is that a particular trait is selected for, is it not? By introducing (enforcing?) random mating, you're not going to see evolution as you'd expect to see it, and you'd murder your chances of seeing different species develop. You'd have to basically work on a hope and a prayer that a mutation would show up, would remain dominant, and would be continued forward by sheer random chance, instead of "Hey, that guy/girl is better at X, therefore I find him attractive". I think that would kind of make the whole scenario pretty useless.

[Serpentine]

Everyone's pretty much covered most of what I'd say (depends on degree of different selection pressures, etc). I would suggest that you're interested in this, that you check out island speciation. Scientists have discovered dramatic changes in animals isolated on islands within a few hundred years, or even decades (such as a complete change in diet, for example), although I'm not sure about breeding potential when populations are brought back together. It's exactly the sort of thing you're wondering about, though.

Given the specific guidelines above, I'd say it would take a lot longer than the island speciation I mention before. The large population, and the fact that it's basically just random selection and genetic drift, would dilute any changes for a long time.

[Nix Nihila]

Random mating? The entire point of evolution is that a particular trait is selected for, is it not? By introducing (enforcing?) random mating, you're not going to see evolution as you'd expect to see it, and you'd murder your chances of seeing different species develop. You'd have to basically work on a hope and a prayer that a mutation would show up, would remain dominant, and would be continued forward by sheer random chance, instead of "Hey, that guy/girl is better at X, therefore I find him attractive". I think that would kind of make the whole scenario pretty useless.

Well, that sounds like sexual selection, natural selection still works without sexual selection. For example, a mutation might cause an animal to have reduced sexual appeal to other members of it's species, but it may also decrease it's chances of being eaten, which, depending on the circumstances, could be beneficial or detrimental.

You might be interested in looking up John Endler's work on guppies, where he explores sexual selection and natural selection. I imagine you could also find work on pheasants or peacocks that illustrates similar things, but I'm not well versed in this area, unfortunately.

[pegase]

The main reason for my question was to determine generally if a population were separated in two, everything else remaining the same, how long would it be until random genetic drift separated the two populations into two distinct species.

[Rising Phoenix]

The main reason for my question was to determine generally if a population were separated in two, everything else remaining the same, how long would it be until random genetic drift separated the two populations into two distinct species.

As other have said it's impossible. It happens whenever chance allows it to happen. When modern biologists estimate when a species split occurred in the past the resulting date is simply the greatest statistical possibility. I.e. according to the math it most likely happened during that time period, but it is also possible that it happened before that date or after. To date we haven't developed a method to determine precisely when a speciation occurs unless it is observed in real time.

The following increase the chance of speciation occuring but do not allow us to predict it.


1) Mutation rate and genetic repair mechanisms. The crapier your genetic repair the faster your population accumulates mutations upon which natural selection can work
2) Reproduction rate, fecundity and generation lifespan, the faster you reproduce, the more young ones you make and the shorter lived a generation the faster you'll likely to evolve. Compare for example a bacterium species to an Elephant. We can be fairly certain that in say 100 years elephants will still be the same species whether the bacterium species may have differentiated into several different species due to it's more rapid reproduction.
3) Population size. Hugely important as discussed by others. If you have several isolated population of a fast breeding species then bottleneck effects and genetic drift will likely take effect faster.
4) The environment... So many thing to list here from climate, to the presence of other species in the same environment, to how many different habitats are found in close proximity, dispersion barriers etc etc.
5) Behaviour. In many bird species dance and song determine whether a female will mate with a mate. As these are very flexible they are prone to change faster.
6) Hybridization. Are hybrid between two species viable? Are they stronger than either of the parent species (hybrid vigor). Is it possible for a hybrid population to form and then proceed to evolve independently of either species (Ala Mariana Mallard and certain North American Warblers)

And for the record speciation can occur in one generation in plants and amphibians. But I'll get back to you on how that works. Been a while since I read about it.


Edit: Can't seem to remember where I've placed that book. It had a nice example with Salamanders... This is the basic idea anyhow: Say you have species A with two pairs of chromosmes and species B with four and they hybridize.

Thus any offspring produced from this union will have two chromosomes from parent A and four from parent B resulting in a new chromosomal number: 6. Six is dividable by two (3 and 3) allowing for meiosis to occur and may enable these young to reproduce with each other resulting in fertile offspring.

However if they try to back cross with either of the parent species the resulting offspring will have either 5 or 7 chromosomes which screws up with meiosis as these numbers aren't dividable by two. So these young ones will very likely be sterile if they are born at all.

In other words the offspring of union A and B are reproductively isolated from each other due to chromosomal number incompatibility and presto you have a new species in the space of one generation.

Note that this is easier done in plants as there few things to screw up in their anatomy. Wheat for example is such a species and the main reason why it is a pain to genetically engineer (can't recall how many different grass genomes make up wheat).

Hope this helps.

R.P

[Kislath]

If everything truly remained the same on each side, then there shouldn't be any significant change for hundreds of thousands of years. Why would there be? Even pure chance mutations would only insert themselves so far in the total population. If you want speciation, you need stimulus.

[Rising Phoenix]

If everything truly remained the same on each side, then there shouldn't be any significant change for hundreds of thousands of years. Why would there be? Even pure chance mutations would only insert themselves so far in the total population. If you want speciation, you need stimulus.

Edit: This is not entirely correct. Speciation (and evolution) is a chance event. They can happen anywhere, anytime. Stimuli certainly help drive things along, but are not needed. (Also note that under normal circumstances a species in an environment is constantly under a large number of stimuli. Constant stimuli in this case. Biological systems are never static.)


Even pure chance mutations would only insert themselves so far in the total population

But if the mutation is advantageous 'against' a particular constant and stable stimulus the it would likely become a selective factor. This happens easier in smaller populations then large ones as it can get 'lost' in a large population.

For such an example look at African Seed Crackers, a species of bird that have sympatrically evolved into two different forms/species to tackle large and fine seeds.

Edit: Alternatively what could happen is that even though the two populations do not change phenotypically they may become genetically incompatible due to different mutations accumulating in their genomes, thus making them different species.

Cheers,

R.P.

[hamishspence]

And it's worth remembering, that in some cases two different species, or even genera, can retain a degree of interfertility despite being dramatically different- the bottlenose dolphin and false killer whale, producing fertile "wolphins" despite being different genera.

This is probably likely to be very much the exception though.

[Serpentine]

This is probably likely to be very much the exception though.Not really. The "no interbreedability" thing is pretty much the ideal, but in practice it's pretty rare. I mean, technically, it's entirely possible humans could breed with chimpanzees. You gonna test it?
I think my preferred general definition of species (and there's many) is probably "able to maintain a distinct population even when coming into contact with other related species".

[hamishspence]

Different chromosome numbers might be the reason why- it might not take much work to produce a human-chimp hybrid- but it would be infertile.

Fertile hybrids of different species are not that uncommon (ducks especially)

fertile hybrids of different genera, seem to crop up much less often.


That said, species, genus, and so on are human constructs- it's possible that those two genera "should" be closer together- maybe redefined as two different Tursiops species.

[Rising Phoenix]

Different chromosome numbers might be the reason why- it might not take much work to produce a human-chimp hybrid- but it would be infertile.

Fertile hybrids of different species are not that uncommon (ducks especially)

fertile hybrids of different genera, seem to crop up much less often.


That said, species, genus, and so on are human constructs- it's possible that those two genera "should" be closer together- maybe redefined as two different Tursiops species.

Differing number of chromosomes usually does result in infertile hybrids, however, if you end up with an even number in a relatively healthy individual that individual may be fully fertile (see hybrid species origin above) which may explain why wholphins are fertile.

And very occasionally you will get a fertile mule or a fertile anser x branta goose hybrid. I don't know what the genetic composition of these guys are though.

[Quietus]

Well, that sounds like sexual selection, natural selection still works without sexual selection. For example, a mutation might cause an animal to have reduced sexual appeal to other members of it's species, but it may also decrease it's chances of being eaten, which, depending on the circumstances, could be beneficial or detrimental.

You might be interested in looking up John Endler's work on guppies, where he explores sexual selection and natural selection. I imagine you could also find work on pheasants or peacocks that illustrates similar things, but I'm not well versed in this area, unfortunately.

The problem here is that Pegase is apparently trying to remove ALL selective pressures. Separating the individuals in question into two groups, keeping them in cages, and whenever the females go into heat, rolling a die to see which male gets to mate with her. At least, that's how I'm understanding his "random mating" mentioned above. Hell, even then you'd have to deal with the fact that they might not mate anyway, so you might have to resort to artificial insemination. I may look up John Endler's work later on today though, as that does sound like it could be an interesting read, thanks.


The main reason for my question was to determine generally if a population were separated in two, everything else remaining the same, how long would it be until random genetic drift separated the two populations into two distinct species.

There's no way of predicting something strictly by random genetic drift, due to it being, well, random.

[Nix Nihila]

The problem here is that Pegase is apparently trying to remove ALL selective pressures. Separating the individuals in question into two groups, keeping them in cages, and whenever the females go into heat, rolling a die to see which male gets to mate with her. At least, that's how I'm understanding his "random mating" mentioned above. Hell, even then you'd have to deal with the fact that they might not mate anyway, so you might have to resort to artificial insemination. I may look up John Endler's work later on today though, as that does sound like it could be an interesting read, thanks.

Ah, I see. Misinterpreted what he was saying. Then I believe the largest factors would be population size and generation length, as others have mentioned.

[Serpentine]

Mutation rate, too.

[Quietus]

Yeah, pretty much. Like I pointed out above, he's pretty much limited his entire though experiment down to a total crapshoot. One with so many variables that there's no way to even make a reasonable guess, even if any of us happen to be highly trained in the proper fields.

[Anxe]

The best example I can think of is Sapiens and Neanderthals. The two species were separated by 90,000 to 20,000 years (I'm not sure which) and were unable to interbreed. That's probably a good baseline, but what the others have said is good stuff. Generation times have to be taken into account. The cool thing about Neanderthals and Sapiens is that we know they didn't have different environments. They were living in the same place. We can guess an average generation time is about 17 years or so. From that we could get a range for "Generations Needed to Properly Speciate."

But again. The warning label on this example is that its only one comparison out of thousands (millions?).

[teratorn]

I think my preferred general definition of species (and there's many) is probably "able to maintain a distinct population even when coming into contact with other related species".

A bit like wolves and coyotes. There's gene flow but morpho and ecotypes remain distinct.

Even with humans things are tricky. Neanderthals contributed something like 1-4% of modern european DNA, and denisovans something like 4% of modern melanesian populations. We're talking about populations that had been relatively isolated for a quarter to half a million years from the groups that later left Africa and contributed most of asian/european genetic makeup.

Edit: I hadn't seen Anxe's post. Neanderthal and Denisovan genomes have shown there was interbreeding.

[hamishspence]

The best example I can think of is Sapiens and Neanderthals. The two species were separated by 90,000 to 20,000 years (I'm not sure which) and were unable to interbreed.

Recent evidence seems to suggest otherwise:

http://en.wikipedia.org/wiki/Neanderthal

and there's some debate over whether they're a separate species or a subspecies.

EDIT: Swordsaged.

[Kislath]

Phoenix, you missed what I said. You are basing your position on differences in the stimuli on the two groups, but I, and the OP, specifically stated there is no difference; both groups share the same stimuli, and while each would evolve, they'd likely do it in the same way.

[teratorn]

Phoenix, you missed what I said. You are basing your position on differences in the stimuli on the two groups, but I, and the OP, specifically stated there is no difference; both groups share the same stimuli, and while each would evolve, they'd likely do it in the same way.

Very likely they wouldn't. Evolution doesn't give you the optimal solution, it might converge to some local fitness maximum, not the highest of them, so even with a similar departure genetic makeup, in a similar changing environment you could end with incredibly distinct populations given enough time.

I'm not an evolutionary biologist by I work with genetic algorithms and it's always cool seeing your «populations» (your guesses to a given problem) filling different niches (the solution where they get stuck) when your fitness function allows for a series of maxima.

[Serpentine]

A bit like wolves and coyotes. There's gene flow but morpho and ecotypes remain distinct.I first really came across that definition when looking at plant speciation, and believe you me, the interbreeding definition is damn near useless when it comes to plant species.

both groups share the same stimuli, and while each would evolve, they'd likely do it in the same way.Actually, in the absence of any specific stimuli, with "random mating", and with no particular selection pressure, we're looking at random mutation and genetic drift. That, we can't really predict.

[Adlan]

The cool thing about Neanderthals and Sapiens is that we know they didn't have different environments. They were living in the same place.

Sapiens originate in the African Savannah, Neanderthals originate in the west of Asia. Others have pointed out their degree of relatedness, their likely capability to interbreed and their status as a subspecies along side us, both evolving out of the same common ancestor.

[teratorn]

I first really came across that definition when looking at plant speciation, and believe you me, the interbreeding definition is damn near useless when it comes to plant species.


Even in vertebrates there are a few problems, how does one consider as a species those pesky parthenogenetic lizards since they don't exchange genetic material in population?

[Kislath]

Well, frankly, "species" itself is a meaningless term. ( Kinda like "fish" What is a fish? A thing we CALL a fish, nothing more; it's otherwise undefinable )
I should have said "similarly" earlier instead of "the same."

[Mando Knight]

Depends on how intelligent the species is, but even being a different species isn't a guarantee of non-compatibility - take a look at ligers (http://en.wikipedia.org/wiki/Liger) and wolfdogs (http://en.wikipedia.org/wiki/Wolfdog).

Wolfdogs technically aren't interspecies hybrids like donkeys and ligers, they're closer to being crossbreeds. Domestic dogs are a subspecies of wolves, having significant differences, but generally being able to crossbreed normally. (Also, selective breeding of foxes reveals that other canids tend to show similar traits to domestic dog breeds when bred for docility)

[Asta Kask]

Actually, in the absence of any specific stimuli, with "random mating", and with no particular selection pressure, we're looking at random mutation and genetic drift. That, we can't really predict.

We could probably give a nice probability curve (if we knew enough about how these things work) even if we can't predict exactly when. Say at T1 there's a 10% probability that they can't interbreed, at T2 there's a 25%... etc. After all we can't predict when a radioactive nucleus will decay but we can still give a probability curve.

[Anxe]

I guess we still don't know if Neanderthals and Sapiens interbreeded. Can't have been often if they could though. As for origination of the two species, does that matter? Didn't they spread pretty much everywhere?

[Rising Phoenix]

Even in vertebrates there are a few problems, how does one consider as a species those pesky parthenogenetic lizards since they don't exchange genetic material in population?

You apply the lineage species concept o them? :smalltongue: (yes,it's not the most accurate...). Personally I like a Biological species approach with a 'dash' of genetic species concept for vertebrates at least.

For plants well... you can have 300 species of Eucalypt with one and only 10 with another cause they all the various 'species' hybridize with each other.

Kislath: Other have said what I would have said. :)

[Serpentine]

Well, frankly, "species" itself is a meaningless term. ( Kinda like "fish" What is a fish? A thing we CALL a fish, nothing more; it's otherwise undefinable )It's no more meaningless than any other word we use, its definition is just a bit more debatable. Words are what we use to categorise the world around us, but overall we do so in a logical manner - it doesn't matter to the Sun what we call it, but the category "sun" or "star" reflect natural states.
I would compare species to sexualities - it's artificially discrete categories for what is actually a gradient. We've got this species/homosexuality, that species/heterosexuality, a hybrid/bisexuality, and any number of permutations in-between. But there's a difference between artificial and meaningless.

We could probably give a nice probability curve (if we knew enough about how these things work) even if we can't predict exactly when. Say at T1 there's a 10% probability that they can't interbreed, at T2 there's a 25%... etc. After all we can't predict when a radioactive nucleus will decay but we can still give a probability curve.True. If we knew the mutation rate, and the probability that any mutation in one population would turn up in the other, and the rough point at which one will be unable to breed with the other, we could probably approximate the time that would take.
For plants well... you can have 300 species of Eucalypt with one and only 10 with another cause they all the various 'species' hybridize with each other.That's my point. The biological species concept is pretty much useless when it comes to plants because they hybridise all over the place yet are quite clearly distinct species. That's why I tend to prefer the "able to maintain distinct populations" variant for practical use.

[Rising Phoenix]

That's my point. The biological species concept is pretty much useless when it comes to plants because they hybridise all over the place yet are quite clearly distinct species. That's why I tend to prefer the "able to maintain distinct populations" variant for practical use.

Or you could use the ecological species concept, though I am confused whether it actually increases the number of species or decreases it. Or you could just say that there's only one type of life on earth (carbon based) and ditch the entire thing :smalltongue: (which is true, but I still enjoy categorizing things :P)

Also worth remembering is that categorizing populations as species, races etc allows us to have this convo in the first place. :)

[Serpentine]

I think the definition I like is something around the Evolutionary Species definition, although I don't think it's in the words I remember reading it.
And uh... I'm not disparaging the use of species :smallconfused: In fact, I just defended it a little while ago...

[Asta Kask]

That's my point. The biological species concept is pretty much useless when it comes to plants because they hybridise all over the place yet are quite clearly distinct species. That's why I tend to prefer the "able to maintain distinct populations" variant for practical use.

It's even worse when we come to bacteria... they have sex all over the place.

[Serpentine]

Yeah, according to Wikipedia they tend to abandon "species" as a concept for bacteria.
...which has interesting implications for that other thread with the button.

[Asta Kask]

Eliminating all bacteria would be a bad idea. Let's just leave it at that.

[Serpentine]

"Destruction of (almost? Plants might be okay) all life on the planet" levels of bad, in fact...

[faceroll]

All you need to know is generation time. Assuming average mammal size, which is about the size of a mouse, we'll go with the generation time of a rat- 5 generations per year. We'll also assume a drift rate of 10^-8. We'll assume a genome of 3 megabases. Going with conserved genes, like CO1, we'll assume a 2% change in genome constitutes a speciation event. Conserved genes like CO1 have a mutation rate of around 10^-8, so our assumptions are little more warranted.

That sets a threshold of 40,000 years.

Math:
2% of 3mb is 60,000 mutation events. There are 1.5 mutations per year (3mb * 5 generations per year * 10^-8). Therefore, we need 60,000/1.5 years to elapse before speciation occurs. I did assume that all mutations are unique and the same bp didn't back-mutate.

Hmmm, seems off by about 2 orders of magnitude for a reproduction barrier to arise. Most (megafaunal) mammals, afaik, that are separated by only 40ky are still crossable. Certainly short enough for morphological speciation to occur.

Mutations don't occur homogeneously, though. A chance mutation in sperm recognition proteins or a chromosomal duplication event would create an almost immediate reproductive barrier. A behavioral change, such as only mating during a certain season could cause another reproductive barrier to occur. Many insects speciate due to changes in genital structure (they use a "lock-and-key" mechanism) or reproductive behavior (breeding during different times of the year or changes in courtship behavior).

Regions that under go concerted evolution, like internal transcribed spacers, would very likely exhibit species level divergences, yet if selective pressures are the same in both populations, it's quite possible that phenological analysis wouldn't be able to tell that they were different species (ie, distinct, isolated populations). ITS drifts rapidly in isolated populations while typical conserved regions stay relatively the same. Interspecies differences in CO1 is like 2%-10% while interspecies differences with ITS2 are 20-80%. Intraspecies divergence in both genes remains very low, about an order of magnitude lower than interspecies divergences.


Random mating? The entire point of evolution is that a particular trait is selected for, is it not? By introducing (enforcing?) random mating, you're not going to see evolution as you'd expect to see it, and you'd murder your chances of seeing different species develop. You'd have to basically work on a hope and a prayer that a mutation would show up, would remain dominant, and would be continued forward by sheer random chance, instead of "Hey, that guy/girl is better at X, therefore I find him attractive". I think that would kind of make the whole scenario pretty useless.

Speciation by drift. Hella common. Darwinian selection is only one form of evolution.


There's no way of predicting something strictly by random genetic drift, due to it being, well, random.

Oh, the magic of Gaussian distributions.

[Kislath]

*smacks forehead* D'OH!
I never even considered the impact of certain uber-important genes just so happening to be the ones to mutate.
Awesome post, faceroll. I always thought Darwin was way off somewhere.

[faceroll]

*smacks forehead* D'OH!
I never even considered the impact of certain uber-important genes just so happening to be the ones to mutate.
Awesome post, faceroll. I always thought Darwin was way off somewhere.

With the discovery of "junk DNA"*, there's a growing body amongst the evolutionary biologists that like to model things that shows a great deal of eukaryotic evolution is due to drift. Drift is just due to small sample sizes and accidents adding up over time. Some go so far as to propose that the evolution of sexual reproduction evolved without any fitness reasons. Pure accident, due to census size.

See, when looking at populations in Hardy-Weinberg equilibrium, your model is assuming several things, one of which is an infinite population. There are no infinite populations. Bacteria approach infinity to a far great estimation than all but the most fecund of eukaryotes. That is one explanation of why prokaryotes lack the "bloated genomes" of eukaryotes- they better approximate an ideal population.

I think drift is a very important driving force of evolution. Perhaps not as powerful as the nullists propose, but I don't think everything needs an adaptationist explanation. That often seems to violate parsimony. Most selection is actually pretty weak, anyway, and easily countered by drift.

Another form of non-Darwinian evolution is lateral gene transfer. It's extraordinarily common amongst prokaryotes. The first 3 billion years of single celled life evolved in a non-Darwinian paradigm. Carl Woese (the guy that discovered the third domain of life; Archeae) recently proposed that the degenerative RNA code for aminos acid is a product of lateral gene transfer. The code is very efficient, and in a Darwinian paradigm, the chance that that particular code would have been arrived it is vanishingly small, as the fitness landscape is full of local maxima, yet somehow we arrived at a nearly global maxima. However, with lateral transfer, evolution could overcome the barriers of local maxima and arrive at a much more optimal solution.


*It's not actually junk, and advances in genomics is likely to reveal that non-coding DNA is pretty damn important for regulating stuff. Blame Crick's Central Dogma and the one gene one product hypothesis for biasing geneticists for generations. It will be interesting to see how our growing knowledge of how the genome functions changes our null models of drift.

[Asta Kask]

But the hyper-important genes can't mutate by very much because otherwise the animal would be unable to breed with everyone around hän.

[Kislath]

I have a long-held theory about junk DNA:
If regular DNA is the "application software" of our cells, then the junk DNA must hold the Operating System.
I'm pretty sure I'm right about this.

[Brother Oni]

Lots of interesting numbers

Is there any resources or books you can recommend to read up on this? I find population genetics fascinating, but I never had the opportunity to study it.


But the hyper-important genes can't mutate by very much because otherwise the animal would be unable to breed with everyone around hän.

There's quite a simple check and balance for that. Since mutation in genes are most likely to occur during meiosis, if the hyper-important gene mutates beyond functionality, the foetus either self-aborts or the organism is so disabled, that it is unable to reproduce successfully and pass on its mutated genes.

There's no way of stopping non-functional genes from occurring, but there is a way of stopping the non-functional genes from spreading, which is what what's most important for a population.


I have a long-held theory about junk DNA:
If regular DNA is the "application software" of our cells, then the junk DNA must hold the Operating System.
I'm pretty sure I'm right about this.

Back when I studied genetics, introns were among the first things lost during telomere duplication and there was no observable adverse effect on the cell, making your 'Operating System' theory less plausible. In addition, if the sequences are outside of the normal reading frame or inbetween the stop/start codons, how are they encoded?

About the only thing they discovered in the introns, were some sequences that resembled wild-type retroviruses, thus it was theorised that they had infected humans, then got 'stuck' in our genome. Since they were outside of the normal reading frame of ribosomes, they'll never got encoded barring a major cellular malfunction.

Of course this is all very old information - I'm sure that there have been several advances that have invalidated all my knowledge. :smallsigh:

[Eldan]

"Destruction of (almost? Plants might be okay) all life on the planet" levels of bad, in fact...

Most plants too, I'd say. Nitrogen fixation is pretty important for them.

[faceroll]

Some intronic regions are exonic and encode functional product when read 3' to 5' instead of 5' to 3'. Some intronic regions are selectively exonic, where mixing and matching regions code for different types of functional product. I believe muscle cells do this when building muscles.

Some regions don't do anything other than modify the tertiary or quaternary structure of DNA, affecting how transcription factors are recruited. These regions are called enhancers and silencers. Others are sites with high TF affinity that recruit the proteins that form a transcription bubble. Promoter elements like the TATA box marks a generic start location of a gene so RNA pol knows where to start. Recognition sequences recruit more specialized transcription factors. Up-regulation of a TF would increase the frequency of binding at those specific sites and would have a downstream effect. Other sites are recognized by endonucleases or methyltransferases which have a regulatory effect on genes.

The most variable region in mtDNA, which is otherwise extraordinarily conserved like its distantly related prokaryotic cousins, is called the Control Region. CR is believed to regulate the functions of the genes on the mt genome by recruiting TFs.

Still other regions that get transcribed but not translated can have catalytic properties, such as ribozymes, interference RNA, microRNAs, and tRNAs. Even pseudogenes can still be important in an evolutionary context. Instead of having to re-evolve an entirely new system, you modify the old one.

For instance, ducks have a gene, gremlin, that deactivates BMP4 in their feet, which prevents apoptosis from destroying the webbing between their toes. This makes their feat good for paddling in water. Chickens, on the other hand, lack the gremlin gene, so BMP4 gives them chicken feet. If you treat embryonic chicken feet with gremlin, deactivation of BMP4 causes the chickens to develop webbed feat. See also homeobox and Hox gene evolution.

I think most selective, phenotypic "speciating" evolution is operating on non-coding DNA, since most selection on functional genes is going to be extremely strong. Take bones, for instance. All vertebrates have very nearly the same structural genes for bones. It's a composite of protein and calcium phosphate. However, look at the vast diversity of vertebrate bones, from airy, lightweight bird bones, to massive, super dense whale bones. Yet it's largely changes in regulatory structure that causes these changes, not the actual genes. It's like all buildings are made out of the same basic materials, but it's the floor plans that create the diversity. Hox gene duplication greatly increased the amount of variability available in regulatory elements, and I think that's why vertebrates are so complex.


"Destruction of (almost? Plants might be okay) all life on the planet" levels of bad, in fact...

I imagine fungi, archeae, and protista would rapidly fill in the niche left by the disappearance of bacteria. Some megafauna would go extinct, certainly, but life's faced some pretty cataclysmic events and seems to bounce back just fine.

[Anxe]

I think faceroll just won this thread.

[Serpentine]

Most plants too, I'd say. Nitrogen fixation is pretty important for them.Oh yeah. I forgot about that.
I imagine fungi, archeae, and protista would rapidly fill in the niche left by the disappearance of bacteria. Some megafauna would go extinct, certainly, but life's faced some pretty cataclysmic events and seems to bounce back just fine.Oh yeah? You think they'll occupy the space in our guts and other places and start fulfilling the same functions in tune with our bodies before we all starve to death?
Somehow, I doubt it.

[Brother Oni]

Oh yeah? You think they'll occupy the space in our guts and other places and start fulfilling the same functions in tune with our bodies before we all starve to death?
Somehow, I doubt it.

I think faceroll meant life in the general, rather than specific species, including us. :smalltongue:

[Knaight]

I think faceroll meant life in the general, rather than specific species, including us. :smalltongue:

We fit into the megafauna that goes extinct category.

[Serpentine]

I think faceroll meant life in the general, rather than specific species, including us. :smalltongue:He said "I imagine fungi, archeae, and protista would rapidly fill in the niche left by the disappearance of bacteria. Some megafauna would go extinct, certainly". Probably every animal on this planet (can't guarantee that's the case, but I expect it would be) has a massive flora of bacteria in our systems. We rely on these to help us digest our food, among other things. If we don't have them, we starve to death. That's not just humans, and not just "some megafauna". That's everything. And it's not including all the plants that, as mentioned, rely on bacteria for nitrogen fixation - pretty much the same deal as with humans.
Could fungi, archeae and protista fill the niche? Possibly, if given enough time. But unless there's already members of these organisms doing that stuff already, they're highly unlikely to do it in time.
Will they themselves be able to survive the disappearance of bacteria? Possibly. I haven't done that much reading on them. I would expect, though, that at the very least they rely on bacteria in some of the same ways as other living things and it would still have a huge impact on them.

So yeah. A long, long way from merely "some of the megafauna".

[Rising Phoenix]

He said "I imagine fungi, archeae, and protista would rapidly fill in the niche left by the disappearance of bacteria. Some megafauna would go extinct, certainly". Probably every animal on this planet (can't guarantee that's the case, but I expect it would be) has a massive flora of bacteria in our systems. We rely on these to help us digest our food, among other things. If we don't have them, we starve to death. That's not just humans, and not just "some megafauna". That's everything. And it's not including all the plants that, as mentioned, rely on bacteria for nitrogen fixation - pretty much the same deal as with humans.
Could fungi, archeae and protista fill the niche? Possibly, if given enough time. But unless there's already members of these organisms doing that stuff already, they're highly unlikely to do it in time.
Will they themselves be able to survive the disappearance of bacteria? Possibly. I haven't done that much reading on them. I would expect, though, that at the very least they rely on bacteria in some of the same ways as other living things and it would still have a huge impact on them.

So yeah. A long, long way from merely "some of the megafauna".

I'm with Serp on this one, pretty much any multicelular life form that's more complex than a sponge (do they rely on bacteria? I don't know) would kick the bucket if bacteria were to dissapear 'overnight'.

(Also earlier I was just discussing species concepts not accusing you of not defending them :smallsmile:. I find them extreemely interesting)

Also top posts face roll (though you're also assuming that you know the mutation rate). I study(ied) evolution but never delved into the maths... cause I don't like maths...

Someone wanna suggest a new discussion topic on evolution? We could even have a 'book club' of sorts...

[faceroll]

Re: endosymbioses and the end of bacteria

I am unsure how much us multicellular creatures depend on bacteria to dissolve ALL our food, and how much of it is simply a competitive advantage over not having endosymbionts. And wouldn't taking antibiotics be a death sentence if losing our bacteria spelled our demise?

Both Isoptera and Blattaria rely on protozoans with an endosymbiotic archeae to produce cellulase. So at least the cockroaches and termites would survive. :smallbiggrin:


He said "I imagine fungi, archeae, and protista would rapidly fill in the niche left by the disappearance of bacteria. Some megafauna would go extinct, certainly". Probably every animal on this planet (can't guarantee that's the case, but I expect it would be) has a massive flora of bacteria in our systems. We rely on these to help us digest our food, among other things. If we don't have them, we starve to death. That's not just humans, and not just "some megafauna". That's everything. And it's not including all the plants that, as mentioned, rely on bacteria for nitrogen fixation - pretty much the same deal as with humans.
Could fungi, archeae and protista fill the niche? Possibly, if given enough time. But unless there's already members of these organisms doing that stuff already, they're highly unlikely to do it in time.
Will they themselves be able to survive the disappearance of bacteria? Possibly. I haven't done that much reading on them. I would expect, though, that at the very least they rely on bacteria in some of the same ways as other living things and it would still have a huge impact on them.

So yeah. A long, long way from merely "some of the megafauna".

I think you dramatically underestimate the resiliency of life. Multicellular life has survived mass extinctions that killed 90% of all life, yet here we are.

You also overestimate the importance of gut flora- Although many animals including humans can live without gut flora (http://www.sciencedirect.com/science/article/pii/S0165247805000052).

While bacteria lets us get nutrients from novel sources, another major advantage is preventing pathogenic bacteria from invading. However, without any bacteria around, potential parasite risk will be much lower. Granted, with increased stress from low diets and increased fungal parasite loads, we can expect to see big fitness drops, there will also be enormous selection pressure on organisms that develop new symbioses.

Basically, expect to see the sort of adaptive radiations that occur after a comet slams into the earth and drives the dinosaurs extinct.


I think faceroll just won this thread.

:smallredface:

[Brother Oni]

Someone wanna suggest a new discussion topic on evolution? We could even have a 'book club' of sorts...

Wouldn't discussing evolution be too much of a hot topic for these boards?

I would be all for it as I understand genetics and evolution from a molecular biology view, rather than the more specialised field that faceroll obviously does.


Re: endosymbioses and the end of bacteria

I am unsure how much us multicellular creatures depend on bacteria to dissolve ALL our food, and how much of it is simply a competitive advantage over not having endosymbionts. And wouldn't taking antibiotics be a death sentence if losing our bacteria spelled our demise?


While losing all your gut flora isn't a death sentence, it is extremely unpleasant as anybody who's been on strong antibiotics will testify.

In addition, these antibiotics don't eliminate all gut flora, just substantial numbers - it's technically unknown what would happen if all gut flora was eradicated in a person (in the few cases that it has, they've usually died from other effects of the event that caused the eradication).

Simple survival is a far cry from flourishing, although I'm fairly sure at our level of technology, supplements can be developed to account for the sudden loss in nutrient update by the disappearing bacteria.

Aside from infection risks, presumably loss of all gut flora would mean nearly all vitamins are upgraded to the 'essential category' that must be derived from the diet?



While bacteria lets us get nutrients from novel sources, another major advantage is preventing pathogenic bacteria from invading. However, without any bacteria around, potential parasite risk will be much lower. Granted, with increased stress from low diets and increased fungal parasite loads, we can expect to see big fitness drops, there will also be enormous selection pressure on organisms that develop new symbioses.


Don't you mean greater parasite risk as the more pathogenic critters like protozoans now have free reign of the gut?



Basically, expect to see the sort of adaptive radiations that occur after a comet slams into the earth and drives the dinosaurs extinct.

I agree with this, but I'm not sure that homo sapiens will be one of those species to reap the fruits of the adaptations, even with our technology to help compensate.

[faceroll]

While losing all your gut flora isn't a death sentence, it is extremely unpleasant as anybody who's been on strong antibiotics will testify.

In addition, these antibiotics don't eliminate all gut flora, just substantial numbers - it's technically unknown what would happen if all gut flora was eradicated in a person (in the few cases that it has, they've usually died from other effects of the event that caused the eradication).

We've got some archeae in there. Bet somewhere, some of them would do something useful, and things would be ok.


Simple survival is a far cry from flourishing, although I'm fairly sure at our level of technology, supplements can be developed to account for the sudden loss in nutrient update by the disappearing bacteria.

I'm just saying, it's certainly possible for an organism to lose its endosymbiont load and still survive. And that's all it takes- survival. Conspecifics that all face the same loss of fitness won't really get to outcompete each other, either.


Don't you mean greater parasite risk as the more pathogenic critters like protozoans now have free reign of the gut?

No; I meant the loss of pathogenic bacteria. I imagine there's quite a bit of opportunistic stuff out there that can't do anything because the competition is too fierce.


I agree with this, but I'm not sure that homo sapiens will be one of those species to reap the fruits of the adaptations.

I actually think humans would be one of the species that would be able to survive because we're so goddamn smart. Just being able to cook our food gives us a huge advantage, but coupled with burning stuff to stay warm and wearing furs and using technology? We're super efficient at minimizing the amount of food calories we use to stay alive by burning stuff or killing it and eating it with a sharp stick instead of trying to wrestle it to death.

[Asta Kask]

However, bacteria-free animals* have been raised in sterile environment. They have a number of gastro-intestinal abnormalities but they survive.

*cavies and rodents mostly

[Rising Phoenix]

Wouldn't discussing evolution be too much of a hot topic for these boards?

I would be all for it as I understand genetics and evolution from a molecular biology view, rather than the more specialised field that faceroll obviously does.


If it's kept a purely scientific discussion, then I don't see a problem with it. Of course the mods have last call on it though.

Returning to the subject of surviving in a suddenly bacteria free biosphere I think that even if we did survive there would definately be an ecosystem collapse resulting in world food shortages, resulting in the end of society as we know it...

[Asta Kask]

Oh, yes. The whole ecosystem would crash and burn. It's just that you could maybe raise a human entirely bacterium-free. In fact, isn't that what you do with the children are seriously immuno-compromised?

Must look into that some day.

[DeadManSleeping]

Correct me if I'm wrong, but don't we need microbes to break down waste and dead life forms to return nutrients to forms consumable by most plants? I never quite understood that part of "the circle of life", but it's something I'd worry about.

[Eldan]

Fungi can do most of that.

[Serpentine]

But to what extent do the fungi employ bacteria? I don't know, but it could well be at least "somewhat"/

[Juggling Goth]

I first really came across that definition when looking at plant speciation, and believe you me, the interbreeding definition is damn near useless when it comes to plant species.


I found this out working with parrots. We've got a pair of two different species of macaw currently sitting on their eggs, and apparently their offspring would be a fertile Harlequin macaw. Which surprised the hell out of me, because until then I'd taken the "produces fertile offspring" species definition as fact.

I'm oddly relieved that the sulphur-crested cockatoo/Amazon parrot pair are highly unlikely to make a baby. I think that would be a bit too weird.

Gotta love animals that pick their mates purely on terms of personal attraction, and ignore such trivial matters as sex and species.

[Asta Kask]

There's something called Sexual Imprinting as well. Konrad Lorenz's geese were imprinted on his boots, which led to some disappointment later in life. And he tells the story of a peacock who was born in the turtle wing due to unforeseen circumstances. From early on, he would steadfastly ignore the young peahens who tried to attract his atttention, in favor of displaying his mighty tail only to passing turtles.

[Juggling Goth]

Correct me if I'm wrong, but don't we need microbes to break down waste and dead life forms to return nutrients to forms consumable by most plants? I never quite understood that part of "the circle of life", but it's something I'd worry about.

Women also need bacteria for not getting thrush (yeast infections). There's a delicate ecosystem going on. Hence why thrush often follows use of antibiotics or antibacterial soap.

[faceroll]

There's something called Sexual Imprinting as well. Konrad Lorenz's geese were imprinted on his boots, which led to some disappointment later in life. And he tells the story of a peacock who was born in the turtle wing due to unforeseen circumstances. From early on, he would steadfastly ignore the young peahens who tried to attract his atttention, in favor of displaying his mighty tail only to passing turtles.

There was an attempt to rear whooping cranes that could survive in the while (knew how to migrate, etc.), so conservationists had them raised by sandhill cranes. Unfortunately, when the whooping cranes reached sexual maturity, they refused to mate with each other and would only court the sandhill cranes. Ooops.


But to what extent do the fungi employ bacteria? I don't know, but it could well be at least "somewhat"/

I am sure there are some fungi that have symbiotic bacteria. There's some evidence that snow algae form symbiotic communities with a bacteria (nitrogen fixation) and fungus (long hyphae for acquiring phosphates). It's currently an uninvestigated hypothesis, though. I don't know much about microbes, just that they've evolved to exploit just about every possible source of carbon and energy.

[Rising Phoenix]

I found this out working with parrots. We've got a pair of two different species of macaw currently sitting on their eggs, and apparently their offspring would be a fertile Harlequin macaw. Which surprised the hell out of me, because until then I'd taken the "produces fertile offspring" species definition as fact.

I'm oddly relieved that the sulphur-crested cockatoo/Amazon parrot pair are highly unlikely to make a baby. I think that would be a bit too weird.

Gotta love animals that pick their mates purely on terms of personal attraction, and ignore such trivial matters as sex and species.

A cockatoo and an Amazon are unlikely to produced offspring... but if they do... please let us know... Birds seem to have an easier time crossbreeding then other vertebrates.

[Eldan]

I am sure there are some fungi that have symbiotic bacteria. There's some evidence that snow algae form symbiotic communities with a bacteria (nitrogen fixation) and fungus (long hyphae for acquiring phosphates). It's currently an uninvestigated hypothesis, though. I don't know much about microbes, just that they've evolved to exploit just about every possible source of carbon and energy.

Given that Lichen are fungi with symbiotic algae, often Cyanobacteria... yes, I'd say they often use bacteria.

[Juggling Goth]

A cockatoo and an Amazon are unlikely to produced offspring... but if they do... please let us know... Birds seem to have an easier time crossbreeding then other vertebrates.

It would be awesome, wouldn't it? And incredibly wrong. Unfortunately, the cockatoo has laid eggs every year for a while now and they never hatch. It's oddly cute seeing them feed and groom each other, though. He's half her size! Sometimes it's like "where's he gone?" and then he'll emerge from under her feathers where she accidentally sat on him.


There's something called Sexual Imprinting as well. Konrad Lorenz's geese were imprinted on his boots, which led to some disappointment later in life. And he tells the story of a peacock who was born in the turtle wing due to unforeseen circumstances. From early on, he would steadfastly ignore the young peahens who tried to attract his atttention, in favor of displaying his mighty tail only to passing turtles.

We don't know the history of most of the parrots that well. They tend to have been seized by the RSPCA (that macaw had a very colourful vocabulary, and one hell of a temper) or they're pets that either outlived their owners or turned out to be a lot higher maintenance than the owners expected. So it's hard to say why they turned out the way they did. The female Amazon seems to have pair-bonded with me, which is a bit odd. I thought she was a really sweet-natured bird, but no: apparently she bites all the other women. It's just me that gets the nibbling and eyebrow-grooming treatment. Apparently that's semi-common: you get accounts of parrots regurgitating food for their owners and attacking their owners' spouses. I try to encourage other people to interact with her and give her some attention. She needs a bit more love, since Amazons are really social but the boy Amazon is just obsessed with the cockatoo.

[Rising Phoenix]

It would be awesome, wouldn't it? And incredibly wrong. Unfortunately, the cockatoo has laid eggs every year for a while now and they never hatch. It's oddly cute seeing them feed and groom each other, though. He's half her size! Sometimes it's like "where's he gone?" and then he'll emerge from under her feathers where she accidentally sat on him.



We don't know the history of most of the parrots that well. They tend to have been seized by the RSPCA (that macaw had a very colourful vocabulary, and one hell of a temper) or they're pets that either outlived their owners or turned out to be a lot higher maintenance than the owners expected. So it's hard to say why they turned out the way they did. The female Amazon seems to have pair-bonded with me, which is a bit odd. I thought she was a really sweet-natured bird, but no: apparently she bites all the other women. It's just me that gets the nibbling and eyebrow-grooming treatment. Apparently that's semi-common: you get accounts of parrots regurgitating food for their owners and attacking their owners' spouses. I try to encourage other people to interact with her and give her some attention. She needs a bit more love, since Amazons are really social but the boy Amazon is just obsessed with the cockatoo.

Is the cocky a Sulphur-crest? They're about the size of your average Amazon if not bigger than them.

Parrots really should come with a warning sign in pet stores "Don't buy me unless you will be able to look after me for the rest of your life. I may even outlive you."

Back to your interesting little flock, parrots, as you know, are highly intelligent and social birds and you really can't breed them unless they like their partner... It's a common woe for a breeder to have a strapping pair of macaws/cockatoos and they simply won't breed cause they don't like each other.

Also, I would recommend you closely related species, like your macaws, seperate. Hybridizing is not good for maintaining a species purity in captivity, especially considering that captive parrot populations may be used for reintroduction programs

This is a serious problem currently with Baer's Pochards and Lesser White-fronted Geese as, even though they are common in captivity gnetic tests reveal that they're ancestors were hybrids thus making these birds unsuitable for release.

Keep up the good work though! :smallsmile:

R.P.

[faceroll]

Given that Lichen are fungi with symbiotic algae, often Cyanobacteria... yes, I'd say they often use bacteria.

Oooh, cyanobacteria. Bye bye oxygen....

[Juggling Goth]

Is the cocky a Sulphur-crest? They're about the size of your average Amazon if not bigger than them.

She's a greater sulphur-crested; he's an orange-winged Amazon. She's about twice as big as him. And he has serious small-man syndrome; he keeps trying to pick fights with the green-winged macaw (ie, the second-biggest parrot on the planet, and this one does not share her species' characteristic gentleness) in the next aviary. Everyone thought the male cockatoos were bullying him; I'm not sure it wasn't the other way around.


Back to your interesting little flock, parrots, as you know, are highly intelligent and social birds and you really can't breed them unless they like their partner... It's a common woe for a breeder to have a strapping pair of macaws/cockatoos and they simply won't breed cause they don't like each other.

Also, I would recommend you closely related species, like your macaws, seperate. Hybridizing is not good for maintaining a species purity in captivity, especially considering that captive parrot populations may be used for reintroduction programs

Yeah. It wasn't intentional. It just sort of happened. Both the male macaw and the cockatoo had access to members of their own species, but the "you're biologically compatible but I hate you" thing kicked in and they picked other mates.

[Eldan]

Oooh, cyanobacteria. Bye bye oxygen....

Ooh. I didn't even think of the oxygen. You're right.

[Serpentine]

Oh yeah. Yup.
Which brings us back to my original point... :smalltongue:

[faceroll]

Oh yeah. Yup.
Which brings us back to my original point... :smalltongue:

We still got other kinds of algae. I wonder how long it would take for that niche to get filled up. Something like 70% of O2 comes from the ocean, but I don't know how much of that comes from algae and how much from bacteria.