Extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination
Date
2019-03-12
Journal Title
Journal ISSN
Volume Title
Publisher
Nature Research (part of Springer Nature)
Abstract
Global climate is warming rapidly, threatening vertebrates with temperature-dependent sex
determination (TSD) by disrupting sex ratios and other traits. Less understood are the effects of
increased thermal fluctuations predicted to accompany climate change. Greater fluctuations could
accelerate feminization of species that produce females under warmer conditions (further
endangering TSD animals), or counter it (reducing extinction risk). Here we use novel experiments
exposing eggs
of Painted Turtles (Chrysemys picta) to replicated profiles recorded in field nests plus
mathematically- modified profiles of similar shape but wider oscillations, and develop a new
mathematical model for analysis. We show that broadening fluctuations around naturally
male-producing (cooler) profiles feminizes developing embryos, whereas embryos from warmer profiles
remain female or die. This occurs presumably because wider oscillations around cooler profiles
expose embryos to very low temperatures that inhibit development, and to feminizing temperatures
where most embryogenesis accrues. Likewise, embryos incubated under broader fluctuations around
warmer profiles experience mostly feminizing temperatures, some dangerously high (which increase
mortality), and fewer colder values that are insufficient to induce male development. Therefore,
as thermal fluctuations
escalate with global warming, the feminization of TSD turtle populations could accelerate,
facilitating extinction by demographic collapse. Aggressive global CO₂ mitigation scenarios
(RCP2.6) could prevent these risks, while intermediate actions (RCP4.5 and RCP6.0 scenarios) yield
moderate feminization, highlighting the peril that insufficient reductions of greenhouse gas
emissions pose for TSD taxa. If our findings are generalizable, TSD squamates, tuatara, and
crocodilians that produce males at warmer temperatures could suffer accelerated masculinization,
underscoring the broad taxonomic threats of
climate change.
Description
CITATION: Valenzuela, N., et al. 2019. Extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination. Scientific Reports, 9:4254, doi:10.1038/s41598-019-40597-4.
The original publication is available at https://www.nature.com
The original publication is available at https://www.nature.com
Keywords
Global climate, Vertebrates -- Reproduction -- Effect of temperature on, Vertebrates -- Effect of environment on, Temperature dependent sex determination, Sex (Biology)
Citation
Valenzuela, N., et al. 2019. Extreme thermal fluctuations from climate change unexpectedly accelerate demographic collapse of vertebrates with temperature-dependent sex determination. Scientific Reports, 9:4254, doi:10.1038/s41598-019-40597-4