New insights into the phylogeny and evolution of lady beetles (Coleoptera: Coccinellidae) by extensive sampling of genes and species

Ladybirds (family Coccinellidae) are one of the most diverse groups
of beetles and globally comprise over 6000 species. Despite their
scientific and economic significance, the taxonomy of Coccinellidae
remains unstable, and we still know little about their evolutionary history. By
using a small number of genes, previous phylogenetic analyses have not reliably
resolved the relationships among major ladybird lineages. In this study, we sequenced 94 nuclear protein-coding genes
for 214 species of Coccinellidae and 14 outgroups, covering 90 genera and 35
tribes. We found that the nucleotide compositional heterogeneity is
present between ladybird tribes so that phylogenetic inference at the amino
acid level is more reliable. Based on the maximum likelihood
analyses of the amino acid dataset, we recognized three subfamilies in
Coccinellidae: Microweisinae, Monocoryninae, and
Coccinellinae. The subfamily relationships are strongly supported as
(Microweisinae, (Monocoryninae, Coccinellinae)). The tribes of ladybirds are
mostly monophyletic, except Ortaliini, Sticholotidini, Scymnini, and
Coccidulini. The phylogenetic relationships among tribes of
Coccinellinae were still not resolved yet, with many nodes weakly supported.
Our divergence time analysis suggests that the crown group of extant lady
beetles occurred in the Early Cretaceous ~143 million years ago (Mya) and
experienced a rapid diversification process during the Late Cretaceous (120 -
70 Mya). We hypothesize that that the boom of angiosperms in the Late
Cretaceous may promote the diversification of herbivorous Sternorrhyncha
insects, especially aphids, which in turn drove the rapid radiation of
predatory lady beetles. In summary, our work provides a
comprehensive time-calibrated phylogeny of Coccinellidae that provides a sound
framework for revising their classification and understanding the origin of
their biodiversity.The data including the concatenated supermatrix of DNA, degenerate DNA and protein dataset and the related tree files in the manuscript.<br><br>