Does a shift in host plants trigger speciation in the Alpine leaf beetle Oreina speciosissima(Coleoptera, Chrysomelidae)?

Abstract

BackgroundWithin the Coleoptera, the largest order in the animal kingdom, the exclusively herbivorous Chrysomelidae are recognized as one of the most species rich beetle families. The evolutionary processes that have fueled radiation into the more than thirty-five thousand currently recognized leaf beetle species remain partly unresolved. The prominent role of leaf beetles in the insect world, their omnipresence across all terrestrial biomes and their economic importance as common agricultural pest organisms make this family particularly interesting for studying the mechanisms that drive diversification. Here we specifically focus on two ecotypes of the alpine leaf beetle Oreina speciosissima (Scop.), which have been shown to exhibit morphological differences in male genitalia roughly corresponding to the subspecies Oreina speciosissima sensu stricto and Oreina speciosissima troglodytes. In general the two ecotypes segregate along an elevation gradient and by host plants: Oreina speciosissima sensu stricto colonizes high forb vegetation at low altitude and Oreina speciosissima troglodytes is found in stone run vegetation at higher elevations. Both host plants and leaf beetles have a patchy geographical distribution. Through use of gene sequencing and genome fingerprinting (AFLP) we analyzed the genetic structure and habitat use of Oreina speciosissima populations from the Swiss Alps to examine whether the two ecotypes have a genetic basis. By investigating a wide range of altitudes and focusing on the structuring effect of habitat types, we aim to provide answers regarding the factors that drive adaptive radiation in this phytophagous leaf beetle.ResultsWhile little phylogenetic resolution was observed based on the sequencing of four DNA regions, the topology and clustering resulting from AFLP genotyping grouped specimens according to their habitat, mostly defined by plant associations. A few specimens with intermediate morphologies clustered with one of the two ecotypes or formed separate clusters consistent with habitat differences. These results were discussed in an ecological speciation framework.ConclusionsThe question of whether this case of ecological differentiation occurred in sympatry or allopatry remains open. Still, the observed pattern points towards ongoing divergence between the two ecotypes which is likely driven by a recent shift in host plant use.

Climatic niche evolution is faster in sympatric than allopatric lineages of the butterfly genusPyrgus

“…Notwithstanding with those potential limitations, the general pattern of our result is in line with a large number of specific case-studies [25][26][27][28]85] but also evidences the substantial role played by niche shifting in sympatry at the macro-evolutionary level. At a wider taxonomical scale, it also complements the findings from one of the few works on diversification of lepidopteran lineages, in which allopatric divergence without niche shift is shown to be commonly rspb.royalsocietypublishing.org Proc.…”

A fine line between species and ecotype: a case study of Anoplistes halodendri and A. kozlovi (Coleoptera: Cerambycidae) occurring sympatrically in Mongolia

“…Thus, the reported environmental adaptation of Anoplistes ha lodendri is the second documented ecotypic speciation in this beetle family. Considering the entire superfamily Chrysomeloidea, several examples of ecotypes were also documented; mostly, however, in the family Chrysomelidae and for the species of high economic importance: Leptinotarsa decemlineata (Say, 1824) (Hsiao 1978), Galerucella aquatica (Geoffroy, 1785) (Lohse 1989), Galerucella lineola (Fabricius, 1781) (Ikonen et al, 2003), and Oreina speciosissima (Scopoli, 1763) (Borer et al 2011).…”

Diversification rates, host plant shifts and an updated molecular phylogeny of Andean Eois moths (Lepidoptera: Geometridae)

“…Host plant affiliations have been recognized as a major driver of radiations among phytophagous insects ever since Ehrlich & Raven's seminal paper on co-evolution [ 1 ]. While instances of strict co-speciation and reciprocal co-evolution have rarely been found among folivorous insects, a growing number of case studies based on well resolved and dated phylogenies reveals that host plant shifts are important drivers of radiations [ 2 , 3 ], thereby contributing to the enormous species richness of megadiverse clades of phytophagous insects, for example among beetles [ 4 ] or butterflies and moths [ 5 ]. The recent advent of ever more powerful methods to estimate diversification rates from molecular phylogenies has set the stage for explicitly testing whether host plant shifts are indeed related to adaptive zones (e.g.…”