EXamining how Past demography affects genetic LOad using Ancient DNA
DNA can survive millennia post-mortem, spanning ecological and evolutionary transitions and providing a unique window into the processes underlying biodiversity. As such sequencing ancient DNA from temporally spaced samples can allow the testing of hypotheses related to evolutionary responses to ecological change and novel selection pressures through direct quantification of ecological and genetic parameters collected before, during and after genetic changes in selection pressures. Here, I propose to do just this, taking advantage of a natural experiment of an emblematic study system in evolutionary biology: parallel independent adaptation to freshwater by marine-adapted threespine sticklebacks through the rise in frequency of freshwater-associated alleles. Utilising palaeogenomics to sample genomes along this evolutionary continuum and the project will address a key and long-standing question: is there a mutational cost to natural selection? This is a timely question, as ongoing rapid global climatic change is a major source of novel selection pressures, therefore, understanding the dynamics of natural selection will provide key insights into potential outcomes for biodiversity. The methods developed in this project will not only benefit the growing field of paleogenomics but also other fields where data is collected in a temporal manner, such as experimental evolution and epidemiology. Ultimately, achievement of these goals requires the formation of a dedicated, closely knit team, focusing on both the methodological challenges as well as their bigger picture application to high-risk high-gain ventures. With ERC funding this can become a reality, enabling the interface of palaeogenomics and evolutionary biology to be pushed to the new limits of the modern sequencing era.