What processes give rise to the incredible biodiversity of life on earth?
The Heil lab studies sources of genetic variation (mutation, recombination, and gene flow) in the budding yeast Saccharomyces cerevisiae and its' relatives. We use genome sequencing, genetics, and experimental evolution to study the following areas:
Hybridization and Genome Evolution
Genome sequencing across the tree of life has revealed that the exchange of genes between related species, often referred to as hybridization, is prevalent across many species of plants, animals, and fungi. We're interested in answering the questions of how hybridization influences the evolution of populations, and whether hybridization provides genetic variation that aids a population in adaptation to new and changing environments. To understand these questions, we utilize Saccharomyces hybrids. Hybrids have been discovered in natural and fermentation environments, and can also be formed between quite divergent species and evolved mitotically for hundreds of generations in the laboratory.
We are studying the genetic basis of adaptive hybrid traits, genotype by environment interactions, and how particular environments affect the creation and persistence of hybrid lineages.
Adapted from Hittinger Trends in Genetics 2013
Evolution of recombination
Meiotic recombination is an essential process that both ensures proper segregation during meiosis, and plays a crucial role in shaping the genomic landscape over time. Historically, population genetics models have assumed a constant recombination rate across the genome, but recent efforts have shown this to be false, and instead recombination rates vary both across the genome and across individuals, populations, and species. This has profound impacts on genome evolution: where recombination rates are high, selection is more efficient and the effect of genetic hitchhiking of neutral and slightly deleterious alleles is decreased. However, the mechanisms that dictate what regions of the genome experience high or low recombination rates demand further study, and particularly what processes give rise to changes in recombination rate over time remains an open question. We are using the Saccharomyces yeasts to understand how life history traits and hybridization influence the recombination landscape, and working to identify modifiers of recombination rate and how they arise in a population.
Yeast and fermentation
While Saccharomyces yeast are found on trees, fruits, and insects, they are best known for their role in fermentations including bread, beer, and wine. Our lab is working in collaboration with several other groups to explore diverse yeasts for their role in breadmaking, and to better understand signatures of S. cerevisiae domestication to bread dough using a large collection of sourdough starters from North America.