Influence of the composition and structure of modified landscapes on the abundance of two marsupials during the dry season in Chiapas, Mexico (original) (raw)
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Influencia de la composición y estructura de paisajes modificados en la abundancia de dos marsupiales durante el periodo de estiaje 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. Los cambios en el paisaje debido a la pérdida y fragmentación del hábitat interactúan con procesos ecológicos poblacionales y definen la abundancia poblacional local. Se evaluaron las relaciones entre la abundancia de dos marsupiales comunes, Didelphis marsupialis (tlacuache común) y Didelphis virginiana (tlacuache de Virginia), y los atributos del paisaje en diferentes niveles de disturbio en Chiapas, Los Altos y la Depresión Central. El objetivo fue identificar efectos de cambios del paisaje sobre sus poblaciones. Con base en las características biológicas de D. marsupialis y D. virginiana, nuestra hipótesis fue observar una mayor abundancia de tlacuaches en áreas con disturbio intermedio. Al mismo tiempo, establecer una relación entre la composición del paisaje y la abundancia de ambas especies. Se colocaron 48 trampas Tomahawk en tres niveles de disturbio. De cada nivel de disturbio se obtuvo la estructura y composición del paisaje. La abundancia por especie fue considerada como el número de individuos capturados. El índice de abundancia relativa fue estimado mediante los individuos capturados por trampas noches. La influencia del nivel de disturbio, paisaje, composición y estructura en la abundancia para cada especie se estimó a partir de regresiones múltiples y modelos lineales generalizados. La abundancia promedio de Didelphis sp. fue mayor en la Depresión Central (5.56 individuos, DE = 4.82). Didelphis marsupialis fue capturada solo en condiciones de bajo disturbio con un promedio de 0.56 individuos (DE = 1.04; Figura 2a), mientras que D. virginiana fue capturada en los tres niveles de disturbio con un promedio de 3.56 individuos (DE = 3.88; Figura 2b). El número de parches (NP) influyó en la presencia de D. marsupialis (P = 0.003), en tanto que para D. virginiana ningún índice del paisaje se asoció con su presencia (Tabla 2). Nuestros resultados sugieren que el nivel de disturbio no influye en la abundancia de D. marsupialis y D. virginiana. Sin embargo, D. marsupialis se relacionó con el número de parches y áreas conservadas; en tanto que D. virginiana no fue afectada por los atributos del paisaje evaluados, i. e. composición y configuración, indicando que el tlacuache de Virginia puede establecer poblaciones relativamente abundantes en paisajes altamente perturbados. Este estudio contribuye al conocimiento de los efectos de los cambios en el paisaje por actividades humanas en especies comunes en México.
Common Distribution Patterns of Marsupials Related to Physiographical Diversity in Venezuela
PLoS ONE, 2014
The aim of this study is to identify significant biotic regions (groups of areas with similar biotas) and biotic elements (groups of taxa with similar distributions) for the marsupial fauna in a part of northern South America using physiographical areas as Operational Geographical Units (OGUs). We considered Venezuela a good model to elucidate this issue because of its high diversity in landscapes and the relatively vast amount of information available on the geographical distribution of marsupial species. Based on the presence-absence of 33 species in 15 physiographical sub-regions (OGUs) we identified Operational Biogeographical Units (OBUs) and chorotypes using a quantitative analysis that tested statistical significance of the resulting groups. Altitudinal and/or climatic trends in the OBUs and chorotypes were studied using a redundancy analysis. The classification method revealed four OBUs. Strong biotic boundaries separated: i) the xerophytic zone of the Continental coast (OBU I); ii) the sub-regions north of the Orinoco River (OBU III and IV); and those south to the river (OBU II). Eleven chorotypes were identified, four of which included a single species with a restricted geographic distribution. As for the other chorotypes, three main common distribution patterns have been inferred: i) species from the Llanos and/or distributed south of the Orinoco River; ii) species exclusively from the Andes; and iii) species that either occur exclusively north of the Orinoco River or that show a wide distribution throughout Venezuela. Mean altitude, evapotranspiration and precipitation of the driest month, and temperature range allowed us to characterize environmentally most of the OBUs and chorotypes obtained.
Habitat use by a Neotropical desert marsupial (Thylamys pallidior): A multi-scale approach
Mammalian Biology - Zeitschrift für Säugetierkunde, 2012
In South America, most didelphid marsupials are associated with tropical and moist forests; however, a few species are adapted to more extreme environments such as desert systems. The desert mouse opossum, Thylamys pallidior, is a small marsupial which inhabits the arid regions of South America and has the broadest distribution of the genus. The objective of this research was to assess the habitat use and selection by the desert marsupial T. pallidior considering different scales and habitat levels of analysis, as well as seasonality. We considered two habitat levels (macro and microhabitat) and the microhabitat was analyzed at two spatial scales (1 ha and 4 m 2 ). We recorded 95 captures of mouse opossums in 27,600 trap-nights. Our study showed that habitat type was not a significant factor for selection; instead mouse opossums selected areas with low complexity and high grass cover. The scale of analysis was also important since the selection was stronger in larger areas. Habitat selection by T. pallidior occurred mainly during the dry season. During the wet season, the species used all habitat areas and types indistinctly. The present study highlights the importance of performing analyses which include multiple spatial and temporal scales for a better understanding of the patterns involved in habitat use and species distribution.
Journal of Mammalogy
Climate change is one of the main threats to biodiversity in the 21st century. However, the effects that it may have on different mammal species are unknown, making it difficult to implement conservation strategies. In this paper, we used species distribution models (SDM) to assess the effect of global climate change on the potential distribution of the 8 of the 9 marsupial species in Mexico, and analyzed their distribution in the current system of natural protected areas (NPAs). We used presence records for each species and bioclimatic variables from the present and the future (2050 and 2080) with 2 contrasting possible scenarios (representative concentration pathways RCP 4.5 and 8.5). We found that Tlacuatzin canescens would have the most stable potential range under any climate change scenario, while the remaining species (Caluromys derbianus, Chironectes minimus, Didelphis marsupialis, D. virginiana, Philander opossum, Marmosa mexicana, and Metachirus nudicaudatus) would undergo...
Influence of habitat characteristics on small mammals in a Mexican high-altitude grassland
Journal of Zoology, 1990
Small mammals in a high-altitude grassland area close to Mexico City were studied. Populations of 10 species were censused using live traps in 48 sample quadrats. Within each quadrat, vegetation characterization, including complete floristic listings, cover values for species and layers and values of habitat modification, were assessed. Habitats were described according to plant communities identified using ordination and classification methods. Nine different plant communities were obtained. Densities and abundance of all small mammal species were calculated for each of the habitats classified. Peromyscus alstoni was the most abundant species in all habitats, reaching maximum densities of55 ha-' in pine forest with densegroundandherb layer. Peromyscus melanotis also occurred in all habitats but at lower densities (maximum 29 ha-'). Reithrodontomys megalotis was found in all habitats except in tall dense grassland. Densities for this species were generally low (1-9 ha-') but reached 19 ha-' in short densegrassland. All other species were largely absent from 4-8 habitats and showed very low densities (0.75-4 ha-'). The densities of the more abundant species were largely correlated with more open habitats and higher indices of habitat modification. Lower altitude grassland habitats have a greater abundance of small mammals and a higher species richness than the medium and higher altitude, physiognomically more complex habitats. Species richness was highest in tallpine-alder forest with a speciesrich, dense herb layer and lowest in pine forest with dense ground and herb layers. Species richness was positively correlated with overall small mammal density.
Biological Conservation, 2008
Knowledge of the habitat requirements of threatened species at both local and landscape scales is crucial for maintaining viable populations and for making conservation and management decisions. Here, we use live trapping and radio-tracking to investigate habitat use by four species of threatened marsupials -burrowing bettongs (Bettongia lesueur), brushtailed bettongs (B. penicillata), greater bilbies (Macrotis lagotis), and bridled nailtail wallabies (Onychogalea fraenata). The study populations had been re-introduced to Scotia Sanctuary in western New South Wales, Australia, within a predator-proof area. All showed preferences for particular macrohabitats while resting by day, with M. lagotis and B. penicillata selecting Eucalyptus woodland with Triodia understorey and B. lesueur and O. fraenata selecting Eucalyptus woodland with shrubs. However, they showed no such partiality at night. Bettongia penicillata used areas with Triodia and litter but few herbs for shelter, while burrows of M. lagotis avoided shrubs. Habitat components that influenced trap captures were: crust cover and herb layer cover (negative) for B. penicillata, trees <5 m in height and number of shrubs (both negative) for B. lesueur, crust cover for M. lagotis, and crust cover and trees <5 m high for O. fraenata (both negative). There was also a negative association at this scale between B.
Gradients of Species Density and Turnover in Marsupials: A Hemispheric Perspective
Journal of Mammalogy, 1997
Although marsupials represent a taxonomically and ecologically diverse group of manunals (Infraclass Metatheria), little is known concerning their large-scale areographic patterns. Distributional data for North and South America were analyzed by statistical techniques to ascertain the degree to which latitude, biome richness, and area account for patterns of species density. In general, mid-latitude accounted for more variation among bands than did other descriptors, but the fonn of the relation between species density and latitude differed between North and South America. Marsupials in North America exhibited more simple relations (quadratic) between species density and latitude than did their South American counterparts (cubic). Nonetheless. both models are consistent with a subtropical maximum. Turnover of species between quadrats within a band did not contribute to latitudinal gradients in species density in a significant fashion in either continent. Such complex results may reflect the dynamic interaction of contemporary ecological forces (habitat selection, competition, physiological constraints) superimposed on a pervasive historical legacy (i.e., extensive radiation in South America, subsequent reduction in diversity after placental invasion during the late Pliocene. re-invasion of Central America from the south).