João Fabrício Mota Rodrigues

Ecological opportunities, habitat, and past climatic fluctuations influenced the diversification of modern turtles.

Habitat may be viewed as an important life history component potentially related to diversification patterns. However, differences in diversification rates between aquatic and terrestrial realms are still poorly explored. Testudines is a group distributed worldwide that lives in aquatic and terrestrial environments, but until now no-one has evaluated the diversification history of the group as a whole. We aim here to investigate the diversification history of turtles and to test if habitat influenced speciation rate in these animals. We reconstructed the phylogeny of the modern species of chelonians and estimated node divergence dates using molecular markers and a Bayesian approach. Then, we used Bayesian Analyses of Macroevolutionary Mixtures to evaluate the diversification history of turtles and evaluate the effect of habitat on this pattern. Our reconstructed phylogeny covered 300 species (87% of the total diversity of the group). We found that the emydid subfamily Deirochelyinae, which forms the turtle hotspot in south-eastern United States, had an increase in its speciation rate, and that Galapagos tortoises had similar increases. Current speciation rates are lower in terrestrial turtles, contradicting studies supporting the idea terrestrial animals diversify more than aquatic species. Our results suggest that habitat, ecological opportunities, island invasions, and climatic factors are important drivers of diversification in modern turtles and reinforce the importance of habitat as a diversification driver.

Time and environment explain the current richness distribution of non‐marine turtles worldwide

Ecological, historical, and evolutionary hypotheses are important to explain geographical diversity gradients in many clades, but few studies have combined them into a single analysis allowing a comparison of their relative importance. This study aimed to evaluate the relative importance of ecological, historical, and evolutionary hypotheses in explaining the current global distribution of non-marine turtles, a group whose distribution patterns are still poorly explored. We used data from distribution range maps of 336 species of non-marine turtles, environmental layers, and phylogeny to obtain richness estimates of these animals in 2o x 2o cells and predictors related to ecological, evolutionary and historical hypotheses driving richness patterns. Then we used a path analysis to evaluate direct and indirect effects of the predictors on turtle richness. Ancestral area reconstruction was also performed in order to evaluate the influence of time-for-speciation in the current diversity of the group. We found that environmental variables had the highest direct effects on non-marine turtle richness, whereas diversification rates and area available in the last 55 million years minimally influenced turtle distributions. We found evidence for the time-for-speciation effect, since regions colonized early were generally richer than recently colonized regions. In addition, regions with a high number of colonization events had a higher number of turtle species. Our results suggested that ecological processes may influence non-marine turtle richness independent of diversification rates, but probably related to dispersal abilities. However, colonization time was also an important component that must be taken into account. Finally, our study provided additional support for the importance of ecological (climate and productivity) and historical (time-for-speciation and dispersal) processes in shaping current biodiversity patterns. This article is protected by copyright. All rights reserved.

Exploring intraspecific climatic niche conservatism to better understand species invasion: the case of Trachemys dorbigni (Testudines, Emydidae)

Niche conservatism at distinct levels of biological hierarchy is still a highly debated topic in ecology. The general evaluation of niche shifts is mainly addressed to species level, with few explorations at lower or higher hierarchical levels. The freshwater turtle Trachemys dorbigni (Black-Bellied Slider) has recently been divided into two subspecies that occur in very different climatic conditions and is also considered to be an invasive species in parts of eastern and southeastern regions in Brazil. Here, we aimed to explore the effects of evaluating climatic niche conservatism at subspecific levels during the invasive process of T. dorbigni. We evaluated niche conservatism based on similarity (whether niches are more similar than expected by chance) and also measured expansion, stability, and unfilling in the invaded niche. We found that the climatic niches of the T. dorbigni recognized subspecies are very different, but when they are merged, the environmental condition created is more similar to the invasive niche of the subspecies T. dorbigni dorbigni. We also found consistent evidence of niche conservatism in invaded areas, which enables the effective use of ecological niche models to forecast T. dorbigni dorbigni invasion in other geographic regions.

Neutral Biogeography of Phylogenetically Structured Interaction Networks

Little is known about how biogeographic processes affect the dynamics of species interactions in space and time, although it is widely accepted that they drive community assemblage. In functional interactions, such as pollination and seed dispersal, species that share common ancestry tend to retain a common number of interactions and interact with similar sets of species, a pattern more commonly observed for animals than plants. On the one hand, the most coherent explanation for the phylogenetic structure of pollination and seed dispersal networks is that species retain ecological traits over evolution, which would cause the conservation of interaction partners. On the other hand, fundamental processes of biodiversity, such as dispersal and evolutionary rates seem to have important roles shaping the observed phylogenetic structure of mutualistic networks, but no model has been created to study the effect of these processes in the phylogenetic structure of mutualistic interactions. Here, we developed a stochastic simulation model to study the evolution of two interacting groups of species, which evolve independently over the same geographical domain. In our model, individuals of the same interaction group share ecological traits, whereas individuals of different trophic groups are ecologically distinct. We show that even in the absence of ecological differences between individuals, and disregarding any conservation of phenotypical and phenological traits between species, the interplay of dispersal and speciation is still a major driver of complex phylogenetic structure of functional interactions, such as pollination and seed dispersal. This article is protected by copyright. All rights reserved.

Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population’s sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

Revisiting the same-sex mounting in chelonians under the concept of whole-animal

Most vertebrate species are bisexual. But as well as the sexual behavior, same-sex mating-like behavior sometimes occurs. Recently, the same-sex mounting reported from chelonians was reviewed. The potential causes for such behavior that were hypothesized, such as dearth of correct mates or expression of dominance, are of the social domain. On further consideration, it may be instructive to view animals more holistically. We propose here two additional hypothetical causes: intersex gonads, on which we present new data, and misleading body size, on which we speculate from recent literature. We also revisit the effect of the sex ratio on the frequency of same-sex mounting.

Sexual dimorphism, deformations, and epibionts of Phrynops tuberosus(Testudines, Chelidae)

Studies focusing on the natural history of species are essential for developing effective conservation measures and evaluating ecological hypotheses. To this end, we describe natural history data of the Cotinga River toadhead turtle, Phrynops tuberosus , in the Banabuiu River in Ceara, Brazil, and evaluated sexual dimorphism, epibionts, and mutilation effects. We hand-captured 134 individuals by snorkeling, over a period of one year, resulting in the capture of 94 males, 24 females, and 16 juveniles. Females had larger head width and body mass than males, while males had longer tail length. One quarter of the turtles captured had some sort of injury or deformation, most common injuries being missing claws, mutilations, and shell deformations. We found no difference in body condition index between mutilated and non-mutilated animals. Mollusks, insects, and leeches were found as epibionts on P. tuberosus and most of the captured turtles had extensive algal cover. Future studies should focus on understanding the effect of mutilations on animal fitness and reproductive success.

Predicting where species could go: climate is more important than dispersal for explaining the distribution of a South American turtle

Species distributions are determined by abiotic and biotic factors as well as dispersal, but most studies focus exclusively on abiotic (mainly climatic) components. In this study, we evaluated the influence of dispersal as a predictor for species distribution models (SDMs) using the turtle Mesoclemmys tuberculata as an example. We specifically tested whether dispersal is a better predictor of the distribution of M. tuberculata than climatic predictors. We sampled occurrence records of M. tuberculata to build SDMs and used the distance of each cell to the nearest river (river distance) as a predictor for dispersal. In addition, three bioclimatic predictors that quantify temperature and precipitation were used. We applied five different algorithms (BioClim, Domain, Maxent, SVM, and Random Forest) to model the distribution of M. tuberculata and evaluate the relative influence of each predictor variable. Although models including dispersal as a predictor performed slightly better than models omitting it, climatic predictors were found to be more important to describe species distribution across all SDMs. Our results suggest that although dispersal limits the potential geographic areas that the species may reach, abiotic parameters determine where M. tuberculata actually lives. Finally, we used consensus maps to prioritize areas for future field surveys.

Effect of climate change in lizards of the genus Xenosaurus (Xenosauridae) based on projected changes in climatic suitability and climatic niche conservatism

Abstract Accelerated climate change represents a major threat to the health of the planets biodiversity. Particularly, lizards of the genus Xenosaurus might be negatively affected by this phenomenon because several of its species have restricted distributions, low vagility, and preference for low temperatures. No study, however, has examined the climatic niche of the species of this genus and how their distribution might be influenced by different climate change scenarios. In this project, we used a maximum entropy approach to model the climatic niche of 10 species of the genus Xenosaurus under present and future suitable habitat, considering a climatic niche conservatism context. Therefore, we performed a similarity analysis of the climatic niche between each species of the genus Xenosaurus. Our results suggest that a substantial decrease in suitable habitat for all species will occur by 2070. Among the most affected species, X. tzacualtipantecus will not have suitable conditions according to its climatic niche requirements and X. phalaroanthereon will lose 85.75% of its current suitable area. On the other hand, we found low values of conservatism of the climatic niche among species. Given the limited capacity of dispersion and the habitat specificity of these lizards, it seems unlikely that fast changes would occur in the distribution of these species facing climate change. The low conservatism in climatic niche we found in Xenosaurus suggests that these species might have the capacity to adapt to the new environmental conditions originated by climate change.