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Author: search.filters.author.Vassa, Chirag NimishSubject: search.filters.subject.Spiny-tailed lizard

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    Heat Hardening and the Influence of Thermal Heterogeneity of Habitat on Aboveground Activity in Spiny-tailed Lizard (Saara hardwickii)
    (Wildlife Institute of India, Dehradun, 2025) Vassa, Chirag Nimish; Dutta, Sutirtha; Kher, Varun
    Human induced climate change has challenged the persistence of many organisms at different biotic levels and alter their interaction with the environment. Ectotherms are particularly vulnerable to anthropogenic climate change due to their reliance on external environment for various life history traits. Thermoregulatory behaviour is often used by many ectotherms especially reptiles to regulate their body temperature and will be crucial in imminent future with intensification of climate change. Although behavioural thermoregulation is widely studied, but studies looking at influence of thermal heterogeneity of a habitat on aboveground activity is limited. Moreover, with escalation in global warming ectotherms might have to rely on another mechanism in addition to thermoregulatory behaviour to combat the effect. One such physiological mechanism is heat hardening a quick response to thermal tolerance that temporarily enhances thermal tolerance, allowing lizards to withstand greater temperatures for a short period. Despite its importance very limited data is available for heat hardening capacity in reptiles. This study examined the influence of thermal heterogeneity of a habitat on aboveground activity in spiny-tailed lizard (Saara hardwickii) and assessed their heat hardening capacity. Additionally, trade-off hypothesis was also tested which has been recently proposed to explain the dynamics of thermal tolerance plasticity. I found positive influence of habitat heterogeneity on aboveground activity of the lizard. However, individuals in both the conditions spent similar amount of time in different behaviours. With respect to phenotypic plasticity i.e. heat hardening, I did not find any evidence of thermal tolerance plasticity during my experimental trials but few individuals did show increased thermal tolerance implying intraspecific variation. Additionally, the results from heat hardening experiments found no support for trade-off hypothesis. My study underscores the importance of habitat heterogeneity for species like spiny-tailed lizard which thrives in extreme temperatures. Furthermore, Lack of phenotypic plasticity in thermal tolerance increases it’s risks to overheating and dependency on behavioural thermoregulation.