Selby Gardens has recently developed, equipped, and implemented a molecular-based research program, known as Molecular Programs. Not simply a project at the Gardens, Molecular Programs is a new resource for Selby scientists to address the Gardens mission of researching and conserving epiphytes and their relatives. Initial research in the new molecular laboratory is focused on one of three focal plant families of Selby Gardens, the Gesneriaceae or gesneriads.
Systematics and Diversity
A major part of the research conducted by Selby Gardens involves systematics, the study of plant diversity and how and why species have evolved over time. To do this, we use classical taxonomy, the study of physical characters to distinguish and classify organisms, as well as molecular systematics, the use of gene sequence data to understand evolutionary relationships. These tools allow us to identify and classify species and genera of plant families of interest and help us understand evolutionary relationships within the entire plant kingdom. Information obtained from systematics research is used to construct phylogenetic trees. Phylogenetic trees are hypotheses of relationships between organisms and are used to address other questions such as how species have evolved, what characters have influenced speciation, and why species are found where they are. These methods are computationally complex and require sophisticated computers and software to conduct analyses. A current project by the Gesneriad Research Center is designed to use advanced computational methods to understand ancestral range evolution in gesneriads.
The objectives of this pilot project are to 1) implement the molecular-based research program and provide the tools required to conduct molecular-based research and 2) utilize the new program by conducting novel research, results of which will be disseminated through public presentations at scientific meetings and through publications in peer-reviewed journals. The current project has been designed based on four criteria: 1) the project must address questions that cannot be answered using non-molecular techniques alone, 2) the project must be reasonably expected to produce meaningful results but remain technically complex enough to illustrate the new program’s strengths, 3) the project must produce results of interest to other museum/botanical gardens worldwide covering a variety of relevant issues in plant systematics, and 4) the project must have a relevance to current research at Selby Gardens, utilize existing collections including preserved and living material.
The plant family Gesneriaceae is a group of about 3400 species found throughout much of the world’s tropics with centers of diversity in Central and South America, Africa, Southeast Asia, and the Pacific. Gesneriads are important horticulturally and commonly known examples include African violets (genus Saintpaulia) and the Lipstick plant (genus Aeschynanthus). Gesneriads are important ecologically and provide nectar rewards for specific pollinators such as moths, bats and birds; their often-fleshy fruit serve as food for birds and other animals.
Although a great diversity of gesneriads are found throughout the world’s tropics, only one genus is found east of the Solomon Islands and Vanuatu, into the remote Pacific: the genus Cyrtandra. The largest gesneriad genus (with ~600 species), Cyrtandra is remarkable in having dispersed throughout the Pacific and provides a good model for studying plant dispersal and diversification: Cyrtandra is broadly distributed over nearly a quarter of the earth’s circumference but individual species within this genus are usually restricted to small areas such as islands. This scenario suggests that individuals are dispersed and then become isolated from the source population, diverging into new species over time. Researching these patterns has provided valuable data useful in better understanding why these patterns exist in Cyrtandra and can be extrapolated to a large number of other plants having similar patterns. Molecular research has proven particular useful in understanding relationships in Cyrtandra, but current studies have not pinpointed the origin and relationships of the Pacific species to more mainland species. Knowing where Pacific Cyrtandra originated and by what routes the genus made it into the Pacific is important baseline information that will help us to better understand island plant dispersal and diversification and be useful in characterizing species limits for conservation of these often rare species that inhabit increasingly imperiled island habitats.
This project will build on existing data secured and analyzed during John R. Clark’s recent dissertation research, DNA and specimens that are now deposited in Selby Gardens’ collection; John’s research provided a detailed hypothesis about the origin and evolution of Cyrtandra that strongly implicated southeastern Melanesia-western Polynesia as an important ‘Interface Zone’ for the genus into the Pacific (Clark et al., Syst. Biol. 57:693-707). On-going collaborations in the Pacific region, and recent fieldwork in May-June 2009 in the Solomon Islands, has provided approximately 100 additional species for analysis. Our analysis will center on using two nuclear ribosomal gene regions, the internal transcribed spacer region (ITS) and the external transcribed spacer region (ETS), and one chloroplast gene region, psbA-trnH, all of which have proven useful in Cyrtandra systematics studies. Molecular data will be generated from newly acquired species from the interface zone and will be combined with data previously collected to construct a more comprehensive hypothesis of relationships in Cyrtandra using likelihood and Bayesian analyses. We will use this hypothesis, inclusive of important species lacking in previous studies, to test our current theory that the interface zone represents the origin of the Pacific species. We will use the method of dispersal-extinction-cladogenesis analysis (Ree and Smith, 2008. Systematic Biology 57:4), an ancestral range analysis method that has proven useful in interpreting the origin and dispersal of organisms, to reconstruct the historical range and dispersal routes in Cyrtandra. Physical data will also be collected and used to address species relationships in approximately 10 species in the closely related Cyrtandra occulta complex and the Cyrtandra samoensis complex, both groups that are well represented in the interface zone and in need of revised species-level study.
A major part of the research conducted by Selby Gardens involves systematics, the study of plant diversity and how and why species have evolved over time. To do this, we use classical taxonomy, the study of physical characters to distinguish and classify organisms, as well as molecular systematics, the use of gene sequence data to understand evolutionary relationships. These tools allow us to identify and classify the species and genera of gesneriads and help us understand evolutionary relationships, not only within the gesneriad family, but within the entire plant kingdom. The GRC uses the information obtained from systematics research to construct phylogenetic trees. Phylogenetic trees are hypotheses of relationships between organisms and are used to address other questions about gesneriads such as how species have evolved, what characters have influenced speciation, and why species are found where they are. These methods are computationally complex and require sophisticated computers and software to conduct analyses. GRC researchers are currently exploring advanced computational methods to understand ancestral range evolution in gesneriads.</p>
Molecular Programs – Welcome to the 21st Century Gardens!
Perhaps no better example of this is the impact of our increased understanding and utilization of DNA, the genetic code, to unravel the mysteries of evolution. Once the stuff of science fiction, molecular research, and its implications in medicine, forensics, and other fields, is commonplace. One can barely turn on the radio or television, or surf the net, without hearing something about DNA – convictions in long unsolved homicides (or overthrown convictions of the wrongly accused), research in gene therapy, the human genome project, the neandertal genome project, paternity tests, etc. The point is that DNA, more precisely molecular research geared towards utilizing DNA to understand life, is changing the way we look at and explore the world around us. The study and conservation of plants is no exception.
Plant systematics, the study of evolutionary relationships between plants and the classification and naming of them, is one of the oldest fields in science. Systematics research had been conducted more or less the same way for a few centuries, that is until DNA analysis came along in the mid-1980’s but most notably in the 1990’s through today. Since then our understanding of the relationships among plants has changed dramatically. Much in the same way DNA is used to identify the father of a child, DNA can be used to understand the relationships of plants in populations, the relationships between different species of plants and even relationships between plant genera, families, and beyond.
Molecular research has been highly informative in notoriously difficult to classify groups, including orchids, bromeliads and gesneriads, and is even providing valuable data useful in conserving these and other plants. Molecular research is indispensable in understanding the genetic diversity of plants in threatened populations, in how those populations are related to other populations, and in determining which individuals or what populations should be used for propagation and reintroduction efforts. Molecular research has also been employed in understanding how non-native plants are impacting rare and endangered native species through habitat competition and cross-species hybridization between introduced and native species.
The new Molecular Programs at Selby Gardens allows research staff to conduct cutting edge science that has become the hallmark of basic evolutionary and conservation research. Dr. Lucinda McDade, Director of Research and Professor of Botany, Rancho Santa Ana Botanic Garden, remarks that a functioning molecular program “permits gardens and museums to be fully engaged players in our discipline [of evolutionary research and education], keeps them current, keeps them contributing, keeps them relevant.” The Rancho Santa Ana Botanic Garden and several other gardens around the world have initiated molecular-based programs and have positioned themselves to provide indispensable services to their public and the scientific community in the form of basic research and education. Furthermore, these gardens are at the forefront of innovation in plant research and act as regional hubs for molecular-based training of future scientists. Molecular Program at Selby Gardens is an investment in institutional capacity that allows Selby scientists to provide similar services in Southwest Florida where no regional institutions are exclusively focused on plant molecular-based research. Molecular-capabilities also provide advanced training opportunities for students and raise the status of Selby Gardens as a leader in scientific research thereby advancing the goals of Selby Gardens’ Strategic Plan.