Global dung webs: high trophic generalism of dung beetles along the latitudinal diversity gradient

Abstract

At the global scale, species diversity is known to strongly increase towards the equator for most taxa. According to theory, a higher resource specificity of consumers facilitates the coexistence of a larger number of species and has been suggested as an explanation for the latitudinal diversity gradient. However, only few studies support the predicted increase in specialisation or even showed opposite results. Surprisingly, analyses for detritivores are still missing. Therefore, we performed an analysis on the degree of trophic specialisation of dung beetles. We summarised 45 studies, covering the resource preferences of a total of 994503 individuals, to calculate the dung specificity in each study region. Our results highlighted a significant (4.3-fold) increase in the diversity of beetles attracted to vertebrate dung towards the equator. However, their resource specificity was low, unrelated to diversity and revealed a highly generalistic use of dung resources that remained similar along the latitudinal gradient.

Co‐declining mammal–dung beetle faunas throughout the Atlantic Forest biome of South America

“…This is a trait-defined cascade phenomenon (Nichols et al 2013a), but our results revealed several positive relationships between the species richness and abundance of dung beetle functional groups and mammal species richness grouped into major trophic guilds. generalist, coprophage and necrophage) were the functional classes least affected by variation in mammal trophic guilds (61% of all comparisons) and this is likely related to high trophic generalism exhibited by dung beetles (Frank et al 2018) which includes coprophagy, necrophagy and saprophagy. Mammals influenced ~78% of the diel activity grouping of dung beetles (i.e.…”

“…Food specialization, particularly on mammalian dung, has clearly played an important role in driving the evolution (Davis et al 2002) and current distribution of dung beetles globally (Frank et al 2018). Food specialization, particularly on mammalian dung, has clearly played an important role in driving the evolution (Davis et al 2002) and current distribution of dung beetles globally (Frank et al 2018).…”

Climate rather than dung resources predict dung beetle abundance and diversity along elevational and land use gradients on Mt. Kilimanjaro

“…Bogoni et al, ; Frank, Brückner, Hilpert, Heethoff, & Blüthgen, ). Other studies discussing the relationship between dung beetle diversity, resource availability and climate conclude that both temperature and mammal diversity constitute drivers of dung beetle diversity (Frank et al, ; Muhirwa et al, ). However, these studies were conducted along small climatic scales compared to our large‐scale 3.6 km elevational and 21°C temperature gradient on Mt.…”

Linking dung beetle‐mediated functions to interactions in the Atlantic Forest: Sampling design matters

“…Although dung beetles are commonly assumed to be generalist feeders (Frank et al , ; Hanski & Cambefort, ), species can show preference toward dung of certain mammal species or trophic guilds (Bogoni & Hernández, ; Santos‐Heredia et al , ). However, few studies have specifically tested the attractiveness of dung from mammal species native to the area of study (but see Enari, Koike, & Sakamaki, ; Frank, Hülsmann, Assmann, Schmitt, & Blüthgen, ).…”

“…Although dung beetles are commonly assumed to be generalist feeders (Frank et al, 2018;Hanski & Cambefort, 1991), species can show preference toward dung of certain mammal species or trophic guilds (Bogoni & Hernández, 2014;Santos-Heredia et al, 2010).…”