Loggerhead sea turtles lay eggs in multiple locations to improve reproductive success

January 28, 2021

Although loggerhead sea turtles return to the same beach where they hatched to lay their eggs, a new study by a USF professor finds individual females lay numerous clutches of eggs in locations miles apart from each other to increase the chance that some of their offspring will survive.

A study published in the journal "Scientific Reports" found that some females lay as many as six clutches as far as six miles apart during the same breeding season.

"Nesting females don't lay all their eggs in one basket. Their reproductive strategy is like investing in a mutual fund. Females divide their resources among many stocks rather than investing everything in a single stock," said Deby Cassill, biology professor at USF's St. Petersburg campus and author of the study.

During their 50-year lifetime, a single female loggerhead will produce around 4,200 eggs and scatter them at 40 different sites on the barrier island. This strategy helps reduce the risk of complete reproductive failure by hurricanes and thunderstorms that could wash out or flood all clutches.

"Because females diversify reproduction in unpredictable patterns over time and space, nearly two-thirds of loggerhead sea turtle hatchlings made it into the Gulf of Mexico," said Cassill.

For the study, Cassill analyzed 17 years of data provided by the Conservancy of Southwest Florida on loggerhead females nesting on Keewaydin Island off the southwestern Gulf coast of Florida. For years, conservancy staff and community volunteers tagged turtles and patrolled the island to monitor and record detailed information on the nesting population.

Though the study shows most sea turtle hatchlings reach the Gulf of Mexico, future impacts due to human encroachment and climate change could affect the population. Increased frequency of extreme storms due to warmer waters and sea-level rise may flood or wash away larger portions of clutches, leading to population declines of the threatened species.

"It's important to follow individuals over time to really get a glimpse of how they mate, find food and ensure that some of their young survive to maturity. Without knowledge of the sea turtle's survival and reproductive biology, we cannot develop and implement effective conservation policies," said Cassill.

The study is one in a series of upcoming articles by Cassill pertaining to her "maternal risk management model," which looks at how natural selection pressures, such as predators, storms and resource scarcity, influence how mothers invest in offspring quantity and quality.

She argues turtles and fish invest in large numbers of offspring when the likelihood their offspring will be killed by predators is high. Mammal mothers like whales and elephants provide extensive care to one offspring at a time when the likelihood their young will starve during seasonal droughts is high.

The model, based on the number and size of offspring produced by a mother, extends Darwin's theory of natural selection by explaining the fusion of parents and offspring into family units and societies.

University of South Florida (USF Innovation)

Related Natural Selection Articles from Brightsurf:

Genetic determinants of fertility and ongoing natural selection in humans
A recent study presented at the ASHG 2020 Virtual Meeting suggests genetic variants may be associated with reproductive success.

Forearm artery reveals humans evolving from changes in natural selection
Humans haven't developed genetic mutations for telepathy or superpowers just yet, but a new study shows our species is still evolving in unique ways and changes in the natural selection could be the major reason.

Novel technology for the selection of single photosynthetic cells
New research, published in the journal Science Advances, demonstrates how microfluidic technologies can be used to identify, isolate and propagate specific single photosynthetically active cells for fundamental industry applications and improved ecosystem understanding.

Genomic selection in dairy cows creates opportunities not possible with traditional selection
The 2019 ADSA Annual Meeting featured the Joint ADSA/Interbull Breeding and Genetics Symposia titled ''Ten Years of Genomic Selection'' and ''Data Pipelines for Implementation of Genomic Evaluation of Novel Traits.'' Because of genomic selection's importance to dairy science, the Journal of Dairy Science invited the speakers to submit articles and share information from these symposia with a wider audience.

Recurrent genomic selection for wheat grain fructans
Development of Climate-Resilient, Nutritionally Improved Wheat

NASA's OSIRIS-REx in the midst of site selection
After a lengthy and challenging process, the team is finally ready to down-select from the four candidate sites to a primary and backup site.

The argument for sexual selection in bacteria
The evolutionary pressure to pass on DNA can produce behavior that otherwise makes no sense in a struggle to survive.

Sexual selection influences the evolution of lamprey pheromones
In 'Intra- and Interspecific Variation in Production of Bile Acids that Act As Sex Pheromones in Lampreys,' published in Physiological and Biochemical Zoology, Tyler J.

Infection biology: Signs of selection in the stomach
Helicobacter pylori, a globally distributed gastric bacterium, is genetically highly adaptable.

Study finds natural selection favors cheaters
Natural selection predicts that mutualisms -- interactions between members of different species that benefit both parties -- should fall apart.

Read More: Natural Selection News and Natural Selection Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.