Selected body temperature of nine species of Mexican horned lizards (Phrynosoma)

Lara‐Reséndiz, Rafael A.; Arenas-Moreno, Diego M.; Beltrán-Sánchez, Elizabeth; Gramajo, Weendii; Verdugo-Molina, Javier; Sherbrooke, Wade C.; Cruz, Fausto R. Méndez–de la

doi:10.7550/rmb.48028

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…Preferred body temperature at our study sites ( T set = 35.7 ± 0.33°C) was in between reported T set from other studies of Texas horned lizards (Table 1 ), but close to the average T set of 20 species of Phrynosomatids (35.1 ± 2.2°C; Clusella‐Trullas & Chown, 2014 ). Field body temperature ( T b = 33.6 ± 0.30°C) was similar to one reported value (33.4 ± 0.45°C; Lara‐Reséndiz, Arenas‐Moreno, et al, 2015 ) and lower than three other reported body temperatures for Texas horned lizards (35.7 ± ND °C, Brattstrom, 1965 ; 37.3 ± 0.30°C, Pianka & Parker, 1975 ; 35.2 ± 3.44 SD °C, Russell, 2001 ). Nonetheless, T b is lower than the mean environmental temperatures available to them ( T e = 35.2 ± 1.1°C) but falls within the lower T set25 range for lizards at our study sites.…”

Section: Discussionsupporting

confidence: 87%

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Tucker

Biffi

Williams

2023

Ecology and Evolution

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Vegetation loss is a primary cause of habitat degradation and results in a decline in reptile species abundance due to loss of refuge from predators and hot temperatures, and foraging opportunities. Texas horned lizards (Phrynosoma cornutum) have disappeared from many areas in Texas, especially from urbanized areas, probably in large part due to loss of suitable habitat. This species still occurs in some small towns in Texas that still contain suitable habitat. Long‐term data from Kenedy and Karnes City, Texas indicate that when study sites experienced significant shrub and vegetation removal horned lizards declined by 79%. We hypothesize the decline was due to the degradation of the thermal landscape for these lizards. We determined the preferred temperature range (Tset25 – Tset75) of lizards at our study sites and took field measurements of body temperature (Tb). Temperature loggers were also placed in three microhabitats across our study sites. Shrubs and vegetation provided the highest quality thermal environment, especially for about 5 h midday when temperatures in the open and buried under the surface in the open exceeded the lizards' critical maximum temperature (CTmax) or were above their preferred temperature range. Horned lizard density was positively related to the thermal quality of the habitat across our sites. Texas horned lizards in these towns require a heterogeneous mix of closely spaced microhabitats and especially thermal refugia, such as shrubs and vegetation along fence lines and in open fields. Maintaining thermal refugia is one of the most important and practical conservation actions that can be taken to help small ectotherms persist in modified human landscapes and cope with increasing temperatures due to climate change.

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Section: Discussionsupporting

confidence: 87%

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Tucker

Biffi

Williams

2023

Ecology and Evolution

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“…Preferred body temperature at our study sites (T set = 35.7 +-0.33oC) was in between reportedT set from other studies of Texas horned lizards (Table 1), but close to the average T set of 20 species of Phrynosomatids (35.1 +-2.2oC;Clusella-Trullas and Chown 2014). Field body temperature (T b = 33.6 +-0.30oC) was similar to one reported value (33.4 +-0.45oC;Lara-Resendiz et al 2015b) and lower than three other reported body temperatures for Texas horned lizards (35.7 ± NDºC, Brattstrom 1965;37.3 ± 0.30ºC, Pianka and Parker 1975;35.2 ± 3.44 SDºC, Russell 2001). Nonetheless,T b is lower than the mean environmental temperatures available to them (T e = 35.2 ± 1.1ºC), but falls within the lower T set25 range for lizards at our study sites.…”

Section: Discussionsupporting

confidence: 86%

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Tucker

Biffi

Williams

2022

Preprint

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Texas horned lizards (Phrynosoma cornutum) have disappeared from many areas in Texas, especially from urbanized areas, probably in large part due to loss of suitable habitat. Our previous studies have found that horned lizards persist and occur at high densities in some small towns in southern Texas. Nevertheless, this species has continued to decline and disappear from these towns. Long-term data from Kenedy and Karnes City indicate that when study sites experienced significant shrub and vegetation removal horned lizards declined by 79%. We hypothesize this may in part be due to the degradation of the thermal landscape for these lizards. We determined the preferred temperature range (T −T) of lizards at our study sites and took field measurements of body temperature (T). Temperature loggers were also placed in three microhabitats across our study sites. Shrubs and vegetation provided the highest quality thermal environment, especially for about 5 hours midday when temperatures in the open and buried under the surface exceeded the lizards’ critical maximum temperature (CT) or were above their preferred temperature range. Horned lizard density was positively related to the thermal quality of the habitat across our sites. Texas horned lizards in these towns require a heterogenous mix of closely spaced microhabitats and especially thermal refugia, such as shrubs and vegetation along fence lines and in open fields. Maintaining thermal refugia is one of the most important and practical conservation actions that can be taken to help small ectotherms persist in human modified landscapes and cope with increasing temperatures due to climate change.

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“…Lower thermal limits generally correlate with environmental conditions these species occupy (e.g. lower critical thermal minimum of species in cold regions; Campbell‐Staton et al., 2017; Lara‐Reséndiz et al., 2015). For example, if T emerg or VT max are lower in the northern than in southern populations, this would increase the time suitable to northern lizards for basking or foraging.…”

Section: Discussionmentioning

confidence: 99%

“…We used published data for the observed body temperature range of 23.8–40.2°C for active P. platyrhinos (Huey & Pianka, 2018), using the lower value for two behavioural thresholds, both temperature of emergence (T emerg ) and basking temperature (T bask ). Preferred temperature (T pref ) is the midpoint value of the range of selected temperatures recorded in a laboratory gradient (34.2°C; Lara‐Reséndiz et al., 2015) and indicates the temperature at which the lizard will begin seeking shade to maintain body temperatures within the voluntary thermal limits. Thermal limits required for the biophysical model are voluntary thermal minimum (VT min ) and maximum (VT max ), which are the range of body temperatures a lizard will tolerate before becoming inactive through behavioural modifications.…”

Section: Methodsmentioning

confidence: 99%

Modelling the effect of environmental temperatures, microhabitat and behavioural thermoregulation on predicted activity patterns in a desert lizard across its thermally diverse distribution

Parlin

Schaeffer

Jezkova

2020

Journal of Biogeography

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Aim: Temperature plays an important role in determining distributions of ectothermic species, yet many ectotherms have wide distributions across diverse environmental conditions. Our goal was to model regional differences in annual and seasonal activity patterns among populations of Phrynosoma platyrhinos across its climatically diverse distribution. We hypothesize that microhabitat availability and behavioural thermoregulation will not mitigate large-scale climatic differences across the species' distribution, resulting in alteration of activity patterns of populations. Location: Western deserts of North America. Taxon: Desert Horned Lizard (Phrynosoma platyrhinos). Methods: We used biophysical models to (a) model microhabitat conditions at 31 localities across the species' range, (b) model body temperature profiles of a theoretical lizard using microhabitat conditions, physiological and thermal parameters and the ability of lizards to thermoregulate behaviourally and (c) predict year-round activity patterns of P. platyrhinos across its range, quantified as the percentage of time permissible for basking or foraging. Results: The models identified that different populations of P. platyrhinos experience differences in predicted activity patterns, both daily and seasonally, with up to 67% more time suitable for foraging in the southern than northern deserts. Southern populations have more potential for year-round activity, but predicted activity is reduced during hot summer months. The northern populations have less time for activity overall because of low temperatures in the spring and fall. However, summerpredicted activity is greater than in the southern regions. Main conclusions: We detected pronounced regional differences in the times available to P. platyrhinos for activity. We conclude that behaviour and microclimate conditions are not able to fully mitigate the effects of large-scale thermal variation, and that lizards compensate for climatic variation by shifting their daily and seasonal predicted activity patterns. These differences can be tied to inter-population variation in life history traits.

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Selected body temperature of nine species of Mexican horned lizards (Phrynosoma)

Cited by 6 publications

References 23 publications

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Thermal refugia and persistence of Texas horned lizards (Phrynosoma cornutum) in small towns

Modelling the effect of environmental temperatures, microhabitat and behavioural thermoregulation on predicted activity patterns in a desert lizard across its thermally diverse distribution

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