Abstract
Aims:We used physiological data, in conjunction with habitat information, to elucidate the interactions between two hybridizing songbirds within a hybrid zone.Background:Hybrid zones are ideal regions to examine a variety of ecological, behavior, and evolutionary processes. In addition to genetics, behavior, and morphology, physiological differences may impact hybrid fitness, genetic introgression, and even the stability of a hybrid zone.Objective:To assess physiological differences in hybridizing species, we investigated selected venous blood analytes in two species of songbirds hybridizing along the Balcones Escarpment in central Texas.Methods:Using a portable blood analyzer, we assayed blood samples from Black-crested Titmouse (Baeolophus atricristatus) and Tufted Titmouse (B. bicolor) individuals along a longitudinal transect that included the contact zone. Ecologically, this transect varies from higher elevation semi-arid regions on the Balcones Escarpment (and west across the Edwards Plateau) to lower elevation mesic forests east of the escarpment.Results:As expected, several blood analytes differed with age, sex, and sedative administration; however, we observed relatively increased blood glucose concentrations in Black-crested Titmice, which occupy the semi-arid habitats of west Texas. Furthermore, glucose concentrations were further elevated following rainfall events. Blood glucose concentrations often increase during stressful conditions and or related to changes in diet.Conclusion:We suspect that Black-crested Titmice have relatively increased blood glucose concentrations as a product of living in a semi-arid environment that causes chronic stress from unpredictable food and water resources. The link between rainfall and glucose may be a result of the increased and greater diversity of food availability after rainfall. Although further research is needed, we suspect that habitat differences and associated lack of physiological adaptations may be a limiting factor in westward range expansion in the more aggressive Tufted Titmice.
Highlights
Geographic regions in which species interbreed or hybridize, commonly known as hybrid zones, are unique locations to examine speciation and adaptation [1 - 3]
As expected, several blood analytes differed with age, sex, and sedative administration; we observed relatively increased blood glucose concentrations in Black-crested Titmice, which occupy the semi-arid habitats of west Texas
Further research is needed, we suspect that habitat differences and associated lack of physiological adaptations may be a limiting factor in westward range expansion in the more aggressive Tufted Titmice
Summary
Geographic regions in which species interbreed or hybridize, commonly known as hybrid zones, are unique locations to examine speciation and adaptation [1 - 3]. As secondary contact zones usually occur at sharp ecological boundaries (ecotones), the impact of physiology on distribution may be a critical component to understanding species or populations interactions, especially hybridization of species [2, 11]. Physiology is known to play a role in limiting geographic range, but some hybrid zone studies have supported physiological differences as limiting factors to distribution [12]. Hybrid zones are ideal regions to examine a variety of ecological, behavior, and evolutionary processes. Behavior, and morphology, physiological differences may impact hybrid fitness, genetic introgression, and even the stability of a hybrid zone
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
