Little Variation Exists Among Garry Oaks
Garry oak, a key member of an endangered ecosystem in British Columbia, shows little genetic variability throughout its range from Courtenay, BC to northern California.
The tree carries about half the diversity typical of other white oak species.
Two genetically differentiated populations span Garry oak's range, separated at Juan de Fuca Strait. The genetic relatedness of various groves suggests that trees established from two separate refugia after the last glaciation. Gene flow among southern BC's inner coastal islands is high, but does not extend to populations in northern Washington State.
Genetic analysis of the two BC mainland populations, at Sumas Mountain and Yale, indicates they are relics of a larger historic range rather than establishing from tree acorns carried inland by humans or birds. The Sumas and Yale populations are not closely related to each other, nor to nearby trees, but instead are most akin to Garry oaks living near the northern end of the present range on Vancouver Island.
K. Ritland, L.D. Meagher, D.G.W. Edwards and Y.A. El-Kassaby. 2005. Isozyme variation and the conservation genetics of Garry oak. Canadian Journal of Botany. 83(11): 1478-1487.