Distribución potencial del cerdo asilvestrado, Sus scrofa (Artiodactyla: Suidae) y el pecarí de collar, Pecari tajacu (Artiodactyla: Tayassuidae) en la región de Laguna de Términos, México

Introducción: La presencia de los cerdos asilvestrados (Sus scrofa) combinado con la fragmentación del hábitat presente en la región de Laguna de Términos, Campeche, puede generar cambios en los patrones de distribución y presencia de pecaríes de collar (Pecari tajacu). Objetivo: Evaluar el traslape o segregación espacial en la distribución de cerdos asilvestrados y pecaríes de collar mediante modelos de distribución potencial de ambas especies en la región de Laguna de Términos, Campeche. Métodos: Se generaron modelos de distribución potencial usando datos de presencia y variables antrópicas y bioclimáticas en Maxent. Resultados: Los modelos mostraron segregación espacial entre ambas especies. Los cerdos asilvestrados fueron positivamente influenciados por la cercanía a cultivos de palma de aceite (Elaeis guineensis) y por la precipitación estacional; la distribución potencial para pecaríes de collar estuvo positivamente correlacionada con la temperatura y la cobertura arbórea. Se confirmó la presencia de cerdos asilvestrados en Escárcega, Carmen, Candelaria y Palizada, en el estado de Campeche y en Balancán y Jonuta en el estado de Tabasco. Nuestros modelos predicen áreas potenciales para los cerdos asilvestrados principalmente en la Reserva de la Biosfera Pantanos de Centla en Tabasco y en áreas cercanas a la frontera con Guatemala. Discusión: Consideramos necesario implementar un plan de control para los cerdos asilvestrados, no solo en la región de Laguna de Términos, sino en áreas aledañas con la finalidad de impedir la expansión de su distribución y el desplazamiento de especies nativas como los pecaríes en otras áreas del sur del país.

Introduction: The presence of feral pigs (Sus scrofa) in addition to habitat fragmentation at Laguna de Términos, Campeche, could cause changes in the distribution patterns and presence of collared peccaries (Pecari tajacu). Objective: Modelling of potential distribution to assess the overlap or spatial segregation of both species at Laguna de Términos, Campeche. Methods: Potential distribution models were generated with presence data, anthropic and bioclimatic variables using the maximum entropy algorithm (Maxent). Results: The potential distribution models showed spatial segregation between both species. The presence of feral pigs was positively influenced by palm oil crops (Elaeis guineensis) proximity and seasonal rainfall; the potential distribution of collared peccaries was positively correlated with temperature and canopy coverage. Evidence of feral pigs presence was confirmed in Escárcega, Carmen, Candelaria and Palizada in Campeche state and in Balancán and Jonuta in Tabasco state. Our models predicted potential areas for feral pigs in Pantanos de Centla Biosphere Reserve in Tabasco and in areas near the Guatemalan border. Conclusions: We believe a control plan for feral pigs is needed, not only in Laguna de Términos region, but also in adjacent areas in order to prevent the range extension and displacement of native species such as peccaries in other areas in Southern Mexico.

Conservation implications for jaguars and other neotropical mammals using highway underpasses.

The Nuevo Xcan-Playa del Carmen highway in Quintana Roo, bisects the vegetation corridor connecting two Jaguar Conservation Units (JCUs): Yum Balaam (north) and Sian Ka´an (south). The project´s main goal was to describe differential use of available crossing structures (wildlife underpasses and culverts) by mammals present along this highway. We set 28 camera traps along the 54km stretch of the highway covering wildlife underpasses (10), and culverts such as box culverts (9) and pipes (9) from September 2016 until March 2017. A total of 24 jaguar crossings have been recorded exclusively using wildlife underpasses, including four males and two females. At least 18 other mammal species including five of the target priority species (protected by Mexican law) were documented, all of which were native except for two invasive species. In terms of species using the crossing structures, we identified 13 species using wildlife underpasses, nine using concrete box culverts and 10 using concrete pipes. Wildlife underpasses show higher diversity values (Shannon´s exponential index = 5.8 and Inverse Simpson´s index = 4.66) compared to culverts because they allow bigger species to cross. We recommend more highways along the jaguar´s distribution should develop mitigation measures to allow for wildlife connectivity. Wildlife underpasses, along with retrofitted culverts, could help secure not only the permanence of this species by facilitating the functional connectivity between populations but have positive impacts on other neotropical mammalian fauna as well.

Can You Judge a Disease Host by the Company It Keeps? Predicting Disease Hosts and Their Relative Importance: A Case Study for Leishmaniasis.

Zoonoses are an important class of infectious diseases. An important element determining the impact of a zoonosis on domestic animal and human health is host range. Although for particular zoonoses some host species have been identified, until recently there have been no methods to predict those species most likely to be hosts or their relative importance. Complex inference networks infer potential biotic interactions between species using their degree of geographic co-occurrence, and have been posited as a potential tool for predicting disease hosts. Here we present the results of an interdisciplinary, empirical study to validate a model based on such networks for predicting hosts of Leishmania (L.) mexicana in Mexico. Using systematic sampling to validate the model predictions we identified 22 new species of host (34% of all species collected) with the probability to be a host strongly dependent on the probability of co-occurrence of vector and host. The results confirm that Leishmania (L.) mexicana is a generalist parasite but with a much wider host range than was previously thought. These results substantially change the geographic risk profile for Leishmaniasis and provide insights for the design of more efficient surveillance measures and a better understanding of potential dispersal scenarios.

Effect of nesting environment on incubation temperature and hatching success of Morelet's crocodile (Crocodylus moreletii) in an urban lake of Southeastern Mexico.

Incubation temperature is an important aspect in terms of biological performance among crocodiles, and several controlled experiments have demonstrated a significant relationship between incubation temperature, success in hatching and survival of hatchlings. However, a few studies have tested these relationships in the wild. The objective of this study was to determine the relationship of nest characteristics and environment (hatch year, nest basal area and height, clutch size, distance to shore line, and vegetation cover), to incubation temperature and hatching success among Morelet's crocodile (Crocodylus moreletii). The study was carried out during the nesting seasons of Morelet's crocodile, from 2007 to 2009 in the Laguna de Las Ilusiones, an urban lake located in Villahermosa, Tabasco, Mexico. We physically characterized 18 nests and inserted a temperature data logger in each nest chamber. At the end of the nesting season and prior to hatching, we recovered the crocodile eggs and data loggers and calculated hatching success, under laboratory conditions. We related the environmental variables of the nest with the mean and fluctuation (standard deviation) of nest temperature, using linear models. We also related the environmental variables affecting the nest, to mean nest temperature and fluctuation in incubation temperature and to hatching success, using linear models. Although we found differences in incubation temperature between nests, mean incubation temperature did not differ between years, but there were differences in nest thermal fluctuation between years. The mean incubation temperature for 11 nests (61.1%) was lower than the suggested Female-Male pivotal temperature (producing 50% of each sex) for this species, and all hatchlings obtained were males. There were no differences in clutch size between years, but hatching success varied. Our study indicates that hatching success depends on certain environmental variables and nest conditions to which the eggs are subjected, including season, nest size and clutch size. We also discuss the importance of the fluctuation of incubation temperature on hatching success and sex determination.

Leishmania (L.) mexicana infected bats in Mexico: novel potential reservoirs.

Leishmania (Leishmania) mexicana causes cutaneous leishmaniasis, an endemic zoonosis affecting a growing number of patients in the southeastern states of Mexico. Some foci are found in shade-grown cocoa and coffee plantations, or near perennial forests that provide rich breeding grounds for the sand fly vectors, but also harbor a variety of bat species that live off the abundant fruits provided by these shade-giving trees. The close proximity between sand flies and bats makes their interaction feasible, yet bats infected with Leishmania (L.) mexicana have not been reported. Here we analyzed 420 bats from six states of Mexico that had reported patients with leishmaniasis. Tissues of bats, including skin, heart, liver and/or spleen were screened by PCR for Leishmania (L.) mexicana DNA. We found that 41 bats (9.77%), belonging to 13 species, showed positive PCR results in various tissues. The infected tissues showed no evidence of macroscopic lesions. Of the infected bats, 12 species were frugivorous, insectivorous or nectarivorous, and only one species was sanguivorous (Desmodus rotundus), and most of them belonged to the family Phyllostomidae. The eco-region where most of the infected bats were caught is the Gulf Coastal Plain of Chiapas and Tabasco. Through experimental infections of two Tadarida brasiliensis bats in captivity, we show that this species can harbor viable, infective Leishmania (L.) mexicana parasites that are capable of infecting BALB/c mice. We conclude that various species of bats belonging to the family Phyllostomidae are possible reservoir hosts for Leishmania (L.) mexicana, if it can be shown that such bats are infective for the sand fly vector. Further studies are needed to determine how these bats become infected, how long the parasite remains viable inside these potential hosts and whether they are infective to sand flies to fully evaluate their impact on disease epidemiology.

Alopecia in bats from Tabasco, Mexico.

We report alopecic syndrome (hair loss in areas of the body, including chest, abdomen, and back) in four frugivorous bat species (Artibeus jamaicensis, Artibeus lituratus, Sturnira lilium, and Sturnira ludovici) within urban and periurban areas of Villahermosa, Tabasco, México, during 2007 and 2008. The overall prevalence of alopecic syndrome was 5.25% (135/2,567 bats). The highest prevalence was found in A. lituratus (5.6%; 62/1,105), followed by A. jamaicensis (5%; 3/1,462). We found a higher prevalence in the dry season, when more than 90% of the alopecic individuals (n=122) were captured. Higher prevalence of alopecia was recorded in urban areas (80% of captured alopecic bats, n=108) than in periurban areas (20%, n=27). Histopathologic studies revealed no evidence of infectious agents. The syndrome may be related to nutritional or endocrinal deficiencies. Spatial and seasonal aggregation in urban areas suggests that anthropogenic activities may interfere with nutritional processes. Further studies are needed to confirm the etiology of the syndrome as well as its impact on population dynamics. This is the first report of alopecic syndrome in sylvatic bats.