S12-13 Thu Jan 7 18:00 – 18:30 Sexual selection on the behavioral, physiological, and genetic dynamics of an avian hybrid zone Long, KM; Tobiansky, DJ*; Goller, F; Braun, MJ; Brawn, JD; Fuxjager, MJ; University of Illinois Urbana-Champaign; Brown University; University of Münster and University of Utah; Smithsonian National Museum of Natural History and University of Maryland; University of Illinois Urbana-Champaign; Brown University firstname.lastname@example.org
Hybrid zones are dynamic systems where natural and sexual selection act upon admixtures of species’ genomes and behaviors. We leveraged a hybrid zone between the golden- and white-collared manakins (Manacus vitellinus and M. candei, respectively). Females of both species prefer yellow-throated and fast-performing males, suggesting these traits should spread into the M. candei range. We reassess the hybrid zone 25 years after the initial transect to determine hybrid zone movement. We identify the genetic and phenotypic transitions and find that these remain unchanged, indicating this hybrid zone remains stable despite putative female preference. Given this stability, we investigate how sexually selected behavioral traits may explain the constancy of the hybrid zone. We examine a socio-sexual display, the roll-snap, which males produce by rapidly hitting their wings together. Hybrids roll-snap at similar speeds to M. vitellinus (≈60 snaps/sec), and both groups display faster than M. candei. Paradoxically, hybrids show suppressed muscle performance (slower muscle twitch speeds). Further analyses suggest that hybrids bypass this constraint by using intrinsic speed/endurance trade-offs, amplifying display speed by sacrificing other elements such as display length (# of snaps). Thus, hybrids produce shorter displays than M. vitellinus. Our study suggests that performance trade-offs provide a route for sexual selection to shape a behavioral phenotype despite genomic incompatibilities, thereby allowing preferred display behaviors to persist, while potentially limiting phenotypic spread due to muscle suppression.