Abstract:
ABSTRACT
HABITAT, SEED DORMANCY, AND ALLOZYME VARIATION OF
THE RARE ENDEMIC Phacelia cookei (BORAGINACEAE)
by
Melissa E. Patterson
Master of Science in Botany
California State University, Chico
Fall 2010
Experimental studies of rare species are the most effective way to create
management strategies to conserve species and prevent further decline and extinction.
We conducted habitat surveys, germination, and population genetic surveys to inform
management priorities for Phacelia cookei Constance & Heckard (Boraginaceae), a diminutive
annual herb only found within a three-mile radius near Mt. Shasta, California,
and it is rare within that geographical range. Habitat surveys included a rapid vegetation
assessment, soil samples, and assessment of ground cover. We found no significant differences
among site category in soil types. An associated species list was created, and
the most closely associated species was Nama densa A. Gray, which was found at four
sites where P. cookei was present. We tested the effects of afterripening, scarification,
stratification, and variable germination temperatures on breaking seed dormancy. Seed
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viability by tetrazolium tests ranged between 89% and 93%, but the highest germination
from any treatment combination was 38.9% after adjusting for seed viability. We resolved
19 putative allozyme loci, only two of which were polymorphic. This species
had low genetic diversity within and among the three large sampled populations when
compared to other endemic species with similar mating systems, and this may ultimately
be an important challenge for maintaining viable populations of the species.
Management plans should consider additional studies to explore the feasibility of restoring
populations in suitable locations by sowing seeds collected from existing populations
is suitable habitat.
