Characteristic of reproductive structure in the hemipopulation of a bat-parasitizing nematode Thominx neopulchra (Nematoda, Capillariidae)

Features of reproductive structure of the Thominx neopulchra hemipopulation from Daubenton's bat from Zhiguli State Reserve are studied. It is established, that females and males of Th. neopulchra have different dynamics of coming in the host population. Males of the parasite invade the of Daubenton's bat population during all the year, while females infest the host only from May to November. Maturing of helminthes become slowed in winter period. Only about a half of of the host population is involved in the forming of the reproductive structure of Th. neopulchra hemipopulation.     

Assessment of genetic diversity in the critically endangered Australian corroboree frogs, Pseudophryne corroboree and Pseudophryne pengilleyi, identifies four evolutionarily significant units for conservation

The iconic and brightly coloured Australian northern corroboree frog, Pseudophryne pengilleyi , and the southern corroboree frog, Pseudophryne corroboree are critically endangered and may be extinct in the wild within 3 years. We have assembled samples that cover the current range of both species and applied hypervariable microsatellite markers and mitochondrial DNA sequences to assess the levels and patterns of genetic variation. The four loci used in the study were highly variable, the total number of alleles observed ranged from 13 to 30 and the average number of alleles per locus was 19. Expected heterozygosity of the four microsatellite loci across all populations was high and varied between 0.830 and 0.935. Bayesian clustering analyses in structure strongly supported four genetically distinct populations, which correspond exactly to the four main allopatric geographical regions in which the frogs are currently found. Individual analyses performed on the separate regions showed that breeding sites within these four regions could not be separated into distinct populations. Twelve mtND2 haplotypes were identified from 66 individuals from throughout the four geographical regions. A statistical parsimony network of mtDNA haplotypes shows two distinct groups, which correspond to the two species of corroboree frog, but with most of the haplotype diversity distributed in P. pengilleyi . These results demonstrate an unexpectedly high level of genetic diversity in both species. Our data have important implications for how the genetic diversity is managed in the future. The four evolutionarily significant units must be protected and maintained in captive breeding programmes for as long as it is possible to do.     

Influence of the phase of the number and demographic structure of the water vole population on its infection by helminthes

In this work we have analyzed results of the long-term investigations of the helminthes distribution in the various demography groups of the water vole population (Arvicola terrestris L.) in North Baraba (Novosibirsk region). The data on the dominant parasites of these rodents: trematodes Notocotylus noyeri (Joyeux, 1922), cestodes Limnolepis transfuga Spassky et Merkuscheva, 1967, nematodes Capillaria wioletti Ruchljadeva, 1950, Longistriata minuta (Dujarden, 1845) and Heligmosomum costellatum (Dujarden, 1845) have shown that the number of parasites in biocenosis are connected with different factors, such as the demographic structure of the host population, the alternation of hosts number and conditions of the environment (dry and damp phases of the climatic cycle). In the dry phase the main parasitize load N. noyeri, L. transfuga and C. wioletti connects with the breeding group; in the damp period - with immature rodents. Independently of the phase climatic cycle and the density of the water vole population the great bulk of nematodes L. minuta and H. costellatum was uncovered of the immature individuals. In any case the number of helminthes changed synchronously with such of the its host.     

Cues used in host‐seeking behavior by frog‐biting midges (Corethrella spp. Coquillet)

We investigated the role of carbon dioxide and host temperature in host attraction in frog‐biting midges (Corethrella spp). In these midges, females are known to use frog calls to localize their host, but the role of other host‐emitted cues has yet not been investigated. We hypothesized that carbon dioxide acts as a supplemental cue to frog calls. To test this hypothesis, we determined the responses of the midges to carbon dioxide, frog calls, and both cues. A significantly lower number of midges are attracted to carbon dioxide and silent traps than to traps broadcasting frog calls. Adding carbon dioxide to the calls does not increase the attractiveness to the midges. Instead, carbon dioxide can have deterrent effects on frog‐biting midges. Temperature of calling frogs is not a cue potentially available to the midges. Contrary to our hypothesis, there was no supplemental effect of carbon dioxide when presented in conjunction to calls. Midge host‐seeking behavior strongly depends on the mating calls emitted by their anuran host. Overall, non‐acoustic cues such as host body temperature and carbon dioxide are not important in long‐distance host location by frog‐biting midges.     

The effect of habitat fragmentation on finescale population structure of wood frogs (Rana sylvatica)

We examined the impact of recent anthropogenic habitat fragmentation on the genetic structure of wood frog (Rana sylvatica) breeding sites in Wellington County of Ontario, Canada. In addition to geographic distance (average pairwise distance ~22 km, greatest distance ~50.22 km), four landscape features hypothesized to contribute to genetic differentiation between breeding sites were considered: road density, a major highway (highway 401), canopy cover, and watershed discontinuity. Analysis of data from 396 samples across nine breeding sites using eight microsatellite DNA loci, revealed a small degree of significant genetic structure between breeding sites. The presence of highway 401 and road density were correlated with small but statistically significant structure observed between several groups of sites. One outlier breeding site outside of Wellington County located within the city of Toronto, had significantly lower allelic richness and much larger population differentiation with the Wellington sites. Our data suggest that recent fragmentation has had an effect on wood frog population structure and also demonstrate the importance of dispersal for this species in maintaining levels of genetic diversity.     

Helminthiasis, metabolic rates and cold resistance in the red-backed vole from a natural population

Estimation of the standard metabolic rate (SMR), maximal oxygen consumption (MOC) and thermoregulation ability in males of red-backed vole (Clethrionomys rutilus Pallas, 1779) have shown that individuals infected with nematodes Heligmosomum mixtum, regardless of intensity of worm infection, had an increased level of oxygen consumption in the cold exposition, while the individuals infected with the cestodes Arostrilepis horrida, had a lover oxygen consumption than non-invaded individuals. Worm burden of A. horrida correlated negatively with MOC value in the hosts. Thermo-conductance of individuals infected with A. horrida was significantly lower than in ones infected with H. mixtum. Opposite effects of these two helminthes seems to be determined by the specificity of pathogenesis and different body mass of parasites. Total body mass of nematodes are usually less than 0.2% of the host body mass whereas the total body mass of cestodes may exceed 5% of the host body mass.     

Phylogeography and host race differentiation in the European mistletoe (Viscum album L.)

Mistletoes are bird dispersed, hemi-parasitic shrubs infecting a large number of woody host plants. Chloroplast fragment length polymorphisms were used to study genetic differentiation among presumed host races, population genetic structure, and to elucidate the postglacial migration history of mistletoe ( Viscum album ) across the entire natural distribution range in Europe. The populations sampled belong to four closely related taxa, three of which are widely distributed and differ in their host trees, whereas a fourth taxon is rare and endemic to the Island of Crete. The molecular analysis of chloroplast DNA variation supported the distinction of these four taxa. We further found evidence for phylogeographical structure in each of the three widely distributed host races. Independent of host race, mistletoe haplotypes from Turkey were distinct and distant from those found elsewhere in Europe, suggesting that highly differentiated populations, and possibly new taxa, exist at the range limit of the species.     

Do rivers function as genetic barriers for the plateau wood frog at high elevations?

Using the plateau wood frog Rana kukunoris from the Hengduan Mountains as a model system, we tested whether rivers form significant genetic barriers (the riverine barrier hypothesis) to high elevation amphibians. Samples were collected from eight sites across three major river drainages, the Min, the Dadu and the Yalong Rivers, and the population genetic structure of these frogs was evaluated with data from eight microsatellite DNA loci. A large amount of genetic structure was found, and the pairwise F _ST ranged from 0.022 to 0.508 and a global F _ST was 0.215. Both analysis of molecular variance and isolation by distance analysis suggested that rivers, mountain ridges and geographic distances all contributed significantly to the population structure. However, no single landscape has prominent barrier effect to the plateau wood frog populations. An assignment analysis using the computer program Structure grouped the eight populations into four population clusters, and no single type of landscape can sufficiently explain the clustering. In conclusion, rivers do not appear to be the leading genetic barriers for the plateau wood frog. The strong population genetic structure is likely the consequence of attributes of the species, as opposed to environmental fragmentation, and the barrier effect of the landscapes is largely swamped by the large amount of intrinsic population structure.     

RAPD marker estimation of genetic structure among isolated northern leopard frog populations in the south-western USA

Amphibians in the south-western United States are currently experiencing population declines. Causal explanations for these population changes as well as the implementation of sound management practices requires an understanding of the genetic structure of natural amphibian populations. To this end, we estimated genetic differences within and among seven isolated populations of northern leopard frogs, Rana pipiens , from Arizona and southern Utah using random amplified polymorphic DNA (RAPD) analyses. Fourteen arbitrarily designed primers detected 38 polymorphic loci in 85 individual frogs. Three types of population structure were observed in this study. (i) Two populations showed low genetic diversity ( D = 0.10 and 0.04) and may have been established by relatively recent events. (ii) Two were not genetically distinct and exhibited a high degree of within-population diversity ( D = 0.35). The possibility of gene flow between these populations is high due to their geographical proximity and their shared genetic structure. (iii) Three populations were genetically distinct from each other and the other populations, and exhibited intermediate within-population variation ( D = 0.19, 0.17, 0.14). Genetic distances among the seven populations ranged from 0.00 to 0.20, suggesting that some of these leopard frog populations are genetically distinct. Although based on relatively small samples, these data suggest that leopard frog populations in the south-west are likely to represent unique genetic entities worthy of conservation. The management implications of these results are that isolated leopard frog populations should be evaluated on an individual basis to best preserve them.     

Differences in population structure of the anther smut fungus Microbotryum violaceum on two closely related host species, Silene latifolia and S. dioica

We investigated the genetic population structure of the sexually transmitted plant pathogen, the fungus Microbotryum violaceum, on the two closely related host species Silene latifolia and S. dioica using microsatellite markers. We found strong deviations from Hardy-Weinberg expectations, with significant heterozygote deficiency in almost all populations. Fungal strains from the two host species were differentiated, and these host races differed in amount of variation within populations and differentiation among populations. Anther smut from S. latifolia harboured significantly less microsatellite diversity and were more genetically differentiated from each other than those from S. dioica. Small effective population sizes, rapid population turnover, and less gene flow among populations could lead to this higher population differentiation and lower within population genetic diversity for anther smut populations on S. latifolia than on S. dioica. These results are in concordance with host ecology because S. latifolia grows in more disturbed habitats than S. dioica and may provide a shorter-lived host environment.     

Genetic Diversity and Population Structure for the Conservation of Giant Spiny Frog(Quasipaa spinosa) Using Microsatellite Loci and Mitochondrial DNA

The giant spiny frog(Quasipaa spinosa) is an endangered species with a relatively small distribution limited to southern China and Northern Vietnam. This species is becoming increasingly threatened because of over-exploitation and habitat degradation. This study provides data on the genetic diversity and population genetic structure of the giant spiny frog to facilitate the further development of effective conservation recommendations for this economically important but threatened species. We examined 10 species-specific microsatellite loci and Cyt b genes(562 bp) collected from 13 wild populations across the entire range of this species. Results of 10 microsatellite loci analysis showed a generally high level of genetic diversity. Moreover, the genetic differentiation among all 12 populations was moderate to large(overall F_(ST) = 0.1057). A total of 51 haplotypes were identified for Cyt b, which suggests high haplotype nucleotide diversities. Phylogeographic and population structure analyses using both DNA markers suggested that the wild giant spiny frog can be divided into four distinct major clades, i.e., Northern Vietnam, Western China, Central China, and Eastern China. The clades with significant genetic divergence are reproductively isolated, as evidenced by a high number of private alleles and strong incidence of failed amplification in microsatellite loci. Our research, coupled with other studies, suggests that Q. spinosa might be a species complex within which no detectable morphological variation has been revealed. The four phylogenetic clades and some subclades with distinct geographical distribution should be regarded as independent management units for conservation purposes.     

Phylogeography of the parasitic fly Batrachomyia in the Wet Tropics of north-east Australia, and susceptibility of host frog lineages in a mosaic contact zone

Parasites could differentially impact intraspecific host lineages due to genetic, phenotypic, ecological, or behavioural differences between the lineages, or the development of reproductive isolation between them. Batrachomyia (Diptera: Chloropidae) are flies that exclusively parasitize Australian frogs, and in the Wet Tropics rainforest of north‐east Australia larvae are largely restricted to the green‐eyed tree frog Litoria genimaculata (Anura: Hylidae). This frog species consists of two highly divergent genetic lineages that overlap in two nearby, but independent, contact zones. At one contact zone there has been extensive phenotypic divergence and speciation between the lineages whereas, at the other contact relatively lower levels of phenotypic divergence and reproductive isolation suggest that speciation has not occurred. In the present study we tested: (1) whether the deep phylogeographic divergence between northern and southern host populations is mirrored by congruent genetic structuring in the parasite populations and (2) whether the host lineages are differentially impacted by parasitism. We found that the two divergent frog lineages are parasitized by a single lineage of Batrachomyia, which exhibits strikingly little phylogeographic structuring. We found a significant difference in Batrachomyia prevalence between the host lineages at mixed lineage sites in both contact zones, with the magnitude and direction of this effect being consistent in both. The pattern did not differ between the two contacts even though recent phenotypic divergence and speciation has occurred between the lineages at one contact but not the other. Taken together, this suggests a fundamental difference in susceptibility between the genetically divergent host lineages. Using weight relative to body length as a measure of body condition, we found no differential impact of parasitism on the body condition of each host lineage, and no evidence that parasitism impacts the body condition of the host in general. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 593–603.     

Disentangling the effects of historic vs. contemporary landscape structure on population genetic divergence

Increasing habitat fragmentation poses an immediate threat to population viability, as gene flow patterns are changed in these altered landscapes. Patterns of genetic divergence can potentially reveal the impact of these shifts in landscape connectivity. However, divergence patterns not only carry the signature of altered contemporary landscapes, but also historical ones. When considered separately, both recent and historical landscape structure appear to significantly affect connectivity among 51 wood frog ( Rana sylvatica ) populations. However, by controlling for correlations among landscape structure from multiple time periods, we show that patterns of genetic divergence reflect recent landscape structure as opposed to landscape structure prior to European settlement of the region (before 1850s). At the same time, within-population genetic diversities remain high and a genetic signature of population bottlenecks is lacking. Together, these results suggest that metapopulation processes – not drift-induced divergence associated with strong demographic bottlenecks following habitat loss – underlie the strikingly rapid consequences of temporally shifting landscape structure on these amphibians. We discuss the implications of these results in the context of understanding the role of population demography in the adaptive variation observed in wood frog populations.     

The Siberian tree frog (<Emphasis Type="Italic">Rana amurensis</Emphasis> Bulenger, 1886) in Yakutia

The paper studies the distribution, life style, propagation, nutrition, helminthes invasion, seasonal fluctuations of hematologic parameters, content of ascorbic acid in the organs and glycogen in the liver of the Siberian tree frog.     

Hepatic cytochrome P-450-dependent monooxygenase systems of the trout, frog and snake--I. Components

1. Components of the hepatic monooxygenase systems (cytochrome P-450, cytochrome b5, NADPH cytochrome P-450- or c-reductase) of the brown trout (Salmo trutta), leopard frog (Rana pipiens) and garter snake (Thamnophis) were considerably lower than those found in the rat. 2. Reactivity of snake NADPH-cytochrome P-450-reductase with cytochrome P-450 was about twice that of the rat reductase; reactivities of trout and frog reductases were similar, but lower than that of the rat. The optimal temperature for the rat, frog and snake reductase activity was 37 degrees C, but 26 C for the trout reductase, regardless of whether cytochrome P-450 or cytochrome c was the electron acceptor for the reaction. 3. A type I substrate (benzphetamine) and a type II substrate (aniline) were less reactive with P-450 cytochrome from the trout, frog and snake than with P-450 cytochrome from the rat. 4. Qualitative differences were seen in the ethylisocyanide spectrum of microsomes from the rat, trout, frog and snake; these differences reflect qualitative differences in the populations of P-450 cytochromes among each of the four species.     

Fungal diversity associated with hawaiian Drosophila host plants

Hawaiian Drosophila depend primarily, sometimes exclusively, on specific host plants for oviposition and larval development, and most specialize further on a particular decomposing part of that plant. Differences in fungal community between host plants and substrate types may establish the basis for host specificity in Hawaiian Drosophila. Fungi mediate decomposition, releasing plant micronutrients and volatiles that can indicate high quality substrates and serve as cues to stimulate oviposition. This study addresses major gaps in our knowledge by providing the first culture-free, DNA-based survey of fungal diversity associated with four ecologically important tree genera in the Hawaiian Islands. Three genera, Cheirodendron, Clermontia, and Pisonia, are important host plants for Drosophila. The fourth, Acacia, is not an important drosophilid host but is a dominant forest tree. We sampled fresh and rotting leaves from all four taxa, plus rotting stems from Clermontia and Pisonia. Based on sequences from the D1/D2 domain of the 26S rDNA gene, we identified by BLAST search representatives from 113 genera in 13 fungal classes. A total of 160 operational taxonomic units, defined on the basis of ≥97% genetic similarity, were identified in these samples, but sampling curves show this is an underestimate of the total fungal diversity present on these substrates. Shannon diversity indices ranged from 2.0 to 3.5 among the Hawaiian samples, a slight reduction compared to continental surveys. We detected very little sharing of fungal taxa among the substrates, and tests of community composition confirmed that the structure of the fungal community differed significantly among the substrates and host plants. Based on these results, we hypothesize that fungal community structure plays a central role in the establishment of host preference in the Hawaiian Drosophila radiation.     

Genetic diversity and fitness in peripheral and central populations of the European tree frog Hyla arborea

Genetic diversity is expected to decrease in small and isolated populations as a consequence of founder effects, bottlenecks, inbreeding and genetic drift. In this study we analyse temporal and spatial effects on genetic variation and progeny viability of the European tree frog (Hyla arborea) at two scales. First, the Swedish distribution has been isolated from the continental distribution for more than 8000 thousand years, and secondly, within Sweden, recent habitat alterations that have taken place during this century have increased isolation between local populations. Genetic variation and progeny survival in relation to isolation was studied within the entire Swedish distribution of the tree frog. Allozyme electrophoresis analysis of froglets, sampled across the Swedish distribution, revealed a low overall genetic variation (1.06 alleles/locus) at the protein level in comparison with continental populations (1.54-1.68 alleles/locus). However, egg hatchability (97%) and early larval survival (95%) were not lower than in other parts of the tree frog distribution or in other anuran species. Within the Swedish distribution, early larval survival was lower in isolated breeding ponds than in more central ones. However, no differences in genetic variation were found in relation to isolation. Polymorphism was detected only at a single locus, and was restricted geographically to the eastern part of the Swedish distribution. Bottlenecks due to climatic changes and fragmentation of suitable habitat (primarily natural pastures with ponds) are suggested as possible causes of the low genetic diversity of the Swedish tree frog population.     

Do landscape processes predict phylogeographic patterns in the wood frog?

Understanding factors that influence population connectivity and the spatial distribution of genetic variation is a major goal in molecular ecology. Improvements in the availability of high-resolution geographic data have made it increasingly possible to quantify the effects of landscape features on dispersal and genetic structure. However, most studies examining such landscape effects have been conducted at very fine (e.g. landscape genetics) or broad (e.g. phylogeography) spatial scales. Thus, the extent to which processes operating at fine spatial scales are linked to patterns at larger scales remains unclear. Here, we test whether factors impacting wood frog dispersal at fine spatial scales are correlated with genetic structure at regional scales. Using recently developed methods borrowed from electrical circuit theory, we generated landscape resistance matrices among wood frog populations in eastern North America based on slope, a wetness index, land cover and absolute barriers to wood frog dispersal. We then determined whether these matrices are correlated with genetic structure based on six microsatellite markers and whether such correlations outperform a landscape-free model of isolation by resistance. We observed significant genetic structure at regional spatial scales. However, topography and landscape variables associated with the intervening habitat between sites provide little explanation for patterns of genetic structure. Instead, absolute dispersal barriers appear to be the best predictor of regional genetic structure in this species. Our results suggest that landscape variables that influence dispersal, microhabitat selection and population structure at fine spatial scales do not necessarily explain patterns of genetic structure at broader scales.