Newly Sequenced Genomes Reveal Patterns of Gene Family Expansion in select Dragonflies (Odonata: Anisoptera)

Abstract

As in many other lineages, the dragonflies, or anisoptera (Insecta: Odonata), contain a myriad of life history and diversification patterns. Two families within anisoptera highlight the diversity of patterns in this sub-order. As the most recently derived anisopteran family, some species of Libellulidae typically live fewer than two years (although generation times vary across the group), and some clades are thought to be tolerant of poor water quality. The family comprises 1500 known species. In contrast, an earlier diverging family of anisoptera, the Petaluridae, live longer than five years, and are some of the only semi-terrestrial dragonflies. Petaluridae contains only 11 extant species, all of which specialize in fen habitats. Here we sequence the genomes of two dragonflies, the petalurid,Uropetala carovei, and the libellulid,Pachydiplax longipennis. By comparing these genomes to previously published genomes of Petaluridae and Libellulidae we identify potential biological functions related to significantly expanding gene families in both lineages. Notably, the Libellulidae have significant expansions of gene families related to the maintenance of homeostasis and gene expression, which we hypothesize could play a role in the ability of the Libellulidae to thrive in low-quality water bodies. The Petaluridae have significantly expanded gene families related to perception of taste and negative regulation of apoptosis, which can plausibly be tied to their semi-terrestrial lifestyle and longevity. Additionally, we demonstrate that Odonata have relatively high rates of gene turnover, and that the difference in gene turnover between Libellulidae and Petaluridae are comparable.SignificanceThis work is the first major analysis of the evolution of gene families in the order Odonata, providing future directions for research in this order, and filling in a major taxonomic gap. Furthermore, this is the first work to tie genomic traits to life history and evolutionary patterns in Odonata. The patterns of gene family evolution identified, and the traits they are linked to, will be of broad interest to evolutionary biologists.