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Abstract Detail

Reproductive Processes

KARRON, JEFFREY DAVID [1], Mitchell, Randall [2], Whitehead, Michael [3].

Ecological and evolutionary mechanisms for among-population variation in plant mating systems.

Classical genetic models predict that disruptive selection on outcrossing rate will cause mixed-mating to be rare and transitory. To more fully characterize the extent of among-population variation in outcrossing, we surveyed all published microsatellite and allozyme studies reporting multilocus outcrossing rates (tm) for three or more natural populations of hermaphroditic Angiosperms. Our dataset includes tm values for 753 populations from 105 species. These taxa are distributed across 43 families and 80 genera. Many of the species in our survey exhibit substantial among-population variation in outcrossing rate. For 32 / 105 species the range between the lowest and highest tm was > 0.3. Nearly two-thirds of all species have at least one mixed-mating population. Given this marked variation among populations, there is a critical need for studies that explore how both ecological context and heritable differences in floral traits influence mating system phenotypes. For mating systems to evolve, there must be heritable variation for mating system traits within natural populations. However, nearly all studies estimate outcrossing rates for entire populations, rather than for individuals, due to violations of assumptions about the local pollen pool and statistical limitation of the maximum likelihood procedure. However, if there is sufficient genetic variation at marker loci to facilitate unambiguous paternity assignment to all sampled offspring, it is possible to quantify individual outcrossing rates, and to explore relationships between outcrossing rate, siring success, and pollen discounting. We are using this approach to characterize individual variation in outcrossing rates within and among populations of Mimulus ringens, a wetland perennial native to eastern North America. By clonally replicating genets and exposing them to different ecological contexts, we can explore how changes in the pollination environment influence the pattern of selection on the mating system. We are complementing these experimental studies with studies of natural populations that address whether rates of selfing and levels of inbreeding depression correlate with natural variation in ecological context and floral display.

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1 - University Of Wisconsin-Milwaukee, Department Of Biological Sciences, PO BOX 413, MILWAUKEE, WI, 53201, USA
2 - UNIVERSITY OF AKRON, Department Of Biology, Department Of Biology, AKRON, OH, 44325-3908, USA
3 - University of Melbourne, School of BioSciences, Melbourne, Victoria, Australia

outcrossing rate
selfing rate
mixed mating
mating system.

Presentation Type: Oral Paper
Session: 30, Reproductive Processes
Location: Fort Worth Ballroom 7/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 1:45 PM
Number: 30001
Abstract ID:26
Candidate for Awards:None

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