Mr Maxim Adams1, Dr Simon Hellemans2, A/Prof Aaron Jex3, A/Prof Thomas Bourguignon2, Dr Emily Remnant1, Prof Kenji Matsuura4

1University Of Sydney, Camperdown, Australia, 2Okinawa Institute of Science and Technology, Onna, Japan, 3University of Melbourne, Melbourne, Australia, 4University of Kyoto, Kyoto, Japan

Biography:

Maxim Adams is a Research Assistant based in the Molecular Ecology, Evolution and Phylogenetics lab at the University of Sydney. He completed his Honours degree last year, with a thesis examining the historical biogeography, systematics and conservation genetics of endemic wood-feeding cockroaches. He has since started a full-time role looking at the genomic evolution of cockroaches, termites and spiders

Abstract:

Chromosomes are a fundamental unit of inheritance, yet their size, structure and number vary dramatically across the Tree of Life. While sex is often determined by a single pair of chromosomes, an increasing number of species have been discovered with multiple sex chromosomes (MSCs), which fuse into multivalent chains during male meiosis. The cytological mechanisms behind MSC systems are reasonably well characterised, however little is known about the evolutionary pressures that drive their emergence within a species. Here we test the hypothesis that MSCs evolve as a means to fix heterozygosity and preserve genetic diversity in response to inbreeding. We are undertaking chromosome-scale long-read genome sequencing of the termite species Glyptotermes nakajimai and Neotermes insularis, both of which have multiple populations with MSC chains of varying lengths. By characterising interpopulation variation in inbreeding, genetic load, heterozygosity and chromosome structure, we aim to provide the first evidence for an association between inbreeding and the occurrence of MSCs. In addition, our comparisons of MSC structure across different populations will reveal whether their formation consistently involves the same translocations and fusions, or whether they form through disparate cytological changes. This work will greatly advance our understanding of sex chromosome and genome evolution, which are fundamental to the process of biological diversification.