Highly pathogenic avian influenza (HPAI) H5N1 viruses have caused dramatic economic losses to the poultry industry of Vietnam and continue to pose a serious threat to public health. As of June 2008, Vietnam had reported nearly one third of worldwide laboratory confirmed human H5N1 infections. To better understand the emergence, spread and evolution of H5N1 in Vietnam we studied over 300 H5N1 avian influenza viruses isolated from Vietnam since their first detection in 2001. Our phylogenetic analyses indicated that six genetically distinct H5N1 viruses were introduced into Vietnam during the past seven years. The H5N1 lineage that evolved following the introduction in 2003 of the A/duck/Hong Kong/821/2002-like viruses, with clade 1 hemagglutinin (HA), continued to predominate in southern Vietnam as of May 2007. A virus with a clade 2.3.4 HA newly introduced into northern Vietnam in 2007, reassorted with pre-existing clade 1 viruses, resulting in the emergence of novel genotypes with neuraminidase (NA) and/or internal gene segments from clade 1 viruses. A total of nine distinct genotypes have been present in Vietnam since 2001, including five that were circulating in 2007. At least four of these genotypes appear to have originated in Vietnam and represent novel H5N1 viruses not reported elsewhere. Geographic and temporal analyses of H5N1 infection dynamics in poultry suggest that the majority of viruses containing new genes were first detected in northern Vietnam and subsequently spread to southern Vietnam after reassorting with pre-existing local viruses in northern Vietnam. Although the routes of entry and spread of H5N1 in Vietnam remain speculative, enhanced poultry import controls and virologic surveillance efforts may help curb the entry and spread of new HPAI viral genes.

Quantifying interannual variation in effective adult breeding number (N(b)) and relationships between N(b), effective population size (N(e)), adult census size (N) and population demographic characteristics are important to predict genetic changes in populations of conservation concern. Such relationships are rarely available for long-lived iteroparous species like lake sturgeon (Acipenser fulvescens). We estimated annual N(b) and generational N(e) using genotypes from 12 microsatellite loci for lake sturgeon adults (n = 796) captured during ten spawning seasons and offspring (n = 3925) collected during larval dispersal in a closed population over 8 years. Inbreeding and variance N(b) estimated using mean and variance in individual reproductive success derived from genetically identified parentage and using linkage disequilibrium (LD) were similar within and among years (interannual range of N(b) across estimators: 41-205). Variance in reproductive success and unequal sex ratios reduced N(b) relative to N on average 36.8% and 16.3%, respectively. Interannual variation in N(b)/N ratios (0.27-0.86) resulted from stable N and low standardized variance in reproductive success due to high proportions of adults breeding and the species' polygamous mating system, despite a 40-fold difference in annual larval production across years (437-16 417). Results indicated environmental conditions and features of the species' reproductive ecology interact to affect demographic parameters and N(b)/N. Estimates of N(e) based on three single-sample estimators, including LD, approximate Bayesian computation and sibship assignment, were similar to annual estimates of N(b). Findings have important implications concerning applications of genetic monitoring in conservation planning for lake sturgeon and other species with similar life histories and mating systems.

For migratory fish like lake sturgeon (Acipenser fulvescens), the period from egg deposition through embryonic and larval development until dispersal (ELDTUD) contributes substantially to variation in survival at the individual level and to population levels of recruitment. Using genetically determined parentage, we examined the relative importance of environmental variables in a stream environment (e.g., temperature and discharge) and maternal effects (including individual female body size, spawning time, and location) to ELDTUD on an individual basis. Adult lake sturgeon (n = 208) spawning in the Upper Black River (Michigan, USA), and larvae (n = 1444) dispersing downstream were captured during the 2007 spawning season. We used generalized mixed models and multimodel inference based on Kullback-Leibler informationtheoretic criteria to demonstrate that environmental variables and the maternal effects of individual female and spawning time were both important predictors of ELDTUD. Decreasing ELDTUD during the season resulted from linearly increasing temperature and nonlinearly decreasing river discharge. Spawning time and individual female explained a large proportion of variation in ELDTUD. The individual-based approach used in this study provided precise estimates of ELDTUD and also facilitated the partitioning of variation in ELDTUD of larvae produced by the same female and among females spawning at different times and different environmental conditions. Résumé : Chez les poissons migrateurs comme l'esturgeon jaune (Acipenser fulvescens), la période qui commence à la ponte des oeufs, comprend les développements embryonnaire et larvaire et s'étend jusqu'à la dispersion (ELDTUD) contribue considérablement à la variation de la survie pendant toute la vie au niveau individuel et au recrutement au niveau de la population. Nous examinons l'importance relative des variables environnementales des cours d'eau (par ex., température et dé-bit) et des effets maternels, en particulier la taille corporelle, le moment de la fraie et la position dans le milieu, sur l'ELDTUD chez des individus dont l'ascendance a été déterminée par des méthodes génétiques. Pendant la saison de reproduction de 2007, nous avons capturé des esturgeons jaunes adultes (n = 208) frayant dans l'Upper Black River (Michigan, É.-U.), ainsi que des larves (n = 1444) qui se dispersaient vers l'aval. Des modèles mixtes généralisés et l'inférence multimodèle basée sur les critères de Kullback-Leibler fondés sur la théorie de l'information nous ont permis de démontrer que tant les variables du milieu que les effets maternels reliés à la femelle et le moment de la fraie sont de bonnes variables pré-dictives d'ELDTUD. La diminution de l'ELDTUD au cours de la saison s'explique par un accroissement linéaire de la température et d'une réduction non linéaire du débit de la rivière. Le moment de la fraie et les femelles individuelles expliquent une forte proportion de la variation de l'ELDTUD. L'approche basée sur l'individu utilisée dans notre étude fournit des es...