Spatiotemporal Variation of Scarab Beetle Assemblages (Coleoptera: Scarabaeidae: Dynastinae, Melolonthinae, Rutelinae) in the Premontane Rain Forest in Costa Rica: A Question of Scale

Abstract

Biodiversity of tropical forests varies at spatial and temporal scales, but at what scale and how the assemblages differ when we consider the same kind of forest and the same altitude has been poorly documented. We examined the variation in species richness and composition of three subfamilies of scarab beetles (Dynastinae, Rutelinae, and Melolonthinae) along a northwest-southeast (NW-SE) transect of premontane rain forests in Costa Rica. Sampling was carried out at six sampling sites comprising three mountain ranges. Two forest sites were selected in each mountain range at the same altitudinal strip and same life zone. We conducted eight field surveys from June 2007 to January 2008. UV light traps were used to catch the beetles. We studied beetle diversity at three spatiotemporal levels: mountain range, forest site, and monthly trap. Species composition and richness varied at the three levels studied, and this variation was not necessarily related with geographic distance. Forest site and monthly trap levels showed higher variation in similarity indices than the mountain range level did. Additive partitioning of diversity showed values of diversity higher than expected only at the spatial levels with the mountain ranges showing the highest contribution to gamma diversity. Our results show high spatiotemporal variation in scarab beetle assemblages across Costa Rican premontane rain forests and underline that the analysis of a variety of spatiotemporal scales within a single kind of forest is crucial to understand scarab beetle biodiversity patterns in forest ecosystems.

Beta diversity at multiple hierarchical levels: explaining the high diversity of scarab beetles in tropical montane forests

“…Specimens were taken from the earlier study of García‐López et al . (), which was based on detailed collecting efforts at six primary forest sites along a north‐west/south‐east transect of 300 km in three mountain ranges (Guanacaste, Central and Talamanca) in Costa Rica (García‐López et al ., ; see Appendix S1 in Supporting Information). These sites were situated in an elevational strip varying from 900 to 1100 m along the Atlantic slope and in the same life zone, the premontane rain forest of Holdridge (), sharing similar environmental characteristics.…”

“…In an attempt to avoid the confounding issue of elevational turnover and environmental variability, García‐López et al . () studied assemblages of Scarabaeidae by selecting sites with similar environmental conditions in montane forests of Costa Rica (see below). Despite the presumably low habitat heterogeneity and short geographical distances between study sites (maximum distance 300 km), only c .…”

“…Here, we extend our studies of Costa Rican montane scarab communities (García‐López et al ., ) to investigate whether the patterns of diversity and turnover indicate the persistence of communities in isolation, which may indicate the historical stability of populations. We analysed community structure at three hierarchical levels (haplotype, species and clades) using DNA sequences of multiple representatives of all species sampled at each study site.…”

Influencia del recambio de especies en la biodiversidad de bosques tropicales: el ejemplo de Costa Rica

“…3). Resultados obtenidos en distintos trabajos llevados a cabo en Costa Rica (García-López et al, 2010;García-López et al, 2011), utilizando como grupo de estudio las subfamilias de escarabeidos Dynastinae, Melolonthinae y Rutelinae (Fig. 4), han demostrado la existencia de una enorme variación espacial de la diversidad a través de estos bosques.…”

“…En el primer caso seis puntos de muestreo fueron distribuidos a través del sistema montañoso del país (dos puntos en la Cordillera de Guanacaste, dos puntos en la Cordillera Central y dos puntos en la Cordillera de Talamanca). Todos estos puntos de muestreo se situaron en una franja de altitud entre los 900 y 1100 metros de manera que todos se encontraran en la misma zona de vida, el bosque lluvioso premontano, y así mantuvieran una homogeneidad ambiental que permitiese evaluar la variación de diversidad cuando las características del ecosistema se mantienen constantes (García-López et al, 2010). En el caso del transecto altitudinal seis puntos de muestreo fueron ubicados en bosques situados a lo largo de un gradiente de 1400 m de elevación en la Cordillera de Guanacaste, abarcando desde los 100 a los 1510 m (García-López et al, 2011).…”