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Abstract Detail



Bryological and Lichenological Section/ABLS

Johnson, Matthew G [1], Shaw, Jonathan [2].

The relationship between mating patterns, sexual condition, and microhabitat preference in Sphagnum.

Bryophytes, by nature of their biology and life cycle, provide unique windows into mating systems that are difficult or impossible to study in flowering plants or animals. In particular, combined sexes in the gametophyte stage (monoicous) allows "true" self-fertilization and the production of completely homozygous sporophytes in a single round of mating. This intragametophytic selfing should have a large impact on mating patterns and genetic diversity, compared to species with separate sexes. Population genetics theory also predicts reduced inbreeding depression for species with combined sexes, due to frequent purging of deleterious alleles. In peatmosses (Sphagnum), most species have gametophytes with separate sexes, while about 15% have bisexual gametophytes. Microhabitat may also play a role in bryophyte mating patterns, as fertilization depends on water availability for swimming sperm. In Sphagnum, species tend to have very narrow microhabitat preferences along a water availability gradient (hummock vs. hollow), and we predict fewer opportunities for outcrossing in hummock species, compared to aquatic species. We surveyed gametophytes and sporophytes 18 populations across 14 species using microsatellites, and characterized each population in genetic diversity, levels of inbreeding depression, and multiple paternity. We find 1) that mating patterns and genetic diversity are connected in species with separate sexes, but not species with combined sexes; 2) there is an interaction effect between sexual condition and microhabitat preference (water availability); and 3) inbreeding depression is not common in Sphagnum populations.

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1 - Duke University, Biology, Box 90338, Durham, NC, 27705, USA
2 - 130 Science Drive, Box 90338, Durham, NC, 27708, USA

Keywords:
Sphagnum
inbreeding depression
mixed mating systems
selfing rate.

Presentation Type: Oral Paper:Papers for Sections
Session: 23
Location: Ascot/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 9:00 AM
Number: 23001
Abstract ID:638
Candidate for Awards:None


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