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Reclaiming disturbed habitats using native grasses : the genetic story of Elymus glaucus (blue wildrye) Ie, Bryan

Abstract

Despite the keen interest in using native grass species for restoration purposes, little is known about their ecology and genetics. By examining the population genetic structure, gene flow, and mating system of Elymus glaucus, recommendations for the successful growth and transfer of seed can be made. Isozymes and morphological traits were used to study 40 Elymus glaucus populations located within British Columbia. F[sub st] values, based upon 21 isozyme loci, were high (0.65) suggesting that species' diversity is predominantly distributed between rather than within populations. Q[sub st] analysis, an index analogous to F[sub st], was used to describe population differentiation of the morphological traits measured. Continuous traits displayed an average Q[sub st][sup c] of 0.80 while the discontinuous trait mean Q[sub st][sup d] was 0.44. It seems that the distribution of diversity follows the same trend set by isozyme distributions in that morphological diversity of this native grass species is partitioned between rather than within populations. F[sub is] and F[sub it] estimates showed a deficiency of heterozygote individuals. This may be due to inbreeding, a colonization effect, or a recent evolutionary bottleneck. Mating system analysis of three Vancouver Island populations indicates that outcrossing does occur within Elymus glaucus. The distribution of Elymus glaucus populations seems characteristic of species undergoing metapopulation dynamics. This observation is supported by its high F[sub st], low geographic structuring (isolation by distance), and the patchiness of its environment. Questions addressed by this thesis pertain to the degree of adaptation and plasticity this grass possesses. In nature, is there any indication of genetic or morphological structuring? Will a high degree of genetic diversity be enough for this grass to successfully evolve and adapt to different environmental conditions? Or does phenotypic plasticity hold the key to its survival in non-local habitats? The answers to these questions will help uncover the evolutionary life history of this native grass species and facilitate the development of successful strategies for reclaiming disturbed habitats using native grasses.

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