Kirk E. Lohmueller
Why Does Natural Selection Vary Across Species?
Due to substantial breakthroughs in DNA sequencing technology, there is a deluge of genetic variation data from many individuals from populations and species across the globe. While the DNA sequences from any two individuals within the same population are quite similar to each other, there are subtle differences between their DNA sequences. For example, two human sequences differ in at one position for every 1000 DNA sites. These differences in DNA sequences are the byproduct of the evolutionary history of each individual. However, the evolutionary signals that we are looking for in these datasets are quite subtle, and require modeling the randomness of the evolutionary process. Thus, my lab develops and uses computational tools to analyze this genetic variation data.
We are determining the mechanisms by which evolutionary processes have given rise to the patterns of genetic variation that are observed individuals. Additionally, we are interested in understanding how genetic variation affects complex traits, like height and diabetes risk.
A major focus of our work is on understanding deleterious mutations. Deleterious mutations are harmful in a specific way: they reduce the number of children that individuals have relative to individuals who do not carry such mutations. We are studying how and why patterns of deleterious variants differ across populations and species. To do this, we are developing new statistical methods to test whether mutations are more deleterious in some species than others. We will also rigorously evaluate the contribution of differences in population history (for example, expansions or contractions in population size) across species may have on patterns of deleterious mutations, and on our ability to infer these patterns. We are applying these methods to genetic variation data from different taxa. This work is important for directing how scientists use genetic variation data to reconstruct population history and to identify targets of adaptive evolution.