Abstract
The article describes the results of morphometric studies of sterlet caught in water areas of two riverbed depressions of the Lower Irtysh (the Tyumen region) The studies were carried out in the period from 2015-2018, the riverbed depressions were remote from each other: Gornoslinkinskaya (the Uvat region), Kondinskaya (the Khanty-Mansiysk region). The geographic distance (the distance between the riverbed depressions is 445 km) and short migration length (about 200 km) prompted the assumption about the probability of significant discrepancies in the signs that suggest the allocation of any subgroups of sterlet. In the catches of sterlet in the Kondinskaya riverbed depression there were 93 specimens aged 1-4 years old. In the water area of the Gornoslinkinskaya riverbed depression 128 specimens were caught at the age of 1-7 years old. The comparison of sterlet groups from remote riverbed depressions was conducted using meristic signs: the number of bone plates (scutes) rays in the fins, the number of stamens on the first gill arch. According to the research results, it has been stated that there are no significant differences in the number of dorsal, lateral and ventral bone plates. Also, no differences were found in the number of stamens on the first gill arch. The greatest differences in the studied groups of sterlet were recorded in terms of the number of rays in the dorsal and anal fins. Additionally, the meristic features have been estimated by Mayr coefficient (1971), the value of which is equal to or greater than 1.28, which suggests the subspecific division. In our study, Mayr coefficient in all cases was less than 1.28, its maximum value (0.38) was established in studying the number of stamens on the 1-st gill arch. As for the remaining signs, this value is even smaller. Thus, geographical distance (over 400 km) of sterlet groups from the 2 riverbed depressions of the Lower Irtysh should not be taken as a reason to single out any subgroup.
Highlights
According to the research results, it has been stated that there are no significant differences in the number of dorsal, lateral and ventral bone plates
И. Обзор данных по биологии стерляди Acipenser ruthenus (Linnaeus, 1758) // Вестн
Summary
При рассмотрении средних значений числа костных пластинок значительных различий, которые указывали бы на присутствие географических и климатических факторов и могли бы повлиять на данный признак, не отмечено. И по настоящее время показатель возможного числа костных пластинок у особей стерляди р. Такими же остались вероятные пределы изменения представленных показателей. Ожидание наличия расхождения в показателях с запада на восток не оправдалось, хотя имеются основания судить о возможном выделении подвида стерляди в р. Важными систематическими признаками являются число лучей в плавниках и число тычинок на первой жаберной дуге [15]. В нашей работе данные показатели также изучены; для анализа географических и временных изменений, как и в случае с костными пластинками, проанализирована информация из литературных источников Средние значения и пределы показателей числа лучей в дорсальном (спинном), анальном, вентральном плавниках, числа тычинок на 1-й жаберной дуге
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