Historical vs. ecological factors influencing global patterns of scarabaeine dung beetle diversity

Abstract

Abstract. There has been much debate concerning the relative influence on biodiversity of historical vs. current ecological factors. Although both are important, we suggest that historical influences might be greater at higher taxonomic level, since one is looking further back into evolutionary history than at lower taxonomic level. Although we are unable to separate ecological from historical effects in the present global study on scarabaeine dung beetles, we are able to demonstrate differences in correlations between major environmental influences (climatic area, numbers of dung types) and major components of diversity (taxon richness, taxon diversity, functional composition) at different taxonomic levels (tribe, genus, species). Current global variation in taxon richness is correlated strongly to current biogeographical variation in the area of suitable climate at all three taxonomic levels. However, generic and species richness is correlated most strongly to climatic combinations which include tropical and warm summer rainfall climate types (I, II). In contrast, tribal richness is correlated most strongly to climatic combinations which include both warm summer rainfall and temperate climate types (II, VI, X). Regional variation in the number of available dung types shows a strong positive correlation to regional variation in taxon richness at higher tribal level but not at lower generic and species levels. Similarly, biogeographical differences in the number of available dung types show a strong negative correlation to dominance indices for taxon diversity at tribal level (distribution of generic numbers between tribes) but none at generic level (species numbers per genus). As functional diversification is linked closely to taxonomic diversification at tribal level, proportions of both ball‐rolling genera and ball‐rolling species also show strong negative correlations to the number of dung types available in each region. In conclusion, the presence of dung type correlations only at higher taxonomic level may reflect historical effects on scarabaeine taxon diversification, whereas differences in correlations to climate type with taxonomic level may reflect both current ecological and historical effects.

An old adaptive radiation of forest dung beetles in Madagascar

“…The ancient isolation of Madagascar is reflected in the composition of its dung beetles, which lack the evolutionarily younger tribes that have become to dominate in abundance the older tribes elsewhere in the world, with the partial exception of the Neotropical region (Davis and Scholtz, 2001). In Madagascar, the vast majority of dung beetles belong to only two tribes, Helictopleurini and Canthonini.…”

“…170 species (Montreuil, 2006;Paulian, 1975). Other tribes of Scarabaeidae in Madagascar include three genera of Scarabaeini, each with one endemic species, and six species of Onthophagus (Onthophagini), two of which are introduced and four are endemic (Davis and Scholtz, 2001;Lebis, 1960).…”

Los Escarabeidos y Geotrúpidos de la Comunidad de Madrid: lista de especies, distribución geográfica y patrones de diversidad (Coleoptera, Scarabaeoidea, Scarabaeidae y Geotrupidae)

“…La actual fauna existente en las región Paleártica seria el resultado de la reciente colonización (PlioPleistocénica) de algunas especies pertenecientes a líneas Afrotropicales y de la diversificación ocurrida durante el Cenozoico de algunos taxa de origen Afrotropical, en respuesta a la radiación de los mamíferos placentarios y la expansión de los biomas herbáceos. Esta colonización y radiación en el Paleártico probablemente ocurrió durante el Mioceno y significó la generación de algunos endemismos a nivel genérico y específico (Davis & Scholtz, 2001;Davis et al 2002;ver también Zunino 1984b, Cambefort, 1991y Martín-Piera, 2000. De este modo, la actual fauna Paleártica sería principalmente el resultado de la diversificación en regiones asiáticas de antiguas líneas africanas, posteriormente diezmadas como consecuencia de los cambios climáticos Cuaternarios.…”

How might intensification of farming influence dung beetle diversity (Coleoptera: Scarabaeidae) in Maputo Special Reserve (Mozambique)?

“…3 Contribution of each component of the landscape (RF = Reserve Forest, FF = Farmed Forest, RG = Reserve Grassland, and FG = Farmed Grassland) to the proportions and numbers of species sampled in the entire landscape (gamma diversity, n = 57 species) (see methods) (Alpha = diversity contributed by habitat, Beta 1* = diversity between habitats, Beta 2** = diversity between land usage types). Proportions contributed by alpha and beta diversity are shown by the divisions within the bars whereas numbers of species are shown inside the bars dung type associations suggest that important categories of dung type comprise: the large, coarse-fibred droppings of monogastric herbivores (e.g., elephant, equines); the large pads of some ruminant herbivores (e.g., buffalo, cattle); the small, strong-odoured droppings of omnivores or carnivores (e.g., pigs, monkeys, humans); and the pellets dropped by smaller herbivores (Davis and Scholtz 2001). Many African dung beetle species are attracted to wide range of droppings and although they often show a bias in distribution towards particular dung types, or dung type categories, this is only extreme in a few cases (Davis 1994;Tshikae et al 2008).…”