AVIAN HAEMOSPORIDIANS IN GREATER SCAUP (AYTHYA MARILA) AND LESSER SCAUP (AYTHYA AFFINIS) FROM WISCONSIN.

Avian haemosporidians are a diverse group of protozoan parasites that infect a wide range of host species. Waterfowl are an ecologically and economically important group of hosts that have been underrepresented in studies of haemosporidians. Diving ducks have unique life history traits, and morphological, behavioral, and dietary differences separate them from more common dabbling ducks.

TAXONOMIC REASSESSMENT AND MORPHOLOGICAL REDESCRIPTION OF NEMATOSTRIGEA SERPENS ANNULATA (DIGENEA: STRIGEIDAE) FROM OSPREY IN NORTH AMERICA.

Digenean trematodes in the strigeid genus Nematostrigea are parasites of various birds, most often ospreys (Pandion haliaetus). Nematostrigea currently contains 2 species, Nematostrigea serpens and Nematostigea hepatica. Nematostrigea serpens is divided into 2 subspecies: N.

Atypical life cycle does not lead to inbreeding or selfing in parasites despite clonemate accumulation in intermediate hosts.

Many parasites utilize asexual and sexual reproduction and multiple hosts to complete their life cycles. How these taxa avoid inbreeding is an essential question for understanding parasite evolution and ecology. Aquatic trematodes that require multiple host species may benefit from diverse genetic parasite assemblages accumulating within second intermediate hosts prior to sexual reproduction in definitive hosts.

Molecular phylogeny of Diplostomum, Tylodelphys, Austrodiplostomum and Paralaria (Digenea: Diplostomidae) necessitates systematic changes and reveals a history of evolutionary host switching events.

The Diplostomidae Poirier, 1886 is a large, globally distributed family of digeneans parasitic in intestines of their definitive hosts. Diplostomum and Tylodelphys spp. are broadly distributed, commonly reported, and the most often sequenced diplostomid genera.

Do New World pitvipers "scale-down" at high elevations? Macroecological patterns of scale characters and body size.

Bergmann's rule describes the macroecological pattern of increasing body size in response to higher latitudes and elevations. This pattern is extensively documented in endothermic vertebrates, within and among species; however, studies involving ectotherms are less common and suggest no consistent pattern for amphibians and reptiles. Moreover, adaptive traits, such as epidermal features like scales, have not been widely examined in conjunction with Bergmann's rule, even though these traits affect physiological processes, such as thermoregulation, which are hypothesized as underlying mechanisms for the pattern.

A revised molecular phylogeny reveals polyphyly in Schistura (Teleostei: Cypriniformes: Nemacheilidae).

There is a general consensus that the genus Schistura (Nemacheilidae), currently with 241 species, is not monophyletic. However, weak morphological synapomorphies and a lack of genetic data for most species of Schistura and their presumptive relatives have prevented meaningful diagnoses of species groups within this genus. To aid in deciphering evolutionary relationships, sequence data from two mitochondrial genes (cytochrome b and D-loop) were implemented in phylogenetic analyses for species of Schistura and other nemacheilids for which data from earlier studies and recently collected material were available.

Experimental investigation of alternative transmission functions: Quantitative evidence for the importance of nonlinear transmission dynamics in host-parasite systems.

Understanding pathogen transmission is crucial for predicting and managing disease. Nonetheless, experimental comparisons of alternative functional forms of transmission remain rare, and those experiments that are conducted are often not designed to test the full range of possible forms. To differentiate among 10 candidate transmission functions, we used a novel experimental design in which we independently varied four factors-duration of exposure, numbers of parasites, numbers of hosts and parasite density-in laboratory infection experiments.

Effects of Echinostoma trivolvis metacercariae infection during development and metamorphosis of the wood frog (Lithobates sylvaticus).

Many organisms face energetic trade-offs between defense against parasites and other host processes that may determine overall consequences of infection. These trade-offs may be particularly evident during unfavorable environmental conditions or energetically demanding life history stages. Amphibian metamorphosis, an ecologically important developmental period, is associated with drastic morphological and physiological changes and substantial energetic costs.

Population-specific toxicity of six insecticides to the trematode Echinoparyphium sp.

The ubiquitous use of pesticides has increased concerns over their direct and indirect effects on disease dynamics. While studies examining the effects of pesticides on host-parasite interactions have largely focused on how pesticides influence the host, few studies have considered the effects of pesticides on parasites. We investigated the toxicity of six common insecticides at six environmentally-relevant concentrations to cercariae of the trematode Echinoparyphium from two populations.

It's a predator-eat-parasite world: how characteristics of predator, parasite and environment affect consumption.

Understanding the effects of predation on disease dynamics is increasingly important in light of the role ecological communities can play in host-parasite interactions. Surprisingly, however, few studies have characterized direct predation of parasites. Here we used an experimental approach to show that consumption of free-living parasite stages is highly context dependent, with significant influences of parasite size, predator size and foraging mode, as well as environmental condition.

The scaling of host density with richness affects the direction, shape, and detectability of diversity-disease relationships.

Pathogen transmission responds differently to host richness and abundance, two unique components of host diversity. However, the heated debate around whether biodiversity generally increases or decreases disease has not considered the relationships between host richness and abundance that may exist in natural systems. Here we use a multi-species model to study how the scaling of total host community abundance with species richness mediates diversity-disease relationships.

Complex life cycles in a pond food web: effects of life stage structure and parasites on network properties, trophic positions and the fit of a probabilistic niche model.

Most food webs use taxonomic or trophic species as building blocks, thereby collapsing variability in feeding linkages that occurs during the growth and development of individuals. This issue is particularly relevant to integrating parasites into food webs because parasites often undergo extreme ontogenetic niche shifts. Here, we used three versions of a freshwater pond food web with varying levels of node resolution (from taxonomic species to life stages) to examine how complex life cycles and parasites alter web properties, the perceived trophic position of organisms, and the fit of a probabilistic niche model.

Does life history mediate changing disease risk when communities disassemble?

Biodiversity loss sometimes increases disease risk or parasite transmission in humans, wildlife and plants. Some have suggested that this pattern can emerge when host species that persist throughout community disassembly show high host competence - the ability to acquire and transmit infections. Here, we briefly assess the current empirical evidence for covariance between host competence and extirpation risk, and evaluate the consequences for disease dynamics in host communities undergoing disassembly.

Biomass and productivity of trematode parasites in pond ecosystems.

1. Ecologists often measure the biomass and productivity of organisms to understand the importance of populations and communities in the flow of energy through ecosystems. Despite the central role of such studies in the advancement of freshwater ecology, there has been little effort to incorporate parasites into studies of freshwater energy flow.

Parasite transmission in complex communities: predators and alternative hosts alter pathogenic infections in amphibians.

While often studied in isolation, host-parasite interactions are typically embedded within complex communities. Other community members, including predators and alternative hosts, can therefore alter parasite transmission (e.g.

Macroparasite infections of amphibians: what can they tell us?

Understanding linkages between environmental changes and disease emergence in human and wildlife populations represents one of the greatest challenges to ecologists and parasitologists. While there is considerable interest in drivers of amphibian microparasite infections and the resulting consequences, comparatively little research has addressed such questions for amphibian macroparasites. What work has been done in this area has largely focused on nematodes of the genus Rhabdias and on two genera of trematodes (Ribeiroia and Echinostoma).

Land use and wetland spatial position jointly determine amphibian parasite communities.

Land use change is one of the most commonly cited contributing factors to infectious disease emergence, yet the mechanisms responsible for such changes and the spatial scales at which they operate are rarely identified. The distributions of parasites with complex life cycles depend on interactions between multiple host species, suggesting the net effects of land use on infection patterns may be difficult to predict a priori. Here, we used an information-theoretic approach to evaluate the importance of land use and spatial scale (local, watershed, and regional) in determining the presence and abundance of multi-host trematodes of amphibians.

When parasites become prey: ecological and epidemiological significance of eating parasites.

Recent efforts to include parasites in food webs have drawn attention to a previously ignored facet of foraging ecology: parasites commonly function as prey within ecosystems. Because of the high productivity of parasites, their unique nutritional composition and their pathogenicity in hosts, their consumption affects both food-web topology and disease risk in humans and wildlife. Here, we evaluate the ecological, evolutionary and epidemiological significance of feeding on parasites, including concomitant predation, grooming, predation on free-living stages and intraguild predation.

Moderate Echinostoma trivolvis infection has no effects on physiology and fitness-related traits of larval pickerel frogs (Rana palustris).

High intensity infections of Echinostoma trivolvis metacercariae decrease survival and growth of young amphibian larvae. However, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. Survival and growth responses at these more-common, low-infection levels remain poorly studied.

Energetics of metamorphic climax in the pickerel frog (Lithobates palustris).

Anuran metamorphosis, the transition from aquatic larvae to terrestrial juveniles, is accompanied by significant morphological, physiological, and behavioral changes. Timing of metamorphosis and final size, which can influence adult fitness, may depend on sufficient energy accumulated during the larval period to support metamorphosis. However, only two species of anurans have been examined for energetic costs of metamorphosis, Rana tigrina and Anaxyrus terrestris.