Abstract Detail

Population Genetics

Madson, Hannah [1], Caruso, Christina [2], Case, Andrea [1].

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.

Broader Impacts:

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

Keywords:
gene flow
genetic drift
gynodioecy
breeding system
Lobelia siphilitica.

Presentation Type: Oral Paper:Papers for Topics
Session: 28
Location: Delaware B/Hyatt
Date: Tuesday, July 10th, 2012
Time: 9:30 AM
Number: 28005
Abstract ID:811