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Abstract Detail

Molecular Ecology and Evolution

Cortes Vera , Andres Javier [1], Liu, Xiaodong [1], Lexer, Christian [2], Sedlacek, Janosch [3], Wheeler, Julia A. [4], Karrenberg, Sophie [5].

Ecological and Genetic Causes of Female-Biased Sex Ratios in Dwarf Willows.

A 1:1 sex ratio is predicted as an evolutionarily stable strategy. Any deviations from that ratio are likely due to ecological selection, gametic selection or genetic determination. Willows are widespread shrubs and trees that present a strongly biased ratio usually towards females (~70:30); their sex determination mechanism is unknown. We explored the causes of female predominance in a common alpine dwarf willow (Salix herbacea). During three years, we sexed and recorded the performance of 227 females and 65 males growing naturally in three elevational transects in the Swiss Alps. Temperature, altitude, microhabitat and biotic stress did not predict the female-biased sex ratio and females did not grow more nor were more vigorous than males. A subset of 127 females and 38 males were genotyped with 99,497 genotyping-by-sequencing-derived SNP markers anchored in a female S. purpurea reference genome. 24 genetic markers distributed in 11 regions and 10 chromosomes predicted sex with a specificity of 88%. Some of those regions blasted against expressed sequences in poplar male catkins. Interestingly, the expected female/male ratio (0.76) persisted after simulating an offspring with the allele frequencies of the sampled populations. This suggests that the sex determination mechanism in S. herbacea likely involves several loci, each with small effects. Together, these results indicate that the multi-loci sex determination system may explain sex bias, rather than unmeasured ecological differences between sexes, for instance at early life history stages.

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Related Links:

1 - Uppsala University, Ecology and Genetics, Norbyvagen 18D, Uppsala, 75236, Sweden
2 - University of Fribourg, Department of Biology, Chemin du Musée 10, Fribourg, 1700, Switzerland
3 - University of Konstanz, Department of Biology, Universitätsstrasse 10, Konstanz, 78457, Germany
4 - WSL Inst. for Snow and Avalanche Research SLF, Flüelastrasse 11, Davos, 7260, Switzerland
5 - Uppsala University, Department of Ecology and Genetics, Norbyvagen 18D, Uppsala, 75236, Sweden

alpine shrubs
ecological selection
gametic selection
genetic determination
GBS-derived SNP-markers
machine learning
sex ratio.

Presentation Type: Oral Paper:Papers for Topics
Session: 11
Location: Firs North/Boise Centre
Date: Monday, July 28th, 2014
Time: 2:00 PM
Number: 11003
Abstract ID:345
Candidate for Awards:Margaret Menzel Award

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