An award has been made to the University of California at Berkeley under the direction of Dr. Chelsea Specht to study the diversification of floral form and the classification of a family of tropical plants known as heliconias. The goal of the proposed research is to develop an understanding of the evolutionary history of Heliconiaceae, an ecologically and economically important family of tropical plants. The family Heliconiaceae (heliconias) comprises approximately 215 species (190 currently recognized with an estimated 25 remaining to be described) in the single genus Heliconia, distributed primarily in the neotropics. While heliconias are grown as tropical ornamentals throughout the world, the native range extends from central Mexico to central South America including the Caribbean, with a group of six closely related species native to Indonesia, New Guinea, and several South Pacific islands. Although heliconias are frequently cultivated as ornamentals, there have been no well-supported hypotheses on relationships among species of Heliconia, primarily due to similarities in flower traits that are specific to hummingbird pollination. Species have been divided taxonomically into subgenera based on morphology, but this classification has not been tested.
Heliconia species each maintain intricate and specialized evolutionary relationships with pollinating hummingbirds and herbivorous rolled-leaf hispine beetles, as well as other mutualistic, parasitic, and predatory partnerships. A comprehensive, well-supported phylogeny is necessary to determine species-level relationships within the family and to understand the evolution of floral and vegetative characters involved in such complex interspecies interactions. This phylogeny will be used to (a) reconcile and revise the taxonomy of the family using evolutionary relationships to determine specialized features of subgeneric groupings and (b) interpret evolutionary trends in pollination relationships, herbivore interactions, and tropical biogeography. Training will take place at both graduate and undergraduate levels, incorporating students into all aspects of the research, including field collections, phylogenetic and biogeographic analyses, and the description of new species and higher-level taxonomic groupings.
It is impossible to logically plan for conserving biological diversity if we don't understand the evolutionary processes that were responsible for generating and maintaining the diversity we have on earth today. As it has become clear that entire ecosystems are in peril due to loss of keystone species, the identification of ecological and evolutionary dynamics in generating our diverse ecosystems is an essential role of basic scientific research. The intellectual merit of this grant were to fully characterize the evolution of the plant family Heliconiaceae, a charismatic group of tropical plants that play important ecosystem services in providing a major component of understory diversity in tropical forests. With approximately 215 species native to Central and South America as well as the Solomon Islands and New Guinea, Heliconia are most diverse in the neotropical (central and south American) rainforests, and are pollinated exclusively by hummingbirds. Their co-diversification with hummingbirds provides insight into the importance of interspecies interactions in driving and maintaining biological diversity. Funded by this grant, we produced the first phylogeny (family tree) of the Heliconiaceae, demonstrating that the group has evolved quite recently and has diversified in response to both pollinator divergence as well as Andean uplift. Closely related species that live close together tend to differentiate in habitat and most importantly in floral morphology, so that they are visited by different hummingbirds or place their pollen on different places of the hummingbird body to avoid cross-fertilization and hybridization. During the tenure of this grant, 12 undergraduate students were trained in phylogenetic methods and plant systematics, 3 graduate students were supported in their studies on plant evolutionary biology, and 2 postdocs were trained in using the latest computational methods for analyzing trait evolution. In addition, they phylogeny will be published open access and digitally with an underlying database so that distribution maps for each species can be generated on demand, allowing any researcher to visualize species distributions by species or by area, enabling the simplification of future research on these plants. The species distributions are tied to phylogenetic placement, so a research can select a related group of plants (a clade, or lineage) and immediately see how these species are distributed relative to one another. This on-demand visualization facilitates studies of geographic evolution, and the methods used to generate and distribute these maps will be published and available to other scientists. Finally, Heliconia are an important plant for horticulture, providing most of the color you observe in any tropical plant boquet. A popular book characterizing Heliconia species and providing information about their ecology and evolution will be published that will be used by growers and horticulturalists to properly classify and better understand the diversity of form and function represented by their tropical displays.
