Ecophysiological conservativeness and size-mediated plasticity in the High Mountain Lizard Atlantolacerta andreanskyi confirm its vulnerability to climate change

Recent studies have reported declines in lizard populations associated with local warming trends and alteration of thermal niches. These studies suggest that there are some key physiological and behavioural parameters that determine the sensitivity of each species to the local context of global warming. The Atlas Dwarf Lizard, Atlantolacerta andreanskyi, is a small lacertid lizard endemic to the High Atlas Mountains (2200-3500 m a.s.l.) of Morocco. Its populations display a disjointed distribution across 440 km, consisting of phylogenetic lineages separated since the Miocene, suggesting a morphologically cryptic species complex. To establish whether this deeply rooted evolutionary divergence has promoted shifts in fundamental niche occupancy, but also whether there is any ecophysiological plasticity, preferred body temperatures (Tpref) and evaporative water loss (EWL) were examined in populations of the central and western High Atlas. Our results revealed no differences in Tpref across populations, but lower thermal preferences in (gravid) females. In contrast, EWL varied between populations, but not between sexes. In both cases, sexual patterns remained similar between populations, and differences were not evident between body sizes. Importantly, Tpref and EWL traded off, even if with a common trend across populations. These results suggest that ecophysiology remains mostly conservative within this species complex and that hydric ecology, which is more closely associated with body size, is more flexible than thermal ecology. The increase of lizard body size with altitude, in agreement with life history trends with seasonality observed in other Mountain Lizards, cannot be interpreted in terms of ecophysiological adaptation since the low-altitude populations of small lizards are the ones most exposed to dehydration. Rather, local environment and possibly aspects of evolutionary history could be involved. Overall, the ecophysiological conservativeness of this endemic species confirms its vulnerability to climate change, and indicates that hydric ecology needs to be incorporated into general models regarding how behavioural plasticity may mediate resilience to such changes. In this context, the low-altitude populations are the most vulnerable ones, and local management measures should focus on the conservation of vegetation and water bodies.