Abstracts (first author)
A population genetic model of allopolyploid speciation
Allotetraploid speciation, i.e. the generation of a hybrid tetraploid species from two diploid species, and the long-term evolution of tetraploid populations and species are important in plants. A population genetic model to infer population genetic parameters of tetraploid populations from data of the progenitor and descendent species is presented. The model links different time-scales: allopolyploid hybrid speciation is presumably rare and probably results in a population bottleneck, i.e., a founder event. Immediately after allopolyploid speciation, selection must be intense, as hybrids of early generations are usually relatively unfit but often evolve to out-compete their parental species and spread to occupy new ecological niches. Later, the accumulation of mutations may render one or the other homeologous copy of a gene dysfunctional and recombination or gene conversion may lead to mixing of two homeologous gene copies. These latter processes are relatively slow. In a first attempt, we develop a population genetic model to capture key parameters and apply this model to a data set of nuclear genes of two yarrow species, Achillea alpina-4x and A. wilsoniana-4x, that arose by allotetraploidization from the diploid progenitors, Achillea acuminata-2x and A. asiatica-2x.