Geographic variation in adult and embryonic desiccation tolerance in a terrestrial-breeding frog

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Intra-specific variation in the ability of individuals to tolerate environmental perturbations is often neglected when considering the impacts of climate change. Yet this information is potentially crucial for mitigating any deleterious effects of climate change on threatened species. Here we assessed patterns of intra-specific variation in desiccation tolerance in the frog <jats:italic>Pseudophryne guentheri</jats:italic>, a terrestrial-breeding species experiencing a drying climate. Adult frogs were collected from six populations across a rainfall gradient and their dehydration and rehydration rates were assessed. We also compared desiccation tolerance of embryos and hatchlings originating from within-population parental crosses from four of the six populations, where selection on desiccation tolerance should be especially strong given that embryos cannot move to escape unfavourable microclimates. Embryos were reared on soil at three soil-water potentials, ranging from wet to dry (ψ = −10, −100 &amp; −400 kPa), and their desiccation tolerance was assessed across a range of traits including survival, time to hatch after inundation, wet mass at hatching, hatchling malformations and swimming performance. We found significant and strong patterns of intra-specific variation in almost all traits, both in adults and first generation offspring. Adult frogs exhibited clinal variation in their water balance responses, with populations from drier sites both dehydrating and rehydrating more slowly compared to frogs from more mesic sites. Similarly, desiccation tolerance of embryos and hatchlings was significantly greater in populations from xeric sites. Taken together, our findings suggest that populations within this species will respond differently to the regional reduction in rainfall predicted by climate change models. We emphasise the importance of considering geographic variation in phenotypic plasticity when predicting how species will respond to climate change.</jats:p>

A genome‐wide search for local adaptation in a terrestrial‐breeding frog reveals vulnerability to climate change

“…Variation within the genic region of PKC zeta may be associated with differential expression of the PKC zeta gene (Liu et al, 2004) threatened, our analysis reveals genetic patterns consistent with population isolation, decline and inbreeding, suggesting the species is at greater risk of extinction than is currently recognized. We provide strong molecular evidence of local adaption, which is supported by a parallel study of P. guentheri that found strong patterns of clinal variation in desiccation tolerance (both in adults and firstgeneration offspring) across a rainfall gradient (Rudin-Bitterli, 2018).…”

“…On this basis, higher levels of inbreeding would be expected in our populations near the northern range edge, yet we observed the opposite pattern. Alternatively, the differences could arise via kin selection in southern populations, or due to differing levels of multiple mating, as implied by marked divergence of male reproductive traits in these same populations (Rudin-Bitterli, 2018), and recognition of complex and variable mating systems in congeners (O'Brien et al, 2018). Alternatively, the differences could arise via kin selection in southern populations, or due to differing levels of multiple mating, as implied by marked divergence of male reproductive traits in these same populations (Rudin-Bitterli, 2018), and recognition of complex and variable mating systems in congeners (O'Brien et al, 2018).…”

“…One explanation is that selection against inbred individuals is particularly strong in the northern populations, as inbreeding depression is more severe in more harsh environments (Miller, 1984). Alternatively, the differences could arise via kin selection in southern populations, or due to differing levels of multiple mating, as implied by marked divergence of male reproductive traits in these same populations (Rudin-Bitterli, 2018), and recognition of complex and variable mating systems in congeners (O'Brien et al, 2018).…”

“…The species is an ideal model for studying responses to climate change due to marked intraspecific variation in the ability of embryonic and adult life stages to withstand desiccation (Rudin-Bitterli, Evans, & Mitchell, 2018). The species is an ideal model for studying responses to climate change due to marked intraspecific variation in the ability of embryonic and adult life stages to withstand desiccation (Rudin-Bitterli, Evans, & Mitchell, 2018).…”

Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

“…This is contrary to our prediction, as smaller salamanders are expected to have higher rates of water loss per unit area [23]. While studies have found evidence for geographic variation in desiccation resistance indicative of local adaptation based on gradients of environmental moisture e.g., [82,83] it is notable that we did not find evidence for plasticity in resistance to water loss based on our moisture treatments. This result has important implications for the ability of salamanders to respond to changes in environmental moisture.…”