Anatomy of a Neotropical insect radiation

Abstract

BackgroundMuch evolutionary theory predicts that diversity arises via both adaptive radiation (diversification driven by selection against niche-overlap within communities) and divergence of geographically isolated populations. We focus on tropical fruit flies (Blepharoneura, Tephritidae) that reveal unexpected patterns of niche-overlap within local communities. Throughout the Neotropics, multiple sympatric non-interbreeding populations often share the same highly specialized patterns of host use (e.g., flies are specialists on flowers of a single gender of a single species of host plants). Lineage through time (LTT) plots can help distinguish patterns of diversification consistent with ecologically limited adaptive radiation from those predicted by ecologically neutral theories. Here, we use a time-calibrated phylogeny of Blepharoneura to test the hypothesis that patterns of Blepharoneura diversification are consistent with an “ecologically neutral” model of diversification that predicts that diversification is primarily a function of time and space.ResultsThe Blepharoneura phylogeny showed more cladogenic divergence associated with geography than with shifts in host-use. Shifts in host-use were associated with ~ 20% of recent splits (< 3 Ma), but > 60% of older splits (> 3 Ma). In the overall tree, gamma statistic and maximum likelihood model fitting showed no evidence of diversification rate changes though there was a weak signature of slowing diversification rate in one of the component clades.ConclusionsOverall patterns of Blepharoneura diversity are inconsistent with a traditional explanation of adaptive radiation involving decreases in diversification rates associated with niche-overlap. Sister lineages usually use the same host-species and host-parts, and multiple non-interbreeding sympatric populations regularly co-occur on the same hosts. We suggest that most lineage origins (phylogenetic splits) occur in allopatry, usually without shifts in host-use, and that subsequent dispersal results in assembly of communities composed of multiple sympatric non-interbreeding populations of flies that share the same hosts.Electronic supplementary materialThe online version of this article (10.1186/s12862-018-1146-9) contains supplementary material, which is available to authorized users.

Host plant associations and geography interact to shape diversification in a specialist insect herbivore

“…Herbivorous insects represent a diverse range of taxa with their extensive diversity stemming from adaptive radiation (Mitter, Farrell, & Wiegmann, ; Schluter, ; Winkler et al, ). Adaptation to new host plant species can promote ecological divergence (Funk, Filchak, & Feder, ) that manifests as differences in habitat preference, temporal isolation and sexual isolation among insect populations occupying alternative host plants (Hood, Zhang, Hu, Ott, & Egan, ; Rundle & Nosil, ; Servedio, ).…”

“…Herbivorous insects represent a diverse range of taxa with their extensive diversity stemming from adaptive radiation (Mitter, Farrell, & Wiegmann, 1988;Schluter, 2001;Winkler et al, 2018).…”

Evaluating DNA Barcoding for Species Identification and Discovery in European Gracillariid Moths

“…To measure the relative impact of geography and host plant shifts on the diversification of gracillariids, we would need a robust phylogeny on which to reconstruct the major ancestral host switches and distributions (Winkler et al, 2018). The latest molecular phylogenetic study revised the classification of Gracillariidae into eight subfamilies, but relationships between them remain largely uncertain (Kawahara et al, 2017).…”

Why are there not more herbivorous insect species?

“…The occurrence of cryptic species with identical host preferences (e.g. Marsteller et al 2009, Forbes et al 2013, Winkler et al 2018 indicates that, in such cases, modes of speciation could have operated other than ecological speciation. Key-innovations (either developmental, such as the complete meta morphosis [Rainford et al 2014], or biochemical, such as the nitrile specifier proteins in Pieridae [Wheat et al 2007]), suddenly appearing during evolution also indicate non-ecological speciation.…”

“…The reconstruction of species relationships within a clade by molecular phylogenetics can provide information on the rate and timing, and to some extents, on causes of speciation (e.g. Barraclough & Nee 2001, Winkler et al 2018. By a similar approach, we propose that the thorough examination of extant patterns of insect-plant associations (host-plant relations) enables one to evaluate available hypotheses on insect specialization and speciation explaining the evolution of those patterns.…”