Does mate limitation in self-incompatible species promote the evolution of selfing? The case of Leavenworthia alabamica

Jeremiah W Busch; Simon Joly; Daniel J Schoen

doi:10.1111/j.1558-5646.2009.00925.x

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Does mate limitation in self-incompatible species promote the evolution of selfing? The case of Leavenworthia alabamica

Journal article

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Does mate limitation in self-incompatible species promote the evolution of selfing? The case of Leavenworthia alabamica

Jeremiah W Busch, Simon Joly and Daniel J Schoen

Evolution, Vol.64(6), pp.1657-1670

06/2010

DOI: https://doi.org/10.1111/j.1558-5646.2009.00925.x

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https://hdl.handle.net/2376/110932

PMID: 20015234

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Abstract

Biological Evolution

Brassicaceae - genetics

Genetic Variation

Gene Flow

Ecosystem

Population Density

Alleles

Inbreeding

Fruit - physiology

Alabama

Microsatellite Repeats

Genetic diversity at the S-locus controlling self-incompatibility (SI) is often high because of negative frequency-dependent selection. In species with highly patchy spatial distributions, genetic drift can overwhelm balancing selection and cause stochastic loss of S-alleles. Natural selection may favor the breakdown of SI in populations with few S-alleles because low S-allele diversity constrains the seed production of self-incompatible plants. We estimated S-allele diversity, effective population sizes, and migration rates in Leavenworthia alabamica, a self-incompatible mustard species restricted to discrete habitat patches in rocky glades. Patterns of polymorphism were investigated at the S-locus and 15 neutral microsatellites in three large and three small populations with 100-fold variation in glade size. Populations on larger glades maintained more S-alleles, but all populations were estimated to harbor at least 20 S-alleles, and mate availabilities typically exceeded 0.80, which is consistent with little mate limitation in nature. Estimates of the effective size (N(e)) in each population ranged from 600 to 1600, and estimated rates of migration (m) ranged from 3 x 10(-4) to nearly 1 x 10(-3). According to theoretical models, there is limited opportunity for genetic drift to reduce S-allele diversity in populations with these attributes. Although pollinators or resources limit seed production in small glades, limited S-allele diversity does not appear to be a factor promoting the incipient breakdown of SI in populations of this species that were studied.

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Title: Does mate limitation in self-incompatible species promote the evolution of selfing? The case of Leavenworthia alabamica
Creators: Jeremiah W Busch - School of Biological Sciences and Center for Reproductive Biology, Washington State University, PO Box 644236, Pullman, Washington 99164, USA. jwbusch@wsu.edu
Simon Joly
Daniel J Schoen
Publication Details: Evolution, Vol.64(6), pp.1657-1670
Academic Unit: Biological Sciences, School of
Publisher: United States
Identifiers: 99900547251601842
Language: English
Resource Type: Journal article