Paleogene forest fragmentation and out‐of‐Africa dispersal explain radiation of the Paleotropical dung beetle tribe Epactoidini trib. nov. (Coleoptera: Scarabaeinae)

Abstract

Paleotropical clades with largely disjunct distributions are ideal models for biogeographic reconstructions. The dung beetle genera Grebennikovius Mlambo, Scholtz & Deschodt, Epactoides Olsouffief and Ochicanthon Vaz-de-Mello are distributed in Tanzania, Madagascar and Réunion, and the Oriental region, respectively. We combine morphology and molecular dataset to reconstruct the phylogenetic relationships between these taxa. Our analyses corroborate previous hypotheses of monophyly of the group, which is here described as new tribe Epactoidini trib. nov. Grebennikovius is recovered as sister to Epactoides, while Ochicanthon emerges as sister to them both. The disjunct distribution of our focal clade is unusual within the subfamily Scarabaeinae. Bayesian divergence time estimates and ancestral range reconstructions indicate an African origin of the crown group of the tribe Epactoidini trib. nov. in the early mid Eocene, ca. 46 Ma. The divergence between Epactoides and its sister is dated to 32.3 Ma, while the crown age for the genus Ochicanthon is dated to 27 Ma. We investigate the factors that may have shaped the current distribution of the tribe Epactoidini trib. nov. The formation of the Gomphotherium landbridge, along with favourable environmental conditions would have allowed dry-intolerant organisms, such as Ochicanthon, to disperse out of Africa. Remarkable climatic stability of the Eastern Arc Mountains was critical for the retention of the monotypic genus Grebennikovius. We suggest two subsequent overwater dispersal events: the migration of the most recent common ancestor (MRCA) of Epactoides from Africa to Madagascar (32.3-29.5 Ma); the lately dispersal of the MRCA of the today's extinct Epactoides giganteus Rossini, Vaz-de-Mello & Montreuil to Réunion island from Madagascar (3.4 Ma). We suggest that the high potential of dispersal of Epactoidini trib. nov. dung beetles and the strict association to forest habitat might have triggered two major radiations, one in Madagascar and one in the Oriental Region.

Metagenomics reveals that dung beetles (Coleoptera: Scarabaeinae) broadly feed on reptile dung. Did they also feed on that of dinosaurs?

“…The authentic insular communities emerged as a result of colonization events from neighboring landmasses. For example, the endemic Madagascan lineages of dung beetles originated from Africa ∼ 38-48 Mya (Miraldo et al, 2011;Rossini et al, 2022). The endemic clades found in New Caledonia and New Zealand dispersed from Australia at 50-55 Mya (Gunter et al, 2016).…”

Metagenomics reveals that Dung Beetles (Coleoptera: Scarabaeinae) broadly feed on Reptile dung and could feed on that of Dinosaurs

“…The authentic insular communities emerged as a result of colonization events from neighboring landmasses. For example, the Madagascan lineages originated from Africa approximately 38-8 Mya (Miraldo et al, 2011; Rossini et al, 2022). The endemic clades found in New Caledonia and New Zealand dispersed from Australia at 50-55 Mya (Gunter et al, 2016).…”

Evolution, systematics and historical biogeography of Palparini and Palparidiini antlions (Neuroptera: Myrmeleontidae): Old origin and in situ diversification in Southern Africa

“…In addition, reconstructing the evolutionary history of this group offers the opportunity of exploring its biogeographic history, which presents a particular interest given the paucity of research focusing on the origin and diversification of Afrotropical insect groups. Indeed, despite the fact that insects are by far the most diverse group in the Afrotropics (more than 150,000 described Afrotropical species are known; Miller & Rogo, 2001), only a few studies have tackled the diversification dynamics and biogeographic history of Afrotropical insect lineages (e.g., Aduse‐Poku et al, 2021; Haran, Beaudoin‐Ollivier, Benoit, & Kergoat, 2021; Hévin et al, 2022; Kergoat et al, 2018; Price, Marshall, Barker, Simon, & Villet, 2019; Rossini et al, 2022). A large fraction of the Palparini diversity (and all three species of Palparidiini) is found in Southern Africa where many species have restricted distribution ranges.…”