SIERA-ex (Single-Island Endemic Representativeness Analysis for ex situ Collections): a Kauaʻi-based plant conservation model

Abstract

Over 260 single-island endemic (SIE) vascular plant taxa are recognized on Kauaʻi. Many face threats inherent to island species with narrow ranges and small populations where there is an increased risk of genetic diversity loss. In order to ensure species resilience, ex situ facilities collaborate to expand metacollection holdings, broadly sampling from multiple genetically diverse individuals. Priorities and relationships of metacollection partners have a major impact on the trajectory of biocultural conservation efforts in Hawaiʻi, as most of the germplasm for habitat restoration is held in these repositories. Curators pool resources, sharing plant material and analyzing datasets to inform strategy and pinpoint conservation gaps. This study introduces SIERA-ex, an empirical framework and accompanying open-source software application for place-based gap analysis that uses geographic and ecological coverage as a proxy for allelic coverage where optimal distance thresholds are poorly known. It can account for known sympatry and admixture, which is beneficial for confounded species delimitation and misidentification. Resolution is buffered across geographic reference area, ecoregion, watershed, moku, ahupuaʻa and wao geospatial layers to the level of 2 km for use over small ranges for Kauaʻi SIE taxa. Metrics are introduced to assign both taxon and subpopulation priority values that incorporate biocultural value, exceptionality, and threat level. A case study of nine Kauaʻi species [Loulu (Pritchardia –7 spp.), Kokiʻo ʻUla (Hibiscus clayi), and Hōlei (Ochrosia kauaiensis)] identified and recommended for conservation priority nearly a dozen underrepresented subpopulations with varying degrees of urgency. Results indicate that curators can best empower reciprocity and maximize resources in the perpetuation of the least conserved SIE species by limiting scope, and prioritizing taxa with high levels of threat assessment, exceptionality, and biocultural value.