Infection sequence alters disease severity—Effects of the sequential exposure of two larval trematodes to Polypedates cruciger tadpoles

Multiple pathogens coexist in nature, and hence, host species often encounter several pathogens simultaneously. The sequence in which the host encounters the parasites influences interactions between parasites and host pathology. Here, the effects of infection by two cercaria (larvae of trematodes) types, pleurolophocercous cercaria of Acanthostomum burminis and a furcocercous cercaria, on the tadpoles of common hourglass tree frog (Polypedates cruciger) were examined. Ten days posthatch, tadpoles (Gosner stage 27/28) were used for infection exposures. First, in a single infection each cercaria type was introduced to the tadpoles separately. Second, coinfection of the two cercaria was carried out by alternating the sequences of exposure. For all the experiments, appropriate controls were instituted. Tadpoles of all groups exposed to parasites had lower survival levels compared to controls. Among the four groups exposed, the highest survival was observed in the coinfection when furcocercous was introduced first (82.5%). The lowest survival was observed in the coinfection when the A. burminis cercaria was introduced first (65.0%). In the coinfections, when A. burminis was introduced prior to furcocercous, survival of the tadpoles was reduced by 17.0% compared to the exposures of furcocercous prior to A. burminis. Prior infection with A. burminis induced negative effect on the host with an increased infection severity, while prior infection with furcocercous had reduced infection severity than lone exposures. These results suggest that furcocercous infections can be beneficial for hosts challenged with A. burminis provided that A. burminis exposure occurs second. None of the treatments had an effect on the growth of the tadpoles, but lengthening of developmental period was observed in some exposures. All exposed tadpoles developed malformations which were exclusively axial—kyphosis and scoliosis. However, there was no difference in the number of malformed individuals in the single infection (19.0%–25.0%) compared to coinfection (20.0%–22.5%) or between coinfections. The results suggest that the sequence of parasite exposure affects host–parasite interactions and hence the disease outcomes. Understanding the effects of coinfection on disease outcomes for hosts provides insight into disease dynamics

EVALUATION OF WILDLIFE HABITATS IN THE VICTORIA· RANDENIGALA·RANTAMBE SANCTUARY USING LlFE·FORM AND HABITAT MODELS

A suitable hahilal evaluation method is an important 1001 for wildlife managers 10manipulate wildlife diversity, to predict how proposed hahital changes will effect differentwildlife communities. as well as 10 determine the quantity and quality of available habitatsfor a particular species. A simple method of habitat evaluation is the use or life-form andhabitat models (Anderson & Gutzwiller. 1994). During this process, all species of animalsfound in it given area arc placed in distinct life-form categories, based on theirpredominant habitat use paucrns for feeding and reproduction, Once the life-form table ismade. more detailed data on habiln! use is presented in hahitat tables for individual speciesunder each Iifc-Ionn category. By adding the number of habitats used by each species forreproduction and breeding, versatility score (V) can be obtained, Species with a highversatility score arc the least sensitive to habitat manipulation. This would also enablewildlife managers to examine the impact of habitat loss/modification and Ii~;t the speciesaffected. This method was applied to evaluate the native vertebrates and their habitats inthe VRR sanctuary, A total of 252 native vertebrates recorded were placed under 22distinct life-form categories. These species were further assessed according to their majorhabitat utilisation pancrns. Six major aquatic habitats and nine major terrestrial habitatswere identified, Based on the versatility score of each species, they were grouped into threesensitivity categories for hahitat manipulation: most sensitive. moderately sensitive andleast sensitive. The most widely used habitat of fauna were recogniscd, based on the lifeforms and habitat models. This simple method could he adopted to evaluate the faunalhabitats in all protected areas of Sri Lanka.

MetaPIGA v2.0: maximum likelihood large phylogeny estimation using the metapopulation genetic algorithm and other stochastic heuristics

<p>Abstract</p> <p>Background</p> <p>The development, in the last decade, of stochastic heuristics implemented in robust application softwares has made large phylogeny inference a key step in most comparative studies involving molecular sequences. Still, the choice of a phylogeny inference software is often dictated by a combination of parameters not related to the raw performance of the implemented algorithm(s) but rather by practical issues such as ergonomics and/or the availability of specific functionalities.</p> <p>Results</p> <p>Here, we present MetaPIGA v2.0, a robust implementation of several stochastic heuristics for large phylogeny inference (under maximum likelihood), including a Simulated Annealing algorithm, a classical Genetic Algorithm, and the Metapopulation Genetic Algorithm (metaGA) together with complex substitution models, discrete Gamma rate heterogeneity, and the possibility to partition data. MetaPIGA v2.0 also implements the Likelihood Ratio Test, the Akaike Information Criterion, and the Bayesian Information Criterion for automated selection of substitution models that best fit the data. Heuristics and substitution models are highly customizable through manual batch files and command line processing. However, MetaPIGA v2.0 also offers an extensive graphical user interface for parameters setting, generating and running batch files, following run progress, and manipulating result trees. MetaPIGA v2.0 uses standard formats for data sets and trees, is platform independent, runs in 32 and 64-bits systems, and takes advantage of multiprocessor and multicore computers.</p> <p>Conclusions</p> <p>The metaGA resolves the major problem inherent to classical Genetic Algorithms by maintaining high inter-population variation even under strong intra-population selection. Implementation of the metaGA together with additional stochastic heuristics into a single software will allow rigorous optimization of each heuristic as well as a meaningful comparison of performances among these algorithms. MetaPIGA v2.0 gives access both to high customization for the phylogeneticist, as well as to an ergonomic interface and functionalities assisting the non-specialist for sound inference of large phylogenetic trees using nucleotide sequences. MetaPIGA v2.0 and its extensive user-manual are freely available to academics at <url>http://www.metapiga.org</url>.</p

Is Chytridiomycosis an Emerging Infectious Disease in Asia?

The disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused dramatic amphibian population declines and extinctions in Australia, Central and North America, and Europe. Bd is associated with >200 species extinctions of amphibians, but not all species that become infected are susceptible to the disease. Specifically, Bd has rapidly emerged in some areas of the world, such as in Australia, USA, and throughout Central and South America, causing population and species collapse. The mechanism behind the rapid global emergence of the disease is poorly understood, in part due to an incomplete picture of the global distribution of Bd. At present, there is a considerable amount of geographic bias in survey effort for Bd, with Asia being the most neglected continent. To date, Bd surveys have been published for few Asian countries, and infected amphibians have been reported only from Indonesia, South Korea, China and Japan. Thus far, there have been no substantiated reports of enigmatic or suspected disease-caused population declines of the kind that has been attributed to Bd in other areas. In order to gain a more detailed picture of the distribution of Bd in Asia, we undertook a widespread, opportunistic survey of over 3,000 amphibians for Bd throughout Asia and adjoining Papua New Guinea. Survey sites spanned 15 countries, approximately 36° latitude, 111° longitude, and over 2000 m in elevation. Bd prevalence was very low throughout our survey area (2.35% overall) and infected animals were not clumped as would be expected in epizootic events. This suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians. The current observed pattern in Asia differs from that in many other parts of the world

Integrating bioacoustics, DNA barcoding and niche modeling for frog conservation – the threatened balloon frogs of Sri Lanka: audio, 16S &amp; maps

This data is associated with the following paper: Integrating bioacoustics, DNA barcoding and niche modeling for frog conservation – the threatened balloon frogs of Sri Lanka: audio, 16S &amp; maps.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Host resistance and tolerance to parasitism: Development-dependent fitness consequences in common hourglass tree frog (Polypedates cruciger) tadpoles exposed to two larval trematodes

Tolerance and resistance to parasites are defense strategies of host organisms. Here, we tested the development-dependent tolerance and resistance of Polypedates cruciger Blyth, 1852 tadpoles to trematode infection. We exposed the tadpoles at Gosner stages 27, 28–29, and 30–31 to two types of cercariae (furcocercous and pleurolophocercous cercariae of Acanthostomum burminis (Bhalerao, 1926)) under laboratory conditions. To determine tolerance (the ability of a host to limit health effects of a given parasite load), we exposed the tadpoles until all cercariae penetrated the host. As a measure of determining resistance, we exposed tadpoles to cercariae for a limited time and counted the number of cercariae penetrating the tadpoles. The survival of tadpoles exposed at early stages was significantly lower than that of tadpoles exposed at later stages (mixed-effect model, p < 0.05), suggesting an age-dependent tolerance to parasitism. Tadpoles exposed at early stages were also smaller, took longer to metamorphosis, showed lower resistance to parasitism (ANOVA, p < 0.001), and developed axial malformations. In the resistance experiment, fewer parasites penetrated later stage tadpoles than early stage tadpoles. Tadpoles of P. cruciger showed a development-dependent tolerance and resistance to parasitism, resulting in greater survival and fewer malformations when parasitism occurs at late stages

A review of the genus Laubuca in Sri Lanka, with description of three new species (Teleostei: Cyprinidae)

Ichthyological Exploration of Freshwaters1917-2

A second extinct big cat from the late quaternary of Sri Lanka

A second extinct big cat, tentatively considered to be a tiger (Panthera tigris), is recorded from Sri Lanka for the first time from a fossil left lower carnassial found in alluvium near Ratnapura in 1962 and a sub-fossil right middle phalanx 14C dated to ~ 16,500 ybp, discovered in 1982 in a prehistoric midden at Batadomba Cave, near Kuruwita. The species is diagnosed from the only other big cats known from Sri Lanka, Panthera pardus and the extinct P. leo sinhaleyus Deraniyagala, 1938. This record significantly advances the timing of dispersal of tigers into the Indian peninsula. Tigers appear to have arrived in Sri Lanka during a pluvial period during which sea levels were depressed, evidently prior to the last glacial maximum ca. 20,000 years ago. The lion appears to have become extinct in Sri Lanka prior to the arrival of culturally modern humans, ca. 37,000 ybp