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Is geographic isolation a sufficient condition for two organisms to be considered separate species?

Anonymous Sat 16 May 10:42:18 2020 No.11678488 View Reply Original Report

Quoted By:

Straight forward question. No other reproductive barriers involved... ie if the organisms were to stop being geographically isolated and they met they'd likely plop out fertile offspring.

I'm really looking for mainstream definitions too preferably.

Anonymous

Anonymous Sat 16 May 2020 11:15:35 No.11678514 Report

Quoted By: >>11678524

Not actually a straight forward at all, it entirely depends on your definition of a species. They could be considered populations of the same species or subspecies, given time they would likely develop into distinct populations at which point you could define them as separate species, or still define them as subspecies

Anonymous

Anonymous Sat 16 May 2020 11:29:11 No.11678524 Report

Quoted By: >>11678534

>>11678514
So the answer is "your choice" ..it either does or does not constitute a sufficient condition to identify separate species?

I feel like there's more to it than that since Neanderthals are "almost" universally considered a separate species than Homo Sapiens (small minority says they're a subspecies) yet the only reproductive barrier was geography.
How can there be such a consensus if it's not a straight forward question?

Anonymous

Anonymous Sat 16 May 2020 11:38:08 No.11678534 Report

Quoted By: >>11678538 >>11678582

>>11678524
The best universal definition I've come across is "separately evolving metapopulation lineage" in which case your example would be the same species as it's a metapopulation lineage, but would be expected to develop into another species given enough time separated.

In the case of neanderthals this happened enough for them to be considered separate species by most definitions, but they still retained the ability to interbreed with homo sapiens, at least to some extent. This is similar to how wolves and dogs can produce fertile offspring yet are considered separate species.

Anonymous

Anonymous Sat 16 May 2020 11:44:51 No.11678538 Report

Quoted By: >>11678544 >>11678582 >>11678617

>>11678534
>In the case of neanderthals this happened enough for them to be considered separate species by most definitions, but they still retained the ability to interbreed with homo sapiens,
a lot of the offspring must have been non-viable though since

1. most of neanderthal dna is in non-coding regions
2. there are no neanderthal Y chromosome which suggest male 'thal + female human was infertile/impossible
3. there isn't even neanderthal mitochondrial DNA in modern humans

Anonymous

Anonymous Sat 16 May 2020 11:47:04 No.11678544 Report

Quoted By:

>>11678538
that's why I ended the sentence with 'at least to some extent'

Anonymous

Anonymous Sat 16 May 2020 11:54:30 No.11678549 Report

Quoted By:

if you want a detailed explanation of the species problem read this. It comes down to the concept of a species just being a construct that we use to more easily talk about populations of similar individuals, rather than being some fundamental part of nature.
https://www.pnas.org/content/102/suppl_1/6600

Anonymous

Anonymous Sat 16 May 2020 12:15:47 No.11678582 Report

Quoted By: >>11678591

>>11678534
>This is similar to how wolves and dogs can produce fertile offspring yet are considered separate species.
The most recent common ancestor between H Sapiens and Neanderthals is presumed at ~800kya but dogs and wolves split ~40kya. It still seems a little arbitrary to me. Especially since the out of africa theory has human groups splitting up to 270kya and thus would form their own "separately evolving metapopulation lineages." Meaning different modern humans around the world could be called outright separate species (not merely subspecies) from each other if we used the same standard.

>>11678538
>2. there are no neanderthal Y chromosome which suggest male 'thal + female human was infertile/impossible
Or the superior human tribal group did not allow rival neanderthal males to mate with their females...but not vice versa.

Anonymous

Anonymous Sat 16 May 2020 12:20:32 No.11678591 Report

Quoted By:

>>11678582
Maybe lions and tigers are a better comparison, they usually produce infertile offspring, but occasionally the offspring is fertile

Anonymous

Anonymous Sat 16 May 2020 12:29:49 No.11678617 Report

Quoted By:

>>11678538
>2. there are no neanderthal Y chromosome which suggest male 'thal + female human was infertile/impossible
Or maybe just because homo sapiens killed and enslaved those neanderthal tribes, the only sex could happen with male homo sapiens fucking a neanderthal female.

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