Will all species with temperature-dependent sex determination respond the same way to climate change? A reply to Kallimanis (2010)

Abstract

Recently, Kallimanis (2010) published a paper proposing a mechanism by which temperature-dependent sex determination (TSD) may play a key role at facilitating species with this strategy to track their climatic niches across space under climate change. Kallimanis hypothesized that TSD species currently inhabiting stable climatic conditions show reduced population growth rates at the edges of their distributional ranges; under warming conditions, these populations will experience faster growth rates and thus are able to colonize new suitable sites. These ideas are based on the assumption that populations of TSD species have balanced sex ratios at the core of their geographic ranges and biased proportions at the edges. However, Kallimanis’ model overlooks complex processes that may produce a more broadly and less predictable aftermath of climate change on TSD species, so we discuss some of his postulates and underlying assumptions. Kallimanis’ model is based only on one of three known TSD strategies in reptiles, thus it lacks generality; and it does not consider the phenological, behavioral, and physiological strategies that TSD species exhibit across their geographic ranges to buffer the potential impacts of climatic variation over the whole reproductive process. We conclude that simple models such as the one proposed by Kallimanis are not broadly applicable; hence, forecasts of TSD species’ responses to climate change will need to be more specific to groups with similar ecologies and modes of TSD.