Phylogenetic Analysis of the Abronia ammophila Green (Nyctaginaceae) Species Complex

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Background

Abronia ammophila Greene and Abronia mellifera Dougl. ex Hook have a disputed taxonomic status. Abronia ammophila is thought endemic to Yellowstone National Park, and Abronia mellifera is thought to enjoy a more widespread distribution in Utah, Wyoming, Idaho, Washington and Oregon. Although the most recent morphological studies separate them into two species, some local botanists disagree with the determination. In fact, some taxonomists lump both species in with the even more widespread congener, Abronia fragrans Nutt. ex Hook, which is thought to range from Texas through Utah.

The existing taxonomy is based on morphological characters. Unfortunately, Abronia species in general tend to show incredible plasticity in morphological characters of interest for taxonomic determination. Indeed, among these two species the most informative characters overlap such that definitive determination to species is nearly impossible. This study was designed to collect molecular characters to build a phylogeny for the Abronia ammophila species complex with the hope that a molecular-based approach would succeed where a morphological approach has resulted in ambiguous and often subjective species determinations for individual plants.

Objectives

The overall objective of this research is to resolve the taxonomy of the Abronia ammophila species complex. Specifically, the research objectives are:

Collect leaf material and voucher specimens from Abronia ammophila Greene, Abronia mellifera Dougl. Ex Hook, and Abronia fragrans Nutt. Ex Hook for molecular analysis;
Investigate the use of molecular characters to build a phylogenetic tree of the species complex.

Accomplishments through 2004

Leaf material was collected from representative samples of Abronia ammophila from Yellowstone National Park, from A. mellifera at Big Piney, WY, and INEEL, ID, and from A. fragrans from Texas and Utah. Leaf material was brought back to the lab at Southern Illinois University for analysis. Deoxyribonucleic acid (DNA) was extracted from all samples. Several regions of the nuclear and chloroplast genomes have been amplified and sequenced in order to find regions evolving at a sufficient rate as to differentiate closely related species. To date, the internal transcribed spacer regions of the ribosomal gene family (ITS I and 2) have been sequenced. These genes exhibit little variation among the Abronia species. However, we are going to evaluate several additional DNA regions that have shown potential in recent studies for resolving species-level relationships.

Investigators and Affiliations

N. Elizabeth Saunders, Graduate Student, Southern Illinois University Carbondale,
Carbondale, IL

Sedonia D. Sipes, Assistant Professor, Southern Illinois University Carbondale, Carbondale, IL

Funding Sources

Southern Illinois University

Wyoming Native Plant Society

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