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Speciation: Darwin's Mystery Of Mysteries

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Speciation was Darwin’s “mystery of mysteries”.

Speciation: the process of one species splitting into two or more species.

Microevolution is a change below the species level while macroevolution is a change above the species level.

Species: group of populations whose members can interbreed in nature and produce viable and fertile offspring, but do not produce viable and fertile offspring with members of other groups.

Reproductive isolation is required for the formation of new species.

Hybrids: offsprings that result because of interspecific mating

The two types of barriers that maintain reproductive isolation are prezygotic barriers and postzygotic barriers. Prezygotic barriers, before the zygote, block fertiilzation from …show more content…

The shells of two different species of snails in the genus Bradybaena spiral in different directions. Since their shells spiral in different directions, that means that the snails’ genital openings are not aligned, which prevent mating from occurring.

Gametic isolation

The sperm of one species may not be able to fertilize the eggs of a different species. (The sperm of one species may not be able to survive in the reproductive tract of a female in a different species OR biochemical mechanisms may prevent the sperm of the male from penetrating the membrane that surrounds the female from a different species’ eggs)
Sea urchins release their sperm and eggs into the water. When in the water, the sperm and eggs fuse to form zygotes However, it is very difficult for gametes from different species to fuse because of the proteins on the surface of both the sperm and egg bind together very poorly.

Postzygotic
Explanation
Example
Reproductive Barriers

Reduced hybrid viability
The genes of parent species that are different from each other may impair the way the hybrid develops and survives in its

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