Rodolfo is a PhD student at Monash University, Melbourne, Australia. He is a herpetologist with an interest in physiology and biogeography. Rodolfo shares his recent work on the ecophysiological strategies used by an Australian skink, Lampropholis guichenoti, to survive in diverse, variable climatic conditions.
Rodolfo on top of Cradle Mountain, Tasmania.
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Institute. School of Biological Sciences, Monash University, Melbourne, Australia.
Academic life stage. PhD student.
Major interests. Herpetology, Ecophysiology and Biogeography.
Current study system. I’m studying lizards. These amazing dry-skinned ectotherms depend on environmental temperatures to keep their own body temperature within suitable limits. They employ several strategies, such as thermoregulatory behaviour and tolerance to extreme temperatures, to cope with climatic variation. In my PhD, I’ve focused on an Australian genus, Lampropholis skinks, to study how the environment interacts with physiology, setting their distribution. Lampropholis skinks are small (1–4 g) and found all down the Australian east coast, spanning ~30 degrees of latitude, and must therefore cope with considerable climatic variation across their range. My work characterises the different ecophysiological strategies used by these skinks to cope with very different climatic regimes.
Recent paper in JBI. Anderson, R. O., Alton, L. A., White, C. R., & Chapple, D. G. Ecophysiology of a small ectotherm tracks environmental variation along an elevational cline. Journal of Biogeography. https://doi.org/10.1111/jbi.14311
The Garden-skink (Lampropholis guichenoti) foraging on the leaf litter. Photo by Jules Farquhar.
Motivation behind this work. The ecophysiology of species, that is, how organisms interact with their environment through their physiology, is key to understanding the limits of its geographic distribution. One species of Lampropholis (the Garden-skink, L. guichenoti) is found across different elevations in the Australian Alps, which are in the southern part of Australia. At the top of their distribution in the Alpine National Park (~1500 masl), in the state of Victoria, temperatures can go below zero and snow is present during the coldest months of the year. By contrast, in the lowlands, the climate is much hotter and drier. This huge disparity across an elevational gradient suggests that Garden skinks must have incredibly flexible physiological strategies. I wanted to know how the ecophysiology – which includes metabolism, thermal physiology, water balance, and locomotion – changes in response to climatic variation. Understanding how ecophysiology shifts across climatic gradients could help reveal how these small animals can inhabit contrasting environments, survive, and potentially expand their geographic range.
Key methodologies. This study comprised three parts. Firstly, I went to the field to collect the skinks, either by hand or by mealworm fishing. I went to four different sites, ranging from the lowlands (near the sea level) up to 1500 masl. Secondly, caught skinks were brought to the lab at Monash University, Melbourne, so I could quantify several ecophysiological traits (e.g., thermal tolerances, water loss, metabolism). Finally, I used the ecophysiological data to develop mechanistic models (NicheMapR) to predict the physiology and behaviour of the skinks in the field. This integrative approach provided interesting insights about the role of behaviour in the survival of these animals, especially in the cold highlands. I found that thermal physiology, metabolism, and rates of water loss, follow the demands of different climates. Skinks in the highlands are more cold tolerant and have a more efficient metabolism. In the drier and warmer lowlands, the skinks have to save their body water content, but they can reach higher locomotor performance. Finally, behavioural thermoregulation can maintain body temperature above freezing conditions and increase the activity time of skinks.
View of the Alpine National Park, Victoria. Garden skinks (Lampropholis guichenoti) can be found to altitudes of up to ~1500 m, where temperatures drop to below zero.
Garden skinks (Lampropholis guichenoti) were collected in dry woodlands across the elevational gradient in the Alpine National Park.
Major results. We demonstrated how an integrative approach can be very fruitful for biogeographical research. We showed that physiology as a whole is affected by climate, going beyond approaches that solely analyse thermal physiology. The environment is complex, and multiple interactions occur between the physical world and organisms. In the same study, we showed that in response to low temperatures, skinks increase their metabolic rate and energy efficiency, and elevate their cold tolerance. In dry and hot environments, skinks have to avoid water loss to prevent dehydration, but they have fewer fitness costs. Therefore, thermal physiology, metabolism and water balance are flexibly modulated to shape the fundamental niche of these skinks. Our work demonstrates that understanding the interaction between physiology and climate is key to understanding how organisms can survive in different types of environments, and hence the processes shaping their geographic distribution.
Unexpected challenges. The fieldwork was certainly the hardest challenge in this project. My field assistants and I had to actively search for the lizards for several days in areas with hard access. The fieldwork was also carried out in late summer/early Autumn, when the temperatures in the highlands drop dramatically at night. In a few instances, we had to refuge in emergency huts to spend the night in the field. Fortunately, all of us survived and we found a sufficient number of skinks for my experiments.
One of the emergency huts where people can find refuge during bad weather conditions. In one of our field works to the Alpine National Park, we spent a night in a similar hut to shelter from the wind and freezing temperatures.
Next steps. A crucial next step would be to disentangle the contributions of plasticity versus adaptation to the ecophysiological changes across elevation in the Garden skinks. To do that, a common garden experiment would be necessary. This would provide a more powerful inference about the fundamental niche and its role in shaping the distribution of these ectothermic animals.
If you could study any organism on Earth, what would it be? It would have to be the Maned Wolf (Chrysocyon brachyurus), or Lobo-Guará in Portuguese, because this extraordinary animal is perhaps the most beautiful mammal in the world, but is sadly a near threatened species. The savannah-like Cerrado in Brazil, where the Maned Wolf lives, is also endangered and deserves more attention from the general public and scientific community.