Estimating sex ratios in Caribbean hawksbill turtles: testosterone levels and climate effects

Aquatic Biology

Charles R. Tyler¹  Lucy A. Hawkes¹  Matthew J. Witt¹  Anke Lange¹  Andrew McGowan¹  Damon Wheatley¹  Jim White¹  Annette C. Broderick¹  Shannon Gore¹  Brendan J. Godley¹ 

关键词: Marine turtles;    Sex ratio;    Climate change;    Hormones;   

DOI  :  10.3354/ab00475

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Evolutionary theory predicts that male and female offspring should be produced at a 1:1 ratio, but this may rarely be the case for species in which sex is determined during incubation by temperature, such as marine turtles. Estimates of primary sex ratio suggest that marine turtle sex ratios are highly skewed, with up to 9 females per male. We captured juvenile hawksbill turtles Eretmochelys imbricata in waters around Anegada, British Virgin Islands, a regionally important foraging aggregation, and analysed concentrations of plasma testosterone and oestradiol-17β from 62 turtles to estimate sex ratio. There were 2.4 to 7.7 times more females than males. Testosterone concentrations correlated with sampling date and sea surface temperature (SST), with higher concentrations in the late summer when SST was highest, suggesting that assigning sex through threshold values of sex hormones must be carried out cautiously. The sex ratio in the juvenile foraging aggregation around Anegada is more male biased than at other locations, suggesting that turtles at Anegada have resilience against feminising effects of climate change. Future work should (1) integrate the relative contributions of different genetic stocks to foraging aggregations and (2) investigate the annual and seasonal cycles of sex hormones, and differences among individuals and life history stages.

【 授权许可】

Unknown