Functional diversity decreases with temperature in high elevation ant fauna

Abstract

1. Severe environmental conditions filter community species compositions, forming clines of functional diversity along environmental gradients. Here, the changes in functional diversity in ant assemblages with severe environmental conditions in the Swiss Alps were investigated.2. Eight sites were sampled along an elevation gradient (1800-2550 m). The variation in functional diversity was analysed along an elevation gradient considering four traits: social structure (monogynous vs. polygynous), worker size, pupal development, and nest structure.3. Ant species richness and functional diversity decreased with decreasing temperature. Species found in colder habitats tended to live in subterranean nests rather than in mounds and exhibit a polymorphism in queen number, either within or across populations. The phylogenetic diversity did not decrease at colder temperature: Formicinae and Myrmicinae occupied the full range of elevations investigated.4. An insulation experiment indicated that mounds are more thermally insulated against the cold compared with soil. The absence of a mound-building ant from high elevations probably results from a reduction in the amount of vegetal materials provided by coniferous trees.5. More severe abiotic conditions at higher elevations act as a filter on ant assemblages, directly through physiological tolerances to the abiotic conditions and indirectly as the vegetation necessary for nest building shifts with elevation.

Differential allocation and deployment of direct and indirect defences by Vicia sepium along elevation gradients

“…; Reymond et al . ). EFNs and higher nectar production are probably to be a better food source for ants at lower elevations and should be guarded by the more aggressive or specialized ant species.…”

“…; Reymond et al . ). In addition, variation in environmental conditions may influence plant metabolic activity and the extent to which defences can be synthesized.…”

Soil protist diversity in the Swiss western Alps is better predicted by topo‐climatic than by edaphic variables

“…As for macroorganisms (D'Amen, Pradervand, & Guisan, ; Dubuis et al, ; McCain, ; Reymond, Purcell, Cherix, Guisan, & Pellissier, ), and increasingly reported for other soil microorganisms (Geml, Morgado, Semenova‐Nelsen, & Schilthuizen, ; Pellissier et al, ; Shen et al, ), protists diversity showed clear spatial and elevational patterns when only topo‐climatic variables were taken into account to build the model (Figure ). This pattern seemed to be driven by summer temperature in most cases (see Appendix S4.11 and Appendix S4.12), either in a positive (Diatomeae, Phytomyxea and Tubulinea), unimodal (Apicomplexa, Sarcomonadea and Spirotrichea) or negative way (Chlorophyceae, Peronosporomycetes).…”

The frequency of multi‐queen colonies increases with altitude in a Nearctic ant

“…Facultatively polygynous species are particularly common in boreal and alpine habitats. Most species of non-parasitic ants reported from areas near the tree line in the Northern hemisphere are facultatively polygynous (Heinze, 1993;Bharti et al, 2013), and a recent study has corroborated this pattern for the Swiss Alps (Reymond et al, 2013). Although the prevalence of facultative polygyny at high latitudes and altitudes is thus well documented, it remains unclear how queen number within facultatively polygynous species varies with geographical traits.…”

“…Although the prevalence of facultative polygyny at high latitudes and altitudes is thus well documented, it remains unclear how queen number within facultatively polygynous species varies with geographical traits. Reymond et al (2013) predicted dominance of monogyny at Correspondence: Jürgen Heinze, Biologie I, Universität Regensburg, 93040 Regensburg, Germany. E-mail: Juergen.heinze@ur.de higher altitudes because young queens from monogynous nests are typically larger and presumably more capable of dispersal than queens from polygynous nests.…”