Assessing Genetic Variation in Wild and Domesticated Pikeperch Populations: Implications for Conservation and Fish Farming

Abstract

The pikeperch is a freshwater/brackish water fish species with growing interest for European aquaculture. Wild populations show signs of decline in many areas of the species natural range due to human activities. The comparative evaluation of genetic status in wild and domesticated populations is extremely useful for the future establishment of genetic breeding programs. The main objective of the present study was to assess and compare the genetic variability of 13 domesticated populations from commercial farms and 8 wild populations, developing an efficient microsatellite multiplex tool for genotyping. Partial cytochrome b gene sequences were also used to infer phylogeographic relationships. Results show that on average, the domesticated populations do not exhibit significantly lower levels of genetic diversity compared to the wild ones and do not suffer from inbreeding. Nuclear data provide evidence that pikeperch populations in Europe belong to at least two genetically differentiated groups: the first one is predominantly present in Northern Europe and around the Baltic Sea, while the second one comprises populations from Central Europe. In this second group, Hungarian origin populations constitute a differentiated stock that needs special consideration. Aquaculture broodstocks analyzed appear to contain fish of a single origin with only a few exceptions.

Keywords: Sander lucioperca; aquaculture; cyt b; differentiation; microsatellites.

Figure 1

Sampling locations (numbers as in Table 1) of wild (dots) and domesticated populations (stars) of pikeperch (Sander lucioperca).

Figure 2

Matrix of pairwise Fst values among pikeperch (Sander lucioperca) populations calculated from microsatellite data with ARLEQUIN (distance method: number of different alleles). All values are statistically highly significant (p < 0.05).

Figure 3

Bayesian individual assignment implemented in STRUCTURE for K = 2, 3 and 16 clusters without using geographical area as a priori. The y-axis represents the proportions of membership of pikeperch (Sander lucioperca) individual genotypes to each K inferred cluster. Assignment of each population to cyt b haplogroups (A or B) is also depicted with greyscale pie diagrams.

Figure 4

Discriminant analysis of principal components (DAPC) scatter plot. Dots represent individuals of pikeperch (Sander lucioperca) with colors denoting sampling population (A) or origin (B) and inclusion of 95% inertia ellipses. Site numbers in A correspond with Table 1.

Figure 5

Median-joining haplotype network for cyt b (571 bp) of pikeperch (Sander lucioperca). Each disc represents a haplotype, and its size is proportional to haplotype frequency. Colors indicate geographic origin. In parentheses are the original names of haplotypes described by Kohlman et al. [13]. The dashed line delimits the two haplogroups based on the analysis of the complete cyt b [13].