Fidelity to nesting sites and orientation ofTrachemys dorbigni(Duméril & Bibron, 1835) (Testudines: Emydidae) female in southern Brazil

Pet distribution modelling: Untangling the invasive potential of Trachemys dorbigni (Emydidae) in the Americas

Human activities have been changing the global biogeographic patterns by the introductions of invasive species. For reptiles, the invasion rate increase of non-native species is remarkably related to the pet trade, especially for freshwater turtles. Here we estimated the invasive potential of the South American turtle Trachemys dorbigni in the Americas using a combination of climatic and human activity variables. We built species distribution models based on data from the native and invasive ranges, using the ensemble model from five different algorithms (GAM, MAXENT, BRT, RF and GBM). We compared the two models' performance and predictions, one calibrated with only climatic variables (climate-driven), and the second also included a descriptive variable of human activity (climate plus human-driven). Suitable areas for T. dorbigni covered occurrence areas of its congeners and highly diversified ecoregions, such as the eastern USA, the islands of Central America, and the south eastern and eastern Brazilian coast. Our results indicate that human activities allow T. dorbigni to establish populations outside of its original climatic niche. Including human activity variables proved fundamental to refining the results to identify more susceptible areas to invasion and to allow the efficient targeting of prevention measures. Finally, we suggested a set of actions to prevent T. dorbigni becoming a highly impacting species in the areas identified as more prone to its invasion.

Contrasting reproductive strategies in a narrow latitude range: the case of D’Orbigny’s slider

Reproductive traits and the level of parental investment in offspring varies between individuals and species. These are central issues in life history theory and evolutionary biology. Maternal body size plays an important role in reproduction, and we usually observe variable investment in offspring by females. Thus, optimal egg size may not be reached in some populations or species. In this study, we tested if reproductive traits differed between populations of D’Orbigny’s slider in a specific geographical area in Brazil. We evaluated the relationship between reproductive traits to maternal body size and clutch size to egg size to determine possible trade-offs across populations. At the population level, maternal body size and reproductive traits of D’Orbigny’s slider were different even in geographically nearby areas. Maternal body size had a positive effect on clutch size, but not on egg size, except in the Arroio Grande population. Nevertheless, we did not observe a negative correlation between clutch and egg size in any population. Although maternal body size had effects in the different populations explaining most of the variation of clutch size, variation in egg size may be the result of decreased survival chances in unpredictable environments and possibly morphological constraints. The trade-off between egg size and number was not observed and this could be expected if resource availability and reproductive allocation by females vary greatly among individuals.