Biology subjects

Kondrashov, A. S.

Publications and source records attributed to Kondrashov, A. S..

4 recordsLinked to original sources

bioRxiv2018

The comparative and genetic methods for East European Unionidae taxonomy

Taxonomy of freshwater mussels from family Unionidae has been ambiguous for a long time. A number of methods used for their identification, including the so-called comparative method, are based on shell morphology. However, this morphology turned out to have a high level of within-species variation, and the shape of the shell of a specimen depends strongly on its environment and conditions of growth. For these reasons, the number of species recognized by the comparative method kept increasing. We applied both the comparative morphological method and methods of molecular genetics to address the taxonomy of Unionidae. We performed the comprehensive study of 70 specimens of Unionidae mussels collected from the River Ivitza, Volga basin. The specimens represented 14 comparative species, belonging to 4 comparative genera of Unionidae: Colletopterum, Pseudanodonta, Unio and Crassiana. Sequencing of the nuclear (ITS1) and mitochondrial (COI, 16S rDNA) genetic regions revealed 5 groups with high within-group genetic homogeneity separated from each other by long genetic distances. According to the comparison with the available sequences, these groups correspond to 3 Eastern European genera and 5 species: Anodonta anatina, Pseudanodonta complanata, Unio pictorum, Unio tumidus and Unio crassus. The results obtained indicate that the comparative method is inappropriate for the taxonomic analysis of East European Unionidae.

zoology↗

bioRxiv2018

Architecture of parallel adaptation to freshwater in multiple populations of threespine stickleback

Threespine sticklebacks adapted to freshwater environments all over the Northern Hemisphere. This adaptation involved parallel recruitment of freshwater alleles in clusters of closely linked sites, or divergence islands (DIs). However, it is unclear to what extent the DIs involved in adaptation and the alleles within them coincide between populations adapting to similar environments. Here, we examine 10 freshwater populations of similar ages from the White Sea basin, and study the repeatability of patterns of adaptation in them. Overall, the 65 detected DIs tend to reside in regions of low recombination, underlining the role of reduced recombination in their establishment. Moreover, the DIs are clustered in the genome to the extent that is not explainable by the recombination rate alone, consistent with the divergence hitchhiking model. 21 out of the 65 DIs are universal; i.e., the frequency of freshwater alleles in them is increased in all analyzed populations. Universal DIs tend to have longer core region shared between populations, and the divergence between the marine and the freshwater haplotypes in them is higher, implying that they are older, also consistently with divergence hitchhiking. Within most DIs, the same set of sites distinguished the marine and the freshwater haplotypes in all populations; however, in some of the DIs, the genetic architecture of the freshwater haplotype differed between populations, suggesting that they could have been established by soft selective sweeps.

evolutionary biology↗

bioRxiv2017

Prevalence of loss-of-function alleles does not correlate with lifetime fecundity and other life-history traits in metazoans

Natural selection is possible only because all species produce more offspring than what is needed to maintain the population. Still, the lifetime number of offspring varies widely across species. One can expect natural selection to be stronger in high-fecundity species. We analyzed the prevalence of loss-of-function alleles in 32 metazoan species and have found that, in contrast to this expectation, the strength of negative selection does not correlate with lifetime fecundity, as well as with other life-history traits. Perhaps, higher random mortality in high-fecundity species negates the effect of increased opportunity for selection.

evolutionary biology↗

bioRxiv2017

Bursts of amino acid replacements in protein evolution

Evolution can occur both gradually and through alternating episodes of stasis and rapid changes. However, the prevalence and magnitude of fluctuations of the rate of evolution remains obscure. Detecting a rapid burst of changes requires a detailed record of past evolution, so that events that occurred within a short time interval can be identified. Here, we use the phylogenies of the Baikal Lake amphipods and of Catarrhini, which contain very short internal edges facilitating this task. We detect 6 radical bursts of evolution of individual proteins during such short time periods, each involving between 6 and 38 amino acid substitutions. These bursts were extremely unlikely to have occurred neutrally, and were apparently caused by positive selection. On average, in the course of a time interval required for one synonymous substitution per site, a protein undergoes a strong burst of rapid evolution with probability at least ~0.01.

evolutionary biology↗