The hypothesis that traits closely associated with fitness will generally possess lower heritabilities than traits more loosely connected with fitness is tested using 1120 narrow sense heritability estimates for wild, outbred animal populations, collected from the published record. Our results indicate that life history traits generally possess lower heritabilities than morphological traits, and that the means, medians, and cumulative frequency distributions of behavioural and physiological traits are intermediate between life history and morphological traits. These findings are consistent with popular interpretations of Fisher's (1930, 1958) Fundamental Theorem of Natural Selection, and Falconer (1960, 1981), but also indicate that high heritabilities are maintained within natural populations even for traits believed to be under strong selection. It is also found that the heritability of morphological traits is significantly lower for ectotherms than it is for endotherms which may in part be a result of the strong correlation between life history and body size for many ectotherms.

/pdf/natural-selection-and-the-heritability-of-fitness-components-4he3tb91vh.pdf

Natural selection and the heritability of fitness components

Electrophoretic data were analysed from 49 species of freshwater fish, 57 species of marine fish, and seven anadromous species. For each species, at least 15 individuals had been assayed for at least 15 loci in two or more subpopulations. The results showed that while average total heterozygosity (HT) was approximately equal in freshwater and marine species (0·062 and 0·064 respectively), subpopulation heterozygosity (Hs) was significantly less in the former group (0·046 and 0·059 respectively). Consequently the average degree of genetic subpopulation differentiation (HST) was significantly greater for freshwater species (0·222 v. 0·062). On average, it is likely that marine subpopulations exchange between 10 and 100 times more migrants per generation than freshwater subpopulations, presumably because of the relative absence of barriers to dispersal in the marine environment. The reduced values of Hs in freshwater species are likely to reflect reduced effective subpopulation sizes relative to marine species. The few andromous species that have been analysed show intermediate levels of GST.

A comparison of genetic diversity levels in marine, freshwater, and anadromous fishes

http://auburn.edu/academic/agriculture/fisheries/genomics/FISH7660%202006/DNA%20marker%20review%20paper-Aquaculture.pdf

DNA marker technologies and their applications in aquaculture genetics.

http://digital.csic.es/bitstream/10261/44729/1/Taranger%20et%20al_%2c%20GCE.pdf

Control of puberty in farmed fish

Polyploid fish and shellfish: Production, biology and applications to aquaculture for performance improvement and genetic containment

Manipulation of fish chromosomes dates back to the early part of this century. The earliest experiments involved induction of gynogenesis with sperm inactivated by radiation or chemical treatments. Temperature or pressure shocks applied soon after fertilization resulted in the retention of the second polar body and reconstitution of diploidy; triploidy resulted from shocks to fish ova fertilized with normal sperm. More recently, it has been possible to suppress the first mitotic division offish eggs with high-pressure or -temperature treatments applied at the time of first cleavage to produce mitotic gynogenetic diploids and tetraploids. Androgenesis has been successfully induced in fish by irradiation of ova, fertilization of eggs with normal sperm, and suppression of the first mitosis with high-pressure treatments. Gynogenetic diploids have been used for cytogenetic studies of meiotic phenomena and gene mapping. The general finding to date is that the arrangement of genes on chromosomes is high...

Ploidy Manipulation and Gynogenesis in Fishes: Cytogenetic and Fisheries Applications

We searched for linkage among 24 polymorphic loci (allozymes, RAPD, microsatellites) in three half-sib backcross families of rainbow trout (Oncorhynchus mykiss) produced by crossing strains divergent for the quantitative trait of upper temperature tolerance. Seven significant and two suggestive pairwise linkage associations between molecular marker loci were observed involving 14 loci clustered into four linkage groups. The association between a pair of allozyme loci (sIDHP-3* and mMEP-2 *) has been reported previously. Recombination rates varied greatly between the sexes and families. Two quantitative trait loci (QTL) were mapped by detecting a significant association between variance in upper temperature tolerance and alleles at the microsatellite loci Omy325UoG and Ssa14DU. The two QTL appear to reside in different linkage groups and account for ≈13 per cent and 9 per cent of the overall additive genetic variance in upper temperature tolerance. No significant interaction was detected between Omy325UoG and Ssa14DU suggesting that the effects of the QTL are additive.

/pdf/identification-of-two-qtl-influencing-upper-temperature-2kv104gr4c.pdf

Identification of two QTL influencing upper temperature tolerance in three rainbow trout ( Oncorhynchus mykiss ) half-sib families

Linkage analysis of quantitative trait loci associated with spawning time in rainbow trout (Oncorhynchus mykiss)

Review of Genetics of Lake Trout in the Great Lakes: History, Molecular Genetics, Physiology, Strain Comparisons, and Restoration Management

Mitochondrial DNA (mtDNA) restriction fragment length polymorphisms (RFLPs) of 2422 brook trout (Salvelinus fontinalis) from 60 units (major drainages, small stream catchments, and isolated lakes) representing 155 populations in eastern North America were examined to test hypotheses regarding postglacial dispersal and recolonization. An analysis of molecular variance (AMOVA) indicated that 38.8% of the variation was partitioned among the units, while approximately 60% was distributed among populations (phiST = 59.3) compared with 40.7% within populations. This distribution of variation suggests a large degree of heterogeneity in population founding events and phylogeographic structuring in this species. Comparisons of mtDNA diversity between fish from putative refugial and recolonization zones for this species indicate that more than one refugial region contributed to northern recolonization. Haplotypic diversities in recolonized regions are greatest in south-central populations (i.e., southern Great Lake...

A major sextet of mitochondrial DNA phylogenetic assemblages extant in eastern North American brook trout (Salvelinus fontinalis): distribution and postglacial dispersal patterns

Peter E. Ihssen

Papers

Ploidy Manipulation and Gynogenesis in Fishes: Cytogenetic and Fisheries Applications

Identification of two QTL influencing upper temperature tolerance in three rainbow trout ( Oncorhynchus mykiss ) half-sib families

Linkage analysis of quantitative trait loci associated with spawning time in rainbow trout (Oncorhynchus mykiss)

Review of Genetics of Lake Trout in the Great Lakes: History, Molecular Genetics, Physiology, Strain Comparisons, and Restoration Management

A major sextet of mitochondrial DNA phylogenetic assemblages extant in eastern North American brook trout (Salvelinus fontinalis): distribution and postglacial dispersal patterns