Phylogeny and diversification of diving beetles (Coleoptera: Dytiscidae)

Abstract

Dytiscidae is the most diverse family of beetles in which both adults and larvae are aquatic, with examples of extreme morphological and ecological adaptations. Despite continuous attention from systematists and ecologists, existing phylogenetic hypotheses remain unsatisfactory because of limited taxon sampling or low node support. Here we provide a phylogenetic tree inferred from four gene fragments (cox1, rrnL, H3 and SSU, 4000 aligned base pairs), including 222 species in 116 of 174 known genera and 25 of 26 tribes. We aligned ribosomal genes prior to tree building with parsimony and Bayesian methods using three approaches: progressive pair-wise alignment with refinement, progressive alignment modeling the evolution of indels, and deletion of hypervariable sites. Results were generally congruent across alignment and tree inference methods. Basal relationships were not well defined, although we identified 28 well supported lineages corresponding to recognized tribes or groups of genera, among which the most prominent novel results were the polyphyly of Dytiscinae; the grouping of Pachydrini with Bidessini, Peschetius with Methlini and Coptotomus within Copelatinae; the monophyly of all Australian Hydroporini (Necterosoma group), and their relationship with the Graptodytes and Deronectes groups plus Hygrotini. We found support for a clade formed by Hydroporinae plus Laccophilini, and their sister relationship with Cybistrini and Copelatinae. The tree provided a framework for the analysis of species diversification in Dytiscidae. We found a positive correlation between the number of species in a lineage and the age of the crown group as estimated through a molecular clock approach, but the correlation with the stem age was non-significant. Imbalances between sister clades were significant for several nodes, but the residuals of the regression of species numbers with the crown age of the group identified only Bidessini and the Coptotomus + Agaporomorphus clade as lineages with, respectively, above and below expected levels of species diversity.

Whole-community DNA barcoding reveals a spatio-temporal continuum of biodiversity at species and genetic levels

“…The large size of the data set required that the TCS software was applied separately to smaller subclades. We, therefore, performed the nested-clade analysis individually on 18 clades defined in a higher-level phylogenetic analysis of Dytiscidae 37 . Custom R and Perl scripts were used for generating relevant input and output files for the various steps.…”

Using Taxonomic Revision Data to Estimate the Global Species Richness and Characteristics of Undescribed Species of Diving Beetles (Coleoptera: Dytiscidae)

“…(sensu Ribera et al [2008]); 4) Hydaticini sl. (sensu Ribera et al [2008], eg. Dytiscinae excluding Dytiscini); 5) Hydroporini sl.…”

“…Dytiscinae excluding Dytiscini); 5) Hydroporini sl. (sensu Ribera et al (2008); 6) Hydrovatini+Vatellini and 7) Laccophilini. These groupings generally had strong molecular support from Ribera et al's (2008) phylogenic analysis.…”

“…Using these criteria we decided on a phylogenetic framework containing 7 groups corresponding to either subfamilies or tribes, collectively containing more than 95% of all dytiscid species and all revised taxa. These groups were: 1) Bidessini+Pachydrini; 2) Colymbetinae sl., including Agabinae, Colymbetinae and Dytiscini, chiefly corresponding to lineage 2 in the PR alignment of Ribera et al (2008); 3) Copelatinae sl. (sensu Ribera et al [2008]); 4) Hydaticini sl.…”

“…These groups were: 1) Bidessini+Pachydrini; 2) Colymbetinae sl., including Agabinae, Colymbetinae and Dytiscini, chiefly corresponding to lineage 2 in the PR alignment of Ribera et al (2008); 3) Copelatinae sl. (sensu Ribera et al [2008]); 4) Hydaticini sl. (sensu Ribera et al [2008], eg.…”