WHERE ARE THE ANCESTOR SPECIES? (not particularly a birding question)

To: "Birding Aus" <>
Subject: WHERE ARE THE ANCESTOR SPECIES? (not particularly a birding question)
From: "Ralph Reid" <>
Date: Mon, 1 Nov 2010 14:55:20 +1100
Greetings all,

A short poser.

Given that all existing species (particularly those of the animal kingdom) are 
descended from a somewhat similar ancestor species, but divergent enough to be 
considered a separate species; and given that the general definition of a 
species is that a species of animal does not/cannot interbreed with another 
separate species (although, admittedly, there are many exceptions - tigers and 
lions interbreed, horses and donkeys interbreed as just two examples, but with 
sterile offspring).  Then, by this definition a species must generally have 
evolved/changed its characte ristics to the extent that members of this species 
now cannot inter-breed with members of the ancestor species.

Does this imply that the descendant species (generally being more fitted to 
exploit a particular environmental niche that the ancestor species) ultimately 
replace the ancestor species, driving that ancestor species into extinction?

Or do the two species continue to co-exist side-by-side, possibly each 
exploiting somewhat different environmental niches, due to sympatric speciation?

If one considers the genus homo, for example, why are all the previous variants 
of hominins not continuing to live today alongside homo sapiens?

So the question arises - are there any known, proven instances of an ancestor 
species continuing existing with a descendant species?  Are there any known 
ornithological examples of this?


Ralph Reid

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