Abstracts (first author)

Talk 

Testing evolutionary models for the maintenance of same-sex sexual behaviour

Author(s): Bailey NW, Hoskins JL, Ritchie MG

Summary:

The evolutionary maintenance of same-sex sexual behaviour (SSB) is an enduring mystery because of its apparent negative impact on reproductive fitness. Two influential genetic models of SSB were developed several years ago by Sergey Gavrilets and William Rice: SSB might be maintained by sexually antagonistic selection for fitness-increasing traits in the opposite sex, and/or it might result from overdominance if alleles enhancing its expression are maintained by a heterozygote advantage. These models make distinct predictions about the genetic architecture of SSB and its correlations with male and female fitness. We present results of an experiment to empirically test these predictions using the Drosophila Genome Reference Panel. We screened 50 highly-inbred, genome-sequenced D. melanogaster lines for male SSB and performed a series of crosses between high and low lines designed to discriminate the two hypotheses. There was substantial additive genetic variation for SSB, strong effects of the social environment, and evidence for G x E. We will discuss genetic variance components contributing to this behaviour, candidate loci found to be strongly associated with its expression, context-dependence of the influence of those loci, and effects of SSB on fitness of males and females. Taken together, the results enable us to statistically compare support for either hypothesis – sexual antagonism vs. overdominance – and provide an intriguing contrast with Drosophila knock-out studies that have found a wide assortment of genes that might contribute to variation in male SSB.



Abstracts (coauthor)

Rapid evolution in the wild: unravelling the genetic basis of a wing mutation in field crickets

Author(s): Pascoal, S, Cezard T, Eik-Nes A, Gharbi K, Majewska J, Payne E, Ritchie MG, Zuk M, Bailey NW

Summary:

The field cricket Teleogryllus oceanicus is a textbook example of rapid evolution in the wild, but little is known about the genetics of this intriguing system. In Hawaii, a mutant variety of silent male crickets has recently arisen and spread in several populations, apparently in response to pressure from an acoustically-orienting parasitoid. The mutation, flatwing, first appeared on the island of Kauai in 2003, but it has since appeared on the neighbouring island of Oahu. It segregates as a sex-linked, sex-limited Mendelian trait in both populations, and it feminizes male wings by erasing the specialized sound-producing structures of a normal wing. The degree of feminization, however, varies between islands. Does this represent convergent evolution, or has gene flow introduced the mutation(s) into a different genomic background, resulting in different phenotypic manifestations? To pinpoint where the mutation or mutations reside within the genome, and to help answer this question, we applied Bulked Segregant Analysis (BSA) using RAD-seq in two different populations with distinct flatwing phenotypes and abundances: Kauai (>95% of males are flatwing, with heavily feminized wings), and Oahu (ca. 50% of males are flatwing, with less strongly feminized wings). We have identified the first group of candidate SNP markers associated with the flatwing phenotypes in each population. Using these, we tested different evolutionary hypotheses that could explain why there is a difference in mutant wing morphology between the two populations. The results provide insight into how convergent phenotypes arise and evolve in real-time, in the wild.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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