Interspecific variation in thermoregulation among three sympatric bats inhabiting a hot, semi-arid environment

Toussaint, Dawn Cory; McKechnie, Andrew E.

doi:10.1007/s00360-012-0683-6

Cited by 43 publications

(28 citation statements)

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“…In small bats, TEWL typically increases two-to 12-fold between T a ! 30ЊC and T a ≈ 40Њ-43ЊC (Herreid and Schmidt-Nielsen 1966;Licht and Leitner 1967;Maloney et al 1999;Cory Toussaint and McKechnie 2012). As is typical in endotherms, increases in heat dissipation in E. wahlbergi at T a approaching T b also included a nonevaporative component, with the changes in dry heat transfer coefficient being quantitatively similar to those in other species (e.g., Marom et al 2006).…”

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confidence: 85%

“…Cory Toussaint and McKechnie (2012) calibrated a subsample of the same batch of PIT tags, and we used the same calibration curves here. Subcutaneous temperature is representative of core T b in bats (Gorman et al 1991).…”

Section: Measurements Of Gas Exchange and Body Temperaturementioning

confidence: 99%

“…In bats, evaporation may constitute 80%-85% of overall water flux (Studier 1970;Arad and Korine 1993;Bassett et al 2009) and has particular thermoregulatory significance for insectivorous species roosting in hot microsites (Maloney et al 1999;Marom et al 2006;Cory Toussaint and McKechnie 2012). Relatively little is known about rates of respiratory evaporation versus cutaneous evaporation in bats (Bassett et al 2009), particularly compared with birds, where it is well established that the relative importance of REWL and CEWL for thermoregulation at air temperatures (T a ) approaching and exceeding T b varies widely among orders (Wolf and Walsberg 1996;Tieleman and Williams 2002;McKechnie and Wolf 2004).…”

Section: Introductionmentioning

confidence: 99%

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Partitioning of Evaporative Water Loss into Respiratory and Cutaneous Pathways in Wahlberg's Epauletted Fruit Bats (Epomophorus wahlbergi)

Minnaar¹,

Bennett²,

Chimimba³

et al. 2014

Physiological and Biochemical Zoology

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The relative contributions of respiratory and cutaneous evaporation to total evaporative water loss (TEWL) and how the partitioning of these two avenues varies with environmental temperature has received little attention in bats. We trained Wahlberg's epauletted fruit bats (Epomophorus wahlbergi) captured in Pretoria, South Africa, to wear latex masks while hanging in respirometry chambers, and we measured respiratory evaporative water loss (REWL) and cutaneous evaporative water loss (CEWL) over air temperatures (T a ) from 10Њ to 40ЊC. The bats' normothermic body temperature (T b ) was approximately 36ЊC, which increased at higher T a to 40.5Њ ‫ע‬ 1.0ЊC at T a ≈ 40ЊC. Both TEWL and resting metabolic rate (RMR) increased sharply at T a 135ЊC, with a mean TEWL at 40ЊC equivalent to 411% of that at 30ЊC. The increase in TEWL was driven by large increases in both CEWL and REWL. CEWL comprised more than 50% of TEWL over the entire T a range, with the exception of T a ≈ 40ЊC, where REWL accounted for 58% of evaporative water loss. Surface area-specific CEWL increased approximately sixfold with increasing T a . Thermoregulation at T a approaching or exceeding T b involved a considerable energetic cost, with RMR at T a ≈ 40ЊC exceeding by 24% that measured at T a ≈ 10ЊC. Our data do not support recent arguments that respiratory gas exchange across the wing membranes represents 5%-10% of the total in E. wahlbergi.

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confidence: 85%

Section: Measurements Of Gas Exchange and Body Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Partitioning of Evaporative Water Loss into Respiratory and Cutaneous Pathways in Wahlberg's Epauletted Fruit Bats (Epomophorus wahlbergi)

Minnaar¹,

Bennett²,

Chimimba³

et al. 2014

Physiological and Biochemical Zoology

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“…The BMRs predicted for E. wahlbergi on the basis of the phylogenetically independent scaling relationship of Cory Toussaint and McKechnie (Cory Toussaint and McKechnie, 2012) are 0.461 W (captive population) and 0.519 W (wild population). Observed values in our study ranged from 100.4% (captive, winter) to 149.4% (wild, summer) of those predicted.…”

Section: Research Articlementioning

confidence: 96%

Summit metabolism and metabolic expansibility in Wahlberg's epauletted fruit bats (Epomophorus wahlbergi): seasonal acclimatisation and effects of captivity

Minnaar

Bennett

Chimimba

et al. 2013

Journal of Experimental Biology

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Summit metabolism (M sum ), the maximum rate of resting metabolic thermogenesis, has been found to be broadly correlated with climatic variables and the use of heterothermy in some endotherms. Far less is known about M sum and metabolic expansibility [ME, the ratio of M sum to basal metabolic rate (BMR)] in bats compared with many other endotherm taxa. We measured BMR and M sum during winter and summer in captive and wild populations of a pteropodid from the southern subtropics, Wahlberg's epauletted fruit bat (Epomophorus wahlbergi) in Pretoria, South Africa. The M sum of fruit bats ranged from 5.178±0.611 W (captive, summer) to 6.006±0.890 W (captive, winter), and did not vary significantly between seasons. In contrast, BMR decreased by 17-25% in winter. The combination of seasonally stable M sum but flexible BMR resulted in ME being significantly higher in winter than in summer, ranging from 7.24±1.49 (wild, summer) to 13.11±2.14 (captive, winter). The latter value is well above the typical mammalian range. Moreover, both M sum and ME were significantly higher in captive bats than in wild individuals; we speculate this represents a phenotypic response to a reduction in exerciseassociated heat production while in captivity. Our data for E. wahlbergi, combined with those currently available for other chiropterans, reveal that M sum in bats is highly variable compared with allometrically expected values for other mammals.KEY WORDS: Acclimatisation, Cold exposure, Helox, Phenotypic flexibility, Thermogenic capacity INTRODUCTIONThe lowest environmental temperature to which an endotherm can defend normothermic body temperature (T b ) is determined primarily by its maximum capacity for metabolic thermogenesis (Scholander et al., 1950). Summit metabolism (M sum ) is the maximum rate of resting metabolic thermogenesis in the absence of exercise-associated heat production (Swanson et al., 1996) [also referred to as cold-induced peak metabolic rate (Wiersma et al., 2007)]. Among mammals, metabolic expansibility [ME, the ratio of M sum to basal metabolic rate (BMR); also referred to as factorial aerobic scope] is typically 4-8, but may be as high as 10-13 (Careau, 2013;Hinds et al., 1993). Most avian ME values are similar to those typical of mammals, with maximum reported values of 9.0-9. production capacity is correlated with climate, with M sum generally being higher in species inhabiting colder regions (Rezende et al., 2004;Swanson and Garland, 2009).One endotherm order about which remarkably little is known in terms of resting heat production capacity is the Chiroptera. The first published estimate of M sum in a bat of which we are aware was for the molossid Tadarida brasiliensis, in which mass-specific M sum was equivalent to ~21× BMR (Canals et al., 2005). The very high ME value for T. brasiliensis contrasts with more recent data for three frugivorous phyllostomids (Artibeus lituratus, Sturnira lilium and Carollia perspicillata) in which ME ranged from 3.4 to 5.2 (Almeida and Cruz-Neto, 2011).A priori, two...

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“…Although Z. virens is widely accepted as a sexually monomorphic species (Hockey et al, 2005;Oatley, 2011;Skead, 1967), male Cape white-eyes were slightly heavier and had significantly lower wholeanimal RMR than females. Thermal PIT tags have been used in physiological studies on reptiles (Bittner et al, 2002;Roark and Dorcas, 2000) and small mammals (Cory Toussaint and McKechnie, 2012) but to our knowledge this is the first study in which these PIT tags have been successfully used for a long-term study in small birds. Mean hourly intraperitoneal T b of Cape white-eyes showed a marked circadian rhythm typical of small diurnal avian insectivores and nectarivores (Clarke and Rothery, 2008;McKechnie and Lovegrove, 2002).…”

Section: Discussionmentioning

confidence: 99%

The potential effects of climate change-associated temperature increases on the metabolic rate of a small Afrotropical bird

Thompson

Brown

Downs

2015

Journal of Experimental Biology

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Studies have only recently begun to underline the importance of including data on the physiological flexibility of a species when modelling its vulnerability to extinction from climate change. We investigated the effects of a 4°C increase in ambient temperature (T a ), similar to that predicted for southern Africa by the year 2080, on certain physiological variables of a 10-12 g passerine bird endemic to southern Africa, the Cape white-eye Zosterops virens. There was no significant difference in resting metabolism, body mass and intraperitoneal body temperature between birds housed indoors at 4°C above outside ambient temperature and those housed indoors at outside ambient temperature. We conclude that the physiological flexibility of Cape white-eyes will aid them in coping with the 4°C increase predicted for their range by 2080.

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Interspecific variation in thermoregulation among three sympatric bats inhabiting a hot, semi-arid environment

Cited by 43 publications

References 40 publications

Partitioning of Evaporative Water Loss into Respiratory and Cutaneous Pathways in Wahlberg's Epauletted Fruit Bats (Epomophorus wahlbergi)

Partitioning of Evaporative Water Loss into Respiratory and Cutaneous Pathways in Wahlberg's Epauletted Fruit Bats (Epomophorus wahlbergi)

Summit metabolism and metabolic expansibility in Wahlberg's epauletted fruit bats (Epomophorus wahlbergi): seasonal acclimatisation and effects of captivity

The potential effects of climate change-associated temperature increases on the metabolic rate of a small Afrotropical bird

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