Abstract Detail

Population Genetics/Genomics

Busch, Jeremiah [1], Bodbyl-Roels, Sarah [2], Tusuubira, Sharif [3], Kelly, John [3].

Pollinator loss causes rapid adaptive evolution of selfing and dramatically reduces genome-wide genetic variability .

Pollinator declines have accelerated in nature and the ability of plants to self-fertilize is often cited as a potential solution to this challenge.  We experimentally evolved large, replicate populations of Mimulus guttatus for nine generations in greenhouses with or without pollinating bees and studied DNA polymorphism in descendants.  Populations without bees adapted to produce more selfed seed yet exhibited striking reductions in DNA polymorphism (13-24% declines in nucleotide diversity) despite large population sizes.  Importantly, the genome-wide pattern of variation cannot be explained by a simple reduction in effective population size, but instead reflects the complicated interaction between selection, linkage, and inbreeding.  Simulations demonstrate that the spread of favored alleles at few loci depresses neutral variation genome-wide in large populations containing fully selfing lineages.  It also generates greater heterogeneity among chromosomes than expected with neutral evolution in small populations.  After applying outlier tests to detect loci under selection, two genome regions were found in populations with bees, yet no adaptive loci were otherwise mapped.  Large amounts of stochastic change in selfing populations simultaneously compromise evolutionary potential and undermine outlier tests for selection.  This occurs because genetic draft in highly selfing populations makes even the largest changes in allele frequency unremarkable. While the adaptive evolution of selfing may resolve the problem of pollinator loss, it nonetheless causes dramatic declines in evolutionary potential on a short time scale.

1 - Washington State University, School Of Biological Sciences, PO Box 644236, Pullman, WA, 99164, USA
2 - Colorado School of Mines, Trefny Innovative Instruction Center, 924 16th St., 211 Green Center, Golden, CO, 80401, USA
3 - University of Kansas, Dept. of Ecology and Evolutionary Biology, Haworth Hall, 1200 Sunnyside Ave., Lawrence, KS, 66045, USA

evolutionary potential
experimental evolution
genetic draft.

Presentation Type: Oral Paper
Number: PGG5006
Abstract ID:103
Candidate for Awards:None

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