Lizards in the mist: Thermal niches constrained by habitat and microclimates in the Andes of southern Bolivia

Abstract

Aim To understand how the activity budgets of ectotherms vary in mountain areas with high microclimatic and habitat heterogeneity, and how these factors together with habitat modulate the assemblage of ectotherm communities. Location Tajzara Basin, Cordillera de Sama (3,600–4,300 m a.s.l.), Department of Tarija, Bolivia. Taxon Four lizard species of the genus Liolaemus. Methods After parameterizing the thermal physiology of each species and recording operative temperature time series with dataloggers, we calculated activity budgets for every species across 30 sampling sites. By multimodel inference we evaluated how activity budgets varied across the topography. We also assessed how abundances of each species were predicted by activity budgets, restriction time, temperature deviation, habitat covers and exposure to cold microclimate. Results Activity budgets were not only influenced by elevation but also by the exposure to cold air that comes through saddles from the eastern side of the mountain divide. Although thermal physiological parameters were relatively similar among the species, their abundances were conditioned to different extents by activity budgets, habitat and microclimates. Main conclusions The abundance and distribution of each species across these lizard communities reflect the microclimatic heterogeneity originated by complex topography, which uncouples activity budgets from elevation. Only one species was confined to cold microclimate refugia with higher exposure to Föhn effect. Despite having a relatively similar thermal aspect of fundamental niches, lizards may differ in their realized niches by habitat selection. Habitat specialization could compromise the persistence of some species under global warming by reducing the dispersal possibilities to certain areas where population sustainability might be impaired in the long term. Understanding the heterogeneity of microclimates and habitats and the physiology of the species partially explains their distribution at local scale, and provides insights on how to best confront upcoming climate change effects.

Description and phylogeny of a new species of Liolaemus (Iguania: Liolaemidae) endemic to the south of the Plurinational State of Bolivia

“…Given that our hypothesis is supported by our morphological analyses, we consider the molecular studies of Aguilar-Puntriano et al [66] and the thermal ecology studies of Jiménez-Robles and De la Riva [105] to provide independent evidence that supports our hypothesis. In their research on convergence within the L .…”

“…montanus group. The work of Jiménez-Robles and De la Riva [105] on an assemblage of four species of Liolaemus over a topographic and altitudinal gradients in the Tajzara Basin demonstrates that the lizards they identified as Liolaemus sp. which we here describe as L .…”

Looking at the past to infer into the future: Thermal traits track environmental change in Liolaemidae*

“…These heterogeneous thermal and hydric gradients pose challenges and opportunities for liolaemid species to exploit a variety microhabitats. For example, environmental changes in montane systems modify habitats and leads species to inhabit suboptimal ecological and physiological conditions or promote the invasion into novel niches (Root et al 2003;Thomas et al 2006;Jiménez-Robles and De la Riva 2019).…”

Thermoregulation in a saxicolous population of the lizard Urosaurus ornatus from the northern Chihuahuan Desert, Mexico

“…In addition, additional data on h r earlier in the spring reproductive period (e.g., April-May; Goldberg, 2014) may help refine the estimates of extinction probabilities for this population. The proximity of numerous rock crevices may provide microclimate refugia for these lizards, potentially allowing them more opportunity to persist in the face of climate warming (Sears et al, 2011(Sears et al, , 2016Jiménez-Robles and De la Riva, 2019). The presence of potential competitors, such as Uta stansburiana whose distribution and habitat overlap with U. ornatus (Hammerson, 2007a), could affect the ability of U. ornatus to thermoregulate and be active, and thus affect the estimated hours of activity for U. ornatus.…”