Although long‐standing theory suggests that biotic variables are only relevant at local scales for explaining the patterns of species' distributions, recent studies have demonstrated improvements to species distribution models (SDMs) by incorporating predictor variables informed by biotic interactions. However, some key methodological questions remain, such as which kinds of interactions are permitted to include in these models, how to incorporate the effects of multiple interacting species, and how to account for interactions that may have a temporal dependence. We addressed these questions in an effort to model the distribution of the monarch butterfly Danaus plexippus during its fall migration (September–November) through Mexico, a region with new monitoring data and uncertain range limits even for this well‐studied insect. We estimated species richness of selected nectar plants ( Asclepias spp.) and roosting trees (various highland species) for use as biotic variables in our models. To account for flowering phenology, we additionally estimated nectar plant richness of flowering species per month. We evaluated three types of models: climatic variables only (abiotic), plant richness estimates only (biotic) and combined (abiotic and biotic). We selected models with AICc and additionally determined if they performed better than random on spatially withheld data. We found that the combined models accounting for phenology performed best for all three months, and better than random for discriminatory ability but not omission rate. These combined models also produced the most ecologically realistic spatial patterns, but the modeled response for nectar plant richness matched ecological predictions for November only. These results represent the first model‐based monarch distributional estimates for the Mexican migration route and should provide foundations for future conservation work. More generally, the study demonstrates the potential benefits of using SDM‐derived richness estimates and phenological information for biotic factors affecting species distributions.

Background: Due to its central role in animal nutrition, the gut microbiota is likely a relevant factor shaping dietary niche shifts. We analysed both the impact and contribution of the gut microbiota to the dietary niche expansion of the only four bat species that have incorporated fish into their primarily arthropodophage diet.Results: We first compared the taxonomic and functional features of the gut microbiota of the four piscivorous bats to that of 11 strictly arthropodophagous species using 16S rRNA targeted amplicon sequencing. Second, we increased the resolution of our analyses for one of the piscivorous bat species, namelyMyotis capaccinii,and analysed multiple populations combining targeted approaches with shotgun sequencing. To better understand the origin of gut microorganisms, we also analysed the gut microbiota of their fish prey (Gambusia holbrooki). Our analyses showed that piscivorous bats carry a characteristic gut microbiota that differs from that of their strict arthropodophagous counterparts, in which the most relevant bacteria have been directly acquired from their fish prey. This characteristic microbiota exhibits enrichment of genes involved in vitamin biosynthesis, as well as complex carbohydrate and lipid metabolism, likely providing their hosts with an enhanced capacity to metabolise the glycosphingolipids and long-chain fatty acids that are particularly abundant in fish.Conclusions: Our results depict the gut microbiota as a relevant element in facilitating the dietary transition from arthropodophagy to piscivory.

The Monarch Butterfly Biosphere Reserve (MBBR) in central Mexico was established in 2000 to protect monarch butterfly (Danaus plexippus) overwintering colonies and contribute to the conservation of the monarch migratory phenomenon. The MBBR has faced forest cover losses due to illegal logging and climate-related factors. Here we report forest cover losses from 2012 to 2018 in the core zones of the MBBR where most monarch overwintering colonies perch. We used aerial ortho-photographs and satellite images complemented with field validation for temporal comparisons. During this period, 163.44 ha of forest cover were affected, 125.44 ha due to climate-related factors (rain and wind), 25.86 ha due to large-scale illegal logging, and 12.14 ha due to small-scale illegal logging. The core zone of the MBBR located in the State of Michoacan showed the highest forest cover loss values with 94.07 ha lost due to climate-related factors, and 38.0 ha lost due to illegal logging. Our study also showed a substantial decrease of ~98% in large-scale illegal logging in the core zones of the MBBR compared to previous reported forest losses from 2001 to 2012. Forest cover loss was similar, yet the periods of the two studies differed, one 12 years in length, this one 6 years. The decrease of forest cover during the period studied suggests that factors elsewhere rather than forest cover loss in the monarch butterfly's winter habitat have strongly contributed to the dramatic population declines observed in monarch overwintering colonies since 2010.

Background and Research Aims: Forest loss and fragmentation have a negative impact on large-sized predators and prey, whose populations are reduced or extirpated locally. We explored the spatiotemporal coexistence of the mesopredators (< 15 kg) coyote, ocelot, and white-nosed coati, with their potential prey (< 15 kg) Mexican agouti, lowland paca, and collared peccary in a defaunated rainforest. Methods: We used two-species occupancy-detection models between mesopredators and their potential prey, overlap index of circular models, and latency time measurements to evaluate temporal and spatial segregation and habitat use of species. Results: Presence of ocelot and coyote was influenced by an increase in the detectability and occupancy of the Mexican agouti. Among most mesopredator–prey species pairs, the correlation for both the capture rates at camera-trap stations and the 1-hr intervals were mainly moderate or low. Some mesopredator–prey species pairs showed low or inverse correlations suggesting species avoidance. The Mexican agouti exhibited a significant negative correlation with the presence of mesopredators. The coyote and ocelot showed a positive correlation with their use of low use trails by people. Conclusions: Spatiotemporal tolerance was observed among mesopredator omnivores and prey herbivores. High temporal overlap of ocelots and potential prey (lowland paca) was observed compared to other tropical forests holding large-sized predators, suggesting behavioral shifts for increasing mesopredator–prey encounters. Furthermore, mesopredator coexistence was mediated by a displacement in the temporal peaks of activity and spatial segregation among species. Implications for Conservation: Defaunated tropical forests need protection to ensure the conservation of remaining species and their ecological interactions.

The immune response is affected by aridity, but it has been rarely examined in desert-dwelling bats. For two consecutive years, we examined the seasonal variation in the innate immune response of an insular desert bat, the fish-eating myotis (Myotis vivesi), in relation to its reproductive activity and ectoparasite load. We evaluated the reproductive activity based on external morphological traits and testosterone levels in the plasma for males and progesterone and estradiol for females. We injected phytohemagglutinin (PHA) into the footpads of the bats to estimate the innate cellular response, and we measured the bacterial killing ability (BKA) of the blood plasma to determine the innate humoral response. Both the external morphological traits and hormone levels indicate that the females were pregnant in spring and lactating in summer, and that the males were reproductively active in autumn, when mating probably occurred. The swelling response of the female and male bats was lower in spring. The BKA in the males did not vary seasonally; the BKA in the females varied seasonally but only in the first year of the study, with lower values in spring and summer. The BKA in spring was lower in the first year of the study, when the females appeared to be in early pregnancy, compared to the second year, when the females were in advanced pregnancy. The swelling increased as the body mass and body conditions of the males increased, but the BKA was not correlated with body mass or body condition in either sex. Ectoparasite abundance and prevalence did not vary among seasons. Ectoparasite abundance was not correlated with the PHA response in both sexes; it was not correlated with the BKA in females, but it was inversely correlated in males. Of the three hormones measured, only estradiol was correlated with the immune response: females with higher estradiol levels had a higher PHA response and BKA. Our findings indicate that the cellular and humoral innate immune responses of the fish-eating myotis varied throughout the year, following the seasonal reproductive pattern of the species. Our evaluation of the proximal factors affecting the expression of the immune response points to the potential immunoregulatory role of sex hormones and body mass.