About This Project
Cyanea (80 spp.) is the most diverse plant genus restricted to Hawaii, and has undergone striking radiations in habitat, growth form, leaf shape, and floral form. More than 90% of its species are restricted to single islands, each of known age. We seek funds to reconstruct the evolutionary history of this remarkable group based on sequencing hundreds of nuclear genes and entire chloroplast genomes, and analyzing morphological, geographic, and ecological data already in hand.
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What is the context of this research?
The Hawaiian lobeliads as a whole – of which Cyanea is the largest genus – are the largest group of plants to have arisen on a single oceanic island or archipelago anywhere on Earth, and have more endangered species than any US genus, and thus are of great interest to evolutionary biologists, ecologists, and conservation biologists. Our previous research (e.g., Givnish et al. 1995, 2004, 2009, 2013) made landmark contributions to our understanding of plant evolution on Hawaii, but included only a small fraction of all Cyanea species. Now we have the exciting ability to include almost all living and extinct species in our analysis. The resulting study should provide some of the most powerful insights in the ecological and geographic evolution of any group of island plants.
What is the significance of this project?
This study will be among the first to apply next-generation DNA sequencing to the study of plant evolution on islands, and will reconstruct the phylogeny (family tree) and patterns of ecological divergence and geographic evolution in the largest plant lineage on islands studied intensively to date. The use of numerous, independently assorting, single-copy nuclear loci will provide extremely powerful tools for estimating both family trees and patterns of hybridization and introgression. Data from this study will be used to test general hypotheses regarding the expected patterns of movement between older and younger islands, speciation as a function of elevation, and extinction related to exceptionally long flowers and pollination by highly specialized birds with long bills.
What are the goals of the project?
We will use our existing collections of Cyanea DNA samples and baits for enriching total DNAs for 400 target loci to estimate the phylogeny and patterns of hybridization for Cyanea and its sister genus Clermontia, which together contain more species than any other plant lineage restricted to the Hawaiian Islands. We will use these evolutionary estimates to infer patterns of evolution in flower form, elevational and geographic distribution, and speciation rates, and to test predictions as to what factors drive the net rate of species diversification in different lineages. We have recently used this kind of approach to reconstruct the phylogeny, diversification, and geographic spread of orchids, the largest family of flowering plants (Givnish et al. 2015, 2016).
We will enrich DNA samples of roughly 60 living species 10 extinct species (extracted from herbarium specimens) for 400 rapidly evolving DNA spacers in the nuclear genome, identified and used successfully in an ongoing study of Cyanea's closest relative, Clermontia, also restricted to the Hawaiian Islands. We will load these enriched samples onto two lanes of an Illumina next-generation DNA sequencer. From the hundreds of millions of DNA reads (300 base-pair sequences) obtained from each lane, we will assemble the sequences of the nuclear spacers and skim the entire
The resulting data will provide a very powerful means to infer evolutionary relationships among species of Cyanea and estimate patterns of past hybridization over the estimated 9 million years of its existence. We will use the family trees and networks inferred from these data to reconstruct patterns of inter-island dispersal, ecological divergence, and species diversification in this extraordinary group.
Meet the Team
Givnish earned his PhD at Princeton in 1976, and then taught at Harvard before joining the faculty at the University of Wisconsin-Madison in 1985. He is an elected Fellow of the American Association for the Advancement of Science, and an elected Fellow of the Linnean Society of London. He has published more than 140 papers and edited two books.
Givnish is known for his research on the functional and ecological significance of several aspects of plant form and physiology related to energy capture, and for his use molecular systematics as a basis for studying patterns of adaptive radiation, geographic spread, and species diversification in several plant lineages, especially those on oceanic islands and tropical mountains. He has conducted ecological and evolutionary studies in several parts of North America, South America, Australia, and the Pacific Basin. He is an expert on the phylogeny and biogeography of several monocot families (bromeliads, rapateads, lilies, orchids, and their relatives), and has made several contributions to the study of carnivorous plants, including the discovery of carnivory in bromeliads native to the tepuis of southern Venezuela, and the creation of a cost-benefit model for the evolution of carnivory.
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