Morphometric characteristics and phenotypic differentiation of roach (Rutilus -rutilus) populations in lakes Aydarkul and Zamonbobo

Abstract

This study provides a comparative assessment of the morphometric structure and phenotypic differentiation of roach (Rutilus-rutilus Linnaeus, 1758) populations inhabiting two ecologically contrasting lentic systems of the Aral Sea basin: Lake Aydarkul and Lake Zamonbobo. Field collections were carried out between 2021 and 2025, yielding a total sample of n=170 specimens (Lake Aydarkul, n=95; Lake Zamonbobo, n=75). Morphometric measurements were processed following I.F. Pravdin’s standard procedure. Statistical analysis revealed significant (p<0.001) divergence in body conformation: individuals from the large, open pelagic zone of Lake Aydarkul displayed a streamlined, low-bodied morphotype (maximum body depth H=26.4±0.25%) with a prolonged caudal peduncle (pl=20.6±0.28%), whereas the isolated, shallow, macrophyte-dominated Lake Zamonbobo favored a deep-bodied littoral morphotype (H=30.5±0.32%). These empirical findings demonstrate the range of phenotypic plasticity and micro-evolutionary adaptation of native cyprinid species under differing hydroclimatic regimes.