Originally posted by Boris Godunov
But you haven't given a definition of speciation you find to be acceptable. Please provide.
But you haven't given a definition of speciation you find to be acceptable. Please provide.
The inability to produce offspring is a good sign that two organisms are seperate species but (aside from the trivial problems with testing for offspring) IMO that definition is limited by the fact that a single mutation may cause the infertility. In a bacteria, for example, a single mutation does not define a new species (and in fact the whole definition of species vs mutants is vague even for bacteria) so how can we presume to use inability to produce offspring as a basis for speciation without knowing the genetic basis for the difference.
If I'm backed into a corner I'd like to see evidence of:
non-mating
very closely related based on substantial analysis of DNA sequence
morphological similarity
clear evidence of isolation (non-anecdotal)
As for the examples, I don't see why you'd say they are "anecdotal." Do you think people are making them up?
Creationists are also notoriously slippery when trying to pin down their definition of "species." Why isnt' the scientifically accepted consensus for things being different species acceptable? What drives your opinion of the their definition of species being problematic?
From UR's link
"There are a variety of different species concept currently in use by biologists. These include folk, biological, morphological, genetic, paleontological, evolutionary, phylogenetic and biosystematic definitions. "
And to go back a bit, why is the observed evolution of micro-organisms not adequate as proof that evolution occurs? As scientists are quick to point out, the only difference between "microevolution" and "macroevolution" is one of degree, not in its nature. Small evolutionary changes compoud to big ones, over time.
Yet again, we have to also qualify what science means by "observed." We observe a fossil record which clearly shows evolution of species over time and the change into different species (such as "transitional" forms). Why is this observational evidence invalid?
We can also "observe" evolution as told by our DNA. It is a veritable recorded history of evolution.
The notion that macroevolution isn't proven because we might not have seen a universally agreed upon case of speciation at a level high enough to suit some nitpickers is silly, considering the abundant amount of evidence there is.
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