Trade-offs between surviving and thriving: A careful balance of physiological limitations and reproductive effort under thermal stress

What I like about this preprint

One of the questions at the forefront of zoology is whether and how species will adapt to climate change as projections predict extreme and unpredictable environmental conditions. This preprinted study investigated how red-sided garter snakes (Thamnophis sirtalis parietalis) balance survival and reproductive effort under thermal stress. What caught my eye was the  multidisciplinary approach where the authors managed to integrate body temperature, behavioural observations and gene expression. In addition, the authors included field observations and laboratory experiments. I appreciate multidisciplinary approaches in zoology as these provide better understanding of the target species and the experimental question(s) posed. Thus, through this approach, the study provides insight into how the red-sided garter snake navigates an extreme thermal environment while maximising reproductive opportunities.

Introduction / Background

Red-sided garter snakes are remarkable animals when considering their wide distribution, migration patterns and extreme cold temperature tolerance. These animals have a brief 4-6 week mating period where they can experience ambient temperatures that result in body temperatures ranging from <1 °C to >40 °C. Thus, during the mating season, male snakes must compete for access to females and avoid predation all while coping with thermal extremes. In this preprint, the authors aimed to gain understanding of the strategies that male red-sided garter snakes use to survive and reproduce in extreme thermal environments.

Key Findings

The authors found that the male snakes show courtship behaviours  (BT_court in Figure 1 below) and operate close to their thermal tolerance limit (maximum body temperature at which they can survive; CT_max in Figure 1 below). They suggest that since there is a narrow window for mating, the males prioritise reproduction until they cannot survive the heat to avoid being outcompeted by other males.

The authors found that changes in gene expression to cope with extreme temperatures occurred before exposure to high and low temperature. Thus, amazingly, protective mechanisms operate in anticipation of, rather in response to, thermal damage.

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