My research over the past two years has focused on the use of molecular approaches to study phylogenetic and taxonomic relationships in the circumboreal genus Braya (Cruciferae). I and my students, in a collaborative project with botanists at the Canadian Department of Agriculture, the Missouri Botanical Garden, and the University of Heidelberg, have used DNA sequence data from the Internal Transcribed Spacer (ITS) region of the nuclear ribosomal DNA and from the trnL region of the chloroplast genome to infer phylogenetic relationships in Braya and its relatives. More recently, we are using sequence-specific PCR primers to provide evidence of a relatively recent hybrid origin of some Braya species.

In addition, I´m pursuing floristic studies in Utah with emphases on high elevation areas, particularly those in the Great Basin, and on cliff communities.

My research interests are in the rare plant biology of plants of Utah and surrounding areas. Our studies include habitat characterization, population characteristics, demographic monitoring, and reproductive biology. Our most recent taxa of interest include Astragalus holmgreniorum, A. ampullarioides, and Arctomecon humilis, which are all narrow endemics of the southwest region of Washington Co., Utah. Voucher specimens are collected and deposited in the UVSC herbarium for the rare species of interest and of species identified as associates of the target species' habitat. We are also interested in understanding the impacts of introduced exotics on the rare native plants. Conservation and managment strategies are a part of our research as information becomes available concerning these taxa and their contribution to the biodiversity of the planet.

The following is a summary of my current research on the molecular systematics of rare endemics in the Mojave Desert and Great Basin:

North America, a region with over 400 species of Astragalus, is one of three major centers of diversity, all of which comprise the majority of the nearly 1750 species of Astragalus worldwide. One of the most diverse species, Astragalus lentiginosus of Section Diphysi, is a polymorphic complex of over 40 varieties, ranging from the West Coast to Texas and the Rocky Mountains. Over half of these varieties are endemic to the Intermountain States of Utah, Nevada and Arizona.

The Palantia was a sectional name within the genus Tium used by Per Axel Rydberg for taxa formerly reduced by Marcus E. Jones to varieties of Astragalus lentiginosus, all of which have cylindrical pods that, unlike the majority of the remaining varieties, do not become bladdery inflated upon maturity. The Palantia, in a modern interpretation, consists of A. lentiginosus var. mokiacensis and A. lentiginosus var. bryantii (traditionally delimited at the species level) plus the scarcely inflated varieties of A. lentiginosus, primarily A. lentiginosus var. maricopae, A. lentiginosus var. palans, A. lentiginosus var. ursinus, and A. lentiginosus var. wilsonii.

Taxa in the Palantia range from widespread taxa to narrow endemics. Astragalus lentiginosus var. palans is the most widespread taxon in this group. It is composed of many small, local populations spread throughout its range in Utah, Colorado, and Arizona, with several, disjunct populations along its margins. Astragalus mokiacensis is an endemic with a narrower range, but much larger local populations (up to 10,000 individuals). Astragalus lentiginosus var. ursinus and A. lentiginosus var. maricopae are highly restricted, narrow endemics. Astragalus lentiginosus var. ursinus is known from four or five populations in the Beaver Dam Mountains, Mohave County, Arizona and Washington County, Utah. This species grows exclusively in limestone to sandy limestone talus on mountain peaks, and can be occasionally be found growing in washes and in limestone crevices on cliff faces below. Astragalus lentiginosus var. maricopae is currently found in the alluvial fans northeast of Scottsdale, Maricopa County, Arizona. Only three, small populations (less than 20 individuals) were relocated in this study. At least four or five historical populations apparently have been extirpated due to urbanization. It is likely than the total number of individuals of A. lentiginosus var. ursinus and A. lentiginosus var. maricopae may not be more than 5,000 each.

Astragalus lentiginosus var. maricopae, A. lentiginosus var. wilsonii, A. lentiginosus var. ursinus do not exhibit the high levels of chloroplast differentiation found in other taxa with peripheral disjunct populations. The taxa with larger populations, A. lentiginosus var.mokiacensis, A. lentiginosus var. araneosus, A. lentiginosus var. yuccanus, and A. lentiginosus var. palans have low diversity, though more populations of these taxa will needed to be sampled to conclusively substantiate this pattern. An alternative explanation is that A. lentiginosus var. maricopae, A. lentiginosus var. wilsonii, and A. lentiginosus var. ursinus are relictual populations of a taxon that gave rise to the more widespread A. lentiginosus var. mokiacensis and A. lentiginosus var. palans. Unfortunately, the molecular and morphologic data do not give many clues to which taxon more closely resembles the ancestor of the Palantia.

The Indra Swallowtail Butterfly (Papilio indra: Lepidoptera) is found in many small, scattered populations across the western United States and lives in habitats and climates ranging from high moist mountain peaks and rugged semiarid badlands to hot arid deserts. The many isolated populations show substantial morphological variation, and 12 subspecies are currently described in the literature. These subspecies vary in both adult and larval appearance, and they frequently utilize different larval host plants all of which are members of the Parsley family (Apiaceae). Only 21 species of this very diverse family are utilized by the butterfly. Several as yet unexplored desert mountain ranges likely support additional distinctly different populations as evidenced by the recent discovery (May 2000) of a genetically distinct population in northern Arizona. Because of the species´ beauty and extreme geographic variation this is probably the most popular and most collector-sought butterfly in North America which, amongst other factors, warrants its conservation. In light of future conservation initiatives and to better understand its population dynamics and evolution we have recently implemented molecular genetic studies of the Indra Swallowtail.

I have studied the biology and ecology of this butterfly and its larval host plants for 12 years; students and I continue this work to delineate the range of the species and subspecies in order to understand its ecological requirements and evolutionary history. Over the past years I have discovered several new populations, some of which are distinctly different. The ranges of some of the subspecies have been extended. Some of the subspecies have been found to overlap in zones of secondary contact where transitional forms are present and will soon be described.

Due to the extreme geographical variation, this butterfly is ideal for studying the speciation process. With this goal in mind, a colleague (Dr. J. V. Price) and I recently began using mtDNA sequencing of COX I and II loci and PAUP phylogenetic software for genomic analysis to determine the historical phylogeography of the species and subspecies. Utilizing modern molecular techniques of biosystematics (PCR, electrophoresis, gene sequencing) we are investigating the degree of genetic divergence between the populations and subspecies, the amount of gene flow between them, and we are working on their phylogenies. Preliminary phylogenies have been computer generated using PAUP software but not all the populations and subspecies have been sequenced and included in the analysis. However some interesting discoveries have been made. Our genetic analysis has shown that some undescribed and unnamed populations show more genetic divergence from concensus Indra than the currently recognized subspecies.

Several of the subspecies are restricted to only one or two of the larval host plant species and, therefore, likely coevolved with them. Because the biogeography of the plants and the butterfly are becoming well known, we have expand the Indra research to include a phylogenetic analysis of the larval host plants. It is expected that with the added plant data, insights will be gained into the evolutionary patterns of divergence of the butterfly subspecies. In the future host plant preference studies will be conducted across the 12 subspecies.