« on: 21/09/2011 10:56:15 »
I watched a doco last night about evolution called Mutant Planet Africa. It focused onThe Grift Rift Vally where it was highlighted that the cichlids fish split into 500 species in a relatively short period (12,500 year old lake).
They described how this speedy evolution may have occurred. e.g where some female fish may have preferred a male fish that built sloping mounds on the lake floor and avoided other males that built flat mounds. The female then breeds with the sloping mounded males. In turn, the female's offspring is most likely to prefer sloping mounded males, and may never breed with the flat mounded males. The narrator explains that this situation can start a new cichlids species.
Now to my question. It seems to me that although the female fish has preference for sloping mounds, I don't see how that can lead to speciation. My logic is that even though she chooses/prefers sloping mounded males, she is still biologically able to breed with the flat mounded males and have offspring. When does this "choice" cross the line into creating a new species that is not able to breed with the old species?
Sorry for the rambling, and if i'm not making any sense! Thanks,