The interrelation between variability of characters, effectiveness of energy utilisation, and karyotype structure in fishes

Nikolsky G. 1976

1) The variability of fishes is an adaptive property. The range of variability is broader in eurybiotic fishes than in steno- biotic ones. Variability in fish species is lower in stenobiotic fishes inhabiting the waterbodies in lower latitudes. 2) Eurybiotic fishes and especially euryphagous ones, occupy broader ecologi- cal niches and a wider range of habitats. At the same time the effectiveness of energy utilisation in eurybiotic fish is lower than in stenobiotic fishes. 3) The range of variability of characters and properties in marine fishes of the same geographical zone is in general lower than in equivalent freshwater fishes. 4) The variability of characters in fishes is correlated with chromosome number, DNA content, and GC value. 5) The range of variability of characters in fishes, the chromosome number, and the DNA content decreases while the effectiveness of food conversion increases from higher to lower latitudes. 6) The phylogenetic status of teleost fishes in general is connected with a diminishing range of variability, with a de- crease in chromosome number and DNA content. The effectiveness of utilisation of energetic resources increases from lower groups of teleost fishes to higher ones.