Geographic variation of life-history traits in the sand lizard, Lacerta agilis: testing Darwin's facundity-advantage hypothesis

The fecundity-advantage-hypothesis (FAH) explains larger female size relative to male size as a correlated response to fecundity selection. We explored FAH by investigating geographic variation in female reproductive output and its relation to sexual size dimorphism (SSD) in Lacerta agilis, an oviparous lizard occupying a major part of temperate Eurasia. We analysed how sex-specific body size and SSD are associated with two putative indicators of fecundity selection intensity (clutch size and the slope of the clutch size-female size relationship), and with two climatic variables throughout the species range and across two widespread evolutionary lineages. Variation within the lineages provides no support for FAH. In contrast, the divergence between the lineages is in line with FAH: the lineage with consistently female-biased SSD (L. a. agilis) exhibits higher clutch size and steeper fecundity slope than the lineage with an inconsistent and variable SSD (L. a. exigua). L. a. agilis shows lower offspring size (egg mass, hatchling mass) and higher clutch mass relative to female mass than L. a. exigua, i.e. both possible ways to enhance offspring number are exerted. As the SSD difference is due to male size (smaller males in L. a. agilis), fecundity selection favouring larger females, together with viability selection for smaller size in both sexes, would explain the female-biased SSD and reproductive characteristics of L. a. agilis. The pattern of intraspecific life-history divergence in L.agilis is strikingly similar to that between oviparous and viviparous populations of a related species Zootoca vivipara. Evolutionary implications of this parallelism are discussed

De novo assembly and analysis of the transcriptome of the Siberian wood frog Rana amurensis

The Siberian wood frog Rana amurensis Boulenger, 1886 is the most hypoxia-tolerant amphibian. It can survive for several months in an almost complete absence of oxygen. Little is known about the mechanisms of this remarkable resilience, in part because studies of amphibian genomes are impeded by their large size. To make the Siberian wood frog more amenable for genetic analysis, we performed transcriptome sequencing and de novo assembly for the R. amurensis brain under hypoxia and normoxia, as well as for the normoxic heart. In order to build a de novo transcriptome assembly of R. amurensis, we utilized 125-bp paired-end reads obtained from the brain under normoxia and hypoxia conditions, and from the heart under normoxia. In the transcriptome assembled from about 100,000,000 reads, 81.5 % of transcripts were annotated as complete, 5.3 % as fragmented, and 13.2 % as missing. We detected 59,078 known transcripts that clustered into 22,251 genes; 11,482 of them were assigned to specific GO categories. Among them, we found 6696 genes involved in protein binding, 3531 genes involved in catalytic activity, and 576 genes associated with transporter activity. A search for genes encoding receptors of the most important neurotransmitters, which may participate in the response to hypoxia, resulted in a set of expressed receptors of dopamine, serotonin, GABA, glutamate, acetylcholine, and norepinephrine. Unexpectedly, no transcripts for histamine receptors were found. The data obtained in this study create a valuable resource for studying the mechanisms of hypoxia tolerance in the Siberian wood frog, as well as for amphibian studies in general

DNA barcoding: how many earthworm species are there in the south of West Siberia?

Earthworms are a widespread and ecologically important group of animals, which has the highest total biomass in some ecosystems and often defines the composition of soil fauna. Earthworms are known to have high cryptic genetic diversity. In this study we attempted to estimate earthworm species diversity in the south of West Siberia by DNA barcoding. This method employs short fragments of the genome to identify species, and allows one to work with specimens that cannot be identified by conventional techniques, as well as to search for new species and predict their phylogenetic affinities. As the target sequence we took a fragment of the mitochondrial cytochrome oxidase 1 (cox1) gene. The studied territory (Novosibirsk and Tomsk oblasts, Altai krai, and the Altai Republic) is known to contain 16 species and subspecies of earthworms. We analyzed 259 individuals from twelve locations and detected 27 genetic clusters. Ten of them correspond to known species (A. caliginosa, E. fetida, O. tyrtaeum, D. r. tenuis, D. octaedra, E. balatonica, E. sibirica, as well as three genetic lineages of E. nordenskioldi nordenskioldi). Seventeen of the 27 clusters do not have close sequence similarity to any known earthworm species. Representatives of some of these novel clusters are morphologically similar to the Eisenia n. nordenskioldi/E. n. pallida species complex and may belong to new genetic lineages of this complex. The rest of the novel clusters probably represent new earthworm species. Therefore, we can conclude that a large portion of earthworm biodiversity in the south of West Siberia is still unexplored

Evaluation of Biological Properties of New Selective Differential Medium for Cholera Vibrios Isolation Based on the Results of Laboratоry Trials

Previously developed selective differential medium for V. cholerae growth was modernized. The modernized medium called SDMV-M was shown to possess the required sensitivity and germination index. The growth of E. coli was entirely inhibited, that of P. vulgaris was inhibited considerably. The medium possessed good differentiating ability: orange V. cholerae colonies were clearly distinguished from concomitant microorganisms. In the laboratory trials SDMV-M demonstrated some advantages as regards V. cholerae isolation from contaminated faeces in comparison with the reference medium TCBS

Overwintering and cold tolerance in the moor frog (Rana arvalis, Anura) across its range

Only two species of boreal Holarctic frogs (genus Rana Linnaeus, 1758) can survive freezing and overwinter on land; they are found in the subarctic and cold regions of North America (Wood Frog, Rana sylvatica LeConte, 1825) and Eurasia (Moor Frog, Rana arvalis Nilsson, 1842) and are an example of an unusual adaptive strategy of overwintering. Freeze tolerance (down to –16 °C) of R. sylvatica has been thoroughly studied; however, little is known about cold resistance of R. arvalis in cold regions. We found that R. arvalis from European Russia and from West Siberia tolerate freezing down to –12 or –16 °C, whereas frogs from the Danish population survived freezing only to –4 °C (Y. Voituron et al. 2009b; J. Comp. Physiol. B, 179: 223–230). All of these populations, according to mitochondrial DNA markers, are closely related. We suggest that the observed differences in cold tolerance (–4 °C vs. –12 or –16 °C) could be caused either by adaptations to climatic factors or by differences in experimental protocols. The northeastern boundary of the geographic range of R. arvalis in Yakutia coincides with the transitional area between discontinuous and continuous permafrost; beyond this area, winter soil temperature sharply declines. The lower lethal temperature and overwintering ecology of R. arvalis in Siberia are similar to those of the North American R. sylvatica.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author