Modelling the establishment and spread of autotetraploid plants in a spatially heterogeneous environment

The establishment and spread of autotetraploids from an original diploid population in a heterogeneous environment were studied using a stochastic simulation model. Specifically, we investigated the effects of heterogeneous habitats and nonrandom pollen/seed dispersal on the critical value (?) of unreduced 2n gamete production necessary for the establishment of autotetraploids as predicted by deterministic models. Introduction of a heterogeneous environment with random pollen/seed dispersal had little effect on the ? value. In contrast, incorporating nonrandom pollen/seed dispersal into a homogeneous environment considerably reduced the ? value. Incorporating both heterogeneous habitats and nonrandom pollen/seed dispersal may lead either to an increase or to a decrease in the ? value compared to that with random dispersal, indicating that the two factors interact in a complex way.