Predicting future climate change impacts on the potential distribution of the black howler monkey (Alouatta pigra): an endangered arboreal primate.

Climate change is one of the main factors affecting biodiversity worldwide at an alarming rate. In addition to increases in global extreme weather events, melting of polar ice caps, and subsequent sea level rise, climate change might shift the geographic distribution of species. In recent years, interest in understanding the effects of climate change on species distribution has increased, including species which depend greatly on forest cover for survival, such as strictly arboreal primates. Here, we generate a series of species distribution models (SDMs) to evaluate future projections under different climate change scenarios on the distribution of the black howler monkey (Alouatta pigra), an endemic endangered primate species. Using SDMs, we assessed current and future projections of their potential distribution for three Social Economic Paths (SSPs) for the years 2030, 2050, 2070, and 2090. Specifically, we found that precipitation seasonality (BIO15, 30.8%), isothermality (BIO3, 25.4%), and mean diurnal range (BIO2, 19.7.%) are the main factors affecting A. pigra distribution. The future climate change models suggested a decrease in the potential distribution of A. pigra by projected scenarios (from - 1.23 to - 12.66%). The highly suitable area was the most affected above all in the more pessimist scenario most likely related to habitat fragmentation. Our study provides new insights into the potential future distribution and suitable habitats of Alouatta pigra. Such information could be used by local communities, governments, and non-governmental organizations for conservation planning of this primate species.

The relationship between pinworm (Trypanoxyuris) infection and gut bacteria in wild black howler monkeys (Alouatta pigra).

Gut bacteria may coexist with other groups of organisms, such as nematode parasites, that inhabit the gastrointestinal tract of primates; however, the possible effects of endoparasites on bacterial communities are frequently overlooked. Here we explored whether infection with Trypanoxyuris, an oxyurid gastrointestinal parasite, is associated with changes in the gut bacterial community of wild black howler monkeys (Alouatta pigra), by comparing gut bacterial communities of consistently infected individuals and individuals that never tested positive for Trypanoxyuris throughout different months across the year. We additionally controlled for other sources of variation reported to influence the primate microbiome including individual identity, social group, and seasonality. Trypanoxyuris infection was not related to differences in gut bacterial alpha diversity, but was weakly associated with differences in gut bacterial community structure. In contrast, among the covariates considered, both individual identity and social group were more strongly associated with variation in the howler gut bacterial community. Our results suggest that gastrointestinal parasites may be associated, to some extent, with shifts in the gut bacterial communities hosted by free-ranging primates, although a causal link still needs to be established. Further studies of wild primate hosts infected with parasite species with different pathogenicity are needed to better elucidate health-related consequences from the parasite-microbiome interplay.

The relative effects of reproductive condition, stress, and seasonality on patterns of parasitism in wild female black howler monkeys (Alouatta pigra).

Parasitic infections in wildlife are shaped by host-related traits including individual reproductive condition. It has been argued that female primates are more susceptible to infectious diseases during pregnancy due to short-term changes in immune function that result in reduced ability to combat infections. Likewise, lactation, which is the most energetically expensive state, may affect immunity and infection risk due to tradeoffs between milk production and maintenance of immune function. Here, we examine the degree to which parasite prevalence and parasite richness are affected by female reproductive condition and stress levels in wild female black howler monkeys (Alouatta pigra). Over the course of one year, we collected fresh fecal samples from 15 adult females belonging to seven black howler groups living in Escárcega, Mexico. Fecal samples were used for parasitological analysis and for measuring fecal glucocorticoid metabolites (i.e., stress biomarker). We found that the prevalence of intestinal parasites and parasite richness did not differ among non-pregnant, pregnant, and lactating females. Fecal glucocorticoid metabolite levels increased significantly during pregnancy and during the first month of lactation, and positively predicted the probability of Controrchis biliophilus infection. Parasite prevalence and richness decreased during the months of increased rainfall. We conclude that reproductive physiology has limited consequences on intestinal parasitic infection risk in female black howler monkeys and that seasonal environmental fluctuations have greater effects.