Contribution of environmental factors to genetic variation in the Pacific white-sided dolphin

Environmental changes driven by pollution and climate change have affected many species globally. The Pacific white-sided dolphin, or Lagenorhynchus obliquidens (L. obliquidens), is threatened by water pollution, which is the product of human actions and can impact the genetic structure of species in affected areas. While researchers have studied genetic differences between populations of L. obliquidens in Japan, they failed to explore the potential environmental drivers of these differences. Our research aimed to identify the major environmental factors impacting the genetic variation of L. obliquidens, which will increase our understanding of how this species responds to changes in the environment. We studied several different variables, including salinity, ocean currents, temperature, and microplastic levels. Due to the significant presence and variation of microplastics in the ocean surrounding Japan, we hypothesized that this would have the most notable impact on the genetic variation of L. obliquidens. We began our research by gathering genetic sequencing data from a preexisting study focusing on populations along the Japanese coast. We collected environmental data and analyzed it alongside a genetic distance matrix, leveraging data analysis and machine learning tools in R. We found that the most impactful variable was current stability, which did not match our original prediction of microplastic levels having the most significant impact. We then investigated why ocean currents may have had such a strong impact on L. obliquidens and proposed that it has a connection to nutrient and prey distribution, which can be majorly impacted by changes in ocean currents.