J Therm Biol. 2016 Aug;60:49-59. doi: 10.1016/j.jtherbio.2016.06.004. Epub 2016 Jun 11.
- 1
- Department
of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn,
AL 36849, USA. Electronic address: cmm0054@auburn.edu.
- 2
- Everglades Holiday Park, Fort Lauderdale, FL 33332, USA. Electronic address: m.easter05@gmail.com.
- 3
- Palo
Verde Biological Station, Organization for Tropical Studies,
Guanacaste, Costa Rica. Electronic address: sergio.padilla@ots.ac.cr.
- 4
- Instituto
Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica,
San José, Costa Rica. Electronic address: msasamarin@gmail.com.
- 5
- Department
of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn,
AL 36849, USA. Electronic address: guyercr@auburn.edu.
Abstract
Spatial
variation in global climate change makes population-specific responses
to this enigmatic threat pertinent on a regional scale. Organisms with
temperature-dependent sex determination (TSD) potentially possess a
unique physiological susceptibility that threatens population viability
if rapid environmental effects on sex ratios render populations
non-viable. A heavily male-biased sex ratio for hatchling American
crocodiles of the Tempisque Basin, Costa Rica requires assessment of how
nest temperature affects sex determination at this site, how females
might compensate for these effects when creating nests, and how current
patterns of climate change might alter future sex ratios and survival in
hatchling cohorts. We demonstrate high within-nest variation in
temperature but predict a female bias at hatching based on nest
temperatures quantified here. Further, our data suggest that egg size
and metabolic heating associated with this factor outweighs microhabitat
parameters and depth in influencing nest thermal regimes. Finally, we
document regional warming in the Tempisque Basin over the last 15 years
and project that further heating over the next 15 years will not yield
hatchling sex ratios as male biased as those currently found at this
site. Thus, we find no support for nest temperature or climate change as
likely explanations for male-biased American crocodile (Crocodylus
acutus) sex ratios in the Tempisque Basin.
Copyright © 2016 Elsevier Ltd. All rights reserved.
KEYWORDS:
Climate change; Crocodylus acutus; Nesting; Sex ratio; Temperature-dependent sex determination
