Old origin for an European-African amphitropical disjunction pattern? New insights from a case study on wingless darkling beetles (Coleoptera: Tenebrionidae: Dendarini)

Authors: KAMINSKI, MARCIN JAN - Northern Arizona University; SMITH, AARON DENNIS - Purdue University; KANDA, KOJUN - US Department Of Agriculture (USDA); IWAN, DARIUSZ - Polish Academy Of Sciences; KERGOAT, GAEL - Center For Biology And Management Of Populations

Submitted to: Journal of Biogeography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2021
Publication Date: 11/30/2021
Citation: Kaminski, M., Smith, A., Kanda, K., Iwan, D., Kergoat, G. 2021. Old origin for an European-African amphitropical disjunction pattern? New insights from a case study on wingless darkling beetles (Coleoptera: Tenebrionidae: Dendarini). Journal of Biogeography. 49:1-12. https://doi.org/10.1111/jbi.14288.
DOI: https://doi.org/10.1111/jbi.14288

Interpretive Summary: Darkling beetles are common pests in arid-land agricultural systems and in grain stores. In this paper, we infer evolutionary relationships in a group of European and African darkling beetles that inhabit arid regions of both continents, and also include a number of pest species in their native range. We incorporate data from extinct fossil species to infer the timing of major diversification events that have occurred in this group. We find that current species distributions in this group are best explained by the fragmentation of rainforests in Africa, which occurred over 40 million years ago. Forest fragmentation and the appearance of dry-land corridors seem to have greatly facilitated the dispersal and diversification of this group. We also find that loss of flight, which is often associated with beetles in arid-habitats, has not hindered this group’s ability to disperse and diversify to near-shore islands. This study will be useful to evolutionary biologists and agricultural researchers interested in species found in arid-land ecosystems.

Technical Abstract: Aim Investigating the origin of wide-ranging disjunction patterns in Mediterranean-type arid regions. We tackle this question in a speciose group of wingless darkling beetles, the Dendarini. This tribe consists of two major clades, both of which have European–African amphitropical disjunct (EAAD) distributions. We study the origin of this striking distribution pattern using a parametric historical biogeography approach, which allows us to test alternative scenarios incorporating estimates of the divergence time between lineages. Location Southern Africa, the Mediterranean region, the Palearctic and eastern Africa. Taxon Darkling beetles from the tribe Dendarini. Methods First, we carried out molecular phylogenetics and dating analyses of a multi-marker molecular dataset including representatives of all major Dendarini lineages. Second, we conducted historical biogeography analyses to pinpoint the origin of the group and determine the sequence and timing leading to present-day wide-ranging disjunction patterns. Results Our analyses provide a robust dated phylogenetic framework supporting the monophyly of all major Dendarini lineages and indicating that the tribe likely started diversifying in Southern Africa during the Middle Eocene. From there several dispersal events are inferred, with representatives of the two major lineages progressively dispersing northwards through an East Africa corridor before ultimately reaching the Mediterranean region. Main conclusions The results of our study suggest that the origin of the EAAD in Dendarini beetles is ancient and better explained by the progressive fragmentation of the pan-African rainforest that started in the Early Eocene. This and the increased aridification associated with the global long-term cooling trend that took place at that time likely facilitated the dispersal of xerophilic organisms such as dendarine beetles through corridors of open habitats. Our study challenges the understanding of the origin of EAAD patterns, highlighting that they do not only result from recent dispersal events between the Pliocene and Pleistocene.