Periodic Reporting for period 1 - OPSINEVOL (Evolution of opsin genes in guppies (Poecilia reticulata) relative to male colour: a window into the genetics of mate choice)
Okres sprawozdawczy: 2015-04-15 do 2017-04-14
The results of this work will provide a cohesive, integrative and multi-faceted understanding of the role of opsin variation in this model system of evolution by sexual selection, and will determine the role of opsins and the visual system in driving female mate preferences and male colour evolution. This project will help us understand the genetic underpinnings of key adaptive traits, linking genes to the phenotype and opening up new research agendas. The initial results of this work have been published in Science Advances (in press) and Nature Communications (8:14251 - doi:10.1038/ncomms14251).
RESULTS:
- Some of the opsin duplicates previously reported for guppies are not present in the genome and thus are the product of amplification artifacts in previous studies.
- I found no evidence of sequence changes that could affect the opsin sensitivity of guppies from different populations.
2. Investigate opsin regulatory evolution across populations: Until recently, studies on animal perception focused on variation in opsin coding sequence and spectral sensitivity, and how changes in these aspects of the visual system could represent adaptations to different light environments. I relied on Nanostring technology to design opsin expression panels in order to measure opsin expression levels in multiple individuals.
RESULTS:
- I found no evidence for differences in opsin expression associated with difference in female preference for colour.
- I found no evidence of sexual dimorphism in opsin gene expression in guppies.
A manuscript with the results of (1) and (2) is currently under preparation.
3. Neurogenomics of female preference. We set up behavioral experiments to quantify differences in female preference for colourful males in various guppy laboratory lines. Based on the results of this initial test, we then set up to investigate the genes involved in mating decisions in guppy females that prefer colourful males and females without such a preference. To do this we designed an experiment where we exposed females to attractive/colourful males or to unattractive/dull males and used RNAseq to measure gene expression in the visual components of the brain (telencephalon and optic tectum) after they evaluate each type of male. We performed this experiment in guppy lines previously shown to differ in the strength of their preference for colorful males to further understand the mechanisms behind variation in female preferences.
RESULTS:
- We found that different laboratory have dramatic differences in female preferences: while some line have a strong and clear preference for colourful males, others do not show evidence of preferring colourful or dull males.
The manuscript “Female brain size affects the assessment of male attractiveness during mate choice"" reporting the results for these initial tests is currently in press in Science Advances.
- We are currently in the process of analyzing the results for the complete experiment. So far we found 12 genes are differentially expressed in the telencephalon between females exposed to attractive and non-attractive males, and 162 in the optic tectum. Some of these genes are associated with and organism’s response to stimulus, steroid hormone activity, synaptic plasticity and social behaviour.
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This project’s research will also contribute to sensory biology and the evolution of visual systems. Comparative studies among closely related species and populations are rare in the study of colour vision and female preferences.