Article Review: Breeding sex ratio and population size of loggerhead turtles from Southwestern Florida

A recent article pertaining to the sex ratio of loggerhead sea turtles was published in January of 2018 in PLOS One by Jacob A. Lasala, Colin R. Hughes, and Jeanette Wyneken.

Male turtles are difficult to account for in the loggerhead population because they do not come ashore as nesting females do. In order to study the sex ratio of adult loggerheads, researchers used breeding sex ratios throughout three seasons of nesting to see how many males and females are involved in breeding and adding diversity to the population that nests in Florida. They were able to genotype 64 of the females that came ashore to nest, and 989 loggerhead hatchlings from nests in the area. From their data, they determined that there were 126 different paternal males and found that there was more than one paternal male in 70 percent of the nesting sites that were evaluated. This high number of individual adult males could be a result of females storing sperm over the course of time between nesting seasons as they travel, accounting for the larger gene-pool. The article also suggests that the breeding sex ratio could be affected by the frequency that each gender mates throughout the year.

This study adds to our understanding of reptile reproduction pertaining to temperature-dependent sex determination, as discussed in lecture. Higher incubation temperatures in most turtles correlates to the undifferentiated gonads becoming ovaries, leading to higher numbers of female hatchlings.

These findings are valuable because global warming is a growing issue, which is a huge concern for the threatened loggerhead sea turtle species due to their temperature-dependent sex determination, where warmer temperatures have the potential to alter the sex ratio. This research exhibits the large number of paternal males contributing to nests along the coast of Florida, giving insight to the adult males that females are able to encounter in the population during their travels. Although the number of female hatchlings is observed to be much higher than male hatchlings, this study can offer a basis for comparison in the years to come to investigate the impact of global warming on the population of loggerhead turtles.

           This research interests me, as I am concerned for the status of the loggerhead sea turtle species and whether or not the temperature affects of climate change are contributing to a detrimental decrease in their population as a whole. I find it very interesting that these researchers used genetics as an alternative in order to investigate the current adult male population.

Citation: Lasala JA, Hughes CR, Wyneken J (2018) Breeding sex ratio and population size of loggerhead turtles from Southwestern Florida. PLoS ONE 13(1): e0191615. <http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0191615&type=printable>