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Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos

Heatwaves are a regular occurrence in Australia, and are predicted to increase in intensity and duration in the future. These changes may elevate temperatures inside lizard nests, shortening the incubation period, so that hatchlings are more likely to emerge during heatwaves. Potentially, developmen...

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Autores principales: Abayarathna, Theja, Murray, Brad R., Webb, Jonathan K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Company of Biologists Ltd 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503992/
https://www.ncbi.nlm.nih.gov/pubmed/31000681
http://dx.doi.org/10.1242/bio.042564
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author Abayarathna, Theja
Murray, Brad R.
Webb, Jonathan K.
author_facet Abayarathna, Theja
Murray, Brad R.
Webb, Jonathan K.
author_sort Abayarathna, Theja
collection PubMed
description Heatwaves are a regular occurrence in Australia, and are predicted to increase in intensity and duration in the future. These changes may elevate temperatures inside lizard nests, shortening the incubation period, so that hatchlings are more likely to emerge during heatwaves. Potentially, developmental plasticity or heat hardening could buffer hatchings from future warming. For example, higher incubation temperatures could shift critical thermal maxima upwards, enabling lizards to withstand higher temperatures. To investigate whether developmental plasticity affects hatchling thermal tolerance, we incubated eggs of the velvet gecko Amalosia lesueurii under two fluctuating incubation treatments to mimic current (mean=24.3°C, range 18.4–31.1°C) and future ‘hot’ (mean=28.9°C, range 19.1–38.1°C) nest temperatures. We maintained the hatchlings under identical conditions, and measured their thermal tolerance (CT(max)) aged 14 days and 42 days. We then released hatchlings at field sites, and recaptured individually marked lizards aged 6 months, to determine whether incubation induced shifts in thermal tolerance were transitory or long-lasting. We found that at age 14 days, hatchlings from hot-temperature incubation had higher CT(max) [mean=39.96±0.25°C (s.d.)] than hatchlings from current-temperature incubation [mean=39.70±0.36°C (s.d.)]. Hatchlings from the current-incubation treatment also had significantly higher heat hardening capacity [mean=0.79±0.37°C (s.d.)] than hatchlings from hot-temperature incubation treatment [mean=0.47±0.17°C (s.d. )]. However, both of these incubation-induced effects did not persist into later life. By contrast, incubation treatment had significant and long-lasting effects on the cold tolerance of hatchlings. At age 14 days, current-incubated hatchlings tolerated colder temperatures [CT(min)=11.24±0.41°C (s.d.)] better than hot-incubated hatchlings [CT(min)=14.11±0.25°C (s.d.)]. This significant difference in cold tolerance persisted into the juvenile life stage, and was present in 6-month-old lizards that we recaptured from field sites. This finding indicates that upward shifts in cold tolerance caused by higher incubation temperatures might affect overwinter survival of lizards, but field studies linking fitness to thermal tolerance are necessary to test this idea. Overall, our results suggest that developmental plasticity for heat tolerance is unlikely to buffer lizard populations from higher temperatures. This article has an associated First Person interview with the first author of the paper.
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spelling pubmed-65039922019-05-08 Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos Abayarathna, Theja Murray, Brad R. Webb, Jonathan K. Biol Open Research Article Heatwaves are a regular occurrence in Australia, and are predicted to increase in intensity and duration in the future. These changes may elevate temperatures inside lizard nests, shortening the incubation period, so that hatchlings are more likely to emerge during heatwaves. Potentially, developmental plasticity or heat hardening could buffer hatchings from future warming. For example, higher incubation temperatures could shift critical thermal maxima upwards, enabling lizards to withstand higher temperatures. To investigate whether developmental plasticity affects hatchling thermal tolerance, we incubated eggs of the velvet gecko Amalosia lesueurii under two fluctuating incubation treatments to mimic current (mean=24.3°C, range 18.4–31.1°C) and future ‘hot’ (mean=28.9°C, range 19.1–38.1°C) nest temperatures. We maintained the hatchlings under identical conditions, and measured their thermal tolerance (CT(max)) aged 14 days and 42 days. We then released hatchlings at field sites, and recaptured individually marked lizards aged 6 months, to determine whether incubation induced shifts in thermal tolerance were transitory or long-lasting. We found that at age 14 days, hatchlings from hot-temperature incubation had higher CT(max) [mean=39.96±0.25°C (s.d.)] than hatchlings from current-temperature incubation [mean=39.70±0.36°C (s.d.)]. Hatchlings from the current-incubation treatment also had significantly higher heat hardening capacity [mean=0.79±0.37°C (s.d.)] than hatchlings from hot-temperature incubation treatment [mean=0.47±0.17°C (s.d. )]. However, both of these incubation-induced effects did not persist into later life. By contrast, incubation treatment had significant and long-lasting effects on the cold tolerance of hatchlings. At age 14 days, current-incubated hatchlings tolerated colder temperatures [CT(min)=11.24±0.41°C (s.d.)] better than hot-incubated hatchlings [CT(min)=14.11±0.25°C (s.d.)]. This significant difference in cold tolerance persisted into the juvenile life stage, and was present in 6-month-old lizards that we recaptured from field sites. This finding indicates that upward shifts in cold tolerance caused by higher incubation temperatures might affect overwinter survival of lizards, but field studies linking fitness to thermal tolerance are necessary to test this idea. Overall, our results suggest that developmental plasticity for heat tolerance is unlikely to buffer lizard populations from higher temperatures. This article has an associated First Person interview with the first author of the paper. The Company of Biologists Ltd 2019-04-15 /pmc/articles/PMC6503992/ /pubmed/31000681 http://dx.doi.org/10.1242/bio.042564 Text en © 2019. Published by The Company of Biologists Ltd http://creativecommons.org/licenses/by/4.0This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
spellingShingle Research Article
Abayarathna, Theja
Murray, Brad R.
Webb, Jonathan K.
Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title_full Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title_fullStr Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title_full_unstemmed Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title_short Higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
title_sort higher incubation temperatures produce long-lasting upward shifts in cold tolerance, but not heat tolerance, of hatchling geckos
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6503992/
https://www.ncbi.nlm.nih.gov/pubmed/31000681
http://dx.doi.org/10.1242/bio.042564
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