The molecular physiology and evolutionary biology of Antarctic insects

Highlights
• Collaboration with British Antarctic Survey (BAS - Prof Pete Convey as co-supervisor) and US Antarctic Program (USAP) to work on key polar terrestrial species.
• State of the art lab based physiological studies of insect responses to climate change and environmental stress.
• Unique comparative genomic studies to enhance our understanding of the evolutionary biology and physiological capacity of extremophiles.

Overview
Antarctica has been isolated from the other Southern Hemisphere continents for at least 28 million years (Myr). Model reconstructions of the last glacial maximum (LGM ~20 000 years BP) have suggested that all low-lying coastal areas on Antarctica, and many sub-Antarctic islands were completely covered by ice. However, this is now challenged by an increasing body of biological evidence which depicts evolutionary phylogenies of terrestrial species separated by many millions of years, strongly suggesting the presence of habitat refugia during the LGM and previous glacial cycles [1, 2].
Some of the most compelling evidence regarding the biogeography of Antarctic terrestrial organisms comes from studies of Antarctic insects (Fig. 1). The flightless midge Belgica antarctica is the southernmost insect and the largest permanent free-living terrestrial animal in Antarctica. It is the only insect endemic to the continent, and divergence dates obtained from sequencing ribosomal RNA indicate 49 Myr separation from its closely related/sister midge species that is endemic to sub-Antarctic South Georgia, Eretmoptera murphyi. Thus, rather than being recent colonists that were pre-adapted to the extreme Antarctic environment, these species have potentially been evolving unique adaptations in complete isolation for almost 30 million years.
Investigating the genomes and physiology of these species offers incredibly powerful comparative models for probing their evolutionary biology as well as responses to extreme temperatures, dehydration, osmotic stress, ultraviolet radiation etc [3]. The recently sequenced genome of B. antarctica was found to be just 99 Mb, making it one of the smallest insect genomes [4]. However, the number of genes was comparable with other Diptera, suggesting that environmental extremes have constrained genome architecture rather than gene content.
This project will be part of an existing partnership between UoB, BAS and USAP to compare a unique sub-set of Antarctic and high latitude southern insects. In doing so, we aim to identify key genomic features and physiological adaptations to polar habitats which can also be compared with other extremophiles. In turn, these data will open the door for comparison with potential invasive species, to assess the risk of ‘alien’ invasions under climate change facilitated by increasing human activity in Antarctica.

Methodology:
Through our existing international collaborations, we already have samples of B. antarctica, E. murphyi and relevant Patagonian species. However, we anticipate at least one Antarctic field season to collect fresh samples and undertake associated ecophysiological experiments.
For genome analysis, next generation sequencing (NGS) will be performed at UoB using an Illumina HiSeq 2500 platform. Genome size will be determined from flow cytometry using well established methods [4]. Standardised stress treatments regularly employed in our labs will be used for comparative studies and to determine the impact of future environmental scenarios on survival and development [5]. For associated gene expression studies, mRNA libraries (paired end 100bp) will be constructed and sequenced on an Illumina HiSeq 2500 platform. Libraries will be 96-fold multiplexed using the NEBNext library barcoding system. Bioinformatic tools developed in house will be employed for comparative genomics and transcriptomic data analysis.


Any further questions about the project, please contact:
Dr Scott Hayward
School of Biosciences
University of Birmingham
e-mail: [Email Address Removed]