Aim Because of their recent evolutionary radiation, capuchin monkeys represent an ideal group with which to investigate ecomorphological adaptations in relation to geography and climate. Our aim was to identify patterns of both skull size and shape variation in capuchins in relation to environmental variables and latitude.Location Tropical and subtropical South America.Methods We performed geometric morphometric analyses of skull shape in 228 capuchin monkey individuals belonging to either the genera Sapajus (seven species) or Cebus (two species), representing 94 localities in South America. Twenty-three homologous landmarks were digitized to describe skull shape. We regressed skull shape against latitude, longitude, skull size and environmental variables, using ordinary and partial least squares regressions. Variation partitioning was used to test for the relative contribution to shape variance by taxonomy, allometry and environment, and their interaction terms. ResultsWe found a significant impact of latitude, climate and size on skull shape. The allometric component of shape variation, although large, is not congruent with shape differences between species, and probably reflects ontogenetic effects. Partial least squares between bioclimatic variables and skull shape explain some 98% of the covariation between environment and shape. Species distributed in drier, more seasonal southern localities exhibit a narrow skull with elongated muzzle and relatively larger teeth. Variation partitioning suggests that the difference in skull shape between species is highly correlated with climatic variation but not with skull size.Main conclusions Skull shape in capuchins is significantly related to both environment and skull size. The former, but not the latter, is significantly associated with shape differences between species. The Sapajus clade originated in the south, and experienced an evolutionary radiation during the Pleistocene. As new Sapajus species moved to the north, they adapted to the local environmental conditions, eventually resembling Cebus in skull shape as they reached the Amazon rain forest, in response to their shared environmental conditions.
Chewing on different food types is a demanding biological function. The classic assumption in studying the shape of feeding apparatuses is that animals are what they eat, meaning that adaptation to different food items accounts for most of their interspecific variation. Yet, a growing body of evidence points against this concept. We use the primate mandible as a model structure to investigate the complex interplay among shape, size, diet, and phylogeny. We find a weak but significant impact of diet on mandible shape variation in primates as a whole but not in anthropoids and catarrhines as tested in isolation. These clades mainly exhibit allometric shape changes, which are unrelated to diet. Diet is an important factor in the diversification of strepsirrhines and platyrrhines and a phylogenetic signal is detected in all primate clades. Peaks in morphological disparity occur during the Oligocene (between 37 and 25 Ma) supporting the notion that an adaptive radiation characterized the evolution of South American monkeys. In all primate clades, the evolution of mandible size is faster than its shape pointing to a strong effect of allometry on ecomorphological diversification in this group.
Xenarthrans—anteaters, sloths, and armadillos—have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, 10 anteaters, and 6 sloths. Our data set includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the southern United States, Mexico, and Caribbean countries at the northern portion of the Neotropics, to the austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n = 5,941), and Cyclopes sp. have the fewest (n = 240). The armadillo species with the most data is Dasypus novemcinctus (n = 11,588), and the fewest data are recorded for Calyptophractus retusus (n = 33). With regard to sloth species, Bradypus variegatus has the most records (n = 962), and Bradypus pygmaeus has the fewest (n = 12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other data sets of Neotropical Series that will become available very soon (i.e., Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans data set. Please cite this data paper when using its data in publications. We also request that researchers and teachers inform us of how they are using these data.
The present study describes ticks associated with small mammals and analyzes the aggregation patterns according to seasonal and host variations in the Cerrado biome, central-western Brazil. Small mammals were systematically captured in 54 woodland fragments from February 2012 to July 2013. A total of 1,040 animals belonging to eight marsupial and 12 rodent species were captured; 265 animals were parasitized by eight tick species (in decreasing order of abundance): Ornithodoros mimon, Amblyomma coelebs, Amblyomma sculptum, Amblyomma ovale, Amblyomma parvum, Amblyomma dubitatum, Amblyomma parkeri, and Ixodes amarali. With few exceptions, collected ticks were larvae and nymphs. Among the more abundant animals, the marsupial Didelphis albiventris showed the highest tick prevalence (84.4 %), mean abundance (19.2), mean intensity (22.8), richness of ticks species (n = 7), and total abundance of ticks (n = 2,457). Amblyomma sculptum and O. mimon were the most generalist species, collected on four host species. Fifteen new tick-host associations are reported for the first time. Most ticks showed higher prevalence and mean intensity in the dry season, regardless of host species. Overall, tick prevalence and mean intensity of infestation were significantly associated with host gender. Finally, the importance of the large number of records of the argasid O. mimon is discussed.
Didelphis albiventris and D. aurita are Neotropical marsupials that share a unique evolutionary history and both are largely distributed throughout South America, being primarily allopatric throughout their ranges. In the Araucaria moist forest of Southern Brazil these species are sympatric and they might potentially compete having similar ecology. For this reason, they are ideal biological models to address questions about ecological character displacement and how closely related species might share their geographic space. Little is known about how two morphologically similar species of marsupials may affect each other through competition, if by competitive exclusion and competitive release. We combined ecological niche modeling and geometric morphometrics to explore the possible effects of competition on their distributional ranges and skull morphology. Ecological niche modeling was used to predict their potential distribution and this method enabled us to identify a case of biotic exclusion where the habit generalist D. albiventris is excluded by the presence of the specialist D. aurita. The morphometric analyses show that a degree of shape discrimination occurs between the species, strengthened by allometric differences, which possibly allowed them to occupy marginally different feeding niches supplemented by behavioral shift in contact areas. Overlap in skull morphology is shown between sympatric and allopatric specimens and a significant, but weak, shift in shape occurs only in D. aurita in sympatric areas. This could be a residual evidence of a higher past competition between both species, when contact zones were possibly larger than today. Therefore, the specialist D. aurita acts a biotic barrier to D. albiventris when niche diversity is not available for coexistence. On the other hand, when there is niche diversification (e.g. habitat mosaic), both species are capable to coexist with a minimal competitive effect on the morphology of D. aurita.
The impact of environmental variation on phenotypic diversification is one major issue in evolutionary studies. Environmental variation is thought to be a primary factor in evolution, especially at high latitudes. In contrast, tropical areas are traditionally viewed as the cradle where the long-term effects of biological interactions on phenotypic change reside. We analyse patterns of skull shape variation in two New World monkey groups: capuchins and howlers. These two monophyletic clades are exceptionally similar in terms of the geographic distribution of their species. Yet, their body size and diet are different: howler monkeys are large and almost exclusively folivorous, whereas capuchins are small omnivorous. We found that the size, and direction of vectors of phenotypic changes across South American biomes in those clades are not statistically different. This similarity persists after removing the strong impact of allometry in our data. Additionally, partial least squares and comparative analyses confirm that "allometry free" skull shape is influenced to the same set of environmental variables in both clades. This study remarks the paramount importance of both body size and environmental variation on phenotypic evolution. �� 2013 Springer Science+Business Media New York
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