Abstract
The genus Chrysodracon has six endemic species in the Hawaii Islands. Chrysodracon hawaiiensis is endemic to Hawaii Island and was described as a distinct species in 1980. It was listed as an endangered species on the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List in 1997. This woody plant species was, at one time, common in exposed dry forests, but it became very rare due to grazing pressure and human development. The tree species Chrysodracon auwahiensis (C. auwahiensis), endemic to Maui and Molokai, still has large adult populations in dry lands of the islands, but unfortunately no regeneration from seed has been reported in those areas for many years. The two endemic species were examined using the molecular technique of random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) to determine the genetic structure of the populations and the amount of variation. Both species possess similar genetic structure. Larger and smaller populations of both species contain similar levels of genetic diversity as determined by the number of polymorphic loci, estimated heterozygosity, and Shannon’s index of genetic diversity. Although population diversity of Chrysodracon hawaiiensis (C. hawaiiensis) is thought to have remained near pre-disturbance levels, population size continues to decline as recruitment is either absent or does not keep pace with senescence of mature plants. Conservation recommendations for both species are suggested.
Highlights
The Hawaiian Islands include a high percentage of endemic species and are one of 25 biodiversity hotspots in the world [1,2,3,4]
Leaf tissues were randomly collected from plants in four extant populations of C. hawaiiensis on Hawaii Island and five extant populations of C. auwahiensis on Maui Island (Hawaii State endangered species permit No P-159 for C. hawaiiensis; special use permits of natural area reserves system (NARS) for both species were obtained from the Hawaii Division of Land and Natural Resources (DLNR))
Results of this study demonstrate several important factors regarding the genetic diversity and structure within these species
Summary
The Hawaiian Islands include a high percentage of endemic species and are one of 25 biodiversity hotspots in the world [1,2,3,4]. Many Pacific Island species, including those from the Hawaiian Islands, have a fragile existence. This is often due to their populations being scattered broadly within or across different islands and a limited genetic diversity due to their recent colonization, isolation from the source population, and/or the population size being restricted within island environments [4,5,7,8]. A consequence of this fragility has resulted in many endemic Hawaiian plant species having become endangered and the level of genetic diversity present becoming severely reduced compounding the problems for species recovery [9,10,11]. The study and conservation of genetic resources in populations, species, and ecosystems are essential to maintaining biodiversity and population dynamics
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