Closely related sympatric species commonly develop different ecological strategies to avoid competition. Ctenomys minutus and C. flamarioni are subterranean rodents parapatrically distributed in the southern Brazilian coastal plain, showing a narrow sympatric zone. To gain understanding on food preferences and possible competition for food resources, we evaluated their diet composition performing DNA metabarcoding analyzes of 67 C. minutus and 100 C. flamarioni scat samples, collected along the species geographical ranges. Thirteen plant families, mainly represented by Poaceae, Araliaceae, Asteraceae and Fabaceae, were identified in the diet of C. minutus. For C. flamarioni, 10 families were recovered, with a predominance of Poaceae, Araliaceae and Asteraceae. A significant correlation between diet composition and geographical distance was detected in C. minutus, whereas the diet of C. flamarioni was quite homogeneous throughout its geographical distribution. No significant differences were observed between males and females of each species. However, differences in diet composition between species were evident according to multivariate analysis. Our results suggest some level of diet partitioning between C. flamarioni and C. minutus in the sympatric region. While the first species is more specialized on few plant items, the second showed a more varied and heterogeneous diet pattern among individuals. These differences might have been developed to avoid competition in the region of co-occurrence. Resource availability in the environment also seems to influence food choices. Our data indicate that C. minutus and C. flamarioni are generalist species, but that some preference for Poaceae, Asteraceae and Araliaceae families can be suggested for both rodents.

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Species with similar ecological requirements coexisting in the same geographic region are prone to competitively exclude each other. Alternatively, they may coexist if character displacement acts to change the niche requirements of one or both species. We used two methodological approaches (ecological niche modeling [ENM] and geometric morphometrics) to test two hypotheses: given their behavioral, morphological, and ecological similarities, one species competitively excludes the other; and, character displacement enables their coexistence at two sites in which the species are known to occur in sympatry. The results from the ENM-based approach did not provide evidence for competitive exclusion; however, the morphometric analyses documented displacement in size of C. minutus. This result, suggests that C. minutus might exclude C. flamarioni from areas with softer soils and higher food availability. We stress the importance of using multiple methodological approaches when testing prediction of competitive exclusion. However, both methods had limited explanatory power given that the focal species possess truly peculiar distributions, being largely parapatric and restricted to narrow, small geographic areas with a strange distribution and there is a need to search for additional methods. We discuss the idiosyncrasy of the ENM-based approach when applied to organisms with subterranean habits.

For rodents that live underground, digging in highly compacted soils requires a higher energy expenditure than digging in poorly compacted soils. We tested how soil hardness affects the bite force as well as the shape and size of the skulls and mandibles of tuco-tucos. Our hypothesis is that species that inhabit harder soils would show a stronger bite force, which should be reflected in the shape of the skull and mandible, while species living in softer soils should have a weaker bite force. We used 24 species of the genus Ctenomys to estimate bite force (through the incisor strength formula) and quantify the shape and size of the skull and mandible. Information on soil bulk density in the regions occupied by each species was obtained from the literature. We used a combination of geometric morphometric and comparative methods to test our hypothesis. A phylogenetic linear regression (PGLS) between bite force (N) and centroid size was used to account for the dependence of bite force on size. We employed a series of two-block partial leastsquares analyses to uncover the covariation between bite force and the shape of the skull and mandible. Finally, we ran five independent PGLS analyses to assess the influence of bulk density on bite force, skull shape and mandible shape, taking into account phylogenetic non-independence. Species with higher bite forces tend to inhabit more-compact soils. However, for most species, the relationship between bite force and soil bulk density was unclear, resulting in a low overall correlation. Nonetheless, differences in skull and mandible shapes were generally associated with bite force (r = 0.60). In denser soils, species with high and low bite forces occur, whereas in lower density soils, we found only species with weak bite forces. Differences in the excavation strategies among species may be responsible for this pattern.

Subterranean rodents are characterized by limited individual mobility and patchy distribution of local populations. Habitat patches where the species is absent may either be unoccupied, but suitable patches, or in fact unsuitable as habitat due to specific habitat features. In the coastal plain of southern Brazil, Ctenomys minutus (Ctenomyidae) inhabits sandy grasslands and dunes. The aim of our study was to analyze the relationship between the distribution of this subterranean rodent and its environment. We considered vegetation and soil features. Our results showed that habitat occupancy patterns of C. minutus are determined by soil moisture and vegetation (food supply), but there might be other habitat features that regulate the habitat choice of this mammal. Habitat discontinuities in the coastal plain of southern Brazil, with numerous barriers to dispersal, are responsible for restricting individuals to their natal areas. This might result in increased intraspecific competition within each population and, consequently, in inbreeding. Os roedores subterrâneos são caracterizados pela baixa mobilidade dos indivíduos e por apresentarem populações distribuídas em manchas de habitat. As manchas em que os indivíduos estão ausentes podem ser locais desocupados, porém que apresentam condições adequadas para a ocupação, ou de fato serem locais inadequados devido a algumas características ambientais específicas. Na planície costeira do sul do Brasil, a espécie Ctenomys minutus (Ctenomyidae) habita regiões de campos arenosos e dunas costeiras. O objetivo do presente estudo foi analisar a relação entre a distribuição deste roedor subterrâneo e o ambiente em que ele habita. Para tal, consideramos características da vegetação e do solo. Nossos resultados demonstraram que o padrão de ocupação de C. minutus é determinado pela umidade do solo e vegetação (recurso alimentar), mas podem existir outras características que regulam a escolha do habitat deste mamífero. As descontinuidades de habitat na planície costeira do sul do Brasil, com inúmeras barreiras para a dispersão da espécie, são responsáveis por restringir os indivíduos as suas áreas natais. Isso pode resultar no aumento da competição intra-específica dentro das populações e, consequentemente, na endogamia.

Mammalian carnivores are considered a key group in maintaining ecological health and can indicate potential ecological integrity in landscapes where they occur. Carnivores also hold high conservation value and their habitat requirements can guide management and conservation plans. The order Carnivora has 84 species from 8 families in the Neotropical region: Canidae; Felidae; Mephitidae; Mustelidae; Otariidae; Phocidae; Procyonidae; and Ursidae. Herein, we include published and unpublished data on native terrestrial Neotropical carnivores (Canidae; Felidae; Mephitidae; Mustelidae; Procyonidae; and Ursidae). NEOTROPICAL CARNIVORES is a publicly available data set that includes 99,605 data entries from 35,511 unique georeferenced coordinates. Detection/non‐detection and quantitative data were obtained from 1818 to 2018 by researchers, governmental agencies, non‐governmental organizations, and private consultants. Data were collected using several methods including camera trapping, museum collections, roadkill, line transect, and opportunistic records. Literature (peer‐reviewed and grey literature) from Portuguese, Spanish and English were incorporated in this compilation. Most of the data set consists of detection data entries (n = 79,343; 79.7%) but also includes non‐detection data (n = 20,262; 20.3%). Of those, 43.3% also include count data (n = 43,151). The information available in NEOTROPICAL CARNIVORES will contribute to macroecological, ecological, and conservation questions in multiple spatio‐temporal perspectives. As carnivores play key roles in trophic interactions, a better understanding of their distribution and habitat requirements are essential to establish conservation management plans and safeguard the future ecological health of Neotropical ecosystems. Our data paper, combined with other large‐scale data sets, has great potential to clarify species distribution and related ecological processes within the Neotropics. There are no copyright restrictions and no restriction for using data from this data paper, as long as the data paper is cited as the source of the information used. We also request that users inform us of how they intend to use the data.

The environment physically limits animal movement and use of space. In the case of subterranean rodents, natural selection is expected to favor burrow structures that minimize energetic costs of digging. However, in some cases the same species is found in habitats that strongly differ in resource availability and soil characteristics, as in Ctenomys minutus. This species is thus a good model in which to estimate the influence of habitat on behavioral characteristics such as home-range size. We evaluated the home-range sizes of two C. minutus populations that inhabit different habitats: sand dunes and sand fields. We radio tracked 19 adult animals, and estimated the home-range size of each individual using the grid cell (2 9 2 m covering all of the radio fixes), and minimum convex polygon (MCP) methods. Our results show that home ranges of C. minutus differ in the two habitats, with average size 1.75 times larger for individuals inhabiting sand dunes. This difference in home-range size between habitats is likely associated with differences in resource availability (plant biomass) or soil conditions.