show Abstracthide AbstractHypocnemis ochrogyna and H. striata hybrid come into geographic contact and form a hybrid zone in between the Rio Teles Pires and Rio Xingu in the headwater regions of these rivers. Here we use genotype by sequencing to sequence thousands of genomic regions and generate a data set of several thousand SNPs. We use these SNPs to study patterns of introgression along the hybrid zone between these species to help us understand how reproductive isolation is accumulating in cryptic Amazonian understory forest birds.