BIOL208 Lecture Notes - Lecture 8: Gradualism, Hybrid Zone, Sympatric Speciation
29 Mar 2018
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Sympatric speciation: speciation takes place in geographically overlapping populations; speciation without geographic separation. If individuals in the subgroup stop mating with individuals of the larger population, they may eventually become a new species. Sympatric speciation can occur if gene flow is reduced by factors including: Polyploidy: is the presence of extra chromosome sets due to accidents during cell division. It can produce new sympatric biological species within a single generation. It is more common in plants than animals (estimated. ~50% of plant species have at least one ancestral polyploidy event in their evolutionary history; many important crops are polyploids). Polyploids can only interbreed with individuals of the same ploidy so they are reproductively isolated from the parent species. Autopolyploid: an individual with more than two chromosome sets, derived from one species. Can arise spontaneous by genome doubling or by fusion of 2n gametes (failure of cell division during meiosis creates gametes with double the number of chromosomes)
