Noteworthy bird records from northeastern Peru reveal connectivity and isolation in the western Amazonian avifauna

Abstract

ABSTRACT Amazonian bird species often have patchy spatial distributions, and previous work has attributed this pattern to habitat specialization and dispersal limitation; however, we know comparatively little about the origins and maintenance of the isolated populations that constitute a patchy distribution. In this study, we ask whether patchy populations are interconnected by dispersal. We formulated 2 alternative hypotheses: (1) patchy populations are relicts of ancient connectivity or dispersal; and (2) patchy populations are centers of local abundance embedded in a matrix of contemporary dispersal or diffuse intervening populations. We confronted these hypotheses with circumstantial evidence derived from a unique suite of noteworthy bird records and geological observations from northeastern Peru. We found support for both hypotheses in different species, and sometimes within single species at different spatial scales. Phenotypically differentiated populations in relictual habitat patches provide stro...