Wright, Margaret E. , Ranker, Tom A. .
A Genetic Comparison of Bog vs. Forest Populations of Metrosideros polymorpha (Myrtaceae) in Hawai'i.
Metrosideros polymorpha is the most abundant native plant in the Hawaiian Islands. M. polymorpha exhibits high levels of apparent local adaptation and ranges in morphology from small shrubs (<1m) to relatively large trees (> 20 m). Despite the high morphological variation and broad ecological amplitude in this species, there have been few studies assessing genetic variation among populations of morphological varieties We used the molecular technique of inter-simple sequence repeats (ISSRs) to examine the genetic diversity and structure of morphologically distinct neighboring populations of M. polymorpha, growing in bogs and adjacent forests across multiple islands. ISSR data using three primers were collected for 287 individuals from five islands. The mean value of Nei’s gene diversity for all populations was 0.2436 Â± 0.172. The majority of genetic variation was found within microhabitat within islands, with an average of 91.34% (80.87%-95.72%). The average amount of genetic variation attributed to differences among microhabitats across the islands was 8.64% (4.28% -19.13%). There was a significant correlation between geographic and genetic distance across all populations. A UPGMA phenogram shows the Kaua’i bog population to have the greatest genetic distance from all other populations. This study demonstrated that morphologically distinct populations of M. polymorpha contain an average amount of genetic diversity within populations and a low amount of genetic differentiation among populations compared to other flowering plant species. These data reflect the fact that M. polymorpha experiences extensive gene flow throughout the Hawaiian Islands and has become a widespread ecological generalist. Detectable levels of genetic differentiation among populations appear to be the result of geographic isolation rather than putative adaptation, and therefore the different morphologies of bog and forest plants are most likely due to phenotypic plasticity and may not have a strong genetic basis.
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1 - University of Colorado, University Museum & Department of Ecology and Evolutionary Biology, 265 UCB, Boulder, Colorado, 80309, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 9:15 AM