Se señalan tres especies nuevas para Chiapas Canthon lituratus (Germar) 1813; Uroxys platypyga Howden & Young, 1981, y Onthophagus yucatanus Delgado, Peraza & DeLoya, 2006, las dos primeras ...nuevas también para México. Todas ellas capturadas en selva alta perennifolia. Las dos primeras especies, cuyas áreas de distribución hacia el norte se amplían notablemente, corresponden biogeográficamente al Patrón de Distribución Neotropical Típico – Penetración Mínima. O. yucatanus tiene una historia biogeográfica distinta, corresponde al Patrón Paleoamericano Tropical.
The state of Chiapas is home to multiple species of shrews (11 species), endemisms (three species from Mexico) and micro-endemisms (5 species from Chiapas). These species inhabit diverse ...physiographic regions and different types of habitats across the state. However, several are known by only very few specimens, mostly collected several years ago, making the knowledge about their natural history extremely scarce. This paper describes the efforts made by the authors along 16 years in search of shrews of Chiapas. Records were obtained from fieldwork, as well as by historical records from scientific collections and public databases. We estimated the relative abundances per species, identifying in each case the area of distribution and association with different types of vegetation and land use, current threats, and future research scenario for conservation purposes. The total trapping effort was 12,340 trap-nights across 13 sampling sites, with a total capture success of 0.18 %. In nine sampling sites, we succeeded in capturing 22 specimens of six species of shrews: Cryptotis griseoventris, C. lacandonensis, C. merriami, C. mexicanus, C. pueblensis, and Sorex cristobalensis. C. griseoventris had the highest relative abundance (31.81 %) and capture success (0.056), while C. lacandonensis showed the lowest relative abundance (4.54 %) and capture success (0.008). We present noteworthy records of shrews: 1) for being barely represented in scientific collections, as in C. griseoventris, and 2) for expanding the previously documented distribution area, as in C. lacandonensis and C. merriami. All of the species currently face serious conservation issues resulting from the loss of habitat. In particular, micro-endemic species such as S. sclateri and S. stizodon are seriously threatened. The specimens and records reported herein should foster further detailed research on the taxonomy, ecology, and biogeography to advance the knowledge of shrews inhabiting the southern border of Mexico.
Ticks of the family Ixodidae are potential transmitters of pathogens to vertebrates, including birds that because of their mobility are important hosts and dispersers of ticks. Knowing the ...interactions can help identify potential emerging sites of tick-borne diseases. Abundance of ticks were assessed on birds captured between February and June 2017 at four sites with different land use in the Calakmul region. Ticks from the captured birds were stored individually in 70% ethanol in tubes for later identification using a stereoscope and taxonomic keys. Of 406 birds captured in 82 species, 2.7% were parasitized by ticks, mostly nymphs and larvae of Amblyomma spp. Only the Passeriformes order was parasitized, most parasitized birds were resident species. The higher number of parasitized individuals was found in the forestry successional vegetation. In total 14 ticks of the family Ixodidae were collected. This is the first study we know that analyzed the abundance of ticks on wild birds in Mexico, and new hosts of ticks of the genus Amblyomma spp. were reported.
The mountain forests of Chiapas, southern Mexico harbor high species richness; however, these systems are seriously altered by human influence. The effect of human disturbances differentially affects ...species based on their functional attributes to effectively respond to environmental pressures. All biological communities are made up of rare and abundant species. The first are generally considered more vulnerable to the transformation of their habitats because they generally have low population densities, are geographically restricted and are found in specific habitats. To test this notion, we evaluated the functional response of rare and abundant tree species recorded in the mountain forests of the Central Highlands, Northern Mountains and Sierra Madre of Chiapas. Four functional traits were selected that reflect an association with the capture of resources, growth and regeneration of the species (tree size, leaf area, type of diaspora, and dispersion mechanism) with this we define a functional response in terms of its successional affinity. A classification analysis based on the similarity of these traits showed that several of rare species were grouped within a group of common species (Quercus spp.). The set of species registered as rare correspond to small trees and slow growth, tolerant to shade, produce fruits like drupes, zoocoric dispersion (birds and small mammals) and have late successional affinity. The foregoing recognizes the risks of forest transformation on these rare species and advocates in favor of their conservation.
RESUMEN: Los bosques de montaña de Chiapas albergan una alta riqueza de especies, sin embargo, estos sistemas se encuentran seriamente alterados por influencia humana. El efecto de los disturbios humanos afecta diferencialmente a las especies con base en sus atributos funcionales para responder efectivamente a las presiones ambientales. En toda comunidad biológica se desarrollan especies que son muy abundantes y especies poco comunes o raras. Estas últimas suelen considerarse más vulnerables ante la transformación de sus hábitats debido a que generalmente tienen bajas densidades poblacionales, están geográficamente restringidas y se encuentran en hábitats específicos. Para probar esta noción, se evaluó la respuesta funcional de especies arbóreas raras y abundantes en los bosques de montaña de la Altiplanicie Central, Montañas del Norte y Sierra Madre de Chiapas, México. Se eligieron cuatro rasgos funcionales que reflejan una asociación con la captura de recursos, crecimiento y regeneración de las especies (tamaño del árbol, área foliar, tipo de diáspora, mecanismo de dispersión) que en conjunto definen una respuesta funcional en términos de su afinidad sucesional. Un análisis de clasificación basado en la similitud de dichos rasgos mostró que las especies raras se agrupan dentro de un grupo de especies comunes (Quercus spp.). El conjunto de especies registradas como raras corresponden a árboles de talla pequeña y crecimiento lento, tolerantes a la sombra, producen frutos drupáceos con dispersión zoocora (aves y mamíferos pequeños) y tienen afinidad sucesional tardía. Lo anterior reconoce los riesgos de la transformación de los bosques sobre estas especies poco comunes y aboga en favor de su conservación.
The Virginia opossum (Didelphis virginiana) is considered highly adaptable to anthropogenic disturbances; however, the genetic effects of disturbance on this marsupial have not been studied in wild ...populations in Mexico. Here we evaluated the genetic diversity of D. virginiana at sites with different levels of disturbance within the Highlands and Central Depression regions of Chiapas in southern Mexico. Twelve microsatellite loci were used and the results demonstrated moderate mean heterozygosity (H
𝑒 = 0.60; 𝐻𝑜 = 0.50). No significant differences in heterozygosity were found among sites with different levels of disturbance in both regions (range 𝐻𝑜 = 0.42–0.57). We observed low but significant levels of genetic differentiation according to disturbance level. The inbreeding coefficient did not differ significantly from zero, suggesting that low genetic differentiation in these environments may be associated with sufficient random mating and gene flow, a result associated with the high dispersal and tolerance characteristics of this marsupial. Our results for D. virginiana in this particular area of Mexico provide a foundation for exploring the impact of human disturbance on the genetic diversity of a common and generalist species.
Changes in vegetative cover and land use in the southern part of the Isthmus of Tehuantepec in Oaxaca, Mexico, were identified by analysing satellite images from 2001 and 2014. Fluctuations in ...population density of mammal species during 2001–2016 in response to these changes were analysed. During 2001–2014 the types of land use that increased in area (per year) were prescribed burning (uncontrolled burning caused by humans) by 105.11 ha, seasonal agricultural plots by 58.14 ha, areas without vegetation by 24.54 ha, and human settlements by 4.13 ha. In the same period, savannahs decreased by 103.94 ha, tropical dry forest by 39.5 ha, secondary forests by 14.46 ha, and human-induced grassland by 0.13 ha per year. The loss of these habitats resulted in low population densities of mammals, including the eastern cottontail Sylvilagus floridanus and the Tehuantepec jackrabbit Lepus flavigularis, which is categorized as Endangered on the IUCN Red List. We recommend establishing a communal ecological reserve in the study area to implement appropriate management strategies for grassland communities and develop a programme of semi-captive breeding to conserve L. flavigularis.
Cattle ranching is one of the main production activities in the Neotropics that has unavoidably led to cattle exposure to the common vampire bat (
Desmodus rotundus
) and rabies virus. Although many ...studies have assessed this issue, the influence of environmental characteristics associated with land use and social and production constraints have received little attention. We used satellite imagery classification to identify a gradient of landscape disturbance and analyzed the effects of cattle management and landscape structure on common vampire bat abundance and feeding prevalence. Evidence of the common vampire bat feeding on cattle was common in the study area: 87.5% of the ranchers interviewed claimed to have experienced this problem. The abundance and feeding prevalence of the common vampire bat was lower in landscapes dominated by open fields, scarce forest cover, and agricultural land. Bat abundance was positively associated with the presence of streams in the proximity of grazing areas, whereas cave’s presence was associated with higher feeding prevalence. We suggest that cattle grazing should avoid the proximity of streams, caves, and forests as much as possible, as these conditions increase the exposure of cattle to the common vampire bat and the potential for feeding, which can increase the likelihood of rabies virus transmission.
La riqueza de especies arbóreas (S) frecuentemente ha sido estimada con inventarios sistemáticos. De manera reciente, la disponibilidad en línea de datos de herbario ha permitido otras ...aproximaciones. ¿Qué tan comparables son estas estimaciones de S? Ajustamos modelos lineales generalizados (GLM) a estimaciones con ambos tipos de datos en 3 regiones montañosas de Chiapas (altitud>1,500 m), relativamente bien conocidas desde una perspectiva florística y para las cuales se dispone de un significativo número de parcelas de inventarios. Se detectó con ambos tipos de datos un total de 792 especies arbóreas. El modelo de Clench estimó con datos de herbarios un total de 862 especies y 425 con inventarios. Los modelos GLM elegidos con los 2 tipos de datos mostraron una correlación positiva de S en 2 de las regiones, pero no en aquella con mayor riqueza. Los inventarios brindan una instantánea de la equidad entre especies en muestras reales de comunidades y representan un acervo útil para entender la estructuración de la diversidad. Los datos de herbario muestran que en la estructura de la diversidad obtenida con inventarios aún pueden estar presentes numerosas especies raras o de distribución restringida. Parece conveniente usar ambos tipos de datos de manera complementaria para evaluar la S en bosques tropicales, en especial cuando son pobremente conocidos.
Estimates of tree species richness (S) have usually been approached with systematic surveys. More recently, with the increasing on-line availability of digital herbaria data, alternative S estimates are possible. How comparable are these two estimates? We fitted generalized linear models (GLM) to obtain estimates of S with both data types from three different mountain regions in Chiapas (>1,500 elevation) for which substantial numbers of both herbarium vouchers and survey plots are available. A total number of 792 tree species were detected with both types of data. Clench's model estimated 862 and 425 tree species with herbarium and survey data, respectively. The selected GLM models rendered S estimates that were positively correlated in two out of the three studied regions (not in the most species-rich region). Systematic surveys provide a snap-shot of species equitability among real samples of forest communities, and therefore, represent a useful set of data to approach the understanding of tree diversity structure. On the other hand, herbarium vouchers allow estimates of how many rare or restricted species may still be absent in the survey-based inventory. It seems convenient to make complementary use of both types of data in order to estimate S in poorly known tropical forests.
Changes in the landscape due to habitat loss and fragmentation interact with ecological processes of populations, and define the local population abundance. We evaluated the relationship between the ...abundance of two common marsupials, Didelphis marsupialis (common opossum) and Didelphis virginiana (Virginia opossum), and landscape features in different levels of disturbance at Chiapas, the Highlands and the Central Depression. The goal was to identify effects of changes in the landscape in their populations. Based on the biological characteristics of D. marsupialis and D. virginiana our expectation was to observe higher abundance of opossums in areas with intermediate disturbance. At the same time, establish a relationship between the landscape composition and the abundance of both species. We placed 48 Tomahawk traps in three disturbance levels of the landscape. Within each disturbance level we obtained the structure and composition of the landscape. The abundance of each species was considered as the number of individuals captured. A relative abundance index was estimated from individuals captured by night traps. The influence of the disturbance levels, the landscape, structure, and composition in the abundance of each species was evaluated using multiple regression and generalized lineal model. The average abundance of Didelphis spp. was higher in the Central Depression (5.56 individuals, SD = 4.82). Didelphis marsupialis was captured only in low disturbance with an average of 0.56 individuals (SD = 1.04; Figure 2a), while D. virginiana was captured in the three levels of disturbance with an average of 3.56 individuals (SD = 3.88; Figure 2b). The presence of D. marsupialis was influenced by the number of patches (NP; P = 0.003), while for D. virginiana landscape index was not associated with its presence (Table 2). Our results suggest that the abundance of D. marsupialis and D. virginiana was not influenced by level of disturbance. However, D. marsupialis was related to the number of patches and conserved areas; while D. virginiana was not affected by the landscape attributes evaluated, i. e. composition and configuration, indicating that Virginia opossum can established relatively abundant populations in landscapes highly disturbed. This study contributes to the understanding of the effects of changes in the landscape in common species in Mexico due to human activities.
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