Blackwell Publishing

Hybrid speciation


Hybrid speciation is an example of sympatric speciation that can occur in plants.

Interspecies hybrids are usually sterile because the chromosome pairs, which consist of one chromosome from one species and another from the second species, do not segregate regularly at meiosis.

When a hybrid species evolves, sterility may be overcome by polyploidy: the chromosome numbers are doubled. Each chromosome pair at meiosis contains two chromosomes from one species, and regular segregation is restored. Polyploidization is encouraged by applying the chemical colchicine in the commercial production of new species, but it can also occur naturally at a low rate. In this case, a new hybrid species may evolve.

The polyploidy hybrids are interfertile among themselves, but reproductively isolated (by the mismatch in chromosome numbers) from the parental species; they are therefore well defined new species.

Many popular species of flower such as tulips (opposite) and orchids are created through artificial hybridization.

What are the difficulties in a new hybrid species forming?

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