Morphological and genetic data suggest a complex pattern of inter-island colonisation and differentiation for mining bees (Hymenoptera: Anthophila: Andrena) on the Macaronesian Islands

Anselm Kratochwil,Martin Husemann,Antonio Miguel Franquinho Aguiar,Angelika Schwabe,Robert J Paxton

doi:10.1007/s13127-021-00513-z

Abstract

Oceanic islands have long been considered engines of differentiation and speciation for terrestrial organisms. Here we investigated colonisation and radiation processes in the Madeira Archipelago and the Canary Islands of the Andrena wollastoni group of bees (subgenus Micrandrena), which comprises six endemic species and five endemic subspecies on the islands. Mitochondrial COI sequences support the monophyly of the four species of the Canary Islands and the two species of the Madeira Archipelago and suggest a relatively young age for all taxa. The data do not support a simple stepping-stone model (eastern-western colonisation from the mainland, with splitting into new taxa), but suggest Andrena gomerensis (extant on La Gomera and La Palma) or its ancestor as the basal lineage from which all other taxa evolved. Andrena lineolata (Tene-rife) or its putative ancestor (A. gomerensis) is sister to A. dourada (Porto Santo), A. catula (Gran Canaria), and A. acuta (also Tenerife). Andrena dourada (Porto Santo) and A. wollastoni (Madeira Island) are sister species. Morphologically and morphometrically defined subspecies were not distinguishable with COI DNA sequences. Colonisation likely led from the Canary Islands to the Madeira Archipelago and not from the mainland directly to the latter.

Highlights

Oceanic islands represent excellent systems to answer questions of biogeography, phylogeography, and evolutionary biology
In contrast to the Hawaiian Archipelago or the Galápagos Islands, the Canary Islands are relatively close to the mainland, providing a prolific source of colonisation events
Andrena lineolata from Tenerife was quite divergent from all other populations

Summary

Introduction

Oceanic islands represent excellent systems to answer questions of biogeography, phylogeography, and evolutionary biology. Patterns of colonisation of the Madeira Archipelago and the Canary Islands have been inferred for a variety of vascular plants (e.g., Böhle et al, 1996; Francisco-Ortega et al, 1996; Francisco-Ortega et al, 1997; Kim et al, 1996; Juan et al, 2000; Francisco-Ortega et al, 2002; Mort et al, 2002; Percy & Cronk, 2002) and vertebrates (Cano et al, 1984; Gonzales et al, 1996; Carranza et al, 1999; Barahona et al, 2000; Brehm et al, 2003; Maca-Meyer et al, 2003), as well as many invertebrates such as Gastropoda (Henriquez et al, 1993), Araneae (Wunderlich, 1991), Diplopoda (Enghoff, 1992), Collembola (Fjellberg, 1992), Hemiptera (Lindberg, 1953), and especially Coleoptera (Dajoz, 1977; Lindberg et al, 1958; Machado et al, 2017) Many of these taxa have undergone radiations associated with island colonisation. The Canary Islands are home to 124 wild bee species, including 64 endemic species and 25 subspecies, 24 of which are endemic (Hohmann et al, 1993; Kratochwil et al, 2018; Kratochwil & Schwabe, 2018b)

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