Yes, good review you've given. I'm not sure when you took your evolution class but we discussed this debate when I took it as an undergrad back in '82 or so. Our professor at that time professed he suspected the concensus definition of species - i.e. groups which won't breed in the wild even if they genetically couldn't - may change as more knowledge of genetics accumulated.
Originally Posted by Fishguy2727
I have to give you by the common definition of hybrid such examples of various color/feather morphs of machaws interbreeding would be "hybrids" but I'd have to ponder by this definition what's the difference between 'species' and 'sub-species'? Among some invertebrates the only way to define species is to ascertain if two groups can produce viable male breeders (There has been recent research on Drosophila yielding new info as to the whys of male hybrid sterility http://academic.research.microsoft.c.../6448402.aspx). It is strange how male sterility is a common trait in hybrids across the spectrum of life though even among vertebrates sex isn't determined by the same pairing of XY and XX but the formation of the male gamate undergoes a homologous mitosis.
The debate in anthropology as to whether neandertals were a 'race' of H. sapiens or another species was somewhat settled through comparisons of neandertal DNA which found they had enough mutational differences to conclude any male offspring resulting from a cro-mag and neandertal union would be a sterile hybrid therefore making neandertals a separate species, designated H. neanderthalensis .
I'm kind of foggy on the hybridization leading to speciation hypotheses. Speciation is caused in good part by isolation of gene pools so any speciation forming from an interbreeding of two previously for a time non-breeding groups would still require a subsequent isolation of that 'hybrid' from either parent group.
But I digress....:-)
My original post was about how I used to have people argue with me that blood parrot cichlids were just inbred deformed creatures and how I knew they were in fact hybrids due to the sterile males.
I'm OK with hybrids, in fact hybrids can sometimes be hardier than either of their parent species, but I'm not so enthusiastic about inbreeding.
"In order to punish me for my contempt of authority the authorities have made me an authority myself" - Albert Einstein.