Evolutionary Genomics Unit (Tom Bourguignon)
Termites are famous and disliked animals, yet, despite their appearance, they are interesting in many ways. Termites are amongst the few animals feeding on the wood lignocellulose and soil organic matter. They do so primarily with the help of their gut microbes and, in some species, fungi they cultivate inside their nests. Because termite's food, cellulose, is the most abundant organic compound on Earth, termites are themselves extremely abundant animals in terrestrial ecosystems. They are also one of the few animal lineages that evolved eusociality, with colonies typically composed of a few reproducing and many sterile individuals. Our unit studies the evolution of these insects and other non-termite cockroaches using high-throughput sequencing technologies and comparative phylogenetic and genomics methods. We primarily study (1) the historical biogeography of termites and cockroaches and the factors at the origin of their cosmopolitan distribution; (2) the evolution of the symbiotic system composed of termites and their gut microbes; (3) the genome evolution of the cockroach endosymbiont Blattabacterium and termite gut bacteria; and (4) the evolution of termite genomes.
(1) Historical biogeography of termites and cockroaches
We use time-calibrated molecular phylogenetic trees to reconstruct the historical biogeography of termites and cockroaches. Phylogenetic trees allow the identification of dispersal and vicariance events and their timing, helping determine how termites and cockroaches acquired their global distribution. We also study the diversification processes of termites and cockroaches and how various biological traits have evolved in these insects using phylogenetic trees.
(2) Evolution of termites and their gut microbes
We study how termites and their gut microbes have coevolved using cophylogenetic methods. We also investigate the functions performed by termite gut microbes, attempting to determine the identity of bacteria involved in functions essential for their termite hosts. Finally, we explore how this host-symbiont system has evolved since its inception ~150 million years ago.
(3) Blattabacterium genome evolution
Most cockroaches host Blattabacterium, a bacterial endosymbiont transmitted vertically across generations of cockroaches for over 200 million years. We study the evolution of Blattabacterium genomes by comparing complete genome sequences from multiple strains. We aim to determine the mechanisms responsible for genome reduction and other genome characteristics in these endosymbionts.
(4) Evolution of termite genomes
We are about to complete the sequencing of ~50 termite genomes. We will compare these genome sequences with the final goal of determining how they have evolved.