Integrating physiology into conservation: an approach to help guide translocations of a rare reptile in a warming environment

Abstract

The physiology of an animal determines the range of environmental conditions under which it can survive. Surprisingly, relatively few conservation studies have used physiology to make predictions about the performances of translocated individuals in their new environment. Tuatara Sphenodon punctatus are of international significance as the last rhynchocephalian reptile. Natural populations are now restricted to $30 offshore islands in northern New Zealand, where survival of at least one population is threatened by climate change. Translocation to cooler regions (further south, but within the past latitudinal range of the genus) is an important option for future management. However, the genetic suitability of available source populations for environments that are currently cooler is unclear. To help predict the success of translocation, we examined the effects of cool temperature on juveniles sourced from one of the most southerly natural populations and compared these with three lizard species that inhabit southern New Zealand. We found that tuatara possess the same range of preferred body temperature, feeding responses to cool temperatures and critical thermal minimum as these three lizard species. However, tuatara did not digest at temperatures below 12 1C, suggesting that new reintroduction sites must offer enough basking opportunities to allow digestion of prey in winter. As tuatara showed responses to cold temperatures similar to lizards from southern New Zealand, we predict that tuatara will survive if translocated south of their current range, but whether they will be able to produce self-sustaining populations still needs investigation. Physiological predictions from the current study should now be combined with measurements of population performance in an experimental translocation.

Investigating Kleptothermy: A Reptile-Seabird Association with Thermal Benefits

“…The tuatara preferred body temperature is in the range 19.5°-23.rC (Besson and Cree 2011), but recordings of ambient temperatures in our study indicated that this preferred body temperature could be achieved within the shaded forest in only one of the three years studied. Fairy prions enable tuatara to maintain a higher body temperature through the night for several months of the year, October to January (austral spring to summer).…”

Investigating Kleptothermy: A Reptile-Seabird Association with Thermal Benefits

“…The tuatara preferred body temperature is in the range 19.5°-23.rC (Besson and Cree 2011), but recordings of ambient temperatures in our study indicated that this preferred body temperature could be achieved within the shaded forest in only one of the three years studied. Fairy prions enable tuatara to maintain a higher body temperature through the night for several months of the year, October to January (austral spring to summer).…”

Interspecific Interactions: A Case Study using the Tuatara-Fairy Prion Association

“…The temperatures selected by the juvenile tuatara were consistent with previous gradient studies (mean range: 19 -25°C, Besson & Cree, 2010b, mean range: 17 -21°C, , and reveal that tuatara exhibit a preference for warm temperatures, regardless of digestive state, humidity or time of day. In contrast to previous studies, where a lack of variation in body temperatures selected between scotophase (dark phase) and photophase (light phase) has been reported for juvenile tuatara (Besson & Cree, 2010a), this study revealed a clear diel trend in thermoregulatory behaviour. In the present study, the tuatara had the same choice of temperatures available to them over both day and night, quite a different scenario to that in the field.…”

A quantitative synthesis of and predictive framework for studying winter warming effects in reptiles

“…Though environmental temperature is the primary cue by which temperate reptiles coordinate their energy use and reproductive cycles, evidence for disruptive or sublethal effects of high winter temperatures on physiological traits (body condition and biological rhythms) was not statistically significant (Fig. 2 ), with as many “positive” outcomes reported at warmer winter temperatures [e.g., enhanced basking, foraging, digestive, and/or nutrient assimilation efficiency (Ruby 1977 ; Besson and Cree, 2011 )] as “negative” (e.g., depletion of nutrient stores and acceleration of mass loss) (Ruby 1977 ; Costanzo 1989 ; Willette et al 2005 ; Zani et al 2012 ; Muir et al 2013 ; Spencer and Janzen 2014 ; Brischoux et al 2016 ). Strong positive effects appeared to arise more frequently in observational studies, possibly because these are more likely to capture cross-seasonal effects during the growing season that could offset energetic costs (Moore et al 2020 ) and risks of mortality incurred overwinter (Zani 2008 ; Clarke and Zani 2012 ; Bestion et al 2015 ).…”

Investigating Kleptothermy: A Reptile-Seabird Association with Thermal Benefits

“…The tuatara preferred body temperature is in the range 19.5°-23.rC (Besson and Cree 2011), but recordings of ambient temperatures in our study indicated that this preferred body temperature could be achieved within the shaded forest in only one of the three years studied. Fairy prions enable tuatara to maintain a higher body temperature through the night for several months of the year, October to January (austral spring to summer).…”

Interspecific Interactions: A Case Study using the Tuatara-Fairy Prion Association

“…The temperatures selected by the juvenile tuatara were consistent with previous gradient studies (mean range: 19 -25°C, Besson & Cree, 2010b, mean range: 17 -21°C, , and reveal that tuatara exhibit a preference for warm temperatures, regardless of digestive state, humidity or time of day. In contrast to previous studies, where a lack of variation in body temperatures selected between scotophase (dark phase) and photophase (light phase) has been reported for juvenile tuatara (Besson & Cree, 2010a), this study revealed a clear diel trend in thermoregulatory behaviour. In the present study, the tuatara had the same choice of temperatures available to them over both day and night, quite a different scenario to that in the field.…”

A quantitative synthesis of and predictive framework for studying winter warming effects in reptiles

“…Though environmental temperature is the primary cue by which temperate reptiles coordinate their energy use and reproductive cycles, evidence for disruptive or sublethal effects of high winter temperatures on physiological traits (body condition and biological rhythms) was not statistically significant (Fig. 2 ), with as many “positive” outcomes reported at warmer winter temperatures [e.g., enhanced basking, foraging, digestive, and/or nutrient assimilation efficiency (Ruby 1977 ; Besson and Cree, 2011 )] as “negative” (e.g., depletion of nutrient stores and acceleration of mass loss) (Ruby 1977 ; Costanzo 1989 ; Willette et al 2005 ; Zani et al 2012 ; Muir et al 2013 ; Spencer and Janzen 2014 ; Brischoux et al 2016 ). Strong positive effects appeared to arise more frequently in observational studies, possibly because these are more likely to capture cross-seasonal effects during the growing season that could offset energetic costs (Moore et al 2020 ) and risks of mortality incurred overwinter (Zani 2008 ; Clarke and Zani 2012 ; Bestion et al 2015 ).…”

Investigating Kleptothermy: A Reptile-Seabird Association with Thermal Benefits

“…The tuatara preferred body temperature is in the range 19.5°-23.rC (Besson and Cree 2011), but recordings of ambient temperatures in our study indicated that this preferred body temperature could be achieved within the shaded forest in only one of the three years studied. Fairy prions enable tuatara to maintain a higher body temperature through the night for several months of the year, October to January (austral spring to summer).…”

Interspecific Interactions: A Case Study using the Tuatara-Fairy Prion Association

“…The temperatures selected by the juvenile tuatara were consistent with previous gradient studies (mean range: 19 -25°C, Besson & Cree, 2010b, mean range: 17 -21°C, , and reveal that tuatara exhibit a preference for warm temperatures, regardless of digestive state, humidity or time of day. In contrast to previous studies, where a lack of variation in body temperatures selected between scotophase (dark phase) and photophase (light phase) has been reported for juvenile tuatara (Besson & Cree, 2010a), this study revealed a clear diel trend in thermoregulatory behaviour. In the present study, the tuatara had the same choice of temperatures available to them over both day and night, quite a different scenario to that in the field.…”

A quantitative synthesis of and predictive framework for studying winter warming effects in reptiles

“…Though environmental temperature is the primary cue by which temperate reptiles coordinate their energy use and reproductive cycles, evidence for disruptive or sublethal effects of high winter temperatures on physiological traits (body condition and biological rhythms) was not statistically significant (Fig. 2 ), with as many “positive” outcomes reported at warmer winter temperatures [e.g., enhanced basking, foraging, digestive, and/or nutrient assimilation efficiency (Ruby 1977 ; Besson and Cree, 2011 )] as “negative” (e.g., depletion of nutrient stores and acceleration of mass loss) (Ruby 1977 ; Costanzo 1989 ; Willette et al 2005 ; Zani et al 2012 ; Muir et al 2013 ; Spencer and Janzen 2014 ; Brischoux et al 2016 ). Strong positive effects appeared to arise more frequently in observational studies, possibly because these are more likely to capture cross-seasonal effects during the growing season that could offset energetic costs (Moore et al 2020 ) and risks of mortality incurred overwinter (Zani 2008 ; Clarke and Zani 2012 ; Bestion et al 2015 ).…”