Osmoregulation in Desert-Adapted Mammals

Donald, John A.; Pannabecker, Thomas L.

doi:10.1007/978-1-4939-3213-9_10

Cited by 23 publications

(15 citation statements)

References 72 publications

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“…This may also explain why animals may have become active during a simulated heat wave to drink water to prevent dehydration [ 19 ], and in turn would prevent kidney oxidative stress. Overall, kidney oxidative stress may be very reliant on the urinary concentrating ability of the animals resulting in different tolerances to hyperosmolality, with desert animals better equipped with kidney oxidative stress [ 107 – 109 ].…”

Section: Discussionmentioning

confidence: 99%

Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus

et al. 2020

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Heat waves are known for their disastrous mass die-off effects due to dehydration and cell damage, but little is known about the non-lethal consequences of surviving severe heat exposure. Severe heat exposure can cause oxidative stress which can have negative consequences on animal cognition, reproduction and life expectancy. We investigated the current oxidative stress experienced by a mesic mouse species, the four striped field mouse, Rhabdomys dilectus through a heat wave simulation with ad lib water and a more severe temperature exposure with minimal water. Wild four striped field mice were caught between 2017 and 2019. We predicted that wild four striped field mice in the heat wave simulation would show less susceptibility to oxidative stress as compared to a more severe heat stress which is likely to occur in the future. Oxidative stress was determined in the liver, kidney and brain using malondialdehyde (MDA) and protein carbonyl (PC) as markers for oxidative damage, and superoxide dismutase (SOD) and total antioxidant capacity (TAC) as markers of antioxidant defense. Incubator heat stress was brought about by increasing the body temperatures of animals to 39–40.8°C for 6 hours. A heat wave (one hot day, followed by a 3-day heatwave) was simulated by using temperature cycle that wild four striped field mice would experience in their local habitat (determined through weather station data using temperature and humidity), with maximal ambient temperature of 39°C. The liver and kidney demonstrated no changes in the simulated heat wave, but the liver had significantly higher SOD activity and the kidney had significantly higher lipid peroxidation in the incubator experiment. Dehydration significantly contributed to the increase of these markers, as is evident from the decrease in body mass after the experiment. The brain only showed significantly higher lipid peroxidation following the simulated heat wave with no significant changes following the incubator experiment. The significant increase in lipid peroxidation was not correlated to body mass after the experiment. The magnitude and duration of heat stress, in conjunction with dehydration, played a critical role in the oxidative stress experienced by each tissue, with the results demonstrating the importance of measuring multiple tissues to determine the physiological state of an animal. Current heat waves in this species have the potential of causing oxidative stress in the brain with future heat waves to possibly stress the kidney and liver depending on the hydration state of animals.

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Section: Discussionmentioning

confidence: 99%

Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus

et al. 2020

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“…Species adapted to harsh environments often display multilevel, interdependent modifications-from genes to life-history traits-allowing them to cope with physical and biotic selection pressures (Childress & Seibel, 1998;Cloudsley-Thompson, 1998;Ihlenfeldt, 1994;Lacey, Patton, & Cameron, 2000;Lindgren et al, 2016). For example, in extremely hot and dry environments, desert mammals exhibit physiological mechanisms that optimize water conservation (Donald & Pannabecker, 2015), nocturnal habits and a fossorial lifestyle to avoid heat stress (Schmidt-Nielsen & Schmidt-Nielsen, 1952;Walsberg, 2000), and cranial adaptations that enhance hearing and facilitate predator avoidance (Alhajeri & Steppan, 2018). Subterranean species tend to have morphological adaptations for digging (reduced limbs and pinnae, robust feet and claws), well-developed sensory systems for exploring dark places (auditory, olfactory and mechanical receptors) and physiological specializations for overcoming chronic hypoxia and hypercapnia (Fang et al, 2014;Lacey et al, 2000;Nevo, 1979;Ramirez, Folkow, & Blix, 2007;Zhu, Ge, Wen, Xia, & Yang, 2018).…”

Section: Introductionmentioning

confidence: 99%

Divergent adaptations in resource‐use traits explain how pikas thrive on the roof of the world

Feijó

Wen

et al. 2020

Functional Ecology

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Life in extreme environments is possible through multilevel adaptations to physical and biotic stresses. At high elevations, species face numerous challenges, besides low oxygen levels, but previous studies have focused on genetic and physiological adaptations to chronic hypoxia while overlooking other key strategies for thriving in alpine landscapes. Here, we investigate resource‐use trait adaptations to extreme elevations using pikas as a model, lagomorphs distributed up to 6,200 m and reaching maximum diversity on the Qinghai‐Tibet plateau, the highest plateau on Earth. Specifically, we assess cranial evolution in pikas using geometric morphometric and phylogenetic comparative techniques to determine whether adaptations among high‐elevation biota shown at the molecular and physiological levels also occur in resource‐use traits. We further explore the roles of two contrasting lifestyles (burrowing and rocky‐dwelling) in cranial evolution. We found that alpine species exhibit striking phenotypic specialization to distinct microhabitats. Contrary to physiological and genetic adaptive convergence, we show that the cranium has undergone adaptive divergence likely reflecting past resource competition in highlands and long‐term association with alpine landscapes. Our analyses also reveal that the evolution of burrowing lifestyle allows high‐elevation pikas to explore novel niches and boosts their phenotypic diversification. In addition to cold and hypoxia tolerance, high cranial specialization, the appearance of burrowing habits and strong niche separation explain how pikas overcome alpine stresses and flourish on the highest plateau on Earth. By contrast, when moving to spatially complex and heterogeneous vegetation zonation, pikas exhibit generalist skull forms able to exploit diverse habitats. These findings mirror previously reported intraspecific patterns in mammals, suggesting a general morphological response in resource‐exploiting traits to cope with distinct selection pressures across elevation zones. Phenotypic diversity is further constrained by rocky habitats, resulting in convergent skulls. Our study highlights that adaptations to extreme environments occur at multiple levels of organization, but can lead to distinct evolutionary paths depending on which selective forces they respond to. The evolution of burrowing behaviour represents a landmark in the evolutionary history of pikas. We further show that rocky habitats impose strong ecological pressures, leading to convergent responses in resource‐use traits, which is rarely documented in mammals.

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“…Among the classical findings of physiological adaptations that minimize water loss, is the ability of some desert mammals to produce highly concentrated urine [14]. This phenotype is mostly associated with desert 'evaders', such as the Australian Hopping mouse, which has the record for highest hyperosmotic urine (above 9000 mOsm/kg) [3,15]. Evaders, part of a classification system proposed by Willmer et al (2000), are small body-sized animals that are able to evade extreme conditions through behavior [5].…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, large-sized mammals unable to shelter from extreme climates that are forced to withstand heat, are called 'endurers', and medium-sized mammals unable to evade nor withstand extremes as efficiently as evaders and endurers are called 'evaporators' [5]. Because mammalian urine concentrating ability (mOsm/Kg) is negatively correlated with body mass [16], desert evaders stand out in this capacity [15]. However, when correcting for differences in body mass, the capacity to highly concentrate urine seems to have independently evolved in deserts.…”

Section: Introductionmentioning

confidence: 99%

Convergent evolution of increased urine concentrating ability in desert mammals

Rocha

Brito

Nielsen

et al. 2020

Preprint

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One of the most celebrated textbook examples of physiological adaptations to desert environments is the unique ability that desert mammals have to produce hyperosmotic urine. Commonly perceived as an adaptation mainly observed in small rodents, the extent to which urine concentrating ability has independently evolved in distinct lineages, including medium-sized and large desert mammals, has not previously been assessed using modern phylogenetic approaches. Here, we explicitly test the general hypothesis that desert-dwelling mammals have evolved increased ability to concentrate urine compared to non-desert species, controlling for body mass and other covariates. Phylogenetic generalized least-squares models show that the mean aridity index of a species range largely predicts its urine concentrating ability, even when accounting for body mass differences and phylogenetic correlations. In contrast, we find much weaker correlations between mass-adjusted basal metabolic rate and environmental variables.

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Osmoregulation in Desert-Adapted Mammals

Cited by 23 publications

References 72 publications

Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus

Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus

Divergent adaptations in resource‐use traits explain how pikas thrive on the roof of the world

Convergent evolution of increased urine concentrating ability in desert mammals

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