Factors that influence the beta-diversity of spider communities in northwestern Argentinean Grasslands

Abstract

Beta-diversity, defined as spatial replacement in species composition, is crucial to the understanding of how local communities assemble. These changes can be driven by environmental or geographic factors (such as geographic distance), or a combination of the two. Spiders have been shown to be good indicators of environmental quality. Accordingly, spiders are used in this work as model taxa to establish whether there is a decrease in community similarity that corresponds to geographic distance in the grasslands of the Campos & Malezales ecoregion (Corrientes). Furthermore, the influence of climactic factors and local vegetation heterogeneity (environmental factors) on assemblage composition was evaluated. Finally, this study evaluated whether the differential dispersal capacity of spider families is a factor that influences their community structure at a regional scale. Spiders were collected with a G-Vac from vegetation in six grassland sites in the Campos & Malezales ecoregion that were separated by a minimum of 13 km. With this data, the impact of alpha-diversity and different environmental variables on the beta-diversity of spider communities was analysed. Likewise, the importance of species replacement and nesting on beta-diversity and their contribution to the regional diversity of spider families with different dispersion capacities was evaluated. The regional and site-specific inventories obtained were complete. The similarity between spider communities declined as the geographic distance between sites increased. Environmental variables also influenced community composition; stochastic events and abiotic forces were the principal intervening factors in assembly structure. The differential dispersal capacity of spider groups also influenced community structure at a regional scale. The regional beta-diversity, as well as species replacement, was greater in high and intermediate vagility spiders; while nesting was greater in spiders with low dispersion capacity. Geographic distance, among other factors (climate, and active and passive dispersion capacity), explains assembly structure and the decrease spider community similarity between geographically distant sites. Spiders with the highest dispersal capacity showed greater species replacement. This may be due to the discontinuity (both natural and anthropic) of the grasslands in this ecoregion, which limits the dispersal capacity of these spiders, and their close dependence on microhabitats. The dispersal capacity of the least vagile spiders is limited by geographic distance and biotic factors, such as competition, which could explain the nesting observed between their communities.

Diversidad estacional de arañas en una reserva natural del Espinal en Corrientes, Argentina

“…al. 2009, Rodriguez et al 2016. Asimismo, la estimación de especies fue superior a la obtenida en gran parte de dichos sitios con el mismo estimador.…”

“…Por otra parte, hay estudios que demuestran que los ensambles de arañas fluctúan en función de la complejidad estructural del hábitat (Uetz 1991, Malumbres-O et al 2013, Rodriguez-A et al 2016) y de los parámetros físicos, como temperatura, precipitaciones y humedad (Ziesche y Roth 2008, Rubio y Acosta 2011, Rodriguez-A et al 2016). La relevancia de estos factores depende de la estacionalidad, por lo que otro factor a tener en cuenta en los estudios ecológicos son las estaciones climáticas (Ziesche y Roth 2008).…”

“…Siguiendo la clasificación fitogeográfica de Cabrera (1976), entre ellos se citan los concretados en la Provincia Fitogeográfica Chaqueña (Avalos et al 2007, Rubio et al 2008, Escobar et al 2012, Achitte-S et al 2016, en la Provincia de las Yungas (Rubio 2015, Torres et al 2017, en los Esteros del Iberá, que comprenden las provincias fitogeográficas Chaqueña, Paranaense y Espinal (Avalos et al 2009) y en un área de la provincia de Corrientes que incluye parte de la Provincia del Espinal y parte de la Provincia Paranaense (Rodriguez-A et al 2016). Dichos trabajos nos permiten contar con parámetros que son importantes a la hora de monitorear los cambios en la diversidad de arañas debido a las perturbaciones ambientales, lo que es indispensable para la toma de decisiones a favor de la conservación (Moreno 2001).…”

Short-term spider community monitoring after cattle removal in grazed grassland

“…Spiders have their diversity dependent of many factors (Foelix, 2011): vegetal structure (Baldissera et al, 2004;Nogueira & Pinto-da-Rocha, 2016), capacity of dispersal and settlement (Rodrigues et al, 2009;Lin et al, 2016) being distance insignificant (Horváth et al, 2009), prey availability and competitive exclusion (Dennis et al, 2015;Rodriguez-Artigas et al, 2016). Moreover, spider are still capable of consume high biomass rate (Nyfeller, 2000;Ott, 2016), are generalist predators in different trophic levels, even eating other spiders (Wise, 2006) and occupying nearly all terrestrial territories (Foelix, 2011), making up great ecological models (Craig et al, 2001;Foelix, 2011).…”

Drivers of the beta diversity of spider assemblages in southern Brazilian temporary wetlands

“…In this sense, variation in local habitat structure is associated with changes in spider assemblage composition (Tews et al ., ; Jiménez‐Valverde & Lobo, ; Carvalho et al ., ; Ávila et al ., ). Previous studies revealed that climate is another important driver of spider distribution on a broader scale (Jiménez‐Valverde & Lobo, ; Finch et al ., ; Jiménez‐Valverde et al ., ; Carvalho et al ., ; Rodriguez‐Artigas et al ., ).…”