Breeding sex ratios of three imperiled marine turtles nesting in southern Florida

Sound assessment of the status of a threatened or endangered organism depends on understanding
key aspects of behavior throughout its life history. Sometimes organisms can be difficult to observe and
key aspects of behavior may not be accessed directly. Alternative assessment techniques include using
molecular markers to identify fundamental relationships among males and females. In the context of
assessing the status of imperiled populations’ sex ratios, population size and the relatedness of the
individuals are important metrics. Environmental sex determination directs developing marine turtle sex
so that primary sex ratios depend upon weather and climate; those sex ratios are estimated by proxies.
Adult population sizes are inferred from numbers of females nesting on the beach, but numbers of
males are unknown. Male breeding population size can be estimated from subtracting maternal
genotypes from genotypes of offspring exclusion analyses. The resulting adult sex ratios differ greatly
from those estimated for hatchlings. To refine current adult sex ratios in ways that are relevant to
production of future generations and add to our understanding of effective population size we compare
the breeding sex ratios the number of males and females contributing to a population of three species
of sea turtles nesting in southern Florida. We will use the same genetic data to measure relatedness of
the female nesters and the male contributors and describe how that relates to genetic flow and
population structure.