Frequent Hybridisation Between Parapatric Lekking Bird-of-Paradise Species

Area of Science:

• Evolutionary Biology
• Genomics
• Ornithology

Background:

• Hybridization is observed across taxa, even in species with strong sexual selection and divergent phenotypes.
• The extent to which hybridization can overcome reproductive barriers in such systems, leading to hybrid zones, is not well understood.
• Birds-of-paradise (Paradisaeidae) represent a model system with extreme phenotypic diversity driven by sexual selection and lek-mating behaviors.

Purpose of the Study:

• To investigate the extent of hybridization and gene flow in birds-of-paradise.
• To identify potential hybrid zones between lekking bird-of-paradise species.
• To assess the role of sexually selected traits and behaviors as reproductive barriers.

Main Methods:

• Genome-wide introgression analysis was performed on birds-of-paradise.
• Focus on two genera, Astrapia and Paradigalla, known for lek-mating behaviors.
• Identification of genomic signals indicative of recent and historical gene flow.

Main Results:

• Multiple signals of recent and historical gene flow were detected between and within Astrapia and Paradigalla genera.
• The study provides the first empirical genomic evidence for a putative hybrid zone between two lekking bird-of-paradise species.
• These species exhibit substantial differences in sexually selected traits and behaviors.

Conclusions:

• Behavioral and phenotypic traits may represent weaker pre- and post-zygotic barriers to gene flow than previously assumed in lek-mating species.
• Hybridization and introgression are significant evolutionary processes in birds-of-paradise.
• Findings challenge traditional views on reproductive isolation in species with strong sexual selection.