Genetic diversity in Canadian Hardwoods: Implications for conservation

Abstract

Hardwoods are diverse, and they are important components in several forest regions of Canada. Yet low demand from the pulp and paper sector, abundant natural regeneration for several species, and high costs associated with seedling production and plantation establishment have restrained industries and governments from investing intensively into basic biological and genetic research of hardwoods. Recently, new interests have emerged for the utilization and conservation of hardwood species. To devise efficient gene conservation and breeding strategies for hardwoods, knowledge is needed about their genetic structure, genecology, and mating systems. Here we review information on the organization of genetic diversity in the few Canadian hardwood species that have been studied. Results derived from analyses of quantitative characters showed extensive genetic variatlon among populations and among individuals within populations in all species. Genetic variation among populations was found to be associated with environmental factors, especially for adaptive traits. Levels of genetic diversity were also found high in allozyme genetic markers. The application of molecular genetic markers at the DNA level in monitoring genetic diversity of hardwoods is also discussed. Information available regarding genetic diversity of Canadian hardwoods is insufficient to design efficient gene conservation strategies. Several programs investigating genetic diversity of hardwoods have been initiated in Canada, and should y~eld urgently needed data.Il existe plusieurs e s e e s de feuillus et ceux-ci constituent une composante importante de plusieurs r6gions forest2res du Canada. A ce jour une faible demande de la part du secteur des pAtes et papiers, une rkgCn6ration naturelle abondante pour plusieurs e s e e s , en plus des coats importants de production de semis et de reboisement ont emgchk les industries et les gouvernements d'investir intensivement dans la biologie fondamentale et la recherche gknetique au niveau des feuillus. Rkemrnent l'utilisation et la conservation des e s M s feuillues ont fait surgir un regain d'intkret. Afin d'instituer une conservation gCn6tique efficiente et de mettre en place des stratkgies d'interfhndation pour les feuillus, il faut accrortre les wnna~ssances relatives B leurs structures gCnktiques, leur gen6cologie et leurs systkmes de fkcondation. Nous rkvisons dans cet article l'information sur l'orgamsation de la diversitk gLn6tique des quelques es@s canadiennes de feuillus que nous avons 6tudi6es. Les rksultats tires des analyses des caractkristiques quantitatives dkmontrent une trks grande variation gCn6tique entre les populations et entre les individus d'une population donn6e et ce pour toutes les e s e e s . On a d6couvert que la variation gkn6-tique entre les populations 6tait associ6e aux 616ments environnementaux, spkialement au niveau des facteurs d'adaptation. Le degr6 de diversit6 gknktique s'est rev616 &re Bevk au sein des marquers g6n6tiques allozymatiques. L'utilisation des marqueurs gkn6-ti...

Molecular Markers in Population Genetics of Forest Trees

“…The literature on these topics is extensive and readers are advised to consult reviews, e.g. by El-Kassaby (1991), Hamrick et al (1992), Li et al (1992), Loveless (1992), Moran (1992). The studies accumulated during the 1980s and 1990s have contributed a great deal to our understanding of various population processes.…”

Ex situconservation of American chestnut (Castanea dentata(Marsh.) Borkh.) and butternut (Juglans cinereaL.), a review

“…These include the intrinsic pattern of rarity (natural), the extrinsic pattern of rarity (current condition), bottleneck information (relic versus remnant populations), potential habitat (potential and realized niche), deterministic factors (environmentallgenetic) and stochastic factors (demographiclgenetic) (Joyce 1995). The first step in conservation management is to conduct a study of the genetic structure (genetic variability within and among populations, proportion and distribution of rare alleles and levels of inbreeding) forthe species of concern (Li et al 1992, Loo 1995. A similar approach taken by Harnrick et al (1991) examines the determinants of genetic diversity as a starting point when designing a gene conservation program These &termhints include; taxonomic status, regional distribution, geographic range, life form, mode of reproduction, breeding system, seed dispersal mechanism, and successional status.…”

“…This high cost is often due to sensitivities to vegetative competition and susceptibilities to animal damage (e.g., rodents, rabbits and deer) (Li et al 1992). In addition, hardwood stands are prone to losses from drought, insect pests, vandalism, and disease.…”

Utilization and management of forest resources in Zaire

“…To achieve improved conservation and sustainable utilization, information is needed on ecological diversity as well as basic information on genetic diversity, spatial distribution of this diversity and, ideally, the underlying causes of the observed patterns of genetic diversity (Li et al 1992). First, this information is essential in designing efficient conservation strategies to preserve genetic diversity, the ultimate source of adaptability for future generations.…”

“…As outlined by Li et al (1992), conservation of biodiversity could proceed at three levels: 1) the diverse landscapes and ecosystems are conserved to preserve diversity of organisms and processes operating at these higher levels of organization, 2) conservation of the species diversity within ecosystems, especially rare and endangered species, and 3) conservation of the genetic diversity within species (gene conservation).…”