Causes of Excess of the Frequency of Mitotype SCH34 in Populationof Amur Sturgeon, Acipenser schrenckii (Acipenseridae),according to Analysis of Complete Mitochondrial Genomes
Most sturgeon species are endangered and included into a variety of Red Lists. The study of the spectrum of allelic frequencies can help in assessing and monitoring the state of their populations. We have sequenced nine complete mitogenomes of the Amur sturgeon, representing seven different variants of the mtDNA control region, one of them (SCH34), according to previously obtained data, has an unusually high frequency in the population. Selectively significant substitutions in the nucleotide sequences encoding proteins, as well as substitutions in other functional regions of the mitochondrial genome that distinguish the SCH34 mitotype among others, were not found. One of the three mitogenomes that had the same mitotype SCH34 of the control region, carried the nucleotide substitution beyond the region. Calculated from this the minimum evolutionary age of the mitotype SCH34 is about 4500–5400 years. The high frequency of SCH34 and mitotypes close to it (derived from it and differing in one or two nucleotide positions) in the contemporary population of the Amur sturgeon could not be caused either by selection or by human activity, and most likely it was due to the passage of one of its isolated populations through the low population phase (“bottleneck”) in the past.