Santa Cruz Island Reserve

10 Jun, 01 AM - 12 Jun, 08 AM

The geographic range of every species is restricted by a series of ecological and evolutionary factors. The fact of range limits poses a major question: Why doesn't natural selection allow populations at range margins to adapt to their surroundings and spread outward? Despite a recent surge of theory on the evolution of range limits, there has been little empirical testing of this theory. The principal model proposes that selection for locally adapted alleles at range margins is countered by the immigration of alleles suited to non-marginal environments resulting in a balance between gene flow and selection that constrains range expansion. Through the analysis of among and within population genetic and demographic structure across the geographic range of two beach endemic species, Camissonia cheiranthifolia and Abronia umbellata, the research proposed here will help us to better understand to evolution of range limits and contribute to conservation strategies for geographically marginal populations. I will study two species endemic to the beach/dune habitat along the West Coast. Camissonia cheiranthifolia ssp. suffruticosa (outcrossing) occurs from El Soccorro, Baja California to Coal Oil Point, Santa Barbara County, California and C. cheiranthifolia ssp. cheiranthifolia (self-compatible) occurs from Jalama Beach, Santa Barbara County, California to Coos Bay, Oregon. Abronia umbellata ssp. umbellata (self-incompatible) occurs from northern Baja California to Pescadero Beach, San Mateo County, California and A. umbellata ssp. breviflora (self-compatible) occurs from Stinson Beach, Marin County, California to Douglas County, Oregon. Coastal strand (dune) habitat provides an ideal opportunity to test evolutionary hypotheses for range limits. As proposed by theory, the geographic ranges of coastal strand endemic species are 1-dimensional and are likely regulated by latitudinal gradient in climate. However, as part of the coastal strand habitat, beach/dune species are highly impacted by habitat fragmentation from urban development and tourism. Fortunately, National parks, State parks and Reserves play a crucial role in the conservation of coastal habitats, and populations within protected land will provide the best opportunity for quantifying natural population structure and evolution. All sites reported to have species occurrence across the ranges will be visited and population data recorded. 2002 field sampling included 58 of approximately 64 C. cheiranthifolia populations and 35 of approximately 40 A. umbellata populations. Observations and collections will be non-destructive and will not involve any disruption of natural habitats. Populations are provisionally defined as the plants growing at each study site. Among population comparisons will include populations equally distributed from across the species' entire geographic range. Populations with less than 50 individuals will be 100% sampled, populations with >>100 individuals and dunes covering >500 m long (parallel to ocean) will be sampled along linear transects. Population genetic analyses will be performed for up to 50 sites distributed evenly across the entire range (Oregon to Baja) including island populations. Collections To test the density and productivity distribution predicted by the gene flow-selection balance model, each population will be non-invasively surveyed for the following measures: area, number individuals, number of reproductive individuals, number of flowers/plant and fruit to flower ratio, number flowers/inflorescence (A. umbellata only), and plant size (ground coverage, proportion leaf tissue to stem, stem length, rosette size). Plants and populations will also be observed for potentially locally significant adaptations, such as location in dune habitat, spatial distribution of plants, pubescence, as well as for other co-occurring species. For genetic analyses, 200 mg leaf tissue (2-10 leaves/plant, depends on leaf size) will be collected from 30 random individuals/population at 50 sites evenly distributed across the range, including island populations. Leaf sampling will follow the population surveying strategy defined above. Tissue will be dried and stored in silica powder. A minimal amount of fruit, 5 fruit/individual for C. cheiranthifolia and 3 fructescences/plant for A. umbellata will be sampled from each population. For analysis of reproductive mode and flower morphology, 25 randomly selected inflorescences (with at least 5 m between collections) will be sampled per population. Flowers will be pickled in 70% ethanol and transported back to the laboratory for morphometric analyses, including pollen and ovule counts, petal size, and stamen and pistil length. Note: in regions where hybridization between A. umbellata and either A. maritima or A. latifolia; and C. cheiranthifolia and C. bistorta is suspected, a minimal amount of leaf tissue (4-5 individuals/population) may be collected from the other species, as well as hybrids, in order to make genetic comparisons and identify species specific markers.

Visit #1235 @Santa Cruz Island Reserve

Approved

Under Project # 1038 | Research

Queen's University - Biology

graduate_student - Queen's University

Reservation Members(s)

Karen Samis Jun 10 - 12, 2003 (3 days)
Karen Samis Jun 10 - 12, 2003 (3 days)

Reserve Resources(s) | Create Invoice

Dorm 2 Jun 10 - 12, 2003
Pickup Truck 2 Jun 10 - 12, 2003