Metapopulation effective size and conservation genetic goals for the Fennoscandian wolf (Canis lupus) population.

The Scandinavian wolf population descends from only five individuals, is isolated, highly inbred and exhibits inbreeding depression. To meet international conservation goals, suggestions include managing subdivided wolf populations over Fennoscandia as a metapopulation; a genetically effective population size of Ne⩾500, in line with the widely accepted long-term genetic viability target, might be attainable with gene flow among subpopulations of Scandinavia, Finland and Russian parts of Fennoscandia. Analytical means for modeling Ne of subdivided populations under such non-idealized situations have been missing, but we recently developed new mathematical methods for exploring inbreeding dynamics and effective population size of complex metapopulations. We apply this theory to the Fennoscandian wolves using empirical estimates of demographic parameters. We suggest that the long-term conservation genetic target for metapopulations should imply that inbreeding rates in the total system and in the separate subpopulations should not exceed Δf=0.001. This implies a meta-Ne of NeMeta⩾500 and a realized effective size of each subpopulation of NeRx⩾500. With current local effective population sizes and one migrant per generation, as recommended by management guidelines, the meta-Ne that can be reached is ~250. Unidirectional gene flow from Finland to Scandinavia reduces meta-Ne to ~130. Our results indicate that both local subpopulation effective sizes and migration among subpopulations must increase substantially from current levels to meet the conservation target. Alternatively, immigration from a large (Ne⩾500) population in northwestern Russia could support the Fennoscandian metapopulation, but immigration must be substantial (5-10 effective immigrants per generation) and migration among Fennoscandian subpopulations must nevertheless increase.

Recent breeding history of dog breeds in Sweden: modest rates of inbreeding, extensive loss of genetic diversity and lack of correlation between inbreeding and health.

One problem in modern dogs is a high occurrence of physical diseases, defects and disorders. Many breeds exhibit physical problems that affect individual dogs throughout life. A potential cause of these problems is inbreeding that is known to reduce the viability of individuals. We investigated the possible correlation between recent inbreeding and health problems in dogs and used studbook data from 26 breeds provided by the Swedish Kennel Club for this purpose. The pedigrees date back to the mid-20th century and comprise 5-10 generations and 1 000-50 000 individuals per pedigree over our study period of 1980-2010. We compared levels of inbreeding and loss of genetic variation measured in relation to the number of founding animals during this period in the investigated dog breeds that we classified as 'healthy' (11 breeds) or 'unhealthy' (15) based on statistics on the extent of veterinary care obtained from Sweden's four largest insurance companies for pets. We found extensive loss of genetic variation and moderate levels of recent inbreeding in all breeds examined, but no strong indication of a difference in these parameters between healthy versus unhealthy breeds over this period. Thus, recent breeding history with respect to rate of inbreeding does not appear to be a main cause of poor health in the investigated dog breeds in Sweden. We identified both strengths and weaknesses of the dog pedigree data important to consider in future work of monitoring and conserving genetic diversity of dog breeds.

Genetic monitoring reveals temporal stability over 30 years in a small, lake-resident brown trout population.

Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and addressing issues of human impact of natural populations. We know little about how representative single samples in time are to reflect population genetic constitution, and we explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake-resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period, with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (N(e)) was assessed from allele-frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean N(e) is estimated as 74. We find indications that N(e) varies over time, but there is no obvious temporal trend. We also estimated N(e) using a one-sample approach based on linkage disequilibrium (LD) that does not account for the effect of overlapping generations. Combining one-sample estimates for all years gives an N(e) estimate of 76. This similarity between estimates may be coincidental or reflecting a general robustness of the LD approach to violations of the discrete generations assumption. In contrast to the observed genetic stability, body size and catch per effort have increased over the study period. Estimates of annual effective number of breeders (N(b)) correlated with catch per effort, suggesting that genetic monitoring can be used for detecting fluctuations in abundance.

Census (N C) and genetically effective (N e) population size in a lake-resident population of brown trout Salmo trutta.

Census (N(C)) and effective population size (N(e)) were estimated for a lake-resident population of brown trout Salmo trutta as 576 and 63, respectively. The point estimate of the ratio of effective to census population size (N(e):N(C)) for this population is 0.11 with a range of 0.06-0.26, suggesting that N(e):N(C) ratio for lake-resident populations agree more with estimates for fishes with anadromous life histories than the small ratios observed in many marine fishes.

Detecting population structure in a high gene-flow species, Atlantic herring (Clupea harengus): direct, simultaneous evaluation of neutral vs putatively selected loci.

In many marine fish species, genetic population structure is typically weak because populations are large, evolutionarily young and have a high potential for gene flow. We tested whether genetic markers influenced by natural selection are more efficient than the presumed neutral genetic markers to detect population structure in Atlantic herring (Clupea harengus), a migratory pelagic species with large effective population sizes. We compared the spatial and temporal patterns of divergence and statistical power of three traditional genetic marker types, microsatellites, allozymes and mitochondrial DNA, with one microsatellite locus, Cpa112, previously shown to be influenced by divergent selection associated with salinity, and one locus located in the major histocompatibility complex class IIA (MHC-IIA) gene, using the same individuals across analyses. Samples were collected in 2002 and 2003 at two locations in the North Sea, one location in the Skagerrak and one location in the low-saline Baltic Sea. Levels of divergence for putatively neutral markers were generally low, with the exception of single outlier locus/sample combinations; microsatellites were the most statistically powerful markers under neutral expectations. We found no evidence of selection acting on the MHC locus. Cpa112, however, was highly divergent in the Baltic samples. Simulations addressing the statistical power for detecting population divergence showed that when using Cpa112 alone, compared with using eight presumed neutral microsatellite loci, sample sizes could be reduced by up to a tenth while still retaining high statistical power. Our results show that the loci influenced by selection can serve as powerful markers for detecting population structure in high gene-flow marine fish species.

Temporally stable genetic structure of heavily exploited Atlantic herring (Clupea harengus) in Swedish waters.

Information on the temporal stability of genetic structures is important to permit detection of changes that can constitute threats to biological resources. Large-scale harvesting operations are known to potentially alter the composition and reduce the variability of populations, and Atlantic herring (Clupea harengus) has a long history of heavy exploitation. In the Baltic Sea and Skagerrak waters, the census population sizes have declined by 35-50% over the last three decades. We compared the genetic structure of Atlantic herring in these waters sampled at least two different times between 1979 and 2003 by assaying 11 allozyme and nine microsatellite loci. We cannot detect any changes in the amount of genetic variation or spatial structure, and differentiation is weak with overall F(ST)=0.003 among localities for the older samples and F(ST)=0.002 for the newer ones. There are indications of temporal allele frequency changes, particularly in one of five sampling localities that is reflected in a relatively small local N(e) estimate of c. 400. The previously identified influence of selection at the microsatellite locus Cpa112 remains stable over the 24-year period studied here. Despite little genetic differentiation, migration among localities appears small enough to permit demographic independence between populations.

Conservation genetics of Nordic carnivores: lessons from zoos.

This paper summarizes results from genetic studies of Nordic carnivore populations bred in captivity. The conservation genetic implications of those results for the management of wild populations of the same species are discussed. Inbreeding depression has been documented in the brown bear (Ursus arctos), wolf (Canis lupus), and lynx (Lynx lynx) populations held in Nordic zoos. The characters negatively affected by inbreeding include litter size (brown bear and wolf), longevity (lynx and wolf), female reproduction, and weight (wolf). In addition, hereditary defects caused by single autosomal alleles occur in the wolf and brown bear populations. These deleterious alleles cause blindness (wolf) and albinism (brown bear) in the homozygous state. The amount of inbreeding depression observed in Nordic carnivores are similar to that documented in other species. The captive populations have the same genetic background as the current wild ones and inbreeding depression is therefore a potential threat to wild carnivore populations in Sweden. This threat is presently not being adequately recognized in the management of these species. Frequently occurring misunderstandings regarding the kind of conclusions that can be drawn from the presented genetic observations are also discussed.