Spatial and environmental correlates of species richness and turnover patterns in European cryptocephaline and chrysomeline beetles

Andres Baselga,Andrea Freijeiro

doi:10.3897/zookeys.597.6792

Abstract

Despite some general concordant patterns (i.e. the latitudinal richness gradient), species richness and composition of different European beetle taxa varies in different ways according to their dispersal and ecological traits. Here, the patterns of variation in species richness, composition and spatial turnover are analysed in European cryptocephaline and chrysomeline leaf beetles, assessing their environmental and spatial correlates. The underlying rationale to use environmental and spatial variables of diversity patterns is to assess the relative support for niche- and dispersal-driven hypotheses. Our results show that despite a broad congruence in the factors correlated with cryptocephaline and chrysomeline richness, environmental variables (particularly temperature) were more relevant in cryptocephalines, whereas spatial variables were more relevant in chrysomelines (that showed a significant longitudinal gradient besides the latitudinal one), in line with the higher proportion of flightless species within chrysomelines. The variation in species composition was also related to environmental and spatial factors, but this pattern was better predicted by spatial variables in both groups, suggesting that species composition is more linked to dispersal and historical contingencies than species richness, which would be more controlled by environmental limitations. Among historical factors, Pleistocene glaciations appear as the most plausible explanation for the steeper decay in assemblage similarity with spatial distance, both in cryptocephalines and chrysomelines.

Highlights

The assessment of large-scale biogeographic patterns has proven a fruitful research discipline for understanding the ecological, evolutionary and historical processes that have determined the current distribution of biological diversity (Brown and Maurer 1989; Farrell 1998; Gaston and Blackburn 2000)
The most prominent pattern in species richness of both cryptocephalines and chrysomelines is the existence of a clear latitudinal gradient
The steepness of the latitudinal richness gradient is subject of a great variation among different beetle taxa (Baselga et al 2012b), with some taxa as families Scolytidae and Silphidae presenting weak gradients, while other taxa as genera Trechus (Carabidae) and Otiorhynchus (Curculionidae) having steep latitudinal gradients

Summary

Introduction

The assessment of large-scale biogeographic patterns has proven a fruitful research discipline for understanding the ecological, evolutionary and historical processes that have determined the current distribution of biological diversity (Brown and Maurer 1989; Farrell 1998; Gaston and Blackburn 2000). From the empirical point of view, one important shortfall is the under-representation of invertebrates in biogeographical studies, caused by the difficulty to sample and identify invertebrate species, compared to vertebrates or plants. This has led to a marked scarcity of invertebrate distribution data that prevented biogeographers to assess invertebrate biodiversity patterns. A potential avenue for progressing towards a full understanding of biodiversity patterns would be to gather invertebrate distribution data and assess large-scale biodiversity patterns

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