Body size–climate relationships of European spiders

Abstract

Aim Geographic body size patterns of mammals and birds can be partly understood under the framework of Bergmann’s rule. Climatic influences on body size of invertebrates, however, appear highly variable and lack a comparable, generally applicable theoretical framework. We derived predictions for body size–climate relationships for spiders from the literature and tested them using three datasets of variable spatial extent and grain. Location Europe. Methods To distinguish climate from space, we compared clines in body size within three datasets with different degrees of co‐variation between latitude and climate. These datasets were: (1) regional spider faunas from 40 European countries and large islands; (2) local spider assemblages from standardized samples in 32 habitats across Europe; and (3) local spider assemblages from Central European habitats. In the latter dataset climatic conditions were determined more by habitat type than by geographic position, and therefore this dataset provided a non‐spatial gradient of various microclimates. Spider body size was studied in relation to latitude, temperature and water availability. Results In all three datasets the mean body size of spider assemblages increased from cool/moist to warm/dry environments. This increase could be accounted for by turnover from small‐bodied to large‐bodied spider families. Body size–climate relationships within families were inconsistent. Main conclusions Starvation resistance and accelerated maturation can be ruled out as explanations for the body size clines recorded, because they predict the inverse of the observed relationship between spider body size and temperature. The relationship between body size and climate was partly independent of geographic position. Thus, the restriction of large‐bodied spiders to their glacial refugia owing to dispersal limitations can be excluded. Our results are consistent with mechanisms invoking metabolic rate, desiccation resistance and community interactions to predict a decrease in body size from warm and dry to cool and moist conditions.

Impact of Habitat Complexity on Body Size of Two Spider Species, Alopecosa cuneata and A. pulverulenta (Araneae, Lycosidae), in River Valley Grasslands

“…Therefore, smaller spiders should occur in more humid habitats, which very often means more dense vegetation. Such regularity was observed by Entling et al (2010) when taking into consideration the mean body size for whole assemblages based on the size of particular species [12]. They revealed that the mean body size of spider species in Europe decreases from warm and dry to cool and moist environments.…”

“…Current knowledge of mechanisms affecting the body size distribution is based mainly on studies involving vertebrates [6][7][8][9], while researches on invertebrates are still rare, although more frequent during last years [10][11][12][13][14][15]. Many of these studies analysed body size patterns of a particular group of invertebrates on a large geographical scale like a continent [10,[12][13][14], whereas knowledge about mechanisms affecting body size distribution on a local scale are still limited [11,[16][17].…”

“…Despite the great number of research on spiderhabitat interactions, only limited studies have included body size. On a large geographical scale, i.e., Europe, Entling et al (2010) showed that the mean body size of spider assemblages increased from cool and moist to warm and dry environments [12]. Research by Drapela et al (2011) revealed that landscape structure (e.g., distance to the nearest woody area) affected the body size of Pardosa agrestis -one of the most abundant spiders in arable fields [24].…”

Distribution and habitat preferences of tiger beetles (Coleoptera: Cicindelidae) of the riverine ecosystems of Sri Lanka

“…In turn, the habitats of the species had a significantly high air temperature and solar radiation, and a low relative humidity reflecting comparatively warm, dry environments. In terrestrial arthropods the body size of ants has been shown to decrease with temperature whereas bees, butterflies and moths show a variety of body size-climate patterns (Entling et al 2010). In tiger beetles large body size has been associated with coastal and reservoir habitats with high wind speed, low soil moisture and high soil pH, while species with small body have been associated with riverine habitats with low wind speed, high soil moisture and low soil pH (Dangalle et al 2013).…”

Fine‐grained climate data alters the interpretation of a trait‐based cline

“…We acknowledge here that our justification for using these three variables is a simplistic way of testing the above hypotheses and a thorough investigation might consider other macroclimatic variables and/or combinations of variables. Moreover, there are other hypotheses on body size patterns for ectotherms (e.g., Table 1 in Entling et al 2010) and so we make no claims for completeness. However, we note that the main purpose of this work was to examine the relative performance of topoclimatic variables over macroclimatic variables, the latter of which are commonly used for testing body-size clines (e.g., Harris et al 2012).…”