The Genetics of Speciation in C. remanei: Post-Zygotic Isolation and Genetic Incompatibilities

Earth is home to an amazing amount of diversity, but the mechanisms through which new species arise are not well understood. Speciation, the study of these mechanisms, is a relatively young field, with significant research only conducted within the past 30 years. Since the start of this research, a large number of reproductive isolating barriers have been identified that inhibit gene flow between species. One such barrier is known as genetic incompatibility, wherein genes of different species, when mixed together in hybrid offspring, interact negatively. These negative interactions hinder the development of offspring, thus ensuring the two species remain isolated. In this study, we research genetic incompatibilities between two different populations of the soil nematode Caenorhabditis remanei. Initial research suggested that genetic incompatibilities arise in the second generation of inbreeding between the two populations, when the process of recombination introduces genes from both genetic backgrounds onto the same chromosome. This result led to further research into genetic incompatibilities between the two populations, focusing on the egg-to-adult viability of ten different combinations of mating crosses. The results of these assays confirm the existence of genetic incompatibilities between these two populations, with the genes likely involved in the incompatibilities located on the X-chromosome. Genome mapping is being conducted to identify possible genes. Through research like this, earth’s diversity may be understood.