Abstract
The Cort-Fitness Hypothesis has generated much interest from investigators integrating field endocrinology with evolutionary biology, ecology, and conservation. The hypothesis was developed to test the assumption that if glucocorticoid levels increase with environmental challenges and fitness decreases with environmental challenges, then there should be a negative relationship between baseline glucocorticoid levels and fitness. Indeed, studies across diverse taxa have found that the relationship between baseline glucocorticoid levels and fitness are not consistent: some studies show a positive relationship, others negative, and some show no correlation. Hence, a deeper understanding of the mechanisms underlying the relationship between baseline glucocorticoid levels, environmental challenges, and fitness is needed. We propose a mathematical model representing the links between baseline glucocorticoid levels, environmental challenges, and fitness. Our model describes how variation in the predictability and intensity of environmental challenges, reproductive strategies, and fitness metrics can all contribute to the variability observed in empirical tests of the Cort-Fitness Hypothesis. We provide qualitative results showing that much of the inconsistency in previous studies can be explained and we discuss how the model can be used to inform future Cort-Fitness studies.
Highlights
Organisms face differing levels of abiotic and biotic challenges throughout their lifetimes that can dramatically affect their fitness (Ricklefs and Wikelski, 2002; Lanctot et al, 2003; Satterthwaite et al, 2010)
We propose a mathematical model representing the links between glucocorticoid levels, environmental challenges, and fitness
The relationship between environmental challenges, glucocorticoid hormones, and fitness is very complicated. It has been primarily investigated through observational studies, but there are many limitations that come with that such as the non-repeatability of these studies, the non-linear dependence between the three components, the choice of fitness metric, as well as individuals’ own life history that shapes how they cope with stress
Summary
Organisms face differing levels of abiotic and biotic challenges throughout their lifetimes that can dramatically affect their fitness (Ricklefs and Wikelski, 2002; Lanctot et al, 2003; Satterthwaite et al, 2010). Have often been considered an indication that an individual is in poor body condition which is often associated with lower quality habitat (Romero and Wikelski, 2001; Bonier et al, 2009a; Kitaysky et al, 2003; Jaatinen et al, 2013) These relationships between plasma glucocorticoid levels and body condition have led to the assumption that individuals or populations with elevated levels of the hormone will exhibit decreased fitness, either through decreased survivorship, decreased reproductive success, or both.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
