2025/11/21 by Kevin F. P. Bennett, Kurt H. Gielow, Alexa N. Conner +1 · 2 voices
Agricultural and Biological Sciences · Environmental Science · #Botanical Studies and Applications #Seedling growth and survival studies #Agroforestry and silvopastoral systems
paper · pdf · doi:10.1080/15594491.2025.2584827
Hybrid birds discovered outside of known hybrid zones have often presented an identification challenge but also a source of insight into evolutionary processes. With the advance of modern genetics, the tools are now available to definitively identify hybrids for which genetic samples are available and, in many cases, determine the identity and the sex of each parent species as well as F1 versus backcross status. Typically, hybrids formed outside of hybrid zones are rare; however, one apparently common hybrid New World warbler (family Parulidae) is the cross between Mourning Warblers (Geothlypis philadelphia) and Common Yellowthroats (G. trichas), which has been reported at least 14 times between 1955 and 2025, though never confirmed genetically. Here we describe the results of genetic and plumage analyses identifying a putative G. philadelphia × G. trichas hybrid captured in July 2017 in New York, USA. We used genotype likelihoods derived from whole-genome sequencing data of the putative hybrid and several species in Geothlypis and Oporornis to confirm the bird’s identity as an F1 hybrid between G. philadelphia and G. trichas. We sequenced one mitochondrial gene and used publicly available sequences of related species to identify the maternal parent as G. philadelphia. Based on this evidence and previous reports, we propose that male G. trichas × female G. philadelphia is the more common direction—and potentially the only one possible—of this hybrid pairing. Finally, we describe the color characteristics of the hybrid compared to its parental species and discuss potential implications for research into the genetic control of plumage color.