Transformation of Baikal sponges (family Lubomirskiidae) after penetration into the Angara River

Genetic and morphological analysis of endemic sponges of the Lubomirskiidae family from Lake Baikal and the upper reaches of the Angara River was performed. Various sponge species acquired a number of similar morphological traits after the transition from the lake into the river. These traits enabled an increase of sponge skeleton strength under the conditions of elevated hydrodynamic activity. The changes significantly impeded morphology-based species identification of Angara sponges. Phylogenetic analysis of ITS regions and noncoding mitochondrial DNA fragments confirmed that the Angara sponges belonged to the Baikalian Lubomirskiidae family and demonstrated the polyphyletic origin of the sponges. The use of combined molecular and morphological data allowed for the clustering of some sponge samples into groups that corresponded to individual species. The absence of genetic isolation between the Baikalospongia intermedia and Lubomirskia baicalensis species was demonstrated, whereas the B. intermedia profundalis subspecies was well separated from B. intermedia. This finding pointed to the necessity of further studies for the clarification of the taxonomic status of this subspecies.     

Multiple asexual reproduction of Asterionella formosa Hass. from Lake Baikal and Angara reservoirs

The living plankton diatom Asterionella formosa from Lake Baikal and the Irkutsk Water Reservoir was studied using light microscopy. New facts were obtained which provide evidence of the occurrence of multiple asexual reproduction of Asterionella formosa.     

Precopulatory mating behavior and sexual dimorphism in the amphipod Crustacea

Accounts in the literature of precopulatory mate-guarding in gammaridean amphipods are that males use one of two strategies for mating: either they mate-guard by carrying or attending their mates until they are ready to molt and be fertilized, or they do not guard, instead searching benthically or swarming pelagically at the time that females are ready to molt. Mate-guarding by carrying has been documented for species of the superfamilies Gammaroidea, Talitroidea, and Hadzioidea. Mate-guarding by attending has been found in the more sedentary Corophioidea and Caprellidea. Non-mate-guarders that search pelagically are species of Ampeliscoidea, Lysianassoidea, Phoxocephaloidea, Oedicerotoidea, and Pontoporeioidea. Non-mate-guarders that mate-search benthically are species of Eusiroidea, Crangonyctoidea, and Haustorioidea. Mate-guarding and non-mate-guarding males develop different secondary sex characters at maturity. Mate-guarding males have enhancements for fighting and signalling. These alterations are more elaborate in males that attend their mates than in males that carry their mates. Non-mate-guarders that search pelagically develop enhancements for swimming and sensing. Non-mate-guarders that remain benthic exhibit little change at maturity. Most mate-guarding males develop their secondary sexual characters over several molts and mate over more than one instar. Pelagic mate-searchers develop their secondary sexual characters at the last molt and mating is confined to the last instar. Females of most mate-guarding species are iteroparous, while fewer than half of non-mate-guarding species are so. It is hypothesized that mate-guarding arose more than once in the evolutionary history of amphipod Crustacea.     

Molecular and morphological evolution of the amphipod radiation of Lake Baikal

Lake Baikal, in Siberia, Russia, contains the highest biodiversity of any extant lake, including an impressive radiation of gammaroidean amphipods that are often cited as a classic case of adaptive radiation. However, relationships among Baikal's amphipods remain poorly understood. The phylogenetic history of 32 Lake Baikal amphipod species, representing most major lineages of the endemic fauna, was examined using three genes (COI, 16S rRNA, and 18S rRNA), and 152 morphological characters. Results support monophyly of the largest and most diverse of the Baikalian families, the Acanthogammaridae. Analyses suggest that a second Baikalian family, the fossorial Micruropodidae, is paraphyletic and composed of two divergent clades, one of which includes Macrohectopus branickii, a morphologically specialized pelagic planktivore traditionally assigned its own family. The extreme morphological and ecological divergence of Macrohectopus from its close genetic relatives, and conversely, the large genetic distances among other morphologically similar micruropodids, suggest that morphological and molecular evolution have often been uncoupled during the radiation of Baikal's amphipods. This study suggests that the amphipod fauna of Lake Baikal is polyphyletic; originating from two independent invasions of the lake.     

Phosphorus Budget of Lake Baikal and the Angara Cascade Water Reservoirs: Modeling,Reconstruction, and Prognosis

A mass balance model of phosphorus flow in a system of connected water reservoirs has been developed and used for quantitative assessment of phosphorus budget elements in Lake Baikal and water reservoirs on the Angara River, the only river that drains Lake Baikal.     

Ecology and sound signaling of relict katydid Deracantha onos (Pallas, 1772) (Orthoptera, Tettigoniidae, Bradyporinae)

Life history and acoustic signaling of a Central Asian species Deracantha onos (Pall.) are described. Males and females produce calling signals and protest sounds. For the first time, electronograms of stridulatory files, oscillograms, and frequency spectra of some acoustic signals are given.     

Phylogeography and systematics of Acanthogammarus s. str., giant amphipod crustaceans from Lake Baikal

Daneliya, M. E., Kamaltynov, R. M. & Väinölä, R. (2011). Phylogeography and systematics of Acanthogammarus s. str., giant amphipod crustaceans from Lake Baikal. —Zoologica Scripta, 40, 623–637. To illustrate the dynamics of evolution of the rich endemic crustacean diversity in the ancient Siberian Lake Baikal, we explored the phylogenetic relationships and intralake phylogeographic structure in members of the genus Acanthogammarus Stebbing (Amphipoda, Gammaridea, Acanthogammaridae), which involves some of the most spectacular gigantic freshwater amphipods in the world. Mitochondrial cytochrome oxidase I gene sequence data gave only partial support to either of the recent competing views of systematic diversity. The three species Acanthogammarus victorii, Acanthogammarus maculosus and Acanthogammarus lappaceus along with a fourth, undescribed taxon endemic to the Ushkanii archipelago, made a monophyletic group corresponding to the subgenus Ancyracanthus. A sister relationship of the vicarious ‘subspecies’A. victorii and A. maculosus was not supported, rather the southerly A. victorii was basal to the cluster of the three other northerly, overlapping species. The data generally supported full species rank for the previously debated subspecies taxa, apart from the purported distinction between ‘Acanthogammarus longispinus’ and Acanthogammarus lappaceus, which seems to represent intraspecies morphological variation, partly related to sexual dimorphism. The sister status of Acanthogammarus godlewskii and A. gracilispinus (and thus subgenus Acanthogammarus) had weak support; reassessment of museum collections showed that they both are widespread and sympatric throughout the lake. The observed interspecies sequence differences were 13–22% (23–64% in terms of model‐based distance), suggesting divergence times of several million years under conventional calibrations, calling the applicability of external clocks into question. Strong patterns of intraspecific, intralake phylogeographic subdivision were found in A. lappaceus, A. maculosus and A. gracilispinus, each comprising several disjunct lineages with 1–5% divergence. Other species showed only slight differentiation. In all, the patterns of geographical differentiation were unique for each species, varying from moderate allele frequency differentiation to well‐established geographically segregated lineages, presumably of Early and Middle Pleistocene age. The patterns of differentiation in Acanthogammarus support an important role of allopatric diversification in the evolution of Lake Baikal fauna.     

The ability of the amphipod Corophium volutator (Pallas) to follow chemical signals from con-specifics

The amphipod Corophium volutator (Pallas) is a tube-dwelling species that only occasionally leaves its burrow. Animals that do crawl on the sediment are mainly males, apparently in search of females. This study was designed to determine whether C. volutator males and females release chemical signals that attract con-specifics, and if so, whether these signals are gender specific. Laboratory experiments were conducted on the over-wintering generation during their reproductive season, using a Y-maze choice test apparatus. The results show that C. volutator females release chemical signals that attract males. In the field, the attractant may guide males in search of burrowed females. In addition, male odour tends to attract males, while females do not follow chemical signals from con-specifics. We thereby show on gender-specific chemical attraction of this species.     

Variation of sponge-inhabiting infauna with the state of health of the sponge Lubomirskia baikalensis (Pallas, 1776) in Lake Baikal

Limnology - Our investigation was conducted during a period of ecological crisis in the coastal zone of Lake Baikal. Mass disease and mortality of the endemic sponges inhabiting the nearshore zone...     

Biology of Amblyomma aureolatum (Pallas, 1772) (Acari: Ixodidae) on some laboratory hosts in Brazil

The ixodid Amblyomma aureolatum is suspected to play a role in the epidemiology of wild life-cycle hemoparasites, which frequently infect dogs in rural and hunting areas in Brazil. Little is known about its bionomics. The objective of the present study was to evaluate some bionomic aspects of A. aureolatum ticks in Brazil. One engorged female, collected from a dog (Canis familiaris) in S?o Sebasti?o das Aguas Claras, State of Minas Gerais, was used to establish a colony in the laboratory. Subsequently its parasitic stage progeny were fed on domestic dogs and laboratory animals. The free-living stages were incubated at 27 degrees C +/- 2 degrees C and minimum 70% relative humidity in a BOD incubator. The egg incubation period ranged from 31 to 34 days; the parasitic period of larvae ranged from 4 to 6 days and ecdysis to nymphs occurred from day 19 up to day 22. The parasitic period of nymphs ranged from 5 to 8 days and the period of ecdysis to adults from 31 to 33 days. The parasitic period of adults ranged from 11 to 15 days, the pre-oviposition period from 6 to 12 days, and the oviposition period from 9 to 38 days. The total duration of the life cycle ranged from 116 to 168 days.     

Karyotypic features of Chironomus entis and Chironomus borokensis (Diptera, Chironomidae) from Lake Kotokel (Lake Baikal Basin)

Karyotypes and chromosomal polymorphism of sympatric sibling species Chironomus entis and Chironomus borokensis from Lake Kotokel were studied. Five inversion banding sequences were found in C. entis, including p’entA16, p’entB9, and p’entF6 that are new for the species; in C. borokensis, four inversion banding sequences were revealed, borA4 being new for the species. The level of chromosome polymorphism in C. entis and C. borokensis can be considered similar: 54.2 and 53.8% heterozygosity, 0.67 and 0.73 inversions per individual, respectively. The new data are compared with those on C. entis population from Lake Kotokel obtained in 1981 and those of C. borokensis from Lake Dukhovoe (Lake Baikal basin) obtained in 1983.     

Karyotype and morphology of Chironomus wulkeri (Diptera, Chironomidae) from Lake Baikal region

The karyotype and morphology of the Palaearctic chironomid, Chironomus wulkeri Filinkova et Belyanina 1993, inhabiting the Baikal coast were studied. The banding patterns of chromosomal arms B, C, and D are presented for the first time. The karyotype and chromosome polymorphism of Ch. wulkeri from the Baikal population have no significant difference from those in northern Sweden and the Polar Ural populations. One heterozygous inversion in arm A was found in 38% of larvae. A comparative morphological analysis of 46 quantitative characters of larvae from Baikal region and the Polar Urals showed that they did not differ from each other. However, there are some differences in the width of the ventromental plates and height of the mentum.     

Cytogenetic characterization of the Zebra Mussel Dreissena polymorpha (Pallas) from Miedwie Lake, Poland

Cytogenetic characterization of D. polymorpha was carried out using banding techniques such as C-banding, fluorochrome CMA3 and silver nitrate treatment. The diploid chromosome number of both investigated D. polymorpha forms (typical and albinotic) was the same 2n = 32 (NF = 56). The karyotype consisted of 5 pairs of metacentric, 7 pairs of submetacentric and four pairs of subtelo-acrocentric chromosomes. Ag-NORs were located in the telomeric position on the largest subtelo-acrocentric chromosome pair. C banding patterns indicate many sites of constitutive heterochromatin mainly located in the telomeric regions and interstitially in some chromosomes. CMA3-sites were observed in almost all chromosomes; apart from the Ag-NORs sites, they were located terminally on the chromosome arms and interstitially on three chromosome pairs. Sixteen chromosomes could be counted at the diakinesis stage of meiosis. No differences in banding chromosome patterns were found neither between both analyzed forms of D. polymorpha nor between males and females.     

Purification and characterization of acetylcholinesterase from the Lake Van fish (Chalcalburnus tarichii Pallas, 1811)

In this study, acetylcholinesterase (AChE; EC 3.1.1.7) was purified from plasma and erythrocytes in the Lake Van fish (Chalcalburnus tarichii P.1811) by affinity chromatography. Enzymatic activity was spectrophotometrically measured according to Ellman's method, at 412 nm. Then, the optimal pH and temperature of the enzyme was determined. According to the results, the optimal pH and the optimum temperature were 8.0 and 25 degrees C, respectively. In order to control the purification of the enzyme, sodium dodecyl-sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was done. SDS-PAGE showed a single band for enzyme. The purification rates for plasma AChE and erythrocyte AChE are 3251.6 and 8500, respectively.     

The evolution of sexual size dimorphism in cottontail rabbits (Sylvilagus,Leporidae)

In mammals, ‘female‐biased’ sexual size dimorphism (SSD), in which females are larger than males, is uncommon. In the present study, we examined Sylvilagus, a purported case of female‐biased SSD, for evolutionary correlations among species between SSD, body‐size, and life‐history variables. We find that: (1) although most species are female‐biased, the degree and direction of SSD vary more than was previously recognized and (2) the degree of SSD decreases with increasing body size. Hence, Sylvilagus provides a new example, unusual for a female‐biased taxon, in which allometry for SSD is consistent with ‘Rensch's Rule’. As a corollary to Rensch's Rule, we observe that changes in SSD in Sylvilagus are typically associated with larger, more significant changes in males than females. Female‐biased SSD could be produced by selection for larger females, smaller males, or both. Although larger female size may be related to high fecundity and the extremely rapid fetal and neonatal growth in Sylvilagus, we find little evidence for a correlation between SSD and various fecundity‐related traits in among‐species comparisons. Smaller male size may confer greater reproductive success through greater mobility and reduced energetic requirements. We propose that a suite of traits (female dispersion, large male home ranges, reduced aggression, and a promiscuous mating system) has favoured smaller males and thus influenced the evolution of SSD in cottontails. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 141–156.     

Craniometric sexual dimorphism inLeontopithecus Lesson, 1840 (Callitrichidae, Primates)

Lion tamarins are among the World's most critically endangered primates. Many studies have been produced under guidance of the International Management Committees for the preservation and management of these tamarins. Primates present morphological sexual differences in a wide range of characteristics, including cranial morphology. Studies of sexual dimorphism in the cranial morphology of theLeontopithecus are few in number and contradictory in their results. In order to check for the existence of sexual dimorphism in lion tamarins the present study analyzed 17 craniometric distances on 56 crania of three species of lion tamarins (Leontopithecus): 20L. rosalia (14 females and 6 males); 13L. chrysomelas (6 females and 7 males); and 23L. chrysopygus (8 females and 15 males). All crania are housed in the CPRJ-FEEMA collection (Primatological Center of Rio de Janeiro) and came from animals born in captivity.L. chrysopygus was more sexually dimorphic (10/17 measurements, 59%) thanL. chrysomelas (9/17 measurements, 53%) orL. rosalia (7/17 measurements, 41%). In all three species, male values are greater than the female ones, except for orbital breadth (m7) inL. rosalia. However, this distance is not sexually dimorphic in this species. This study reveals that some cranial distances, especially in the facial region, are sexually dimorphic in lion tamarins.     

The developmental cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae)--a parasite of the Arctic grayling from Lake Baikal

The life cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae), a parasite of Siberian glame (Thymallus arcticus), was repeated under experimental conditions. The first intermediate hosts, the copepods Epischura baicalensis, Cyclops kolensis and C. vicinus, were determined. The developmental time of P. thymalli in the first intermediate host was determined and the morphology of the larval and adult phases was described.