The effect of diet on the structure of gut bacterial community of sympatric pair of whitefishes (Coregonus lavaretus): one story more

In the Coregonus lavaretus complex may be found lacustrine sympatric pairs, which serves as an intriguing model for studying different aspects of fish evolutionary biology. One such sympatric whitefish pair inhabits Teletskoye Lake (West Siberia, Russia) and includes a “large” form (Coregonus lavaretus pidschian (Gmelin, 1789)) and a “small” form (C. l. pravdinellus (Dulkeit, 1949)). C. l. pravdinellus has a narrow trophic specialization and feeds on zooplankton, whereas the diet of C. l. pidschian is based on benthic prey. In the present study we aimed to address the question of how the gut microbial community reflects the divergence in diet of a sympatric pair of whitefish. Studied samples included the mucosa and content were collected for cardiac and pyloric stomach, anterior, middle, and posterior intestine, but only mucosa was collected for the pyloric caeca. In addition, water, sediment, macrophyte (environmental microbiota) and invertebrate (microbiota of prey) samples were collected in the same location. The V3–V4 region of the 16S rRNA genes was chosen for microbiome analysis and the software PICRUSt used to estimate the difference functional roles of the microbiota. The number of OTUs and Chao1 index in mucosa and content of cardiac and pyloric stomach were significantly different between whitefish. Significant differences were observed between whitefish for content from different parts of the intestine in terms of OTU number and Chao1 indices, whereas for mucosa from the same parts of intestine these differences were absent. No significant differences were found for diversity estimates of mucosa and content of different parts of the gut (there were a few exceptions) between whitefish. The form of whitefish and the segment of the digestive system were factors with a significant determinative effect on the structure of the microbiota from gut mucosa and content. The most dominant phyla in mucosa and content of cardiac and pyloric stomach was Proteobacteria (57.0–84.0%) for both whitefish. Throughout the intestine of C. l. pidschian the dominant phyla in mucosa were Proteobacteria (38.8%) and Firmicutes (15.6%), whereas for C. l. pravdinellus–Tenericutes (49.6%) and Proteobacteria (28.1%). For both forms, the phylum Spirochaetes was found in a significant amount (20.0–25.0%) in the mucosa of the posterior intestine. While for the content obtained from anterior, middle and posterior intestines, the dominant bacterial phyla were the same as those described for mucosa from the same parts of the intestine for both whitefish. The bacterial community of the prey and environment was significantly different from bacterial communities found for all parts of the gut mucosa for both whitefish, with the exception of the mucosa of the cardiac stomach. According to PICRUSt the highest level of differences between whitefish at the L3 level were found for the intestinal mucosa (75.3%), whereas the lowest one was registered for stomach content (38.8%).info:eu-repo/semantics/publishedVersio

Intraspecific structure of the Coregonus lavaretus complex in water bodies of Siberia: a case of postglacial allopatric origin of Yukagirian whitefish

The results of morphological and genetic analyses of forms/species of the Coregonus lavaretus pidschian (Gmelin, 1789) complex from the Indigirka and Kolyma river basins are presented in the context of there being recent postglacial speciation events. It has been found that the studied whitefishes belong to the sparsely rakered and low lateral-line forms and have previously been described as Coregonus lavaretus pidschian n. jucagiricus Drjagin (Berg), 1932. Based on these characters, this whitefish does not differ from most Arctic whitefish populations (in particular from Coregonus lavaretus glacialis Kirillov, 1972). Analysis of variability of the ND1 gene (mtDNA) showed that whitefishes from the Indigirka and Kolyma basins belong to a distant phylogenetic lineage, which is significantly different from all previously studied whitefish lineages from the Ob, Yenisei, Lena, Anadyr, and Amur river basins. Analysis of variability of the ITS1 fragment (nDNA) showed that all studied forms/species (from Ob River to Amur River basins), including C. l. pidschian n. jucagiricus, have a tandem arrangement of two identical nucleotide fragments and very similar nucleotide composition of the ITS1 region. Based on contemporary data, this phylogenetic lineage of the C. pidschian complex could be considered a young postglacial allopatric species.info:eu-repo/semantics/acceptedVersio

Unexpected endemism in the Daphnia longispina complex (Crustacea: Cladocera) in Southern Siberia.

The biological significance of regional cladoceran morphotypes in the montane regions of the central Palearctic remains poorly understood. In the Holarctic Daphnia longispina complex (Cladocera: Daphniidae), several variants, lineages and species have been proposed as endemic for Southern Siberia. Daphnia turbinata Sars, for example, named after its unusual head shape, is known only from Southern Siberia. Here we sequence DNA of Daphnia from three mitochondrial genes (12S rRNA, 16S rRNA, and NADH dehydrogenase subunit 2, ND2) from 57 localities in Russia and Mongolia (the majority being from Southern Siberia) and place them in evolutionary context with existing data. Our aim was to examine regional endemism of the Daphnia longispina complex in Southern Siberian; to improve the phylogenetic understanding with improved taxonomic and regional sampling, and to better understand the influence of Pleistocene glaciation on the biogeography of these lineages. At least three lineages showed genetic evidence for endemism in Southern Siberia. There was strong support for D. turbinata as a sister lineage to to D. longispina/D. dentifera. Another endemic, Siberian D. cf. longispina, is a sister group to the longispina group in general. Within D. longispina s. str. there was an endemic Siberian clade with a western range boundary near the Yenisei River Basin. Gene flow estimates among populations (based on FST values) were very low for clades of D. longispina on a regional (the original 12S dataset), and on a pan-Eurasian (the extended 12S dataset) scale. Negative values of Fu's FS and Tajima's D tests prevailed for the species examined with significant values found for two D. longispina clades, D. dentifera, D. galeata and D. cristata. Our results support the notion that Southern Siberia is an important biogeographic region for cladocerans as it contained unexpected diversity of endemics (such as D. turbinata, D. cf. longispina and lineages of D. umbra and D. longsipina s.str.) and from being the geographic meeting place of expanding postglacial lineages from eastern and western refugia

Morphological Differentiation, Mitochondrial and Nuclear DNA Variability Between Geographically Distant Populations of Daphnia galeata and Daphnia cucullata (Anomopoda, Daphniidae)

Несмотря на то, что представители р. Daphnia (Anomopoda, Daphniidae) являются одними из наиболее распространенных водных беспозвоночных и используются в качестве модельных организмов в таксономических, экологических и эволюционных исследованиях, их систематика остается весьма запутанной. Настоящее исследование посвящено изучению морфологической дифференциации и генетической изменчивости географически удаленных популяций сестринских видов Daphnia galeata Sars, 1864 и Daphnia cucullata Sars, 1862 (Anomopoda, Daphniidae) из пресноводной части Балтийского моря - Куршского залива (Россия, Калининградская область) и Новосибирского водохранилища (Россия, Новосибирская область). Морфологическая дивергенция между видами и их популяциями оценивалась по диагностическим признакам и на основании анализа изменчивости формы тела по набору морфометрических признаков. Самыми изменчивыми были признаки, характеризующие форму головы, шлема и хвостовой иглы. Реконструкция филогенетических отношений между видами выполнена на основе изменчивости 16S и 12S генов митохондриальной ДНК и фрагмента ITS2 ядерной ДНК. Дивергенция между видами D. galeata и D. cucullata на основе генов митохондриальной ДНК была значительной и свидетельствует об их монофилетическом происхождении, тогда как внутривидовые генетические дистанции оцениваются как незначительные.Although members of genus Daphnia (Anomopoda, Daphniidae) are the most common water invertebrates and are considered as model organisms for many taxonomic, ecological and evolutionary studies their systematics remains unresolved. Here, morphological differentiation and genetic polymorphism between the geographically distant populations of the sister species Daphnia galeata Sars, 1864 and Daphnia cucullata Sars, 1862 in the Curonian Lagoon, a large shallow freshwater lagoon of the Baltic Sea (Russia, Kaliningrad Oblast) and Novosibirsk Reservoir (Russia, Novosibirsk Oblast) are presented. The divergence between species and their populations was analyzed based on traditional morphological traits and a large set of morphometric traits describing the body shape. The traits describing the shape of head and helmet, and spine were the most variable morphological characters. Phylogenetic relationships between species and populations were constructed based on variation in mitochondrial 16S and 12S rRNA genes and nuclear ITS2 rDNA sequences. The mitochondrial DNA divergence between D. galeata and D. cucullata species was significant and reflected their monophyletic origin, whereas intraspecific genetic distances are estimated as insignificant

Contrasting phylogeographic patterns and demographic history in closely related species of Daphnia longispina group (Crustacea: Cladocera) with focus on North-Eastern Eurasia.

Species with large geographic distributions present a challenge for phylogeographic studies due to the logistic difficulties of obtaining adequate samples. Daphnia O.F. Müller (Anomopoda: Daphniidae) is a model genus for evolutionary biology and ecology, but many regions such as the remote areas of Siberia, remain poorly studied. Here we examined genetic polymorphism in the ribosomal 12S and the protein-coding ND2 mitochondrial genes of three closely related taxa of the Daphnia (Daphnia) longispina complex, namely D. galeata Sars, D. longispina O.F. Müller and D. dentifera Forbes. We estimated the phylogenetic relationships among these taxa based on a concatenated alignment of these two genes. Using sequences from the present study and those available in GenBank, we investigated the geographic distributions of the mitochondrial haplotypes of these species and proposed an evolutionary scenario for each taxon. Network structures, haplotype distribution patterns, and FST values indicated significant differences in the evolutionary history of the examined species. Our analysis of D. galeata populations confirmed its recent and fast expansion, without a previous phase of a strong population disconnection. In contrast, the high haplotype diversity in D. dentifera and D. longispina could be explained by the survival of different phylogroups in several glacial refugia located in different geographic regions. For all studied species, maximum haplotype diversity was recorded in the remote regions of Siberia-lakes of the Yenisei River and Transbaikalia. Our study is an important step in our understanding of the evolutionary history of the Daphnia longispina group and provides further evidence of the biogeographic significance of Siberia for freshwater taxa

Morphological Differentiation, Mitochondrial and Nuclear DNA Variability Between Geographically Distant Populations of Daphnia galeata and Daphnia cucullata (Anomopoda, Daphniidae)

Несмотря на то, что представители р. Daphnia (Anomopoda, Daphniidae) являются одними из наиболее распространенных водных беспозвоночных и используются в качестве модельных организмов в таксономических, экологических и эволюционных исследованиях, их систематика остается весьма запутанной. Настоящее исследование посвящено изучению морфологической дифференциации и генетической изменчивости географически удаленных популяций сестринских видов Daphnia galeata Sars, 1864 и Daphnia cucullata Sars, 1862 (Anomopoda, Daphniidae) из пресноводной части Балтийского моря - Куршского залива (Россия, Калининградская область) и Новосибирского водохранилища (Россия, Новосибирская область). Морфологическая дивергенция между видами и их популяциями оценивалась по диагностическим признакам и на основании анализа изменчивости формы тела по набору морфометрических признаков. Самыми изменчивыми были признаки, характеризующие форму головы, шлема и хвостовой иглы. Реконструкция филогенетических отношений между видами выполнена на основе изменчивости 16S и 12S генов митохондриальной ДНК и фрагмента ITS2 ядерной ДНК. Дивергенция между видами D. galeata и D. cucullata на основе генов митохондриальной ДНК была значительной и свидетельствует об их монофилетическом происхождении, тогда как внутривидовые генетические дистанции оцениваются как незначительные.Although members of genus Daphnia (Anomopoda, Daphniidae) are the most common water invertebrates and are considered as model organisms for many taxonomic, ecological and evolutionary studies their systematics remains unresolved. Here, morphological differentiation and genetic polymorphism between the geographically distant populations of the sister species Daphnia galeata Sars, 1864 and Daphnia cucullata Sars, 1862 in the Curonian Lagoon, a large shallow freshwater lagoon of the Baltic Sea (Russia, Kaliningrad Oblast) and Novosibirsk Reservoir (Russia, Novosibirsk Oblast) are presented. The divergence between species and their populations was analyzed based on traditional morphological traits and a large set of morphometric traits describing the body shape. The traits describing the shape of head and helmet, and spine were the most variable morphological characters. Phylogenetic relationships between species and populations were constructed based on variation in mitochondrial 16S and 12S rRNA genes and nuclear ITS2 rDNA sequences. The mitochondrial DNA divergence between D. galeata and D. cucullata species was significant and reflected their monophyletic origin, whereas intraspecific genetic distances are estimated as insignificant