Local and regional ecological morphology of dung beetle assemblages across four biogeographic regions

Abstract

Aim Niche partitioning within species assemblages is thought to influence species packing and/or total niche space occupied. The evolution of dung beetles (Scarabaeinae) is likely to have been strongly influenced by inter-specific competition, leading to niche partitioning. We consider whether local-scale processes leave a signature in regional patterns of functional diversity in dung beetle assemblages, and investigate the correlation between total exploited ecomorphological space and density of species packing with increased species richness. We test whether ecomorphological space occupied by local assemblages reflects that of their regional species pool, and the extent to which ecomorphological space is convergent or divergent within functional groups across regional pools.Location Neotropics, Africa, Australia and Madagascar.Methods Dung beetle assemblages were collected in a standardized manner from four biogeographic regions. Ecomorphological similarity among the assemblages was assessed by multivariate analysis of 19 linear measurements for 300 species and three functional nesting types (roller, tunneller or dweller), firstly on a local level within the Neotropics and Afrotropics, and then between the regional species pools.Results Key body measurements, in particular the hind tibia, separated rollers and tunnellers into largely non-overlapping entities along the first three axes of the shape analysis. Three Neotropical assemblages, which vary widely in species numbers, each harboured a similar amount of morphometric variation, resulting in increasingly dense species packing with greater species richness. Similar findings were obtained in two South African assemblages. Assemblages in the four biogeographic regions showed largely similar distributions of ecomorphological variation, including the separation of rollers and tunnellers, despite their distant phylogenetic relationships. Ecomorphological similarity among regions was particularly high in tunnellers, whilst the rollers exhibited greater regional differentiation.Main conclusions Local assemblages evidently represent the full diversity of functional groups available in the regional pool, even in species-poor assemblages. There is a strong trend towards convergence in morphology separating tunnellers and rollers in phylogenetically independent lineages. The ecomorphological similarity of regional assemblages suggests that morphological convergence is the result of common selective forces active within the assemblages themselves. This lends support to the widely hypothesized effect of inter-specific interactions and niche partitioning in determining assemblage composition and lineage evolution in the Scarabaeinae.

The Evolution of Morphospace in Phytophagous Scarab Chafers: No Competition - No Divergence?

“…Striking morphospace divergence between some sister lineages with divergent feeding habits reveals that at least in the past (at the origin of these lineages) strong directed selection on morphospace was also likely to be linked with resource partitioning although being catalyzed by other factors such as feeding related locomotion behavior. But the same is true for scarabaeine dung beetles [17]. However, poor autecological knowledge of most pleurostict species and lacking community studies on assemblage level (competition acts only on individuals of all developmental stages in local assemblages) make it hard to investigate the linkage between divergence and competition in more detail.…”

Biodiversity and environmental context predict dung beetle‐mediated seed dispersal in a tropical forest field experiment

“…2) using a Leica M250 microscope and Life Measurement software (Leica, Wetzlar, Germany); with digital calipers (0.01-mm resolution) we measured pronotum height; and dry biomass was determined using a Shimadzu AY220 balance (Shimadzu Corporation, Kyoto, Japan) with precision to 0.0001g. Because these morphological traits may not fully capture all functionally relevant behavioral information (Inward et al 2011), we also included three categorical traits: nesting strategy (roller, tunneller, or dweller; for description see Hanski and Cambefort 1991), activity period (nocturnal, diurnal, crepuscular, or generalist), and diet (coprophagous or generalist). Front tibia and femur area were summed to provide a total front leg area, and pronotum height and area were multiplied to estimate pronotum volume.…”

Morphological structure of ant assemblages in tropical and temperate forests

“…4 within a taxon fills a morphospace) (McClain et al 2004), responses of assemblage structure to habitat complexity (Willis et al 2005, Montaña andWinemiller, 2010), and convergent or divergent patterns of morphology among continents (Ricklefs and Travis 1980, Winemiller 1991, Inward et al 2011, Ricklefs 2012, Montaña et al 2014. Morphological data also have been used to test the relative importance of environmental filtering and limiting similarity in structuring species assemblages (e.g., Cadotte et al 2013Cadotte et al , 2015.…”