Population structure across four Xiphophorus hybrid zones with varying anthropogenic impact

This project used low-coverage whole genome sequencing to assess spatial variation in the degree of reproductive isolation between the sister species Xiphophorus malinche and Xiphophorus birchmanni. Whole-genome ancestry fractions of fishes from 44 sampling sites across 4 subcatchments of the Rio Atlapexco were tied to environmental measurements capturing both natural variation and anthropogenic impact. Paired sequencing of pregnant mothers and their embryos at two sites on the Rio Calnali was used to assess the degree of assortative mating by ancestry upstream and downstream of an urbanized area.