Phylogenetic relationships in the Neotropical bruchid genus Acanthoscelides (Bruchinae, Bruchidae, Coleoptera)

Abstract

Adaptation to host-plant defences through key innovations is a driving force of evolution in phytophagous insects. Species of the neotropical bruchid genus Acanthoscelides Schilsky are known to be associated with specific host plants. The speciation processes involved in such specialization pattern that have produced these specific associations may reflect radiations linked to particular kinds of host plants. By studying host-plant associations in closely related bruchid species, we have shown that adaptation to a particular host-plant (e.g. with a certain type of secondary compounds) could generally lead to a radiation of bruchid species at the level of terminal branches. However, in some cases of recent host shifts, there is no congruence between genetic proximity of bruchid species, and taxonomic similarity of host plants. At deeper branches in the phylogeny, vicariance or long-distance colonization events seem to be responsible for genetic divergence between well-marked clades rather than adaptation to host plants. Our study also suggests that the few species of Acanthoscelides described from the Old World, as well as Neotropical species feeding on Mimosoideae, are misclassified, and are more closely related to the sister genus Bruchidius.

Fifty years after Ehrlich and Raven, is there support for plant–insect coevolution as a major driver of species diversification?

“…Instead, another pattern emerges, in which most herbivores display a narrow host range and phylogenetic conservatism in host use, so that phylogenetically close species tend to use chemically similar and thus often phylogenetically close hosts, with host switches to more distantly related taxa occurring at relatively low frequency (Spencer, ; Thompson, ; Kergoat et al., ; Alvarez et al., ). Winkler & Mitter () and Nyman et al.…”

Climate oscillations and species interactions: large‐scale congruence but regional differences in the phylogeographic structures of an alpine plant and its monophagous insect

“…Stochastic parameters thus strongly reduce the rate of successful dispersal in the beetle, which would require a longer time period to disperse effectively in the pursuit of its ecological niche during climate shifts, such as the one we are currently experiencing. This conclusion strongly contrasts with the example of bruchid beetles: these species‐specific phytophagous insects are specialized on angiosperm seeds and tend to disperse within the seed of their host (Alvarez et al. , 2005, 2006, 2007), therefore increasing the chance of success of dispersal and establishment of new populations on their specific host plant.…”

When insects help to resolve plant phylogeny: evidence for a paraphyletic genus Acacia from the systematics and host‐plant range of their seed‐predators

“…), it appears that two genera ( Acanthoscelides and Bruchidius ) are likely paraphyletic (Borowiec 1987; Kergoat & Silvain 2004; Kergoat et al . 2005a; Alvarez et al . 2006).…”