DOI: 10.5061/dryad.2bvq83brs
title: Climatic conditions and functional traits affect spider diets in agricultural and non-agricultural habitats worldwide

description: Spiders are dominant predators in terrestrial ecosystems and feed on prey
 from the herbivore and detritivore subsystem (dual subsystem omnivory) as
 well as on other predators (intraguild predation). Little is known about
 how global change potentially affects the importance of different prey
 groups in predator diets. In this meta-analysis we identify the impact of
 climatic conditions, land-use types and functional traits of spider
 species on the relative importance of Hemiptera, Araneae and Collembola
 prey in spider diets. We use a dataset including 78 publications with 149
 observational records of the diet composition of 96 spider species in
 agricultural and non-agricultural habitats in 24 countries worldwide. The
 importance of Hemiptera prey was not affected by climatic conditions and
 was particularily high in smaller spider species in agricultural habitats.
 Araneae prey was most important for actively hunting, larger spider
 species in non-agricultural habitats. Collembola prey was most important
 for small, actively hunting spider species in regions with higher
 temperature seasonality. Spider species with a higher importance of
 Araneae prey for their diet also had higher importances of Collembola and
 lower importances of Hemiptera prey. Future increases of temperature
 seasonality predicted for several regions worldwide may go along with an
 increasing importance of Collembola prey which also related to a higher
 importance of intraguild prey here. Two global change drivers predicted
 for many regions of the world (increasing climatic seasonality and ongoing
 conversion of non-agricultural to agricultural land) both hold the
 potential to increase the importance of Collembola prey in spider diets.
 The importance of Hemiptera and Araneae prey may however show contrasting
 responses to these two drivers. These complex potential effects of global
 change components and their impact on functional traits in spider
 communities highlight the importance to simultaneously consider multiple
 drivers of global change to better understand future predator-prey
 interactions.
description: This study is based on a global database about the diet
 composition of hunting and web-building spider species in natural
 ecosystems used in Birkhofer and Wolters (2012) with the addition of data
 from agricultural ecsoystems and updates from Diehl et al. (2013b),
 Michalko & Pekár (2015a), Arvidsson et al. (2020) and Mezőfi et
 al. (2020). All data in the original publications are derived by direct
 visual records of prey or prey remains in spider species in field studies,
 not including data from molecular or experimental studies. Note that only
 subsets of data from the original database from non-agricultural (82
 cursorial and web-building spider species in natural habitats: Birkhofer
 & Wolters 2012) or only for web-building spiders (63 spider
 species in agricultural, natural and forest habitats: Birkhofer et al.
 2018) were previously published. The database includes 118 unique
 publications that reported 310 datasets about diet compositions in
 individual spider species worldwide. All datasets that were based on fewer
 than 20 recorded prey items per spider species in individual studies or
 did address spider species in forest habitats were excluded for this
 study. The selection of a minimum of 20 records was based on the fact that
 spiders in each study could theoretically reach the maximum diet breadth,
 including prey from all 20 prey orders that were originally recorded
 across datasets (see Birkhofer & Wolters 2012). The selection of
 non-forest habitats was based on the aim to compare habitats that share a
 major structural characteristic by not being dominated by dense, natural
 tree cover. Forests further have a very different invertebrate community
 compared to grasslands and arable fields (e.g. Birkhofer et al. 2015),
 which would limit a comparison of diets between major habitat types. The
 remaining 78 publications provided 149 datasets on the diet composition of
 96 spider species worldwide (Figure 1). This database was used to
 calculate the relative contribution of each prey order to the overall diet
 in each dataset as percentage value. The percentages of Hemiptera,
 Collembola and Araneae prey were then extracted to reflect the relative
 contribution of these prey orders to the diet of individual spider
 species.
description: No missing values