Havran, J , Stutts, L .
Geographic and ecological patterns of morphological variation in the Hawaiian endemic Planchonella sandwicensis (A. Gray) Pierre.
Planchonella sandwicensis (A. Gray) Pierre is a morphologically variable and historically taxonomically confusing tree endemic to the Hawaiian archipelago. Previous studies have addressed patterns of morphological variation within the species, but none have used multivariate statistical techniques. In an attempt to better describe patterns of morphological variation in P. sandwicensis, we analyzed 298 herbarium specimens from the Hawaiian Islands of Kauai, Oahu, Maui Nui (Molokai, Lanai, and Maui) and Hawaii. Continuous traits measured included lamina length, lamina width from the midvein to the leaf margin at intervals of 30 degrees, apex and base angles, fruit size, pedicle length, sepal length, and sepal width. Binary traits included presence or absence of abaxial trichomes, presence or absence of adaxial trichomes, leaf margin type (erose or entire), and sepal apex shape (obtuse or acute). Collection site data from herbarium labels were used to estimate mean annual rainfall from which specimens were originally collected. Results from a canonical variates analysis indicate an east-west dichotomy of leaf morphologies in P. sandwicensis across the Hawaiian Islands. Analysis of Variance and Tukey-Kramer Multiple Comparisons results showed significant (p < 0.05) differences in leaf length and width between western and eastern Hawaiian Islands. Planchonella specimens were distributed throughout estimated mean annual rainfall zones of 250 to 4500 mm/yr. Lamina length is positively correlated with mean annual rainfall (r = 0.17; p < 0.05). Increases in lamina size in accordance with increasing rainfall have been seen in other angiosperms and may explain patterns of variation in this polymorphic species.
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1 - Campbell University, Biology Department, 205 Day Dorm Rd, Buies Creek, NC, 27506, USA
2 - Campbell University, 205 Day Dorm Rd, Biology Department, Buies Creek, North Carolina, 27506, United States
Presentation Type: Oral Paper:Papers for Topics
Location: Franklin B/Hyatt
Date: Monday, July 9th, 2012
Time: 11:45 AM