Madson, Hannah , Caruso, Christina , Case, Andrea .
Do stochastic processes affect female distribution in a gynodioecious flowering plant?
Gynodioecy, a breeding system in which females and hermaphrodites coexist in a population, is useful for examining patterns of population differentiation in plants because sex ratio often varies across the species' range. This variation may reflect gene flow and/or genetic drift affecting the distribution of sex-determining alleles. Here, we use neutral markers (chloroplast sequences and nuclear microsatellites) to determine whether stochastic processes can explain why females of Lobelia siphilitica are common in the southern-central portion of the species range. We sampled 72 widely distributed populations, and found high levels of diversity at both markers: mean cp haplotype diversity was 0.248; 98.6% of populations were polymorphic at all three microsatellite loci, with an average of 15.44 alleles per population. Populations were highly differentiated (chloroplast Fst = 0.68; microsatellite Fst = 0.190), but did not vary consistently with population size, a proxy for the strength of drift. Population sex ratio and geographic location did explain a significant portion of the microsatellite, but not cp haplotype, variation. Weak isolation-by-distance suggests that gene flow does not necessarily contribute to spatial variation in sex ratio. We conclude that female distribution in L.siphilitica may be a reflection of population history or selective processes.
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1 - Kent State University, Box 5190, 256 Cunningham Hall, Kent, OH, 44242-0001, USA
2 - University Of Guelph, Department Of Integrative Biology, New Science Complex, 50 Stone Road East, GUELPH, ON, N1G 2W1, Canada
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 9:30 AM