De novo assembly of SNPs in VCF format for 112 individuals of Campylorhynchus in western Ecuador

Climate variability has a significant impact on the evolution of
biodiversity, which results in genetic and phenotypic diversity within
species. A balance between gene flow and selection maintains changes in
the frequency of genetic and phenotypic variants that occur along an
environmental gradient. Here, we investigate a hybrid zone in western
Ecuador involving C. zonatus, C. fasciatus, and admixed populations. We
hypothesized that different ecological preferences and geographical
distances result in limited dispersal between populations along the
precipitation gradient in western Ecuador. In the context of testing IBE
and IBD shaping distributions of C. zonatus, C. fasciatus, and potential
hybrids, we asked (1) Is there evidence of genetic admixture and
introgression between these taxa in Western Ecuador? And (2) What is the
relative contribution of IBE and IBD on patterns of genetic
differentiation and admixture patterns? We analyzed 4409 SNPs from the
blood of 112 individuals sequenced using ddRadSeq. The most likely
clusters ranged from K=2-4, corresponding to categories defined by
geographic origins, known phylogenetics, and physical or ecological
constraints. Evidence for IBE was weak but stronger for IBD. We observed
gradual changes in genetic admixture between C. f. pallescens and C.
zonatus along the environmental gradient. Genetic differentiation of the
two populations of C. f. pallescens could be driven by a previously
undescribed potential physical barrier near the center of western Ecuador.
Lowland habitats in this region may be limited due to the proximity of the
Andes to the coastline, limiting dispersal and gene flow, particularly
among dry-habitat specialists.