Abstract
Sex-specific maternal effects can be adaptive sources of phenotypic plasticity. Reptiles with temperature-dependent sex determination (TSD) are a powerful system to investigate such maternal effects because offspring phenotype, including sex, can be sensitive to maternal influences such as oestrogens and incubation temperatures. In red-eared slider turtles (Trachemys scripta), concentrations of maternally derived oestrogens and incubation temperatures increase across the nesting season; we wanted to determine if sex ratios shift in a seasonally concordant manner, creating the potential for sex-specific maternal effects, and to define the sex ratio reaction norms under fluctuating temperatures across the nesting season. Eggs from early and late season clutches were incubated under a range of thermally fluctuating temperatures, maternally derived oestradiol concentrations were quantified via radioimmunoassay, and hatchling sex was identified. We found that late-season eggs had higher maternal oestrogen concentrations and were more likely to produce female hatchlings. The sex ratio reaction norm curves systematically varied with season, such that with even a slight increase in temperature (0·5 °C), late-season eggs produced up to 49% more females than early-season eggs. We found a seasonal shift in sex ratios which creates the potential for sex-specific phenotypic matches across the nesting season driven by maternal effects. We also describe, for the first time, systematic variation in the sex ratio reaction norm curve within a single population in a species with TSD. A lay summary is available for this article.
Original language | English (US) |
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Pages (from-to) | 876-884 |
Number of pages | 9 |
Journal | Functional Ecology |
Volume | 31 |
Issue number | 4 |
DOIs | |
State | Published - Apr 1 2017 |
Externally published | Yes |
Keywords
- fluctuating temperature
- maternal effect
- oestrogen
- season
- sex ratio
- temperature-dependent sex determination
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics