Meeting Abstract
Species that display temperature dependent sex determination are at risk for decline due to increasing global temperatures. High temperatures can decrease hatching rates and cause hatchlings to be increasingly female, which may skew adult sex ratios. The relationship of hatchlings sex ratios to adult sex ratios remains complicated. Adult sex ratios are difficult to assess because marine turtles are widely distributed, individuals may or may not breed annually, and males remain at sea. A functional alternative measure is sought: breeding sex ratio (BSR). One method to quantify BSR is to identify the number of males that successfully contribute to each nest by examining paternity of hatchlings. We sampled nesting Leatherback (Dermochelys coriacea) mothers and their hatchlings from two mainland beaches in southeastern Florida and conducted exclusion analyses to identify breeding males. Sampling occurred over multiple nesting seasons (2014-2017) and included over 180 nests and over 2500 hatchlings. We found that female Leatherbacks nesting in both locations were from the same population and that the breeding sex ratios are 1.9M : 1F. These US mainland nesting Leatherback turtles may be more promiscuous than at other Atlantic island nesting sites (57% of all nests analyzed had multiple paternal contributions). We found over 225 individual males that contributed individually to nests, but only one example of a male mating with more than one female, suggesting this population is highly polyandrous. Baseline breeding sex ratios are important because they establish how mating affects the population structure of these turtles before effects of extreme environmental impacts drive changes in demographics and behavior.
