Sex change and effective population size : implications for population genetic studies in marine fish

Coscia, I; Chopelet, J; Waples, R; Mann, B; Mariani, S

Abstract

Large variance in reproductive success is the primary factor that reduces effective population size (Ne) in
natural populations. In sequentially hermaphroditic (‘sex-changing’) fish, the sex ratio is typically skewed
and biased toward the ‘first’ sex, while reproductive success increases considerably after sex change.
Therefore, sex-changing fish populations are theoretically expected to have lower Ne than gonochorists
(separate sexes), assuming all other parameters are essentially equal. In this study, we estimate Ne from
genetic data collected from two ecologically similar species living along the eastern coast of South
Africa: one gonochoristic, the ‘santer’ sea bream Cheimerius nufar, and one protogynous (female-first)
sex-changer, the ‘slinger’ sea bream Chrysoblephus puniceus. For both species, no evidence of genetic
structuring, nor significant variation in genetic diversity, were found in the study area. Estimates of
contemporary Ne were significantly lower in the protogynous species, but the same pattern was not
apparent over historical timescales. Overall, our results show that sequential hermaphroditism may affect
Ne differently over varying time frames, and that demographic signatures inferred from genetic markers
with different inheritance modes also need to be interpreted cautiously, in relation to sex-changing life
histories.

Citation

Coscia, I., Chopelet, J., Waples, R., Mann, B., & Mariani, S. (2016). Sex change and effective population size : implications for population genetic studies in marine fish. Heredity, 117, 251-258. https://doi.org/10.1038/hdy.2016.50

• Journal Article Type: Article
• Acceptance Date: May 23, 2016
• Online Publication Date: Aug 10, 2016
• Publication Date: Oct 1, 2016
• Deposit Date: Jun 6, 2016
• Publicly Available Date: Feb 10, 2017
• Journal: Heredity
• Print ISSN: 0018-067X
• Electronic ISSN: 1365-2540
• Publisher: Nature Publishing Group
• Volume: 117
• Pages: 251-258
• DOI: https://doi.org/10.1038/hdy.2016.50
• Publisher URL: http://dx.doi.org/10.1038/hdy.2016.50
• Related Public URLs: http://www.nature.com/hdy/index.html
• Additional Information: Funders : Science Foundation Ireland; Projects : RFP06 - Population Genetic Consequences of Sex Change in Fish