Abstract
Oviparous animals, such as turtles, lay eggs whose success or demise depends on environmental conditions that influence offspring phenotype (morphology, physiology, and in many reptiles, also sex determination), growth, and survival, while in the nest and post-hatching. Consequently, because turtles display little parental care, maternal provisioning of the eggs and female nesting behavior are under strong selection. But the consequences of when and where nests are laid are affected by anthropogenic habitat disturbances that alter suitable nesting areas, expose eggs to contaminants in the wild, and modify the thermal and hydric environment experienced by developing embryos, thus impacting hatchling survival and the sexual fate of taxa with temperature-dependent sex determination (TSD) and genotypic sex determination (GSD). Indeed, global and local environmental change influences air, water, and soil temperature and moisture, which impact basking behavior, egg development, and conditions within the nest, potentially rendering current nesting strategies maladaptive as offspring mortality increases and TSD sex ratios become drastically skewed. Endocrine disruptors can sex reverse TSD and GSD embryos alike. Adapting to these challenges depends on genetic variation, and little to no heritability has been detected for nest-site behavior. However, modest heritability in threshold temperature (above and below which females or males develop in TSD taxa, respectively) exists in the wild, as well as interpopulation differences in the reaction norm of sex ratio to temperature, and potentially also in the expression of gene regulators of sexual development. If this variation reflects additive genetic components, some adaptation might be expected, provided that the pace of environmental change does not exceed the rate of evolution. Research remains urgently needed to fill current gaps in our understanding of the ecology and evolution of nest-site choice and its adaptive potential, integrating across multiple levels of organization.
Highlights
Reproduction is an essential component of individual fitness, and it must take place at the appropriate place and time for it to be successful
We first briefly review turtle maternal effects and nesting behavior, the challenges posed by climate change and other anthropogenic disturbances, mostly in turtles with environmental sex determination, and in turtles with sex ratios insensitive to temperature whose biology is still vulnerable to environmental change
Here we show that variables not typically considered in the literature on nesting behavior can have profound effects, such as (1) how water temperature impacts basking behavior, an abiotic factor that influences female physiology, which in turn may alter the timing of nesting and resource allocation to the eggs; or (2) how biotic factors such as social facilitation influences nest-site choice; or (3) how water and not just air and soil temperature may affect the conditions experienced by developing embryos in the nest
Summary
Reproduction is an essential component of individual fitness, and it must take place at the appropriate place and time for it to be successful. Temperatures within turtle nests are influenced by global climate but by multiple environmental factors at micro-geographic and micro-temporal scales, such that the temperatures experienced by the developing embryos, including during the thermosensitive period for sex determination (Valenzuela, 2008; Mitchell et al, 2013; but see Gómez-Saldarriaga et al, 2016), are affected by the nest-site choices females make.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
