Abstract Detail

Conservation Biology

Bridgens, Rachel [1], Philpott, Megan [2], Culley, Theresa [3], Pence, Valerie [4], Ching, Susan [5].

Genetic evaluation of the critically endangered woody species, Gardenia brighamii and hybridization with ornamental Gardenia tahitensis in the Hawaiian Islands.

Genetic diversity is often scarce in critically endangered flora as a result of genetic drift, high inbreeding potential, and severely reduced population sizes. Genetic variation is a major determinant of long-term population health, so this lack of diversity increases the vulnerability of extremely small, endangered plant populations. This is especially true for Gardenia brighamii, one of many critically endangered native Hawaiian plant species. While G. brighamii is believed to have been previously abundant on all eight major Hawaiian Islands, it is now only extant on O’ahu and Lanai. Of the 15 remaining individuals, 14 are on Lanai and only one resides on O’ahu. A previously existing O’ahu individual, now dead, produced a fruit that appears to be the product of a hybridization event between G. brighamii and G. tahitensis, an introduced garden variety species with high ornamental value in Hawai’i. Seedlings from this potential-hybrid fruit are now growing ex situ but their genetic composition is not definitively known. In this study, we aim to genetically classify six of the possible hybrid individuals. Microsatellite markers were initially used, which revealed only minimal genetic variation, before shifting to amplified fragment length polymorphisms (AFLPs) to better quantify inconspicuous DNA polymorphisms, and thus provide a more comprehensive analysis. We used six AFLP primer combinations previously optimized for G. brighmaii in this study to genetically analyze 53 G. brighamii individuals (from both ex situ and in situ collections), two G. tahitensis individuals, and the six possible hybrids. The high ornamental use of G. tahitensis in Hawai’i and the close evolutionary relationship of the two species may have provided ideal crossbreeding conditions making it very likely that these six unknown individuals are hybrids. While it is true that the genetic variation provided by a G. tahitensis crossbreeding event may improve the health of the wild population of G. brighamii, this outcome is never certain. Hybridization will, however, severely jeopardize the genetic purity of this culturally important species. The assessment of this particular wild mating event will provide useful information about the remaining genetic diversity of G. brighamii, how we can better protect its genetic purity, and aid in our work to conserve many other endangered Hawaiian plants.

1 - University Of Cincinnati, 703 Rieveschl Hall , 318 College Dr. , Cincinnati, OH, 45221, United States
2 - Cincinnati Zoo & Botanical Garden, CREW, 3400 Vine St., Cincinnati, OH, 45220, United States
3 - University Of Cincinnati, Dept Biological Sciences, 614 Rieveschl Hall, Cincinnati, OH, 45221, United States
4 - Cincinnati Zoo & Botanical Garden, Center for Conservation & Research of Endangered Wildlife (CREW), 3400 Vine St, Cincinnati, OH, 45220, USA
5 - Department of Land and Natural Resources , 2551 Waimano Hm Rd, Pearl City , HI , 96782, USA

Genetic diversity.

Presentation Type: Oral Paper
Number: CB1003
Abstract ID:586
Candidate for Awards:None

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