Abstract Detail

Reproductive biology

Christopher, Dorothy [1], Chang, Shu-Mei [1].

Geographic variation in population sex ratio in the gynodioecious Geranium maculatum.

While most plant species produce bisexual flowers, several exceptions to this norm have evolved across the angiosperms. Gynodioecy, in which female and hermaphroditic individuals co-occur in a species, has evolved independently multiple times. There is tremendous variation in the sex ratio of gynodioecious populations. In Geranium maculatum, female frequency ranges from 0-50%. The goal of this study is to identify the mechanisms by which females are introduced into populations and then to make inferences regarding factors that are likely to be important in maintaining females. There are two possible scenarios by which females can invade a hermaphroditic population. In the first, females may arise independently in each population due to endogenous male sterility mutations. In this case, we expect to see dimorphic populations isolated from each other. In the second scenario, male sterility may be introduced to a population via a migration event from another dimorphic population. Here we expect to see high levels of gene flow between populations. We used a population genetic approach to differentiate between these two scenarios by examining the patterns of genetic connectivity between dimorphic and hermaphroditic populations. We located 28 populations from across the range of the species in the eastern US. We sampled 24 individuals per population and genotyped them at microsatellite loci. We found high levels of gene flow between all populations, which points to the role of migration of male sterility alleles in maintaining gynodioecy in G. maculatum.

1 - University of Georgia, Plant Biology, 120 Carlton St, 2502 Miller Plant Sciences, Athens, GA, 30602, USA

Keywords:
sexual systems
gynodioecy
population genetics.

Presentation Type: Oral Paper:Papers for Topics
Session: 2
Location: Salon 1/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 8:30 AM
Number: 2003
Abstract ID:1183
Candidate for Awards:None