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Internal sources of infraorbital series and lateral line scale count variability in six Labeobarbus species composing the Lake Tana (Ethiopia) species flock

Shkil, F. N., Smirnov, S. V., Kapitanova, D. V.
Journal of applied ichthyology 2018 v.34 no.2 pp. 465-471
Labeobarbus, flocks, genetic background, heritability, interspecific variation, intraspecific variation, lakes, phenotype, rearing, thyroid hormones, Ethiopia
The study of the nature of intra‐ and interspecific variation is essential for understanding of the mechanisms underpinning species divergence and evolution. Here, we examined the variability of two characters, infraorbital bone number and lateral line scale count, in six Labeobarbus species: L. intermedius, L. brevicephalus, L. crassibarbis, L. megastoma, L. truttiformis, and L. macrophtalmus composing Lake Tana (Ethiopia) species flock. For this aim, in 2006‐2014, we assessed the variability of both traits in natural populations and in sixteen experimental homo‐ and heteronomic crossings reared under standard conditions. As a result, high level of natural intraspecific variability was detected, whereas significant interspecific differences in the range of variability were not revealed. However, evaluation of heritability coefficients in experimental crossings indicated the genetic background of the variability for both traits. This finding along with the previously revealed dependence of investigated characters upon the thyroid hormones allowed us to hypothesize that observed natural variability is a phenotypic consequence of genetically determined fluctuations in the activity of thyroid hormone axis.