Speciation of Yeast

While groundbreaking discoveries have been made in plant and animal speciations, studies focusing on the evolution of microbial species have been limited. Microbial species such as yeast play an important role in our world but their speciation processes are challenging to study because of their microscopic size. 

A previous student in my lab, Dantang Jiang, studied populations of Saccharomyces paradoxus yeast that are located in North America and in Europe, as well as a population that migrated from Eurasia to North America and have since genetically evolved from its ancestors. Using a comparative genomic approach to study the speciation between these populations, a single gene, PET111, appeared to have undergone positive selection. PET111 is located in the nuclear genome, but codes for a protein that regulates proteins encoded in the mitochondrial genome. This research leads the way for further investigation of speciation in the wild yeast and how the selection for PET111 may have been a result of migration. My research goal is to study microbial speciation at the genetic level by focusing on the PET111 gene. The specific hypothesis I am testing is that the evolution of an incompatibility between the nuclear and mitochondrial genomes (mito-nuclear co-evolution) may be a part of the speciation process between the European population and its migrants in North America.

I will use CRISPR to insert the PET111 gene of a strain from one population of S. paradoxus into the DNA of strains of another population. I will then observe how the yeasts react to foreign PET111 genes in their DNA. I hypothesize that PET111Eur will cause the migrants to be petite, and the PET111Mig will cause the Eurasians to become petite. 


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