Concordant yet unique neutral and adaptive genomic responses to anthropogenically modified landscapes in Rhinella horribilis

Anthropized environments are significantly challenging for wild species. Rapid adaptation to such habitats is thus key for their long-term persistence. Deciphering the environmental factors associated with species tolerance to modified habitats is fundamental for understanding the genetic and connectivity patterns of individuals and the local adaptation of their populations. We studied the Giant Toad, Rhinella horribilis, from two landscapes with distinct levels of anthropogenic habitat modification, assessed their genomic diversity, structure and connectivity with ddRAD-seq genomic data, identified potential outlier loci and their relationship with environmental and physicochemical water variables, and evaluated if populations from the two study sites showed signals of parallel adaptation. Both concordant and unique patterns were found regarding landscape factors and genotype-environment associations related with the degree of anthropic modification between landscapes. Genomic structure and connectivity were significantly associated with the presence of temporary water bodies, low vegetation cover, high humidity, solar radiation, and temperature. Notably, we identified both shared and distinct outlier SNPs and annotated functional genes for the two landscapes. Genes were enriched for biological processes and metabolic pathways, which were in turn correlated with environmental and physicochemical water variables. Genes and metabolic pathways were associated mainly with embryonic development, sexual maturation and immune responses. Studies such as this one, in an often-disregarded species, illustrate how parallel and un-parallel adaptive landscape genomic patterns arise in the stressful conditions of anthropized habitats.