| The Hawaiian violets represent a monophyletic lineage of angiosperms restricted to the subaerial islands of the Hawaiian archipelago. Violets in similar habitat types (montane bog, cloud forest, and mesic streambank) exhibit remarkable similarities in growth form and leaf morphology. To identify the role that environmental parameters may play in directing the morphological evolution of the Hawaiian violets, the lineage was investigated to determine its biogeographic history, the ecological parameters that may define a particular habitat type, and the reproductive isolation mechanisms that currently exist to limit gene flow between populations. Maximum likelihood, parsimony, and ACCTRAN reconstructions of the Hawaiian violet lineage using the Internal Transcribed Spacer (ITS) sequence suggest that the Hawaiian violets most likely had their origin on the island of Kaua'i. Following establishment, two replicate sublineages were established on Kaua'i and Moloka'i. Each island has a representative of the montane bog (V. kauaensis and V. maviensis ) and cloud forest (V. wailenalenae and V. robusta) habitats. Multivariate analyses of the edaphic and light characteristics of the bog and cloud forest habitat types suggest that volumetric water content, pH, nitrogen, and Carbon contribute to the separation of bog and cloud forest habitat types. Despite similarities in ecology and morphology, montane and bog violets on Kaua'i and Moloka'i do not exhibit the same pre-zygotic isolation strategies. Violets are most likely infrequently visited by insect pollinators and have co-opted a variety of selfing strategies found in ancestral violet species. Reproductive studies suggest that the violet species on Moloka'i are currently at an earlier stage in the process of peripatric speciation than those on Kaua'i. |
