Recently Delisted Songbird Harbors Extensive Genomic Evidence of Inbreeding, Potentially Complicating Future Recovery

Area of Science:

• Conservation genomics
• Avian population genetics

Background:

• Kirtland's warbler (Setophaga kirtlandii) faced near extinction, leading to federal protection under the Endangered Species Act.
• Intensive conservation efforts resulted in population recovery and delisting in 2019.
• Understanding the genomic impact of population bottlenecks is crucial for long-term species survival.

Purpose of the Study:

• To investigate the genomic consequences of the Kirtland's warbler's population bottleneck and recovery.
• To compare genomic architecture with closely related, stable populations (Hooded Warbler, American Redstart).
• To assess the distribution of homozygosity and deleterious genetic variation in Kirtland's warblers.

Main Methods:

• Whole-genome sequencing was employed for comparative genomic analysis.
• Characterization of runs of homozygosity to identify inbreeding patterns.
• Analysis of deleterious genetic variation to assess genetic load.

Main Results:

• Kirtland's warblers exhibit genetic patterns indicative of recent inbreeding.
• An excess proportion of deleterious genetic variation was found in Kirtland's warblers compared to related species.
• These genetic patterns suggest potential challenges for the long-term viability of this conservation-reliant species.

Conclusions:

• Genomic data provides critical insights into the long-term health of recovering populations.
• Genetic monitoring is essential for species delisted from federal protection.
• Advancements in genome sequencing facilitate the assessment of genetic landscapes for ensuring independent species survival.