Communities are complex and dynamic systems that change with time. The first attempts to explain how they were structured involve contemporary phenomena like ecological interactions between species (e.g., competition and predation) and led to the competition-predation hypothesis. Recently, the deep history hypothesis has emerged, which suggests that profound differences in the evolutionary history of organisms resulted in a number of ecological features that remain largely on species that are part of existing communities. Nevertheless, both phylogenetic structure and ecological interactions can act together to determine the structure of a community. Because diet is one of the main niche axes, in this study we evaluated, for the first time, the impact of ecological and phylogenetic factors on the diet of Neotropical snakes from the subtropical-temperate region of South America. Additionally, we studied their relationship with morphological and environmental aspects to understand the natural history and ecology of this community. A canonical phylogenetical ordination analysis showed that phylogeny explained most of the variation in diet, whereas ecological characters explained very little of this variation. Furthermore, some snakes that shared the habitat showed some degree of diet convergence, in accordance with the competition-predation hypothesis, although phylogeny remained the major determinant in structuring this community. The clade with the greatest variability was the subfamily Dipsadinae, whose members had a very different type of diet, based on soft-bodied invertebrates. Our results are consistent with the deep history hypothesis, and we suggest that the community under study has a deep phylogenetic effect that explains most of the variation in the diet.

Giraudo, 2001;Franco et al., 2007). Es un género poco conocido, como lo demuestra la descripción reciente de una nueva especie (Franco et al., 2007). Hydrodynastes gigas (Dúmeril; Bibron y Dúmeril, 1854), denominada ñacaniná por los aborígenes guaraníes, es una de las serpientes sudamericanas más grandes, alcanzando hasta 3 m de longitud total (Bernarde y Moura-Leite, 1999). Algunas características intrínsecas de su historia de vida como su gran tamaño corporal y sus necesidades de

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Species distribution models (SDMs) estimate the geographical distribution of species although with several limitations due to sources of inaccuracy and biases. Empirical tests arose as the most important steps in scientific knowledge to assess the efficiency of model predictions, which are poorly rigorous in SDMs. A good approach to the empirical distribution (ED) of a species can be obtained from comprehensive empirical knowledge, that is, well‐understood distributions gathered from large amount of data generated with appropriate spatial and temporal sample coverage. The aims of this study were to (a) compare different SDMs predictions with an ED; and (b) evaluate if fuzzy global matching (FGM) could be used as an index to compare SDMs predictions and ED. Six algorithms with 5 and 20 variables were used to assess their accuracy in predicting the ED of the venomous snake Bothrops alternatus (Viperidae). Its entire distribution is known, thanks to thorough field surveys across Argentina, with 1,767 records. ED was compared with SDMs predictions using Map Comparison Kit. SDMs predictions showed important biases in all methods used, from 70% sub‐estimation to 40% over‐estimation of ED. BIOCLIM predicted ≈31% of B. alternatus ED. DOMAIN predicted 99% of ED, but over‐estimated 40% of the area. GLM with five variables calculated 75% of ED, while Genetic Algorithm for Rule‐set Prediction showed ≈60% of ED; the last two presenting overpredictions in areas with favorable climatic conditions but not inhabited by the species. MaxEnt and RF were the only methods to detect isolated populations in the southern distribution of B. alternatus. Although SDMs proved useful in making predictions about species distribution, predictions need validation with expert maps knowledge and ED. Moreover, FGM showed a good performance as an index with values similar to True Skill Statistic, so that it could be used to relate ED and SDMs predictions.

One of the current challenges of evolutionary ecology is to understand the effects of phylogenetic history (PH) and/or ecological factors (EF) on the life‐history traits of the species. Here, the effects of environment and phylogeny are tested for the first time on the reproductive biology of South American xenodontine snakes. We studied 60% of the tribes of this endemic and most representative clade in a temperate region of South America. A comparative method (canonical phylogenetic ordination—CPO) was used to find the relative contributions of EF and PH upon life‐history aspects of snakes, comparing the reproductive mode, mean fecundity, reproductive potential, and frequency of nearly 1,000 specimens. CPO analysis showed that PH or ancestry explained most of the variation in reproduction, whereas EF explained little of this variation. The reproductive traits under study are suggested to have a strong phylogenetic signal in this clade, the ancestry playing a big role in reproduction. The EF also influenced the reproduction of South American xenodontines, although to a lesser extent. Our finding provides new evidence of how the evolutionary history is embodied in the traits of living species.

Revista Mexicana de Biodiversidad 86 (2015) 674-684 Biogeografía Relaciones biogeográficas de los grandes ríos de la cuenca del Plata basadas en ensambles de serpientes Biogeographical relationships of the large rivers of the Plata Basin based on snake assemblages Resumen Los grandes ríos del Plata fluyen hacia el sur desde latitudes intertropicales a templadas y extienden la distribución de especies tropicales. Examinamos las siguientes hipótesis sobre relaciones biogeográficas de la ofidiofauna entre tramos de los ríos: el Alto Paraná tiene mayor afinidad con el Alto Uruguay, el Paraná Medio con el Paraguay Inferior respecto otros tramos del propio Paraná, y el Delta Superior tiene mayor afinidad con el Paraná Medio y el Delta Inferior con el Uruguay Inferior. Comparamos los tramos de los ríos y estos con las unidades fitogeográficas, usando 13,039 ejemplares de 104 taxones, mediante análisis de parsimonia de endemismos y similitud. Los resultados apoyan las 2 primeras hipótesis, no la tercera. El Delta Superior-Delta Inferior formaron un grupo con elevada similitud relacionado con el Uruguay Medio-Uruguay Inferior, y con el análisis de parsimonia de endemismos formaron un clado separado. Los tramos se relacionaron con las biorregiones que atraviesan, aunque el Uruguay Medio-Inferior solo con la provincia Paranaense (análisis de parsimonia de endemismos), debido a especies atlántico-paranaenses que alcanzan mayores latitudes por este río. El Paraná Medio-Paraguay Inferior-Paraná Superior se relacionan con el Chaco Húmedo y se discuten criterios de regionalización previos. Los ríos del Plata constituyen áreas de transición biogeográfica importantes para su conservación debido a la superposición de componentes bióticos tropicales y templados. Derechos Reservados © 2015 Universidad Nacional Autónoma de México, Instituto de Biología. Este es un artículo de acceso abierto distribuido bajo los términos de la Licencia Creative Commons CC BY-NC-ND 4.0. AbstractThe large rivers of the Plata flow southward from intertropical to temperate latitudes, extending the distribution of tropical species. We tested biogeographic hypotheses about relationships among sections of the rivers comparing their snake fauna: the High Paraná has greater affinity with the High Uruguay, the Middle Paraná with Lower Paraguay regarding other sections of Paraná itself, and the Upper Delta has greater affinity with the Middle Paraná and the Lower Delta with Lower Uruguay. We compared sections of rivers and these with phytogeographical units, by means of 13,039 records of 104 taxa, using parsimony analysis of endemicity and similarity. Our results support the first two hypotheses, not the third one. Upper Delta-Lower Delta formed a group with high similarity related to the Middle Uruguay-Lower Uruguay, and with PAE it formed a separate clade. Sections were associated with the bioregions that they crossed, although the Middle-Lower Uruguay did it only with the Parana * Autor para correspondencia.Correo electrónico: vanearzamendia@gmail.com (V. Arza...

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Studying life history (LH) allows a broader understanding of organisms and populations’ responses to their environments. Snakes display an immense diversity in terms of reproductive traits, which is reflected in LH traits. The aim of this study is to compare reproductive biology and morphological variables in viviparous and oviparous snakes of a temperate South American community. We studied nearly 1000 specimens of eight oviparous and seven viviparous species pertaining to the four taxonomic families that inhabit the Paraná basin floodplain. Dimorphic variables did not show a different tendency between oviparous and viviparous species. Our results showed that the reproductive mode determined some reproductive traits of a snake’s LH, such as reproductive frequency and reproductive potential. Oviparous snakes reproduce annually, while viviparous snakes reproduce biannually or multi-annually. All species showed seasonal reproductive cycles and no correlation between clutch size (fecundity) and maternal body size. The reproductive strategy of both oviparous and viviparous species of the Paraná River floodplain was to adjust their reproductive cycles to both hydrological cycle of the river and temperature regime. The reproductive traits under study are suggested to have been influenced by environmental factors as well as by genetic characteristics. The studied assemblage is the result of an admixture of evolutionarily distinct clades, each contributing a set of species with different reproductive traits. Although we do not ignore this fact, we emphasize the importance of studying reproductive LH as raw material for an integrative analysis.