The weather in the sun of the dragon mothers Jacky affects their children

A new study conducted at the University of New South Wales and published in the November / December 2020 issue of Physiological and biochemical zoology highlights a possible connection between an animal’s environmental conditions and the characteristics of its offspring. The study, Maternal temperature, corticosterone and body condition as mediators of maternal effects in Jacky dragons (Amphibolurus muricatus), focused on how maternal conditions and stress hormone (corticosterone) levels in jacky dragons (Amphibolurus muricatus) potentially translate a mother’s exposure to heat actually affects her offspring.

Ectothermic species, such as lizards, often rely on external heat sources to manage body temperature. It turns out that maternal temperature can affect offspring traits such as sex and growth rate. Although these trait changes have been documented, the means by which information is passed from parent to offspring are poorly understood.

Maternal effects theory, in particular, has helped answer a number of important biological questions related to evolution. However, the mechanisms for how these effects occur have not been as well developed, leading to unanswered questions regarding proximate physical causes.

“The mechanisms by which thermal information can be transmitted to offspring have been under-explored,” writes study author Gracie Liu. “Here, we investigated corticosterone as a potential mediator of maternal thermal effects.”

The study placed female jacky dragons in two different heat regimens, one exposing the subject to 7 hours of heat treatments per day, the other exposing the subject to 11 hours of the same treatment each day, then measured the levels. of corticosterone in the subjects’ blood and examined every possible relationship related to their offspring.

Corticosterone is a steroid hormone associated with the “stress” response, the mobilization of energy and the suppression of the immune system. Such hormones often serve as a potential link between the phenotypes of the offspring and the mother’s environment, as they transfer from mother to offspring and can play a role in physiology, behavior and similar factors.

The results indicated that this “thermal opportunity” has an effect on mothers and their offspring. Notably, lizards exposed to the longer 11-hour regimen show significantly higher corticosterone levels in their bloodstream than those exposed to the 7-hour regimen.

However, it was the connection of corticosterone to the condition of the maternal body that led to increased reproductive production – which included both the number of eggs in a subject’s brood and the overall size of the brood – as well as an increased size in offspring at hatching. However, it did not have a corresponding effect on the growth of those children or their gender.

More specifically, basking treatment appeared to be related to maternal corticosterone levels and body condition. This, in turn, had an interactive effect on the resulting friction, suggesting that the combination of condition, corticosterone, and overall maternal temperature could transmit information about the mother’s external environment to her offspring.

“These results indicate that thermal opportunity alters physiology,” Liu writes. “With potential consequences for fitness.”