Domestication and genetic diversity — should we be concerned?

Abstract

Despite the fact that forest trees are in their early stages of MalgrC le fait que les arbres forestiers en sont aux premikres domestication, there has been little direct evaluation of the Ctapes de la domestication, il existe peu d'information sur 1'Cvalugenetic diversity throughout this process. The dynamic changes ation directe de la diversit6 gCnCtique au cours du processus. in the genetic structure of wild conifers were monitored through Les changements dynamiques dans la structure gCnCtique des several bottlenecks, namely: phenotypic selection, seed orchards, coniferes indigknes ont Ct C observCs lors d7Ctapes dCcisionnelles, seed processing and storage methods, and seedling production.A savoir: la sClection phCnotypique, les vergers 2 graine, lesThe genetic structure of phenotypically vs. randomly selected mCthodes de manipulation et d'entreposage des semences, et la individuals of two conifers with known contrasting diversity production de semis. La structure gCnCtique d'individus cholevels is compared. The biology and management methods pracisis pour des raisons phCnotypiques ou au hasard parmi deux ticed in seed orchards are evaluated, and seed extraction and coniferes dont on a reconnu des niveaux marquis de diversitC, storage procedures are assessed to evaluate common practices est comparCe. La biologie et les pratiques d'amknagement on biological peculiarity. Finally, the cultural practices of conutilisCes dans les vergers a graine sont CvaluCes, de m&me que tainer nurseries were monitored and their impact on the genetic l'extraction des semences et les procCdures d'entreposage sont structure of future forests is evaluated.CtudiCes afin d'haluer l'effet des pratiques courantes sur les particularitCs biologiques. Finalement, les mCthodes de culture au sein des pCpinikres en contentant ont Ct C examinCes et leur impact sur la structure gCnCtique des futures for&ts est CvaluC.

Clonal variation in cone and seed production in black and white spruce seed orchards and management implications

“…The year-to-year variation in cone and seed production among clones should be evaluated to see if similar pattems occur through time. O'Reilly et al (1982) suggested that the best reproductive balance is achieved in years with good cone crops; this was also illustrated by El-Kassaby (1992). This study took place in a very good cone year for both species.…”

“…For example the average sound seeds tree-' ranged from 1 to 2819 for black spruce and 121-40950 for white spruce. While this study was not designed to estimate heritabiIity of cone and seed production, these traits have been shown to be under strong genetic control in other conifers (El-Kassaby 1992). White spruce produced more than twice as many cones tree-' as black spruce (250 versus 104) and over seven times as many seeds tree-' (6365 versus 797).…”

Assessment of the Genetic Diversity in Forest Tree Populations Using Molecular Markers

“…Another marker type that played an important role in assessing genetic diversity in plants was isozymes [12,13]. Isozymes had a long history in genetic variability studies in forestry, to assess the genetic diversity present within natural forest stands [14,15] or to determine whether domestication practices had led to a reduction in diversity [16][17][18]. However, the problem of these biochemical marker assays is that they are affected by plant phenological stage and their limited availability, and therefore, they would never allow for a genome-wide scan of variability (as only 0.1% of the total variation is detectable by this technique, [19]).…”

Pollination dynamics in a Douglas-fir seed orchard as revealed by pedigree reconstruction

“…Breeding populations are managed to maintain higher levels of genetic variability for sustained long-term genetic response, while capturing genetic gain is the sole function of production populations (Namkoong et al, 1988). Thus, they represent the linkage between breeding and silviculture activities; thus, their * Corresponding author: y.el-kassaby@ubc.ca genetics and the quality of their seed crops should be given increased attention (El-Kassaby, 1992).…”

“…Bloom delay involves the application of an overhead fine water mist during later parts of winter and early spring to slow heat sum accumulation, thus delaying and effectively isolating the orchard's reproduction and thereby reducing the exposure to pollen migration from external pollen sources (Silen and Keane, 1969). This technique has proven to be effective in delaying (Fashler and Devitt, 1980) and compacting reproductive phenology resulting in improved panmixia (Fashler and El-Kassaby, 1987), reduced pollen contamination (El-Kassaby and Ritland, 1986), and increased outcrossing rate (El-Kassaby andDavidson, 1990, 1991). SMP involves the broadcast application of viable pollen to nonisolated receptive strobili to increase the gametic representation of desirable genotypes in seed crops.…”