Species vs Race?

[genovese]

What defines species is the fact that one species cannot reproduce with another species. A Bluejay cannot breed with an Eagle. They are genetically incompatible. Race is not the same as species. Race is just variation within a species, yet they can still breed offspring.

Agreed. But would birds of the same race use their acute vision to discriminate against any variations which might accelerate the process to lead on to another species?

[MrMistery]

The concept of a species in not so simple as you might think: how would you determine if 2 animals that lived in the Jurasic are the same species or not? How about 2 bacteria? How about two species of the genus Pipilo that only do not reproduce because a forest divides their habitats?

[genovese]

I agree that it is only clear-cut when a member of a defined species breeds and reproduces viable offsprings which can also breed. When we obtain hybrids between what we take to be different species it must mean that the speciation of either one is not yet fully completed. One would expect this to happen as slight mutations etc may not initially achieve a New Species.

Small organisms like bacteria where genetic material seems to pass quite easily between different bacteria must take even longer to change to another species (although this is counteracted by the rapidity of reproduction).

The point I am asking is do animals having good vision (like birds) who can detect small changes of form amongst themselves use these subtle changes in form to avoid mating with variations within the species. If so, this would be like geographic isolation and may accelerate the production of a greater number of species within the group of animals known as birds. ie Is form discrimination an accelerator to speciation?