Abstract
BackgroundMeligethes are pollen-beetles associated with flowers of Rosaceae as larvae. This genus currently consists of 63 known species in two subgenera, Meligethes and Odonthogethes, predominantly occurring in the eastern Palaearctic. We analyzed 74 morphological and ecological characters (169 states) of all species, as well as of 11 outgroup species from 7 Meligethinae genera (including Brassicogethes), to investigate their phylogeny. We also conducted a parallel molecular analysis on 9 Meligethes, 9 Odonthogethes, 3 Brassicogethes and 2 Meligethinus species based on DNA sequence data from mitochondrial (COI, 16S) and nuclear (CAD) genes.ResultsMorphological phylogenetic reconstructions supported the monophyly of the whole genus and clades corresponding to purported subgenera Meligethes s.str. and Odonthogethes. Main species-groups were mostly confirmed, however some unresolved polytomies remained. Molecular data placed members of Brassicogethes (including 42 mostly W Palearctic species associated with Brassicaceae) as sister to Odonthogethes, with this clade being sister to Meligethes s.str. This phylogenetic scenario suggests that monophyletic Meligethes s.str., Odonthogethes and Brassicogethes should be regarded alternatively as three subgenera of a monophyletic Meligethes, or three genera in a monophyletic genus-complex, with mutually monophyletic Brassicogethes and Odonthogethes. Molecular analyses estimated the origin of this lineage at ca. 14–15 Mya from a common stem including Meligethinus.ConclusionsWe hypothesize that the ancestor of Meligethes specialized on Rosaceae in the Middle Miocene (likely in Langhian Age) and subsequently radiated during Late Miocene and Plio-Pleistocene maintaining a trophic niche on this plant family. This radiation was primarily due to geographic isolation in E Asiatic mountain systems. Combined evidence from morphology, ancestral state parsimony reconstruction of host-plant associations and molecular evidence suggested that Rosoideae (Rosa spp.) represented the ancestral hosts of Meligethes s.str., followed by an independent shift of ancestral Odonthogethes (ca. 9–15 Mya) on Rubus (Rosoideae) and members of Rosaceae Spiraeoideae. Other ancestral Odonthogethes probably shifted again on the unrelated plant family Brassicaceae (maybe 8–14 Mya in S China), allowing a rapid westward radiation of the Brassicogethes clade.
Highlights
Meligethes are pollen-beetles associated with flowers of Rosaceae as larvae
Combined evidence from morphology, ancestral state parsimony reconstruction of host-plant associations and molecular evidence suggested that Rosoideae (Rosa spp.) represented the ancestral hosts of Meligethes s.str., followed by an independent shift of ancestral Odonthogethes on Rubus (Rosoideae) and members of Rosaceae Spiraeoideae
A similar pattern occurs in Meligethes s.l., and in its constituent subgenera, species-groups and complexes [1, 2, 7]. Due to these above mentioned botanical phylogenetic and biogeographic scenarios, we comprehensively explored the evolutionary trajectories within Meligethes s.l. to provide some hints on the role of the relationships between this group of pollen beetles and their larval host plants
Summary
Meligethes are pollen-beetles associated with flowers of Rosaceae as larvae This genus currently consists of 63 known species in two subgenera, Meligethes and Odonthogethes, predominantly occurring in the eastern Palaearctic. Meligethes, even as presently bounded [2] [Fig. 1a (a), (b)], is still a rather species-rich genus, consisting of more than 60 species predominantly occurring in the Eastern Palaearctic [7,8,9,10] (Fig. 1 b-c; Table 1). This group includes species that are all associated with flowers of Rosaceae as larvae [2]. Some locally common Meligethes [e.g. M. atratus (Oliver, 1790), M. flavimanus Stephens, 1830, M. violaceus Reitter, 1873)] represent economically significant potential pests, attacking blossoms of ornamental roses (Rosa spp.) and plum trees (Prunus spp.) in Europe, Japan, and elsewhere [1, 11,12,13]
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