RESUMO
Resource partitioning, and especially dietary partitioning, is a mechanism that has been studied for several canid species as a means to understand competitive relationships and the ability of these species to coexist. Coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are two canid species that are widely distributed, in Mexico, and they are sympatric throughout most of their distribution range. However, trophic dynamic and overlap between them have not been thoroughly studied. In order to better understand their ecological relationship and potential competitive interactions, we studied the trophic niche overlap between both canids in a temperate forest of Durango, Mexico. The results are based on the analysis of 540 coyote and 307 gray fox feces collected in 2018. Both species consumed a similar range of food items, but the coyote consumed large species while the gray fox did not. For both species, the most frequently consumed food categories throughout the year and seasonally were fruit and wild mammals (mainly rodents and lagomorphs). Coyotes had higher trophic diversity in their annual diet (H' = 2.33) than gray foxes (H' = 1.80). When analyzing diets by season, trophic diversity of both species was higher in winter and spring and tended to decrease in summer and autumn. When comparing between species, this parameter differed significantly during all seasons except for summer. Trophic overlap throughout the year was high (R0 = 0.934), with seasonal variation between R0 = 0.821 (autumn) and R0 = 0.945 (spring). Both species based their diet on the most available food items throughout each season of the year, having high dietary overlap which likely can lead to intense exploitative competition processes. However, differences in trophic diversity caused by differential prey use can mitigate competitive interactions, allowing these different sized canid species to coexist in the study area.
Assuntos
Coiotes/fisiologia , Cadeia Alimentar , Raposas/fisiologia , Animais , Florestas , MéxicoRESUMO
White-nosed coatis (Nasua narica) are widely distributed throughout North, Central, and South America, but the patterns of temporal and spatial diversification that have contributed to this distribution are unknown. In addition, the biogeographic history of procyonid species in the Americas remains contentious. Using sequences from three mitochondrial loci (Cytochrome b, NAHD5 and 16S rRNA; 2201â¯bp) and genotypes from 11 microsatellite loci, we analyzed genetic diversity to determine phylogeographic patterns, genetic structure, divergence times, and gene flow among Nasua narica populations throughout the majority of the species' range. We also estimated the ancestral geographic range of N. narica and other procyonid species. We found a high degree of genetic structure and divergence among populations that conform to five evolutionarily significant units. The most southerly distributed population (Panama) branched off much earlier (â¼3.8 million years ago) than the northern populations (<1.2 million years ago). Estimated gene flow among populations was low and mostly northwards and westwards. The phylogeographic patterns within N. narica are associated with geographic barriers and habitat shifts likely caused by Pliocene-Pleistocene climate oscillations. Significantly, our findings suggest the dispersal of N. narica was south-to-north beginning in the Pliocene, not in the opposite direction during the Pleistocene as suggested by the fossil record, and that the most recent common ancestor for coati species was most likely distributed in South or Central America six million years ago. Our study implies the possibility that the diversification of Nasua species, and other extant procyonid lineages, may have occurred in South America.