The Biodiversity Consequences of Autopolyploidy

Whole genome duplication or autopolyploidy occurred repeatedly during the evolution of land plants and likely acts as a major driver of evolutionary change. When genome duplications first occur within species they potentially result in immediate reproductive isolation of autopolyploids within populations. If autopolyploid lineages are considered “good species,” they may be a source of hidden biodiversity.

Our project seeks to test whether shifts in ploidy are phylogenetically structured within a complex of cryptic moss species, the Physcomitrium pyriforme complex, which is widespread in North America and Europe. The complex harbors seven karyotypes worldwide and exhibits much morphological variation, as reflected by the 29 synonyms. These annual, bisexual and selfing mosses are easily grown, and genome doubling is readily induced in vitro from sporophytic tissue, enabling tests of reproductive isolation among wild and artificial autopolyploids.

Our project addresses four inter-related objectives:

1. Reconstruct the phylogenomic relationships of 400 populations of P. pyriforme complex using targeted sequencing of 800 low-copy nuclear genes.
2. Characterize the karyotype and genome size of 400 populations of the P. pyriforme-complex across Europe, and infer frequencies of ploidal shifts within a phylogenomic hypothesis.
3. Identify morphological signatures of artificial genome duplication and through comparison with wild populations test whether these erode through time
4. Complement these inferences with experiments testing for reproductive isolation among wild and artificial polyploids and thereby for the evolutionary significance of autopolyploidy.