PS 36-186 - The effect of temperature fluctuations on the sex ratio of the Atlantic silverside (Menidia menidia), a species with Temperature-Dependent Sex Determination

Tuesday, August 16, 2022

5:00 PM – 6:30 PM EDT

Located in: ESA Exhibit Hall

Presenting Author(s)

GH

Grace M. Hancock

Student
Kalamazoo College
Kalamazoo, Michigan, United States

Coauthor(s)

GS

Gorka Sancho

Professor
College of Charleston, United States
sS

santiago Salinas

Assistant Professor of Biology
Kalamazoo College, United States

Background/Question/Methods

In species with temperature-dependent sex determination (TSD), the temperature of the environment during development determines the sex of the individual. This phenomenon has been studied in reptiles and fishes using constant temperature treatments, but the effects of daily fluctuating temperatures remain underexplored, particularly in fishes. Fluctuating temperatures lead to significant differences in organisms’ physiology and are, of course, more ecologically relevant. Therefore, relying on results from constant-temperature experiments (and parameterizing models for projections) can result in erroneous predictions. Given the expected increases in temperature variability, it is important to understand how a fluctuating temperature regime interacts with the sex determination process in TSD species. In this study, we quantified the effect of diel fluctuating temperatures on the sex ratio of a TSD fish, Menidia menida. We exposed M. menidia to three different conditions (constant: 28°C, small fluctuations: 28±2°C, and large fluctuations: 28±4°C) and compared the resulting sex ratios, length-at-age, and CTmax (upper thermal tolerance).

Results/Conclusions

Daily thermal fluctuations influenced the physiology and sex determination of M. menidia. We found that, when reared under fluctuating temperatures, the fish produced a higher proportion of females than in the constant temperature treatment (28°C: 10%, 28±2°C: 16%, 28±4°C: 17%). They also exhibited higher CTmax and lower length-at-age values. The results are discussed in the context of current temperature variability in the collection site, and the potential effects along the latitudinal range of the species. We conclude that, as we continue to predict responses to climate change, it is important to incorporate diel temperature variation in experimental work.