Speciation involves the splitting of a single evolutionary lineage into two or more genetically independent lineages. Extinctions essentially happen over a long period of time but due to different human activities, extinction is becoming more and more frequent as compared to before. I was just wondering if it was possible for extinct species to once again speciate under favourable conditions through evolution
Dear Cherry
Theoretically, the species extinction occurs due to changes in the environment, so the new species which appear must be suitable for the new environment, and for your supposition when the environment change again to the past environment will change the genotype and appear new species may be similar but not identical to the extinct species.
Good Luck
Even if the environment were the same it would take some amazing luck. A collage of traits making up an organism doesn't have to be optimal, it just has to be better than others in terms of selection of the fittest. So I say, in all practicality, the answer is no.
No. Even if both species were 100% identical (i.e. same ecology, morphology, genetics) they would be different species. Each species has its own unique evolutionary history and originates in a speciation event. The "new" species would have originated in a different speciation event than the original species and would have a different evolutionary history.
Respeciation does occur in the wild (cichlids in Lake Malawi, for example) but consider the preconditions: you would need very much the same ancestral stock, the same conditions under which the previous species originated, and roughly the same contingent events. At the end of that process you might have some population of organisms that could in theory reproduce with the extinct species, if they were not extinct, and which had pretty much the same phenotype.
However, the likelihood of it happening is vanishingly small in the majority of conceivable cases. It is like saying that another version of you could, in principle, be born from closely related stock, but that clone would be different in many ways just from variations in the conditions under which it was raised compared to your maturation.
Martin Heiserman's answer is, I think (and I cannot believe I am saying this, speaking as a philosopher) overly philosophical, and relies on the identity of a species being its spatiotemporal contingent boundaries. I think most of us would have no problem saying those cichlid fishes are the same species as the one they can now, after speciation from a shared ancestor, interbreed with. A comparable argument is that the species name refers only to the population that arose from the first speciation, but while that might be technically true, it is equivalent to saying with Hennig that a species only exists between speciation events: it is a claim about the reference of taxonomic identities, not biological facts.
But I wouldn't hold my breath...
As John S Wilkins has already said, some cases of parallel speciation have been proposed in the literature and they are considered exceptional cases. Parallel speciation might be more frequent in the case of hybrid speciation (see Gross and Riesberg 2005). Still, don't expect to see live dodos any time soon.
Article The Ecological Genetics of Homoploid Hybrid Speciation
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