A preliminary approach to the theory of geographical gene genealogy for plant genomes with three different modes of inheritance and its application.

This paper extends to hermaphrodite outcrossing plant populations the existing gene genealogy theories for a sample of genes randomly chosen from geographically discrete or continuously distributed populations. Three plant genomes (nuclear, chloroplast and mitochondrial DNA) with different modes of inheritance are considered separately due to the difference in migration rates. It is shown that on certain assumptions, the previous coalescence theories can be applied to plant by appropriate reparametrization of the effective population size and migration rate specific to each genome. One result is that estimation of the ratio of pollen to seed flow from a sample of n (n > or = 2) individual genes can be obtained in terms of the number of segregating sites between and within populations that are discretely distributed in space. Another result of theoretical interest is that in the discrete model of population structure, mean coalescent time is the shortest for the paternally inherited genes (cpDNA in conifers) and, given certain conditions, is the longest for the maternally inherited genes (cpDNA in angiosperms and mtDNA in conifers and angiosperms). However, these results are difficult to obtain in the model of population that is continuously distributed in space.