Thompson, Stacey Lee , Bérubé, Yanik , Bruneau, Anne , Ritland, Kermit .
Asexual reproduction promotes inbreeding and relatedness in the Alaska cedar, Callitropsis nootkatensis.
Layering, a form of clonal growth where low-lying branches root adventitiously, may promote inbreeding and relatedness in long-lived coniferous trees. In this first microsatellite study of asexual reproduction in the Alaska cedar (Callitropsis nootkatensis), 485 trees from nine plots within three mountain ranges were surveyed for variation at five loci to identify clones, compare levels of clonal growth and genetic diversity, and estimate the contribution of clonal ramets to geitonogamy, biparental inbreeding and relatedness. We used a novel procedure that uses the ratio of three-gene to two-gene coefficients of identity to contrast the contributions of clonal versus non-clonal individuals to population structure. Clonal extent differed significantly among plots and was positively correlated with inbreeding, while overall levels of genetic variation were invariable. Clonal ramets contributed excessively to three-gene to two-gene coefficients of identity, indicating that layering was responsible for local inbreeding and relatedness. Despite adaptations that promote outcrossing, including monoecy and tall stature, the increased inbreeding due to Alaska cedar ramets concurs with the pervasive dogma that geitonogamy is a tolerated by-product of other processes. The genetic load accompanying inbreeding may contribute to the poor sexual recruitment in natural stands of Alaska cedar.
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1 - Université de Montréal, Institut de Recherche en Biologie Végétale, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada
2 - University of British Columbia, Department of Forest Sciences, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
3 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
higher-order gene coefficents of identity.
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 4:00 PM