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Abstract Detail


Population Genetics

Cruse-Sanders, Jennifer [1], Friar, Elizabeth [2].

Patterns of genetic structure and hybridization between Hawaiian Dubautia species.

SPECIES of the Hawaiian silversword alliance are well known for their subdivision of available habitat based on water availability. An example of this fine-level habitat subdivision is the Dubautia arborea and D. ciliolata species pair that co-occur on Mauna Kea on the island of Hawaii (substrates date to 0.13 MYA). The two species are fully interfertile and occur in parapatry, but maintain distinct morphologies and ecological specialization. Previous studies have shown that gene flow follows a landscape model which maintains species cohesiveness where populations of D. arborea and D. ciliolata exchange genes among plants with similar ecological or morphological types regardless of geographic proximity. This study used microsatellites to study the distribution of genotypes at a fine scale and estimate patterns of gene flow between Dubautia arborea and D. ciliolata. A well-documented hybrid zone occurs in the transitional habitat of Waipahoehoe Gulch on the slopes of Mauna Kea, Hawaii, and contains plants that represent a continuous morphological spectrum between the parental species. Plants were mapped within a core region of the hybrid zone and sampled for genetic analysis using eight microsatellite loci. Within the active hybrid zone, mating appeared to be random with respect to plant phenotype, generating a wide array of intermediate forms. Results from a preliminary study indicated that gene flow followed an isolation by distance model. Therefore, within the hybrid zone, genetic structure between D. arborea and D. ciliolata followed a different pattern than at other locations within the range of the two species. Reanalysis with respect to hybrid morphological types provided greater insights into pattern of genetic structure within the hybrid zone. The hybrid zone also provides further opportunities to study spatial patterning and the correlation of morphology, genetic diversity, physiology, and habitat, as well as to directly measure gene flow via pollen and seeds.


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1 - Salem College, Biology, 601 S. Chruch St., Winston-Salem, North Carolina, 27108, USA
2 - Rancho Santa Ana Botanical Garden, 1500 North College Avenue, Claremont, California, 91711, USA

Keywords:
Hawaiian silversword alliance
Dubautia
gene flow
fine-scale differentiation
genetic diversity
hybrid zone
geographic distance
speciation.

Presentation Type: Oral Paper:Papers for Topics
Session: 10-5
Location: 120/SSKU
Date: Monday, July 31st, 2006
Time: 9:30 AM
Abstract ID:654


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