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Abstract Detail

Anatomy and Morphology

Dietrick, Alexander [1], Stacy, Elizabeth [2].

Floral characters vary in the landscape-dominant tree, Metrosideros polymorpha: data from a Hawaii Island common garden.

Metrosideros polymorpha, Hawaii's most abundant and variable tree species, is famous for its ecological amplitude and vegetative character variation, and is emerging as a model for studies of adaptive radiation in trees. In contrast to the species' exceptional variation in vegetative characters, however, variation in floral characters has not been examined. Metrosideros has typically red, "shaving-brush" flowers that occur in inflorescences of variable size. We examined floral character variation across 93 adult individuals of M. polymorpha in an established East Hawaii Island common garden. Common garden trees were derived from open-pollinated seeds collected in 1994 from pubescent and glabrous maternal trees ranging across two substrate ages and five elevations on East Hawaii Island; all maternal trees occurred within a continuous population that spans 0 to ~2,500 m above sea level and comprises three varieties of M. polymorpha. In the garden, the number of flowers per inflorescence decreased steadily and significantly with elevation. Trees from the two lower elevations had both significantly shorter styles and stamens and a greater number of stamens per flower than trees from the three higher elevations. The longer, narrower flowers characteristic of the high-elevation variety, M. polymorpha var. polymorpha, may reflect stronger adaptation to bird pollination at high elevations. Across all three lower elevations, stigma-anther separation was significantly greater for trees derived from glabrous maternal trees than from those derived from pubescent maternal trees. This finding may be consistent with weaker selection against self-pollination in early-successional (pubescent) M. polymorpha var. incana in low-density stands on young lava flows. Nectar cup diameter did not vary consistently with elevation or maternal tree type, but varied significantly in response to an interaction between elevation and maternal tree type. These results indicate that in addition to divergence in vegetative traits associated with adaptation to contrasting abiotic conditions, the varieties of M. polymorpha on Hawaii Island show heritable differences in floral characters that may be associated with biotic factors (pollinators and population density).

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1 - University of Nevada Reno, 1664 N Virginia St, Reno, NV 89557, Reno, NV, 89557
2 - University of Nevada Las Vegas, School of Life Sciences; Mail Stop 4004, 4505 S. Maryland Parkway, Las Vegas, NV, 89154, USA

Floral traits

Presentation Type: Poster
Session: P, Anatomy and Morphology
Location: Grand Ballroom - Exhibit Hall/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PAM018
Abstract ID:969
Candidate for Awards:None

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