Ontogeny constrains phenology: opportunities for activity and reproduction interact to dictate potential phenologies in a changing climate

Levy, Ohad; Buckley, Lauren B.; Keitt, Timothy H.; Angilletta, Michael J.

doi:10.1111/ele.12595

Cited by 55 publications

(69 citation statements)

References 51 publications

(117 reference statements)

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“…Moreover, predictive models must be able to realistically capture this microclimatic variation in addition to the behavioural thermoregulatory capacity for organisms to exploit it (Briscoe et al., ; Buckley, ; Kearney, ; Kearney, Isaac, & Porter, ; Kearney & Porter, ; Levy, Buckley, Keitt, & Angilletta, ; Sears, Raskin, & Angilletta, ; Sears et al., ). It is equally important to test whether activity time is indeed a significant limiting factor from a thermal perspective, and to put activity budgets into the context of the life cycle, phenology and life history (Kearney, ; Levy, Buckley, Keitt, & Angilletta, ; Maino, Kong, Hoffmann, Barton, & Kearney, ). The modelling tools for such analyses are becoming increasingly available, and such analyses will be of particular importance when considering the management of endangered species to ensure the optimum allocation of resources to the most relevant threatening processes.…”

Section: Discussionmentioning

confidence: 99%

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Moore

Stow

Kearney

2018

Journal of Animal Ecology

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For ectotherms such as lizards, the importance of behavioural thermoregulation in avoiding thermal extremes is well-established and is increasingly acknowledged in modern studies of climate warming and its impacts. Less appreciated and understood are the buffering roles of retreat sites and activity phase, in part because of logistical challenges of studying below-ground activity. Burrowing and nocturnal activity are key behavioural adaptations that have enabled a diverse range of reptiles to survive extreme environmental temperatures within hot desert regions. Yet, the direct impact of recent global warming on activity potential has been hypothesised to have caused extinctions in desert lizards, including the Australian arid zone skink Liopholis kintorei. We test the relevance of this hypothesis through a detailed characterisation of the above- and below-ground thermal and hydric microclimates available to, and used by, L. kintorei. We integrate operative temperatures with observed body temperatures to construct daily activity budgets, including the inference of subterranean behaviour. We then assess the likelihood that contemporary and future local extinctions in this species, and those of similar burrowing habits, could be explained by the direct effects of warming on its activity budget and exposure to thermal extremes. We found that L. kintorei spent only 4% of its time active on the surface, primarily at dusk, and that overall potential surface activity will be increased, not restricted, with climate warming. The burrow system provides an exceptional buffer to current and future maximum extremes of temperature (≈40°C reduction from potential surface temperatures), and desiccation (burrows near 100% humidity). Therefore, any climate warming impacts on this species are likely to be indirect. Our findings reflect the general buffering capacity of underground microclimates, therefore, our conclusions for L. kintorei are more generally applicable to nocturnal and crepuscular ectotherms, and highlight the need to consider the buffering properties of retreat sites and activity phase when forecasting climate change impacts.

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Section: Discussionmentioning

confidence: 99%

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Moore

Stow

Kearney

2018

Journal of Animal Ecology

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“…Such behaviors involve retreating to thermal refugia to avoid lethally high temperatures (Dunham, 1993;Sheldon, Yang, & Tewksbury, 2011;Sinervo et al, 2010) and to limit the costs of maintenance metabolism during periods of seasonal dormancy and nocturnal inactivity (Bennett, 1982;Dunham, Grant, & Overall, 1989;Huey, 1982). Thus, for lizards, rising temperatures linked to climate change could constrain foraging, growth, reproduction, and other critical life-history processes in ways that reduce vital and population growth rates and increase extinction risks Kearney, 2013;Kearney et al, 2009;Levy, Buckley, Keitt, & Angilletta, 2016;Sinervo et al, 2010). Evaluating these threats and understanding how they are influencing communities, however, requires long-term, multispecies datasets that are rarely available.…”

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confidence: 99%

Long‐term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation

Flesch

Rosen

Holm

2017

Global Change Biology

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Understanding how climatic variation affects animal populations and communities is essential for addressing threats posed by climate change, especially in systems where impacts are projected to be high. We evaluated abundance dynamics of five common species of diurnal lizards over 25 years in a Sonoran Desert transition zone where precipitation decreased and temperature increased across time, and assessed hypotheses for the influence of climatic flux on spatiotemporal variation in abundances. We repeatedly surveyed lizards in spring and summer of each year at up to 32 sites, and used hierarchical mixture models to estimate detection probabilities, abundances, and population growth rates. Among terrestrial species, abundances of a short-lived, winter-spring breeder increased markedly by an estimated 237%-285% across time, while two larger spring-summer breeders with higher thermal preferences declined by up to 64%. Abundances of two arboreal species that occupy shaded and thus sheltered microhabitats fluctuated but did not decline systematically. Abundances of all species increased with precipitation at short lag times (1-1.5 years) likely due to enhanced food availability, but often declined after periods of high precipitation at longer lag times (2-4 years) likely due to predation and other biotic pressures. Although rising maximum daily temperatures (T ) are expected to drive global declines of lizards, associations with T were variable and weak for most species. Instead, abundances of all species declined with rising daily minimum temperatures, suggesting degradation of cool refugia imposed widespread metabolic or other costs. Our results suggest climate warming and drying are having major impacts on lizard communities by driving declines in species with traits that augment exposure to abiotic extremes and by modifying species interactions. The complexity of patterns we report indicates that evaluating and responding to the influence of climate change on biodiversity must consider a broad array of ecological processes.

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“…Recent studies have highlighted the importance of understanding how heat stress influences early life stages in order to predict population-level consequences of warming (Levy et al, 2016(Levy et al, , 2015. In lizards, the embryos of some species may experience thermally stressful temperatures during summer heatwaves (Levy et al, 2015), which are predicted to occur more frequently in future (Cowan et al, 2014;Hansen et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Hotter nests produce hatchling lizards with lower thermal tolerance

Dayananda

Murray

Webb

2017

Journal of Experimental Biology

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In many regions, the frequency and duration of summer heatwaves is predicted to increase in future. Hotter summers could result in higher temperatures inside lizard nests, potentially exposing embryos to thermally stressful conditions during development. Potentially, developmentally plastic shifts in thermal tolerance could allow lizards to adapt to climate warming. To determine how higher nest temperatures affect the thermal tolerance of hatchling geckos, we incubated eggs of the rock-dwelling velvet gecko, Amalosia lesueurii, at two fluctuating temperature regimes to mimic current nest temperatures (mean 23.2°C, range 10-33°C, 'cold') and future nest temperatures (mean 27.0°C, range 14-37°C, 'hot'). Hatchlings from the hot incubation group hatched 27 days earlier and had a lower critical thermal maximum (CT max 38.7°C) and a higher critical thermal minimum (CT min 6.2°C) than hatchlings from cold incubation group (40.2 and 5.7°C, respectively). In the field, hatchlings typically settle under rocks near communal nests. During the hatching period, rock temperatures ranged from 13 to 59°C, and regularly exceeded the CT max of both hot-and cold-incubated hatchlings. Because rock temperatures were so high, the heat tolerance of lizards had little effect on their ability to exploit rocks as retreat sites. Instead, the timing of hatching dictated whether lizards could exploit rocks as retreat sites; that is, cold-incubated lizards that hatched later encountered less thermally stressful environments than earlier hatching hot-incubated lizards. In conclusion, we found no evidence that CT max can shift upwards in response to higher incubation temperatures, suggesting that hotter summers may increase the vulnerability of lizards to climate warming.

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Ontogeny constrains phenology: opportunities for activity and reproduction interact to dictate potential phenologies in a changing climate

Cited by 55 publications

References 51 publications

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Under the weather?—The direct effects of climate warming on a threatened desert lizard are mediated by their activity phase and burrow system

Long‐term changes in abundances of Sonoran Desert lizards reveal complex responses to climatic variation

Hotter nests produce hatchling lizards with lower thermal tolerance

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