Niche Overlap

Although the feeding ecology of sympatric anurans has been studied, less is known about the food habits of co-occurring invasive and native frog species, particularly in the Neotropics. We compared the food habits of invasive bullfrogs (Lithobates catesbeianus) and native thin-toed frogs (Leptodactylus cf. latrans) in a locality of Southeastern Brazil. Monthly field surveys and stomach content analyses were performed between September 2008–April 2009 and September–November 2009. Prey items were identified to the lowest taxonomic level and diet overlap was estimated. Juveniles of both species had similar body sizes, but adult thin-toed frogs were smaller than adult bullfrogs. Insects and spiders dominated the diets of juveniles of both species and of adult thin-toed frogs, whereas anurans and water bugs predominated in adult bullfrog diets. Thin-toed frogs consumed a larger number of prey items than bullfrogs, which in turn consumed more voluminous prey items. Aquatic and amphibious prey items were more common in bullfrog diets. Adult thin-toed frogs preyed on juvenile bullfrogs, although the opposite was not observed. Diet overlap of equivalent age groups varied from low to intermediate between species. Our results showed that that dietary differences may be one of the factors allowing the coexistence of both species at the studied area, although not excluding possible negative impacts on native thin-toed frogs because of the presence of invasive bullfrogs.

neanderthals (Homo neanderthalensis) were distributed across a vast region from europe to western and central Asia. the neanderthals' paleoecology and distribution has been extensively studied in europe where the species originated. However, very little is known about their paleoecology in southwestern Asia. Here, we employed species distribution modelling and 45 Middle Palaeolithic (c. 200,000-40,000 years BCE) sites location associated with fossil and/or lithic artefacts made by the neanderthals to examine the expansion of the neanderthals on the iranian plateau in southwestern Asia. We estimated the niche overlap between neanderthals and wild goat, wild sheep and persian gazelle by modelling their past distribution using 200, 143 and 110 occurrence records respectively. the results show that neanderthals had highest niche overlap with wild goat in the study area. this analysis revealed that the most suitable neanderthals' habitats in southwestern Asia were located in the Zagros Mountains stretches from northwestern and western and some isolated patches in the central parts of the iranian plateau. the annual precipitation and maximum temperature of the warmest month were the most important predictor of the species' distribution. This finding shows that the southern edge of the neanderthals distribution was limited by warm summer. our results provide important information for future field investigations and excavations in the area. Our closest relative, Neanderthals, separated from the modern human lineage around 800,000-1,200,000 years ago 1 and became extinct around 40 kya 2. During that time, Neanderthals were distributed across Europe and Asia (ibid) and experienced several glacial and interglacial periods. Besides of the questions concerning their coexistence with Homo sapiens and replacement, there are still many other basic questions which are not fully answered such as Neanderthals' expansions and their adaptation capabilities in different environments. Despite Neanderthals being extensively studied across Europe 3-10 and in the Levant 11-13 , very little is known about its paleoecology on the Iranian Plateau. Knowing Neanderthals paleoecology promotes deciphering the drivers of Neanderthal range expansion, their extinction and identifying the Homo neanderthalensis and Homo sapiens contact zone and understanding our own species past ecology. The Iranian Plateau, the southern east-most expansion of the Neanderthals, is located in southwestern Asia and has been recognized as an important dispersal corridor for Pleistocene hominin species and played a prominent role in their evolution 14-16. Over the past decades, Middle Palaeolithic (c. 200,000-40,000 years BCE) occupations have been discovered in a number of different Palaeolithic sites in the Iranian Plateau 15-19 , but no study was performed to determine the species paleo-distribution and identify abiotic drivers of its distribution, both of which are necessary in understanding the Middle Palaeolithic species paleoecology. Recently, Species Distribution Models (SDMs) have found many applications in paleoecology and paleobiogeography 20,21. Rapid advances in species distribution modelling 22,23 and availability of environmental data characterizing past climatic conditions 24 made it possible to reconstruct the past distribution of species 21. This gives paleoecologists and historical biogeographers an opportunity to study and test hypotheses regarding species dispersal and evolution 20,25. These models were recently applied in studying paleoecology of hominin species and increased our knowledge of their paleodistributions 26-29. For example, Benito et al. 28 reconstructed open 1