Local- versus broad-scale environmental drivers of continental β -diversity patterns in subterranean spider communities across Europe

Abstract

Macroecologists seek to identify drivers of community turnover ( β -diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale β -diversity patterns remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of continental β -diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35–70° latitude). Generalized dissimilarity modelling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of β -diversity, with differential contributions of each factor according to the level of subterranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterranean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.

Continental data on cave-dwelling spider communities across Europe (Arachnida: Araneae)

“…Similar high-resolution data are rarely associated with broad-scale datasets used for macroecological analyses. Therefore, the CAWEB dataset can be used to explore a range of biogeographical and macroecological questions, potentially extending beyond arachnology and subterranean biology (see Mammola et al 2019b for an example).…”

“…Huber 2018, Mammola et al 2018, Cardoso 2012) and the lack of broad-scale databases about their distribution (Culver et al 2013, Mammola 2019), global-scale diversity patterns of subterranean spiders remain virtually undescribed (Mammola et al 2018a, Mammola and Isaia 2017). In an attempt to overcome this impediment, we created an international network of araneologists and cavers (that we called the "CAWEB" network; Mammola et al 2017) to compile the first continental-scale geo-referenced dataset of cave-dwelling and other subterranean spider communities (Mammola et al 2019b). In this data paper, we describe these datasets and make them freely available online for future use.…”

Trogloregions: delimiting subterranean faunistic identities in Afrotropics and Neotropics

“…Therefore, it is argued that the maintenance of greater subterranean biodiversity in certain regions may be the result of constant precipitation rates in the long term, favoring a greater resource availability to the hypogean environment 27 . It has also been found that changes in temperature on the surface are one of the main factors responsible for variations in the similarity patterns of subterranean fauna, especially for nonspecialized fauna, providing more similar communities in more climatically similar regions 46 . Thus, it is very likely that the patterns veri ed with the delimitation of the Trogloregions were partly shaped by the environmental transformations and characteristics of the surface.…”

Fundamental research questions in subterranean biology

“…Recent macroecological studies have shown that historical climatic variability, spatial heterogeneity, and energy contribute to species richness patterns of subterranean taxa in Europe. However, the contributions of these factors vary regionally and across taxa (Eme et al ., 2015; Bregović & Zagmajster, 2016; Bregović, Fišer, & Zagmajster, 2019; Mammola et al ., 2019 a ). At a landscape scale, linking environmental factors with speciation, extinction, and dispersal dynamics (Q29), as well as diversification processes (Q30), remains challenging and requires the use of phylogenetic methods and a large number of specimens for DNA analysis (Stern et al ., 2017).…”