Geographic isolation drives speciation in Nearctic aphids

Abstract

Across herbivorous insect clades, species richness and host-use diversity tend to positively covary. This could be because host-use divergence drives speciation, or because it raises the ecological limits on species richness. To evaluate these hypotheses, we performed phylogenetic path model analyses of the species diversity of Nearctic aphids. Here, we show that variation in the species richness of aphid clades is caused mainly by host-use divergence, whereas variation in speciation rates is caused more by divergence in non-host-related niche variables. Aphid speciation is affected by both the evolution of host and non-host-related niche components, but the former is largely caused by the latter. Thus, our analyses suggest that host-use divergence can both raise the ecological limits on species richness and drive speciation, although in the latter case, host-use divergence tends to be a step along the causal path leading from non-host-related niche evolution to speciation.

Discordance between phylogenomic datasets in aphids: who is telling the truth?

“…Our results nevertheless seem to mirror the taxonomic discussions that resulted in including "Phyllaphidinae" in a group called "Callaphididae" (see classifications of (Börner 1952;Lee et al 2022) The proximity of subfamilies Chaitophorinae and Drepanosiphinae is consistently found across our analyses. This agrees with previous aphid molecular phylogenies (Ortiz-Rivas and Martinez-Torres 2010;Ortiz-Rivas et al 2004;Hardy et al 2022), and more specific phylogenetic investigations within Chaitophorinae (Wieczorek et al 2017). The validity of this clustering in relation to morphological investigations has been thoroughly discussed in (Wieczorek et al 2017).…”

“…We also systematically recovered sister group relationships between Anoeciinae, Thelaxinae and Hormaphidinae. This again agrees with the early phylogenetic investigation of (Ortiz-Rivas et al 2004) and recent phylogenomic studies (Owen and Miller 2022;Hardy et al 2022). Those three aphid groups, were initially clustered in Borner's classification within a group that also included Mindarinae and Phloeomyzinae.…”

“…Across all datasets, subfamilies as defined by Remaudière and Remaudière (1997) appear monophyletic except for Eriosomatinae, which is generally scattered into two groups (a cluster made of Pemphigini and Fordini and a cluster made of Eriosomatini) and Calaphidinae that always includes Phyllaphidinae. The non-monophyly of Eriosomatinae was found in previous phylogenetic studies of Aphididae (Novakova et al 2013;Hardy et al 2022) and studies dedicated to the subfamily (e.g. Qiao and Zhang, 2008, where Eriosomatinae is referred to as Pemphiginae).…”

“…Below the subfamily level, our analyses retrieved the monophyly of all the tribes represented except for Macrosiphini, as Cavariella, Pterocomma genera and Muscaphis are positioned as sister groups of a clade made of Aphidini and the remaining Macrosiphini. The non monophyly of Macrosiphini was already suggested by (Novakova et al 2013;Hardy et al 2022) and a study dedicated to Macrosiphini (Choi et al 2018). Using a very different sampling and set of DNA markers, all three studies show that Macrosiphini are not monophyletic and that Cavariella and/or Pterocomma (depending on species sampling) are allied and form a separate clade probably with several other Aphidinae genera.…”

“…A few published molecular phylogenetic studies have focused on solving this puzzle. Among the most influential are the study of Novakova et al (2013) using five DNA markers found on the primary symbiont genome of aphids, Buchnera aphidicola; the study of Chen et al (2017) based on the whole mitogenomes from 33 aphid species and two recent phylogenomic investigations using respectively transcriptome data (Owen and Miller 2022) and ultra-conserved Elements (Hardy et al 2022) each yielding thousands of nuclear markers (Fig. 1).…”