The demography of the lizard Tropidurus torquatus (Squamata, Tropiduridae) in a highly seasonal Neotropical savanna

The demography of a population of Tropidurus torquatus was studied from March 1996 until December 1998, in the Cerrado biome of the Central Brazil, using the method of capture and recapture. Population size, number of incoming individuals in the population, and age structure varied seasonally, reflecting the reproductive cycle of the species. The instantaneous rate of population increase did not differ from zero throughout the study. In general, the permanence rate of juveniles and adults were low, indicating a large turnover of individuals in the population, with a maximum life expectancy of three years. The sex-ratio among adults was biased toward females. Since no bias was observed among juveniles and there was no difference in adults permanence between sexes, we suggestet that the biased adult sex-ratio resulted from a lower permanence of males during a short ontogenetic period, when secondary sexual characteristics develop. When compared to T. itambere, the studied population of T. torquatus attained a higher density and a greater female bias in the sex-ratio. In general, the studied population presented characteristics that, according to life history theory, should be associated with early age at maturity and polyginy: short life expectancy, high population turnover, and female biased sex-ratios

Formulating conservation targets for a gap analysis of endemic lizards in a biodiversity hotspot

Species gap analyses that adopt conservation targets based on individual species attributes recognize that some biodiversity features need more protection than others and should lead to better outcomes than uniform conservation targets. In the Brazilian Cerrado hotspot, 4 of the 30 endemic lizard species are included in the IUCN or Brazilian red lists of threatened species. For 18 species with more than 5 occurrence records, we produced distribution models using Maxent and for 12 species with less than 5 occurrence records we used a 5. km radius around the records to indicate distributions. For all species, we estimated habitat loss after discounting cleared areas from indicated distributions. Non-modeled species were considered as truly restricted-range endemics and had conservation targets set a priori as 100%. We formulated conservation targets for 18 modeled species based on three characteristics: natural rarity, vulnerability, and life-history. We estimated vulnerability from a model of future habitat loss across the Cerrado, derived with Maxent. We then performed a gap analysis considering strictly protected conservation areas. We applied percentage targets (between 12% and 23%) to estimated species distributions prior to habitat loss and evaluated the targets against the presence of the species within strictly protected conservation areas. Disturbingly, only one species is adequately protected by the current system of protected areas. We also found that one species is a minor conservation gap, whereas the remaining 28 species are either major (13) or total (5) conservation gaps. Habitat loss has erased a significant fraction of the original distribution of Cerrado endemic lizards and the existent network of protected areas is wholly inadequate to ensure their conservation. The use of conservation targets based on natural rarity, vulnerability, and life-story will support more defensible conservation guidelines than commonly used uniform targets for this threatened Neotropical savanna biome. © 2014 Elsevier Ltd

Microhabitat variation explains local-scale distribution of terrestrial Amazonian lizards in Rondonia, Western Brazil

We investigate the role of ecology and phylogeny in the association between lizard abundance and microhabitat variables in an Amazon rain forest site. Using pitfall trap arrays, we collected data from 349 individuals belonging to 23 lizard species. After accounting for spatial autocorrelation and using a canonical correspondence analysis (CCA), we found that lizard captures were significantly associated with microhabitat variables, which accounted for 48 percent of the observed variation. Furthermore, a canonical phylogenetic ordination (CPO) indicated that microhabitat variables are more important in determining the distribution of lizard species than phylogenetic relationships among species. Termite nests, canopy openness, and tree circumference were strongly associated with the number of captures of certain lizard species. Our results confirm autecology studies of individual lizard species for which data are available. We suggest that maintaining heterogeneous forested microhabitats should be a central goal for sustaining a high lizard biodiversity in Amazon rain forests

Time Of Activity is a Better Predictor of The Distribution of a Tropical Lizard than Pure Environmental Temperatures

© 2020 Nordic Society Oikos. Published by John Wiley & Sons Ltd Environmental temperatures influence ectotherms’ physiology and capacity to perform activities necessary for survival and reproduction. Time available to perform those activities is determined by thermal tolerances and environmental temperatures. Estimates of activity time might enhance our ability to predict suitable areas for species’ persistence in face of climate warming, compared to the exclusive use of environmental temperatures, without considering thermal tolerances. We compare the ability of environmental temperatures and estimates of activity time to predict the geographic distribution of a tropical lizard, Tropidurus torquatus. We compared 105 estimates of activity time, resulting from the combination of four methodological decisions: 1) how to estimate daily environmental temperature variation (modeling a sinusoid wave ranging from monthly minimum to maximum temperature, extrapolating from operative temperatures measured in field or using biophysical projections of microclimate)? 2) In which temperature range are animals considered active? 3) Should these ranges be determined from body temperatures obtained in laboratory or in field? And 4) should thermoregulation simulations be included in estimations? We show that models using estimates of activity time made with the sinusoid and biophysical methods had higher predictive accuracy than those using environmental temperatures alone. Estimates made using the central 90% of temperatures measured in a thermal gradient as the temperature range for activity also ranked higher than environmental temperatures. Thermoregulation simulations did not improve model accuracy. Precipitation ranked higher than thermally related predictors. Activity time adds important information to distribution modeling and should be considered as a predictor in studies of the distribution of ectotherms. The distribution of T. torquatus is restricted by precipitation and by the effect of lower temperatures on their time of activity and climate warming could lead to range expansion. We provide an R package ‘Mapinguari’ with tools to generate spatial predictors based on the processes described herein

Time Of Activity is a Better Predictor of The Distribution of a Tropical Lizard than Pure Environmental Temperatures

© 2020 Nordic Society Oikos. Published by John Wiley & Sons Ltd Environmental temperatures influence ectotherms’ physiology and capacity to perform activities necessary for survival and reproduction. Time available to perform those activities is determined by thermal tolerances and environmental temperatures. Estimates of activity time might enhance our ability to predict suitable areas for species’ persistence in face of climate warming, compared to the exclusive use of environmental temperatures, without considering thermal tolerances. We compare the ability of environmental temperatures and estimates of activity time to predict the geographic distribution of a tropical lizard, Tropidurus torquatus. We compared 105 estimates of activity time, resulting from the combination of four methodological decisions: 1) how to estimate daily environmental temperature variation (modeling a sinusoid wave ranging from monthly minimum to maximum temperature, extrapolating from operative temperatures measured in field or using biophysical projections of microclimate)? 2) In which temperature range are animals considered active? 3) Should these ranges be determined from body temperatures obtained in laboratory or in field? And 4) should thermoregulation simulations be included in estimations? We show that models using estimates of activity time made with the sinusoid and biophysical methods had higher predictive accuracy than those using environmental temperatures alone. Estimates made using the central 90% of temperatures measured in a thermal gradient as the temperature range for activity also ranked higher than environmental temperatures. Thermoregulation simulations did not improve model accuracy. Precipitation ranked higher than thermally related predictors. Activity time adds important information to distribution modeling and should be considered as a predictor in studies of the distribution of ectotherms. The distribution of T. torquatus is restricted by precipitation and by the effect of lower temperatures on their time of activity and climate warming could lead to range expansion. We provide an R package ‘Mapinguari’ with tools to generate spatial predictors based on the processes described herein