Phylogeny and Mating System Evolution of Tolpis (Asteraceae) in Macaronesia

Abstract

Tolpis (Asteraceae) is a flowering plant genus with a center of distribution in the Macaronesian archipelagos. The genus has gained considerable interest, most recently, for elucidating patterns of mating system evolution, hybrid speciation, and genetic breakdown of self-incompatibility. The evolutionary history of this genus has, notwithstanding, been difficult to reveal due to recent divergence within the genus and the lack of sufficient molecular variation afforded by traditional molecular markers (e.g. inter-simple sequence repeats, chloroplast DNA restriction sites, external and internal transcribed spacers). Here we present a robust inference of the evolutionary relationships of Tolpis within the Macaronesian archipelagos of the Azores, Canary Islands, and Madeira. This phylogenetic study reinforces the efficacy of multiplexed shotgun genotyping (MSG) in elucidating the evolutionary history of recently-diversified plant lineages with resolution and support from the population to inter-archipelago levels. Lastly, we used the same genotyping approach to determine the mating system in two populations of Tolpis from Graciosa island in the Azores, where self-compatibility mutations have either arisen or been introduced. We apply genomic data and Bayesian inference (BORICE) to determine outcrossing rates, inbreeding coefficients, siring patterns for these two populations.