Diet dependent sex ratios in Tigriopus californicus: Evidence for environmental sex determination in a system with polygenic sex determination

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dc.contributor.authorHornell, Erin Charmaine
dc.contributor.supervisorAnholt, Bradley Ralph
dc.contributor.supervisorPerlman, Steven John
dc.date.accessioned2017-10-19T17:56:09Z
dc.date.available2017-10-19T17:56:09Z
dc.date.copyright2017en_US
dc.date.issued2017-10-19
dc.degree.departmentDepartment of Biology
dc.degree.levelMaster of Science M.Sc.en_US
dc.description.abstractBy controlling the inheritance of sex, the sex determination mechanism constrains sex allocation strategies and sex ratio adaptation; however, sex ratio selection also influences the evolution of sex determination mechanisms. Much of the sex determination literature focuses on how sex determination mechanisms transition between genetic and environmental factors (i.e. GSD vs. ESD), and if genetic sex factors are involved, how many (e.g. chromosomal vs polygenic systems). The study of sex allocation largely focuses on deviations in sex ratio from a theoretically 1:1 evolutionarily stable strategy, such as when sex ratios reflect ‘cost’ differences between the sexes. Tigriopus californicus is a tidepool copepod with polygenic sex determination, and shows wide variability in sex ratios in the field and lab that cannot be explained by genetic and stochastic processes alone, which suggests that an environmental variable might influence sex ratio. Females and their offspring were fed diets of different nutritional quality in a crossed design, and the sex ratio of each clutch was recorded for up to 8 clutches from a given female: this design allowed the influence of female diet vs. that of her offspring to be distinguished. The clutch sex ratio changed over the laying order according to the offspring’s diet, which is evidence for environmental sex determination in this species. Sex ratio also showed the influence of maternal diet, consistent with sex allocation theory. While dietary carotenoids showed no association with sex ratio or clutch size, long chain polyunsaturated fatty acids (particularly EPA and DHA) were implicated as the agent of sex ratio effect, providing a direction for future studies. The situation of T. californicus at the intersection of major themes in sex evolution makes this system an ideal model for selection studies.en_US
dc.description.embargo2018-09-13
dc.description.scholarlevelGraduateen_US
dc.identifier.urihttp://hdl.handle.net/1828/8695
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectcopepoden_US
dc.subjectTigriopus californicusen_US
dc.subjectenvironmental sex determinationen_US
dc.subjectpolygenic sex determinationen_US
dc.subjectdiet dependenceen_US
dc.subjectsex ratioen_US
dc.titleDiet dependent sex ratios in Tigriopus californicus: Evidence for environmental sex determination in a system with polygenic sex determinationen_US
dc.typeThesisen_US

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