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Abstract Detail



Population Genetics

Mcdaniel, Stuart [1], Norrell, Tatum [1], Jones, Kelly [1], Payton, Adam [1], Ponciano, Jose Miguel [1].

Genetic conflict over meiotic sex ratio in the moss Ceratodon purpureus.

Sex ratio variation is a common but unexplained phenomenon in natural populations of many species with chromosomal sex determination, including many mosses. Sex determination in dioecious mosses happens at the haploid (gametophyte) stage of the life cycle, immediately following meiosis. Sex ratio bias in moss populations can be caused by sexual dimorphism or sex specific mortality at meiosis or over the course of gametophyte maturation. If the bias is caused by meiotic events, unlike the sexual dimorphism and differential gametophyte mortality hypotheses, biased sex ratios result directly from spore death and thus should be evident at or before germination. To test this hypothesis we estimated the number of spores from 353 sporophytes from a population in Connecticut and estimated the sex ratio of each sporophyte using a PCR test. We then modeled the relationship between sex ratio and fitness using a novel statistical model that explicitly accounts for biological heterogeneity in spore production among sporophytes, germination among spores within a sporophyte, and in sex ratios among sporophytes. We found an overall male biased sex ratio and significant genetic variation for offspring sex ratio among sporophytes, unequivocally demonstrating that events early in spore development or germination are sufficient to generate the biased sex ratios found in natural populations of C. purpureus. Strikingly we also found evidence for a significant association between sex ratio and total spore production, pointing to a previously unexplored genetic correlation between meiotic sex ratio and resource allocation between maternal gametophytes and their nutritionally dependent offspring sporophytes. These results provide a foundation for further studies of genetic conflict using bryophyte model systems.

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1 - University of Florida, Biology Department, Gainesville, FL, 32611, USA

Keywords:
sex ratio
bryophyte
fitness
meiosis.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PPG003
Abstract ID:727
Candidate for Awards:None


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