Hawaiian Plant Lineage With an Identity Crisis

Using current technological and scientific advances, we are able to observe a snapshot of a plant group that is rapidly diversifying.

Climbing in and out of gulches on the island of Maui was Destiny’s first exposure to the shared grief of botanists and conservationists alike. As she made her way down the gulch, Destiny found quickly identifiable plant species. However, as she walked a few more yards, she encountered a plant without a clear identity. That left her pondering: Is this plant a new species? Is it a rare species? Is this a hybrid? Do resources need to be allocated toward preservation of this plant? These questions have left Destiny, and many others, on the edge of their seats in the quest to determine what is truly a ‘pure species’ versus a putative hybrid to best conserve species diversity. Hawaiian Cyrtandra is no stranger to these questions and leaves various outstanding questions.

Cyrtandra is a genus of flowering plants found throughout the Hawaiian Islands in the Gesneriaceae family. This genus is the second-richest family in regard to species diversity with about 62 species. However, there are more known hybrids than species with about 89 observed putative hybrids. Hybrids are formed when two parental species crossbreed in a common locality and give rise to plants with intermediate morphology. Hybridization between species of Cyrtandra appears to be prominent and has created discordance in conservation efforts. The intermediate morphological variation gives rise to uncertainty about species boundaries and the consequences of hybridization – is one species swamping out another or is it resulting in new variation that can lead to more diversification? This can lead to discourse about species preservation and the potential of negative, or positive, consequences of hybridization.

Destiny Brokaw’s Ph.D. dissertation aims to help resolve species relationships and hybridization across the islands to assist in conservation efforts. During her fellowship at the Smithsonian National Museum of Natural History (NMNH), she processed hundreds of leaf samples, with guidance from NMNH Research Botanists, Warren Wagner and Jun Wen, which were collected from both herbarium specimens and fieldwork expeditions. Throughout the course of her fellowship, she gained guidance from botany lab technician, Gabe Johnson, to extract DNA from these leaf samples and prepare them for sequencing. The sequenced DNA will be assessed in computational analysis to help determine their phylogenetic relationships- essentially a family tree of all species of Hawaiian Cyrtandra. This information will be utilized to assess species presence and rates of hybridization across the islands.

Alongside the genetic components, Destiny has assessed the morphological distinctions between species using electron microscopy. In these analyses, she has identified various structural differences in trichomes (hairs) and glands present on the leaf surfaces with preliminary evaluations at Washington State University’s Franceschi Microscopy & Imaging Center (FMIC). With the help of the Smithsonian herbarium collection (U.S.) and the SEM (scanning electron microscopy) technician, Scott Whitaker, Destiny has been able to evaluate various specimens to determine consistency in proposed morphological differences. These findings provide more aid in identification efforts for field biologists as well as potential insight into the ecological factors that may have allowed for these traits to arise.

Using current technological and scientific advances, we are able to observe a snapshot in time of a plant group that is rapidly diversifying which may provide more insight into a plant’s evolutionary processes and enable further understanding of other plant relationships. In a multi-collaborative effort with the Smithsonian NMNH, Washington State University, National Tropical Botanical Garden, Plant Extinction Prevention Program, and beyond, Destiny hopes to provide insight into a decades-long enigma.

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Destiny Brokaw was a Graduate Student Fellow at the Smithsonian NMNH with the advice and guidance of NMNH Research Bontantists, Warren Wagner and Jun Wen. Destiny obtained her B.S. in Biology from Abilene Christian University and conducted a diverse range of research projects in microbiology and plant systematics. Destiny furthered her education with a M.S. from Auburn University in Plant Pathology where she studied community dynamics of the phyllosphere microbiome. Destiny is currently a Ph.D. student in Eric Roalson's lab at Washington State University studying the Diversification of Hawaiian Cyrtandra.