Population Genomics Informs Conservation Strategies for Critically Endangered Kokia Species in Hawai'i

Area of Science:

• Botany
• Genetics
• Conservation Biology

Background:

• Island endemic species, like the Hawaiian Kokia genus, face high extinction risk due to limited ranges and habitat loss.
• Despite over a century of conservation focus, historical records for Kokia species are scarce.
• Recent genome sequencing provides a foundation for understanding genetic diversity and population structure.

Purpose of the Study:

• To analyze the genetic diversity and population structure of the three extant Kokia species using whole genome resequencing.
• To identify patterns of genetic variation relevant for conservation and restoration strategies.
• To inform ex situ conservation collections and managed populations.

Main Methods:

• Whole genome resequencing of Kokia cookei (n=23), Kokia drynarioides (n=92), and Kokia kauaiensis (n=45).
• Analysis of nucleotide diversity and population structure.
• Identification of genetic clusters and novel variation sources.

Main Results:

• Kokia drynarioides exhibits the lowest nucleotide diversity, while Kokia kauaiensis shows the most.
• Kokia cookei has higher than expected diversity, with a novel variation source identified in a mislabeled plant.
• Population structure analysis revealed one population for K. cookei and three for K. drynarioides and K. kauaiensis.

Conclusions:

• Genomic insights provide a framework for Kokia conservation, guiding efforts to restore and maintain genetic diversity.
• Understanding population structure is key for effective management of endangered Hawaiian flora.
• Identification of genetic clusters aids in optimizing breeding programs and ex situ collections for critically endangered species.