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Climate change is impacting species globally, with many populations declining at an accelerated rate toward extinction. Ectothermic species are particularly vulnerable given their reproductive success is linked to environmental temperatures. Studies of the effect of temperature on reproductive success in oviparous squamates have focused mostly on nest temperatures, after eggs are deposited. However, in some species gravid females are known to thermoregulate differently than other adults to increase reproductive success. It is essential to understand what influences the thermal biology of breeding adults in a population to implement targeted conservation strategies. The Florida scrub lizard Sceloporus woodi is an endemic species listed as near‐threatened due to decreasing populations. This study is the first to document the thermal biology of these breeding adults in relation to size, sex, and reproductive status. A t test was used to determine whether sexual dimorphism was present in the sampled S. woodi. Full linear mixed‐effects models were used to test the influence of size, sex, and reproductive status on the thermal biology of S. woodi. Despite female‐biased sexual size dimorphism, there were no sex‐based differences in body temperature in the studied population. Interestingly, reproductive status influenced thermal biology of females during the breeding season, with gravid females maintaining lower body temperatures compared to nongravid females. However, gravid females did not regulate their body temperatures more precisely compared to nongravid females. These results indicate the population viability of this endemic species is potentially linked to the different thermoregulatory requirements of gravid females as compared to other adults. Lower body temperatures of gravid females, exacerbated by their lack of thermal precision, have disconcerting conservation implications in the face of climate warming. Future studies focusing on gravid females are warranted to attain effective biodiversity conservation strategies mitigating the impacts of climate warming., Interestingly, reproductive status was an important influence on thermal biology during breeding season, with gravid females maintaining lower body temperatures compared to nongravid females and males. Furthermore, gravid females did not regulate their body temperatures more precisely compared to nongravid females. Gravid females’ lower body temperatures exacerbated by their lack of thermal precision differences compared to nongravid females have disconcerting conservation implications for the endemic Florida scrub lizard in the face of climate warming.

The expansion of human-altered landscapes affects biodiversity on every continent. In the Cerrado biodiversity hotspot of central Brazil, Eucalyptus plantations increasingly claim large tracts of native habitats thanks to favorable soils, climate and booming pulp firm profits. Yet, the highs and lows of the economy including government incentives over the years riddled the landscape with abandoned plantations, which are not subject to active restoration. Despite the well-documented pattern anthropogenic disturbances negatively affect Cerrado biodiversity, little is known about the processes driving species co-existence within these abandoned plantations. Herein, we use phylogenetic community structure indices to test if potential processes assembling lizard communities differ between undisturbed Cerrado habitats and disturbed abandoned Eucalyptus plantations; and if so, are these processes predictable. In addition, we explore the applicability of phylogenetic community structure indices as ecological indicators of anthropogenic disturbance in the Cerrado biodiversity hotspot. We address these questions at a local scale, recording lizard species richness and abundance along transects of undisturbed Cerrado and adjacent disturbed abandoned Eucalyptus plantations. Morphological measurements were collected from captured lizards to test for trait conservatism. We investigated if phylogenetic community structure is altered in a predictable manner by comparing (i) phylogenetic species variability, (ii) phylogenetic species richness and (iii) phylogenetic species evenness. To test for significant differences between undisturbed and disturbed communities, we performed two-tailed paired t-tests for each phylogenetic community index. We also test for phylogenetic clustering and overdispersion to determine if potential processes assembling lizard communities differ between undisturbed and disturbed communities. Furthermore, we compare phylogenetic community structure indices to other commonly used diversity indices (taxonomic, functional and phylogenetic diversity) to evaluate their applicability as ecological indicators of anthropogenic disturbance in the Cerrado. We demonstrated phylogenetic clustering in two out of three of the undisturbed Cerrado lizard communities supporting habitat filtering as the potential dominant assembly process; whereas 67% of the disturbed Eucalyptus communities showed phylogenetic overdispersion supporting competition as the potential predominate assembly process. This indicates anthropogenic disturbance, in the form of abandoned Eucalyptus plantations, may alter phylogenetic community structure in a predictable manner, leading to the loss of closely related species in the disturbed plantation forests. The highly endemic biota of the Cerrado is composed of closely related species that share similar traits for survival, most likely a consequence of frequent episodic fires during the dry season. Interestingly, phylogenetic community structure indices and diversity indices did not converge on the same disturbed site to prioritize for active restoration; thereby, providing a cautionary tale on the applicability of the indices as ecological indicators for the Cerrado biodiversity.

Insular species are predicted to broaden their niches, in response to having fewer competitors. They can thus exploit a greater proportion of the resource spectrum. In turn, broader niches are hypothesized to facilitate (or be a consequence of) increased population densities. We tested whether insular lizards have broader dietary niches than mainland species, how it relates to competitor and predator richness, and the nature of the relationship between population density and dietary niche breadth. We collected population density and dietary niche breadth data for 36 insular and 59 mainland lizard species, and estimated competitor and predator richness at the localities where diet data were collected. We estimated dietary niche shift by comparing island species to their mainland relatives. We controlled for phylogenetic relatedness, body mass and the size of the plots over which densities were estimated. We found that island and mainland species had similar niche breadths. Dietary niche breadth was unrelated to competitor and predator richness, on both islands and the mainland. Population density was unrelated to dietary niche breadth across island and mainland populations. Our results indicate that dietary generalism is not an effective way of increasing population density nor is it result of lower competitive pressure. A lower variety of resources on islands may prevent insular animals from increasing their niche breadths even in the face of few competitors.

Aim The species population density–range size relationship posits that locally abundant species are widely distributed. However, this proposed pattern has been insufficiently tested. The few tests conducted were usually limited in scale and gave conflicting results. We tested the generality of the positive population density–range size relationship. We then studied whether similar environmental niche requirements are correlated with range size and with population density to search for mechanisms driving the hypothesized link between population density and range size. Location Worldwide. Methods We collected data on population density, range size and environmental niche for a global dataset of 192 lizard, 893 bird and 350 mammal species. Assessing the relationship between population density and range size and environmental niche parameters, we corrected for phylogenetic relationships, body mass, diet and study area. Results Our findings reveal that density had a weak negative correlation with bird range size and was unrelated to lizard and mammal range size. These trends were consistent at the global scale and across the biogeographical realms. Range size was related to relatively similar environmental niche parameters in all groups. Population density, however, was explained by taxon-specific factors and was therefore unrelated to range size by common causation. Main conclusions We suggest that the positive relationship between population density and range size identified in previous studies might be an artefact arising through incomplete sampling of range sizes. Our results indicate that the mechanisms shaping population density and range size may be independent.

Aim Dietary niche breadth has long been hypothesized to decrease towards lower latitudes as the numbers of competitors increase. Geographical variation in niche breadth is also hypothesized to be linked to high ambient energy levels, water availability, productivity and climate stability – reflecting an increased number of available prey taxa. Range size and body size are also hypothesized to be strongly and positively associated with niche breadth. We sought to determine which of these factors is associated with geographical variation in niche breadth across broad spatial scales and thus potentially drive the latitudinal diversity gradient. Location Global. Methods We collated volumetric dietary data for 308 lizard species. For each species, we gathered data on number of sympatric lizard species (a proxy for the number of competitors), annual temperature and precipitation, net primary productivity, seasonality, range size and body size. We examined the relationship between dietary niche breadth and focal parameters using both ordinary and phylogenetic generalized least squares regressions. Results Niche breadth was positively related to annual precipitation, temperature seasonality and range size, and negatively related to body size. Lizard species richness increased towards lower latitudes. Dietary niche breadth, however, was unrelated to parameters reflecting diversity gradients, such as primary productivity, annual temperature, precipitation seasonality and, crucially, the number of potential competitors. Main conclusions Contrary to prevailing ecological theory, competition is unrelated to dietary niche breadth. We found no support for interspecific competition driving the latitudinal diversity gradient. Rather, we found variation in niche breadth to be associated with water availability, climate stability, range size and body size. Our study casts doubt on the common assumption that tropical species are specialists, promoting greater alpha diversity, and on the assumption that the number of sympatric species is reflected in the intensity of interspecific competition.

The rapid expansion of human altered landscapes affects biodiversity on every continent. A fundamental goal of conservation biologists is to understand why certain species are at risk of extinction while others are able to persist in human altered landscapes. Afforestation, the conversion of unforested lands to planted forest, is rapidly altering many natural landscapes worldwide. In the Cerrado (Brazilian savanna), a global biodiversity hotspot, a shortage of government incentives has the landscape riddled with abandoned plantation forests that are not subject to active restoration projects. Studies investigating the impacts of abandoned plantations on biodiversity are strikingly limited. We examine the effects of abandoned Eucalyptus plantations on the structure of Cerrado lizard communities. We assessed changes in lizard capture, richness and equitability along cerrado sensu stricto—Eucalyptus transects. Our results indicate abandoned Eucalyptus plantations have subsets of Cerrado species persisting with a great loss of endemic species. The cerrado sensu stricto—Eucalyptus linear transect analysis demonstrated distance from native habitat is positively correlated with loss of biodiversity. We performed correspondence analyses to summarize the variation in species captures across different sites, habitats and pitfall array positions. These analyses depicted strong species associations between habitats and their pitfall array positions. This study is the first to show the negative impacts of abandoned Eucalyptus plantations on Cerrado lizard communities, serving as a cautionary tale of Cerrado biodiversity non-resilience in abandoned Eucalyptus plantations. Mitigation requires that abandoned Eucalyptus plantations are made more suitable to Cerrado lizards by implementing targeted habitat heterogeneity restoration.