Meeting Abstract
The rapid stress-induced elevation of plasma glucocorticoids (CORT) is well documented in a variety of animals. In many species, including Florida Scrub-Jays ( Aphelocoma coerulescens ), the magnitude and time course of increased CORT during a stressor varies greatly among individuals. In Florida scrub-jays, these among individual differences are repeatable throughout the adult lifespan (up to nine years), which indicates they are persistent aspects of the individuals’ phenotypes. These hormonal differences are also correlated with a number of behavioral differences, such as the degree of neophobia, suggesting they are a part of a broader physiological-behavioral phenotype. Why this phenotypic diversity persists in the population is not known, but by monitoring jays throughout their entire lives (up to 14 years), clear sex-specific differences in lifespan have been documented. More stress responsive females (faster CORT release and higher levels of CORT during a stressor) live significantly longer than females that are less stress-responsive. However, the opposite relationship is true for males, with less stress-responsive males living significantly longer. Interestingly, life-long reproductive success (offspring surviving to adulthood) does not closely follow lifespan, and parental effort appears to differ between the phenotypes. This suggests that individuals of the same sex, but with different stress-responsive phenotypes, employ different reproductive strategies. Further, it suggests that males and females with similar phenotypes are either employing different reproductive strategies or that they incur different costs and benefits from employing similar reproductive strategies.
