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Biosystematics of the endemic Hawaiian species of Lysimachia (Primulaceae)

University of British Columbia

The endemic Hawaiian species of Lysimachia were examined using a combination of analyses of metric and non—metric morphological characters, allozyme variaton and crossing studies. The purpose was to produce a taxonomic revision and to investigate the degree of genetic divergence and type of reproductive isolation that has accompanied speciation. Principal components analysis of metric characters produced an ordination of OTU’s, that was used as a first step toward understanding the range of variation. However, greater reliance was placed on non—metric characters for the taxonomic revision. Sixteen species and four subspecies, including three previously undescribed species are now recognized. Allozyme variation was analyzed in 15 taxa from 48 populations. Genetic identities ranged from 0.71-1.00, indicating high genetic similarity and supporting the hypothesis of a monophyletic origin. These values are intermediate to those of other insular genera. There is a low correlation between morphological variation and allozyme variation. Total genetic diversity, Ht, within species, ranges from 0.02-0.22. Genetic diversity within populations does not decrease in an entirely linear manner from the oldest to the youngest island. However, there is a step—wise decrease in genetic diversity among taxa within an island from the oldest through to the youngest island. All interspecific crosses that were attempted produced fertile seeds. Pollen stainability was quite variable in all species and in the F1 hybrids of most species pairs. The reduced stainability of the parents involved in the crosses makes it difficult to interpret the significance of reduced stainability of some hybrids. Approximately 80% of self pollinations within flowers failed. This appears to be due to protogyny, not to self-incompatibility. Adaptive radiation in Lysimachia has resulted in species that have diverged in corolla pigmentation, leaf size and shape, and ecological preferences. Speciation has occurred without the types of divergence between species that often accompanies speciation on continents, i.e., internal, post- zygotic barriers to reproduction and low genetic identities. This pattern of morphological and genetic variation is similar to that seen in other insular groups.

Thesis/Dissertation

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2009-04-23

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http://hdl.handle.net/2429/7513

Botany

University of British Columbia

UBCV

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