Six groups of ground-dwelling arthropods show different diversity responses along elevational gradients in the Swiss Alps

Abstract

Elevational gradients along mountain slopes offer opportunities to study key factors shaping species diversity patterns. Several environmental factors change over short distances along the elevational gradient in predictable ways. However, different taxa respond to these factors differently resulting in various proposed models for biodiversity patterns along elevational transects. Using a multi-taxa approach, we investigated the effects of elevation, area, habitat and soil characteristics on species richness, individual abundance and species composition of six groups of ground-dwelling arthropods along four transect lines in the Swiss National Park and its surroundings (Eastern Alps). Spiders, millipedes, centipedes, ants, ground beetles and rove beetles were sampled using standardized methods (pitfall traps, cardboard traps, visual search) in 65 sites spanning an elevational range from 1800 to 2750 m a.s.l.. A total of 14,782 individuals comprising 248 species were collected (86 spider, 74 rove beetle, 34 ground beetle, 21 millipede, 19 centipede and 14 ant species). Linear mixed model-analysis revealed that rarefied species richness in five out of the six arthropod groups was affected by elevation (the quadratic term of elevation provided the best fit in most cases). We found three different patterns (linear decrease in centipedes, low elevation plateau followed by a decrease in ants and rove beetles, and midpoint peak in spiders and millipedes). These patterns were only partially mirrored when considering individual abundance. Elevation influenced species composition in all groups examined. Overall, elevation was the most important factor explaining the diversity patterns, while most local habitat and soil characteristics have little influence on these patterns. Our study supports the importance of using multi-taxa approaches when examining effects of elevational gradients. Considering only a single group may result in misleading findings for overall biodiversity.

Elevational variation of spider and insect communities in the Swedish mountains

“…Elevational variations in diversity have been quantified previously for both spiders and insects, but the patterns have not been uniform among different studies. For instance, the taxonomic diversity of spiders has shown declines with elevation (Winkler et al, 2018), hyperbolic relationships with elevation (Gilgado et al, 2022), and no elevational variation (Dolson et al, 2020). Similar variation has been observed in how insect communities respond to elevational gradients (e.g., Despland et al, 2012; Winkler et al, 2018).…”

Community diversity and composition of ground-dwelling arthropods in major habitat types of the KwaZulu-Natal Sandstone Sourveld.

“…These results match the findings by Gilgado et al (2022) where soil pH affected the species composition of ants, beetles, and centipedes when these parameters were compared at different levels of elevation. However, this contrast with Pan et al (2018), where soil pH was invariable in influencing the species composition of ground-dwelling arthropods.…”

Ant Species Diversity in the Central and Northern Parts of the Western Sichuan Plateau in China

“…The results of previous studies showed that ant species richness decreased as the elevation increased [25,38,[55][56][57]. However, in the eight elevational transects of the central and northern Sichuan Plateau, this trend is not consistent.…”

“…Two main patterns of biodiversity along elevational gradients have been identified: (1) a monotonous decrease with elevation [25,26]; and (2) a unimodal pattern with maximum diversity at middle elevation [27]. Although there have been many studies describing elevational ant diversity patterns [28][29][30][31][32][33][34][35][36][37][38], a unanimous conclusion about patterns remains elusive. Therefore, further investigation is required in different regions, especially in previously unstudied areas.…”