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20 thoughts on “Allopatric and sympatric speciation | Biology | Khan Academy

  1. In terms of the two types of squirrels, could the difference in geography from the two sides of the canyon really be sufficient in diversifying the two's genes to the point where they were no longer compatible in producing any fertile offspring? The idea seems cloudy to me on this one, on how life on either side of the canyon could be drastically different.

  2. +Khan Academy So how do some modern peoples' genomes contain up to 3% Neanderthal DNA? Wouldn't that have to mean that at some point a Homo sapiens and a Neanderthal would have mated to produce a fertile offspring, which was then able to further mate with other H. sapiens? If so, doesn't that question the interbreeding definition of 'species'?

  3. Can any one tell me the difference between reproductive isolation in sympatric speciation and allopatric speciation?

  4. Why is not a simple gene expression? Why is it evolution? If you can interbread the species it means that you are interbreading variations of the same species.

    You can still try to create new variations of dogs… It will still be dogs and not directional selection that is evolution in one direction. As we learn in school.

    Does this have any epigene involved in this?

  5. The explanation of the squirrels is not correct. They separated only about 10,000 years ago and the Grand Canyon (which started about six millions years ago) was already an insurmountable barrier by then. It is not like it suddenly appeared in the past few thousand years. More likely is that the original single population lived elsewhere upstream where it was possible to cross the river. The population moved southwards and now the canyon was a barrier that stopped gene flow and led to speciation. The Grand Canyon is a barrier, but the forming of the canyon is NOT what separated this population of squirrels.

  6. I was wondering do you really need a tetraploid to create a triploid or can it be just one plant with an error mixing with a haploid that can make a triploid

  7. i have to say i am disappointed that you didn't mention anything about how a tetraploid becomes a hexaploid.

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