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Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers.

ABSTRACT: Global warming appears to favour smaller-bodied organisms, but whether larger species are also more vulnerable to thermal extremes, as suggested for past mass-extinction events, is still an open question. Here, we tested whether interspecific differences in thermal tolerance (heat and cold) of ectotherm organisms are linked to differences in their body mass and genome size (as a proxy for cell size). Since the vulnerability of larger, aquatic taxa to warming has been attributed to the oxygen limitation hypothesis, we also assessed how body mass and genome size modulate thermal tolerance in species with contrasting breathing modes, habitats and life stages. A database with the upper (CTmax) and lower (CTmin) critical thermal limits and their methodological aspects was assembled comprising more than 500 species of ectotherms. Our results demonstrate that thermal tolerance in ectotherms is dependent on body mass and genome size and these relationships became especially evident in prolonged experimental trials where energy efficiency gains importance. During long-term trials, CTmax was impaired in larger-bodied water-breathers, consistent with a role for oxygen limitation. Variation in CTmin was mostly explained by the combined effects of body mass and genome size and it was enhanced in larger-celled, air-breathing species during long-term trials, consistent with a role for depolarization of cell membranes. Our results also highlight the importance of accounting for phylogeny and exposure duration. Especially when considering long-term trials, the observed effects on thermal limits are more in line with the warming-induced reduction in body mass observed during long-term rearing experiments. This article is part of the theme issue 'Physiological diversity, biodiversity patterns and global climate change: testing key hypotheses involving temperature and oxygen'.

SUBMITTER: Leiva FP

PROVIDER: S-EPMC6606457 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers.

Leiva Félix P FP Calosi Piero P Verberk Wilco C E P WCEP

Philosophical transactions of the Royal Society of London. Series B, Biological sciences 20190617 1778

Global warming appears to favour smaller-bodied organisms, but whether larger species are also more vulnerable to thermal extremes, as suggested for past mass-extinction events, is still an open question. Here, we tested whether interspecific differences in thermal tolerance (heat and cold) of ectotherm organisms are linked to differences in their body mass and genome size (as a proxy for cell size). Since the vulnerability of larger, aquatic taxa to warming has been attributed to the oxygen lim ...[more]

PMID: 31203753

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Project description:The adaptive potential of livestock under a warming climate is increasingly relevant in relation to the growing pressure of global food security. Studies on heat tolerance demonstrate the interplay of adaptation and acclimatization in functional traits, for example, a reduction in body size and enhanced tolerance in response to a warming climate. However, current lack of understanding of functional traits and phylogenetic history among phenotypically distinct populations constrains predictions of climate change impact. Here, we demonstrate evidence of parallel evolution in adaptive tolerance to heat stress in dwarf cattle breeds (DCB, Bos taurus indicus) and compare their thermoregulatory responses with those in standard size cattle breeds (SCB, crossbred, Bos taurus indicus × Bos taurus taurus). We measured vital physiological, hematological, biochemical, and gene expression changes in DCB and SCB and compared the molecular phylogeny using mitochondrial genome (mitogenome) analysis. Our results show that SCB can acclimatize in the short term to higher temperatures but reach their tolerance limit under prevailing tropical conditions, while DCB is adapted to the warmer climate. Increased hemoglobin concentration, reduced cellular size, and smaller body size enhance thermal tolerance. Mitogenome analysis revealed that different lineages of DCB have evolved reduced size independently, as a parallel adaptation to heat stress. The results illustrate mechanistic ways of dwarfing, body size-dependent tolerance, and differential fitness in a large mammal species under harsh field conditions, providing a background for comparing similar populations during global climate change. These demonstrate the value of studies combining functional, physiological, and evolutionary approaches to delineate adaptive potential and plasticity in domestic species. We thus highlight the value of locally adapted breeds as a reservoir of genetic variation contributing to the global domestic genetic resource pool that will become increasingly important for livestock production systems under a warming climate.

Dataset Information

Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers.

Publications

Scaling of thermal tolerance with body mass and genome size in ectotherms: a comparison between water- and air-breathers.

Similar Datasets

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