The factors that drive the evolution of specialized pollination systems are considered a central tenant of future research in the field of pollination ecology. We seek to bring further understanding to a poorly understood but taxonomically widespread specialized pollination system. Synchronous dichogamy, the synchronized temporal separation of sexual function, is found in Canella winterana, a woody tree species native to the West Indies and southern Florida. In this system all flowers within a plant bloom synchronously as functional females and after 24 hours they synchronously switch to functional males. In this way, pollen is dispersed away from the plant to other individuals in the environment. Theoretically, synchronous dichogamy should reduce the amount of self‐pollination in these plants, thus promoting the deposition of congeneric pollen via animal‐mediated pollen dispersal. However, there is little empirical evidence for synchronous dichogamy as a specialized pollination syndrome and little is known about how this affects the genetic structure of populations. The aim of this study is to bring further understanding to how this specialized pollination system promotes gene flow in populations of Canella by assessing the genetic structure of populations found in the Bahamas and southern Florida. Findings from this research will influence conservation of Canella in the United States, which is endangered in part of its natural range in the Florida.
Results/Conclusions
I have identified 15 polymorphic microsatellite loci for Canella using transcriptome data from the 1KB Project, an initiative to sequence the transcriptomes of 1000 different flowering plant species. These loci were amplified and sequenced in 200 individuals from 15 different populations of Canella in southern Florida and the Bahamas: 3 populations from state parks in the Florida Keys and 12 populations from Andros and Eleuthera in the Bahamas. Given the highly synchronized form of sexual expression found in these plants I predicted that pollen mediated gene flow would be highly directional, causing high levels of genetic admixture within and between populations of plants that are geographically related. The initial results of my population genetic analysis suggest that this is indeed the case. There are high levels of within population genetic variation, although there is little evidence for genetic admixture between populations. Likely this is the result of pollen-mediated gene flow via specific pollinator activity. Future directions will be aimed at characterizing propagule establishment to further characterize the population genetic comparisons between populations.