31° South: the physiology of adaptation to arid conditions in a passerine bird.
- Ribeiro, Ângela M, Puetz, Lara, Pattinson, Nicholas B, Dalén, Love, Deng, Yuan, Zhang, Guojie, da Fonseca, Rute R, Smit, Ben, Gilbert, M. Thomas P
- Authors: Ribeiro, Ângela M , Puetz, Lara , Pattinson, Nicholas B , Dalén, Love , Deng, Yuan , Zhang, Guojie , da Fonseca, Rute R , Smit, Ben , Gilbert, M. Thomas P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441508 , vital:73894 , https://doi.org/10.1111/mec.15176
- Description: Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.
- Full Text:
- Date Issued: 2019
- Authors: Ribeiro, Ângela M , Puetz, Lara , Pattinson, Nicholas B , Dalén, Love , Deng, Yuan , Zhang, Guojie , da Fonseca, Rute R , Smit, Ben , Gilbert, M. Thomas P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441508 , vital:73894 , https://doi.org/10.1111/mec.15176
- Description: Arid environments provide ideal ground for investigating the mechanisms of adaptive evolution. High temperatures and low water availability are relentless stressors for many endotherms, including birds; yet birds persist in deserts. While physiological adaptation probably involves metabolic phenotypes, the underlying mechanisms (plasticity, genetics) are largely uncharacterized. To explore this, we took an intraspecific approach that focused on a species that is resident over a mesic to arid gradient, the Karoo scrub‐robin (Cercotrichas coryphaeus). Specifically, we integrated environmental (climatic and primary productivity), physiological (metabolic rates: a measure of energy expenditure), genotypic (genetic variation underlying the machinery of energy production) and microbiome (involved in processing food from where energy is retrieved) data, to infer the mechanism of physiological adaptation. We that found the variation in energetic physiology phenotypes and gut microbiome composition are associated with environmental features as well as with variation in genes underlying energy metabolic pathways. Specifically, we identified a small list of candidate adaptive genes, some of them with known ties to relevant physiology phenotypes. Together our results suggest that selective pressures on energetic physiology mediated by genes related to energy homeostasis and possibly microbiota composition may facilitate adaptation to local conditions and provide an explanation to the high avian intraspecific divergence observed in harsh environments.
- Full Text:
- Date Issued: 2019
An experimental test of the allotonic frequency hypothesis to isolate the effects of light pollution on bat prey selection:
- Bailey, Lauren A, Brigham, R Mark, Bohn, Shelby J, Boyles, Justin G, Smit, Ben
- Authors: Bailey, Lauren A , Brigham, R Mark , Bohn, Shelby J , Boyles, Justin G , Smit, Ben
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158309 , vital:40171 , https://0-doi.org.wam.seals.ac.za/10.1007/s00442-019-04417-w
- Description: Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths’ ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths’ evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness.
- Full Text:
- Date Issued: 2019
- Authors: Bailey, Lauren A , Brigham, R Mark , Bohn, Shelby J , Boyles, Justin G , Smit, Ben
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158309 , vital:40171 , https://0-doi.org.wam.seals.ac.za/10.1007/s00442-019-04417-w
- Description: Artificial lights may be altering interactions between bats and moth prey. According to the allotonic frequency hypothesis (AFH), eared moths are generally unavailable as prey for syntonic bats (i.e., bats that use echolocation frequencies between 20 and 50 kHz within the hearing range of eared moths) due to the moths’ ability to detect syntonic bat echolocation. Syntonic bats therefore feed mainly on beetles, flies, true bugs, and non-eared moths. The AFH is expected to be violated around lights where eared moths are susceptible to exploitation by syntonic bats because moths’ evasive strategies become less effective. The hypothesis has been tested to date almost exclusively in areas with permanent lighting, where the effects of lights on bat diets are confounded with other aspects of human habitat alteration. We undertook diet analysis in areas with short-term, localized artificial lighting to isolate the effects of artificial lighting and determine if syntonic and allotonic bats (i.e., bats that use echolocation frequencies outside the hearing range of eared moths) consumed more moths under conditions of artificial lights than in natural darkness.
- Full Text:
- Date Issued: 2019
An oversimplification of physiological principles leads to flawed macroecological analyses
- Boyles, Justin G, Levesque, Danielle L, Nowack, Julia, Wojciechowski, Michal S, Stawski, Clare, Fuller, Andrea, Smit, Ben, Tattersall, Glenn J
- Authors: Boyles, Justin G , Levesque, Danielle L , Nowack, Julia , Wojciechowski, Michal S , Stawski, Clare , Fuller, Andrea , Smit, Ben , Tattersall, Glenn J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440505 , vital:73788 , https://doi.org/10.1002/ece3.5721
- Description: In light of the rapidly changing climate, there is an urgent need to develop a mechanistic understanding of how physiological functioning mediates ecological patterns. Recently, there has been a spate of papers using analyses that scale up from a standard physiological model, the Scholander–Irving model, to make predictions about range constraints on endothermic vertebrates (Buckley, Khaliq, Swanson, and Hof, 2018; Fristoe et al., 2015; Khaliq, Böhning‐Gaese, Prinzinger, Pfenninger, and Hof, 2017; Khaliq, Hof, Prinzinger, Böhning‐Gaese, and Pfenninger, 2014). Here, we argue that oversimplifications of the Scholander–Irving model and the use of questionable datasets lead to questionable macrophysiological analyses. Many of these problems have been addressed elsewhere, directly and indirectly (eg, McKechnie, Coe, Gerson, and Wolf, 2017; Mitchell et al., 2018), although the focus has largely been on the applicability of the Scholander–Irving model to warm environmental temperatures, which are often seen as more relevant to climate change. However, one specific aspect of the Scholander–Irving model, the assumption that energy expenditure of an endotherm below the thermoneutral zone (TNZ) can be described by basic Newtonian physics, has been used incorrectly in several papers. While not the only paper based on this assumption, the recent work by Buckley et al.(2018) reinvigorated discussions among physiologists about improper interpretations of the Scholander–Irving model. Our concerns are not new and have been voiced repeatedly in the past (Calder and Schmidt‐Nielsen, 1967; King, 1964; Tracy, 1972), but many of these ideas seem to have been buried by time.
- Full Text:
- Date Issued: 2019
- Authors: Boyles, Justin G , Levesque, Danielle L , Nowack, Julia , Wojciechowski, Michal S , Stawski, Clare , Fuller, Andrea , Smit, Ben , Tattersall, Glenn J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440505 , vital:73788 , https://doi.org/10.1002/ece3.5721
- Description: In light of the rapidly changing climate, there is an urgent need to develop a mechanistic understanding of how physiological functioning mediates ecological patterns. Recently, there has been a spate of papers using analyses that scale up from a standard physiological model, the Scholander–Irving model, to make predictions about range constraints on endothermic vertebrates (Buckley, Khaliq, Swanson, and Hof, 2018; Fristoe et al., 2015; Khaliq, Böhning‐Gaese, Prinzinger, Pfenninger, and Hof, 2017; Khaliq, Hof, Prinzinger, Böhning‐Gaese, and Pfenninger, 2014). Here, we argue that oversimplifications of the Scholander–Irving model and the use of questionable datasets lead to questionable macrophysiological analyses. Many of these problems have been addressed elsewhere, directly and indirectly (eg, McKechnie, Coe, Gerson, and Wolf, 2017; Mitchell et al., 2018), although the focus has largely been on the applicability of the Scholander–Irving model to warm environmental temperatures, which are often seen as more relevant to climate change. However, one specific aspect of the Scholander–Irving model, the assumption that energy expenditure of an endotherm below the thermoneutral zone (TNZ) can be described by basic Newtonian physics, has been used incorrectly in several papers. While not the only paper based on this assumption, the recent work by Buckley et al.(2018) reinvigorated discussions among physiologists about improper interpretations of the Scholander–Irving model. Our concerns are not new and have been voiced repeatedly in the past (Calder and Schmidt‐Nielsen, 1967; King, 1964; Tracy, 1972), but many of these ideas seem to have been buried by time.
- Full Text:
- Date Issued: 2019
Behaviour of an alpine range-restricted species is described by interactions between microsite use and temperature
- Oswald, Krista N, Smit, Ben, Lee, Alan T K, Cunningham, Susan J
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Cunningham, Susan J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441531 , vital:73896 , https://doi.org/10.1016/j.anbehav.2019.09.006
- Description: Climate change predictions include increased mean temperatures and increased frequency of heatwaves. Short-term responses to high air temperatures can allow animals to conserve water while maintaining a safe body temperature. For birds, cooling is often through evaporative water loss, which can be physiologically costly. Microsite use is an effective means of conserving water via reducing environmental heat load, so long as there are no negative trade-offs with other necessary functions, such as foraging. We examined behavioural responses to temperature in Cape rockjumpers, Chaetops frenatus (hereafter: ‘rockjumper’), an alpine specialist bird. We hypothesized that rockjumper behaviours would be temperature and microsite dependent. We collected data on rockjumper microsite use (sun, rock shade), behaviour (activity, foraging, preening, panting) and temperature (air, environmental). Rockjumpers made increased use of rock shade as air temperature increased. However, birds in rock shade foraged less. Depending on where their main food source is located, this suggests that when foraging demands are high, birds may need to remain in the sun despite risks of high thermal load, or else may suffer costs of lost foraging opportunities when using shade. The relationship between air temperature and heat dissipation behaviour (panting) was also mediated by microsite: birds showed significant increases in panting with increasing air temperature only when in the sun. The lack of increase in panting for birds in rock shade suggests that shade seeking may buffer physiological thermoregulatory costs (i.e. water expenditure). Individuals may therefore be able to mitigate some potential negative effects of high temperatures by making use of cooler microsites, although this could come at a cost to foraging.
- Full Text:
- Date Issued: 2019
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Cunningham, Susan J
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441531 , vital:73896 , https://doi.org/10.1016/j.anbehav.2019.09.006
- Description: Climate change predictions include increased mean temperatures and increased frequency of heatwaves. Short-term responses to high air temperatures can allow animals to conserve water while maintaining a safe body temperature. For birds, cooling is often through evaporative water loss, which can be physiologically costly. Microsite use is an effective means of conserving water via reducing environmental heat load, so long as there are no negative trade-offs with other necessary functions, such as foraging. We examined behavioural responses to temperature in Cape rockjumpers, Chaetops frenatus (hereafter: ‘rockjumper’), an alpine specialist bird. We hypothesized that rockjumper behaviours would be temperature and microsite dependent. We collected data on rockjumper microsite use (sun, rock shade), behaviour (activity, foraging, preening, panting) and temperature (air, environmental). Rockjumpers made increased use of rock shade as air temperature increased. However, birds in rock shade foraged less. Depending on where their main food source is located, this suggests that when foraging demands are high, birds may need to remain in the sun despite risks of high thermal load, or else may suffer costs of lost foraging opportunities when using shade. The relationship between air temperature and heat dissipation behaviour (panting) was also mediated by microsite: birds showed significant increases in panting with increasing air temperature only when in the sun. The lack of increase in panting for birds in rock shade suggests that shade seeking may buffer physiological thermoregulatory costs (i.e. water expenditure). Individuals may therefore be able to mitigate some potential negative effects of high temperatures by making use of cooler microsites, although this could come at a cost to foraging.
- Full Text:
- Date Issued: 2019
Differences in the use of surface water resources by desert birds are revealed using isotopic tracers
- Smit, Ben, Woodborne, Stephan, Wolf, Blair O, McKechnie, Andrew E
- Authors: Smit, Ben , Woodborne, Stephan , Wolf, Blair O , McKechnie, Andrew E
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440532 , vital:73790 , https://doi.org/10.1093/auk/uky005
- Description: The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modeling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by (i) observations at waterholes and (ii) tracing spatial water-use patterns during summer by isotopically labeled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that 2 methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
- Full Text:
- Date Issued: 2019
- Authors: Smit, Ben , Woodborne, Stephan , Wolf, Blair O , McKechnie, Andrew E
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440532 , vital:73790 , https://doi.org/10.1093/auk/uky005
- Description: The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modeling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by (i) observations at waterholes and (ii) tracing spatial water-use patterns during summer by isotopically labeled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that 2 methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
- Full Text:
- Date Issued: 2019
Multi-directional effects of warming temperatures on the reproductive success of a threatened alpine-endemic bird, and implications for conservation management
- Oswald, Krista N, Lee, Alan T K, Diener, John P, Diener, Elizabeth F, Cunningham, Susan J, Smit, Ben
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
- Date Issued: 2019
- Authors: Oswald, Krista N , Lee, Alan T K , Diener, John P , Diener, Elizabeth F , Cunningham, Susan J , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441624 , vital:73902 , https://eco.confex.com/eco/2019/meetingapp.cgi/Paper/78223
- Description: Mitigating the current biodiversity crisis requires a better understanding of how species will respond to future climate change and human impacts on habi-tat. Decreased reproductive capability, due to changes in phenology, output, and success, is one of the main indicators of species’ vulnerability. For terres-trial ground-nesting birds, overall reproductive success is often related to nest-site selection (e.g. increased nest concealment), and weather changes (e.g. higher air temperatures alter nest success). We investigated the reproductive success of Cape Rockjumpers (Chaetops frenatus; “Rockjumpers”), a ground-nesting alpine bird, endemic to the Fynbos biome of South Africa, whose popu-lation decline correlates to warmer temperatures. We predicted that breeding success would be positively correlated with increased nest concealment, and negatively correlated with increasing temperature. We collected data over three years, including two full breeding seasons, from 2016 to 2018 (n=5, n=20 and n=43 respectively), which included nest-site selection variables (i.e. vege-tative cover, rock cover, time since fire in years), success or failure (whether nest resulted in ≥ fledgling), and cause if nest failed (i.e. predation events, weather). We tested the overall success in relation to nest-site selection varia-bles, and then examined how nest failure (specifically snake predation) was correlated with air temperature.
- Full Text:
- Date Issued: 2019
The functional significance of facultative hyperthermia varies with body size and phylogeny in birds
- Gerson, Alexander R, McKechnie, Andrew, Smit, Ben, Whitfield, Maxine C, Smith, Eric K, Talbot, William A, McWhorter, Todd J, Wolf, Blair O
- Authors: Gerson, Alexander R , McKechnie, Andrew , Smit, Ben , Whitfield, Maxine C , Smith, Eric K , Talbot, William A , McWhorter, Todd J , Wolf, Blair O
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441609 , vital:73901 , https://doi.org/10.1111/1365-2435.13274
- Description: Facultative hyperthermia, the elevation of body temperature above normothermic levels, during heat exposure, importantly affects the wa-ter economy and heat balance of terrestrial endotherms. We currently lack a mechanistic understanding of the benefits hyperthermia provides for avian taxa. Facultative hyperthermia has been proposed to minimize rates of water loss via three distinct mechanisms: M1) by maintaining body temperature (Tb) above environmental temperatures (Te), heat can be lost non‐evaporatively, saving water; M2) by minimizing the thermal gradient when Te > Tb, environmental heat gain and evaporative water loss rates are reduced; and M3) by storing heat via increases in Tb which reduces evaporative heat loss demands and conserves wa-ter. Although individuals may benefit from all three mechanisms during heat exposure, the relative importance of each mechanism has not been quantified among species that differ in their body size, heat toler-ance and mechanisms of evaporative heat dissipation. We measured resting metabolism, evaporative water loss and real‐time Tb from 33 species of birds representing nine orders ranging in mass from 8 to 300 g and estimated the water savings associated with each proposed mechanism. We show that facultative hyperthermia varies in its benefits among species.
- Full Text:
- Date Issued: 2019
The functional significance of facultative hyperthermia varies with body size and phylogeny in birds
- Authors: Gerson, Alexander R , McKechnie, Andrew , Smit, Ben , Whitfield, Maxine C , Smith, Eric K , Talbot, William A , McWhorter, Todd J , Wolf, Blair O
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441609 , vital:73901 , https://doi.org/10.1111/1365-2435.13274
- Description: Facultative hyperthermia, the elevation of body temperature above normothermic levels, during heat exposure, importantly affects the wa-ter economy and heat balance of terrestrial endotherms. We currently lack a mechanistic understanding of the benefits hyperthermia provides for avian taxa. Facultative hyperthermia has been proposed to minimize rates of water loss via three distinct mechanisms: M1) by maintaining body temperature (Tb) above environmental temperatures (Te), heat can be lost non‐evaporatively, saving water; M2) by minimizing the thermal gradient when Te > Tb, environmental heat gain and evaporative water loss rates are reduced; and M3) by storing heat via increases in Tb which reduces evaporative heat loss demands and conserves wa-ter. Although individuals may benefit from all three mechanisms during heat exposure, the relative importance of each mechanism has not been quantified among species that differ in their body size, heat toler-ance and mechanisms of evaporative heat dissipation. We measured resting metabolism, evaporative water loss and real‐time Tb from 33 species of birds representing nine orders ranging in mass from 8 to 300 g and estimated the water savings associated with each proposed mechanism. We show that facultative hyperthermia varies in its benefits among species.
- Full Text:
- Date Issued: 2019
The role of ambient temperature and body mass on body temperature, standard metabolic rate and evaporative water loss in southern African anurans of different habitat specialisation
- Mokhatla, Mohlamatsane, Measey, John, Smit, Ben
- Authors: Mokhatla, Mohlamatsane , Measey, John , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440571 , vital:73794 , 10.7717/peerj.7885
- Description: Temperature and water availability are two of the most important variables affecting all aspects of an anuran’s key physiological processes such as body temperature (T b), evaporative water loss (EWL) and standard metabolic rate (SMR). Since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (VPD), sex and body mass (M b). However, a limited number of studies have tested the generality of these results across a wide range of ecologically relevant ambient temperatures (T a), while taking habitat use into account. Thus, the aim of this study was to investigate the role of T a on T b, whole-animal EWL and whole-animal SMR in three wild caught African anuran species with different ecological specialisations: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis).
- Full Text:
- Date Issued: 2019
- Authors: Mokhatla, Mohlamatsane , Measey, John , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440571 , vital:73794 , 10.7717/peerj.7885
- Description: Temperature and water availability are two of the most important variables affecting all aspects of an anuran’s key physiological processes such as body temperature (T b), evaporative water loss (EWL) and standard metabolic rate (SMR). Since anurans display pronounced sexual dimorphism, evidence suggests that these processes are further influenced by other factors such as vapour pressure deficit (VPD), sex and body mass (M b). However, a limited number of studies have tested the generality of these results across a wide range of ecologically relevant ambient temperatures (T a), while taking habitat use into account. Thus, the aim of this study was to investigate the role of T a on T b, whole-animal EWL and whole-animal SMR in three wild caught African anuran species with different ecological specialisations: the principally aquatic African clawed frog (Xenopus laevis), stream-breeding common river frog (Amietia delalandii), and the largely terrestrial raucous toad (Sclerophrys capensis).
- Full Text:
- Date Issued: 2019
Wand plant architecture in the Fynbos: Testing the rodent herbivory hypothesis
- Bailey, Lauren A, Potts, A J, Cowling, R M, Whitfield, Maxine C, Smit, Ben
- Authors: Bailey, Lauren A , Potts, A J , Cowling, R M , Whitfield, Maxine C , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440583 , vital:73795 , https://doi.org/10.1016/j.sajb.2019.03.035
- Description: Throughout the Cape Floristic Region, in a range of local environments, can be found a distinctive growth form: “wand” plants. This curious plant architecture comprises perennial plants which have slender (wand-like) stems that extend high above the matrix vegetation. We explore whether the evolution of wand-plants may have been driven by plant–herbivore interactions with rodents, where such architecture reduces access to nutrient rich flowers and seeds. To test this idea, we determined if (i) wand-plants were more flexible than non-wand congeners, and (ii) a stabilised wand plant was favoured for climbing (by laboratory mice) over a free-standing wand plant in a laboratory setting. Under a phylogenetic independent contrast framework, wand-plants were not more flexible (across a range of diameters) than non-wand congeners.
- Full Text:
- Date Issued: 2019
- Authors: Bailey, Lauren A , Potts, A J , Cowling, R M , Whitfield, Maxine C , Smit, Ben
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440583 , vital:73795 , https://doi.org/10.1016/j.sajb.2019.03.035
- Description: Throughout the Cape Floristic Region, in a range of local environments, can be found a distinctive growth form: “wand” plants. This curious plant architecture comprises perennial plants which have slender (wand-like) stems that extend high above the matrix vegetation. We explore whether the evolution of wand-plants may have been driven by plant–herbivore interactions with rodents, where such architecture reduces access to nutrient rich flowers and seeds. To test this idea, we determined if (i) wand-plants were more flexible than non-wand congeners, and (ii) a stabilised wand plant was favoured for climbing (by laboratory mice) over a free-standing wand plant in a laboratory setting. Under a phylogenetic independent contrast framework, wand-plants were not more flexible (across a range of diameters) than non-wand congeners.
- Full Text:
- Date Issued: 2019
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