Climate Change May Cause More Sea Turtles to Become Female

Climate change may just be causing more sea turtles to become female. Researchers have taken a closer look at the ratio of males to females and have found that these animals may be vulnerable to feminization due to temperature rises.

The sex of sea turtles is determined by incubation temperatures on nesting beaches. In fact, warmer sand temperatures usually produce more females. Knowing this, the researchers decided to investigate the sex ratios of these turtles.

Six species of sea turtles that inhabit U.S. waters are listed as either threatened or endangered. In this latest study, the researchers used an enzyme-linked immunosorbent assay (ELISA) to test the sex of juvenile turtles. The researchers found that there was a female bias of 2.83 females to each male among the 69 green turtles tested.

"What really surprised us was that the immature turtles in the San Diego Bay aggregation were even more biased toward females, with 78 percent of them being female," said Camryn Allen, one of the researchers, in a news release.

Several factors may explain female biases in sea turtle foraging populations. However, the most likely is female-biased hatchling sex ratios. Because the gender of hatchlings are determined by incubation temperatures, climate change may actually be causing sex ratios to change.

With that said, female-biases in breeding populations may be beneficial for species recovery due to an increase in the number of breeding females, and therefore, population growth potential. However, if the scale tips too far towards females, there may not be enough males to maintain genetic diversity.

The findings are published in the journal PLOS One.

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