Simultaneous radiation of bird and mammal lice following the K-Pg boundary

Abstract

The diversification of parasite groups often occurs at the same time as the diversification of their hosts. However, most studies demonstrating this concordance only examine single host-parasite groups. Multiple diverse lineages of ectoparasitic lice occur across both birds and mammals. Here, we describe the evolutionary history of lice based on analyses of 1107 single-copy orthologous genes from sequenced genomes of 46 species of lice. We identify three major diverse groups of lice: one exclusively on mammals, one almost exclusively on birds and one on both birds and mammals. Each of these groups radiated just after the Cretaceous-Paleogene (K-Pg) boundary, the time of the mass extinction event of the dinosaurs and rapid diversification of most of the modern lineages of birds and mammals.

Keywords: Phthiraptera; coevolution; host–parasite interactions; phylogenomics; systematics.

Figure 1.

Phylogeny of parasitic lice (Phthiraptera) based on RAxML partitioned concatenated maximum-likelihood analysis of 1107 single-copy orthologue genes assembled using aTRAM from genome sequencing reads. Numbers indicate bootstrap support. Bird (red–light) and mammal (blue–dark) hosts indicated by colours. Pie charts are relative likelihoods for ancestral state (bird or mammal host) reconstruction under the equal rates model. Blue hashes on branches indicate the four inferred switches to mammals if ancestral host is a bird, and red hashes indicate four inferred switches to birds if ancestral host is a mammal. Images indicate generalized host associations for louse genera. (Attributions for images provided in electronic supplementary material, table S2.) Branch lengths are calculated from MCMCtree analysis with the ML topology and four calibration points (see §2). Scale unit is Mya. (Online version in colour.)