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.

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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

Allelic frequencies for six polymorphic allozyme loci (27 loci examined), as determined by starch-gel electrophoresis, were not significantly different for alewife, Alosa pseudoharengus, among the Great Lakes (Ontario, Erie, Huron, and Michigan). Alewife from one of the Finger Lakes (Cayuga Lake) had allelic frequencies similar to Great Lakes alewife, and the alleles of Great Lakes alewife form a subset of those found in Cayuga Lake. In contrast, Maritime Canada populations (Gaspereau, Miramichi, and St. John rivers) were distinct from each other and from the Great Lakes and Cayuga Lake populations. Highly significant allelic frequency differences were observed among the Maritime populations and between the Maritime populations and the Great Lakes or Cayuga Lake populations. Fifteen alleles were not shared between the Great Lakes and the Maritime populations. We concluded from these results that Great Lakes alewife and Cayuga Lake alewife form a contiguous stock and that Great Lakes alewife are a recent i...

Peter E. Ihssen

Papers

Allozyme Variation of Great Lakes Alewife, Alosa pseudoharengus: Genetic Differentiation and Affinities of a Recent Invader

Selection of fingerling rainbow trout for high and low tolerance to high temperature

Inheritance of Q band chromosomal polymorphisms in lake trout

Growth and mortality of diploid and triploid tiger trout (Salmo trutta × Salvelinus fontinalis)

Early mortality of tiger trout (Salvelinus fontinalis × Salmo trutta) and the effects of triploidy