All-male hybrids of a tetrapod Pelophylax esculentus share its origin and genetics of maintenance.

Background: Sexual parasites offer unique insights into the reproduction of unisexual and sexual populations. Because unisexuality is almost exclusively linked to the female sex, most studies addressed host-parasite dynamics in populations where sperm-dependent females dominate. Pelophylax water frogs from Central Europe include hybrids of both sexes, collectively named P.

Genetic diversity and distribution patterns of diploid and polyploid hybrid water frog populations (Pelophylax esculentus complex) across Europe.

Polyploidization is a rare yet sometimes successful way for animals to rapidly create geno- and phenotypes that may colonize new habitats and quickly adapt to environmental changes. In this study, we use water frogs of the Pelophylax esculentus complex, comprising two species (Pelophylax lessonae, genotype LL; Pelophylax ridibundus, RR) and various diploid (LR) and triploid (LLR, LRR) hybrid forms, summarized as P. esculentus, as a model for studying recent hybridization and polyploidization in the context of speciation.

Post-zygotic selection against parental genotypes during larval development maintains all-hybrid populations of the frog Pelophylax esculentus.

Background: Hybridization between two species usually leads to inviable or infertile offspring, due to endogenous or exogenous selection pressures. Yet, hybrid taxa are found in several plant and animal genera, and some of these hybrid taxa are ecologically and evolutionarily very successful. One example of such a successful hybrid is the water frog, Pelophylax esculentus which originated from matings between the two species P.

Genomic effects on advertisement call structure in diploid and triploid hybrid waterfrogs (Anura, Pelophylax esculentus).

Background: In anurans, differences in male mating calls have intensively been studied with respect to taxonomic classification, phylogeographic comparisons among different populations and sexual selection. Although overall successful, there is often much unexplained variation in these studies. Potential causes for such variation include differences among genotypes and breeding systems, as well as differences between populations.

Gamete production patterns, ploidy, and population genetics reveal evolutionary significant units in hybrid water frogs (Pelophylax esculentus).

The European water frog Pelophylax esculentus is a natural hybrid between P. lessonae (genotype LL) and P. ridibundus (RR).

Long-term study of an infection with ranaviruses in a group of edible frogs (Pelophylax kl. esculentus) and partial characterization of two viruses based on four genomic regions.

Several edible frogs (Pelophylax kl. esculentus) collected into a single group from various ponds in Europe died suddenly with reddening of the skin (legs, abdomen) and haemorrhages in the gastrointestinal tract. Ranavirus was detected in some of the dead frogs using PCR, and virus was also isolated in cell culture.

Coexistence of diploid and triploid hybrid water frogs: population differences persist in the apparent absence of differential survival.

Unlabelled: The role of differential selection in determining the geographic distribution of genotypes in hybrid systems has long been discussed, but not settled. The present study aims to asses the importance of selection in structuring all-hybrid Pelophylax esculentus populations. These populations, in which the parental species (P.

Genetic diversity in water frog hybrids (Pelophylax esculentus) varies with population structure and geographic location.

Pelophylax esculentus is a hybridogenetic frog originating from matings between P. ridibundus (RR) and P. lessonae (LL).

From clonal to sexual hybrids: genetic recombination via triploids in all-hybrid populations of water frogs.

Speciation via interspecific hybrids is very rare in animals, as compared to plants. Whereas most plants overcome the problem of meiosis between different chromosome sets by tetraploidization, animal hybrids often escape hybrid sterility by clonal reproduction. This comes at the expense of genetic diversity and the ability to purge deleterious mutations.

Mating with the wrong species can be right.

The evolutionary importance of interspecific hybridisation has been a controversial issue for quite some time. Some view mating between different species as a maladaptive process; others stress the adaptive value of choosing heterospecific mates under ecological conditions that favour hybrids. A recent paper by Pfennig is the first study to make a priori predictions of how adaptive choice between con- and heterospecific partners should vary with ecological conditions, and then testing these predictions experimentally.

Mutation accumulation and fitness effects in hybridogenetic populations: a comparison to sexual and asexual systems.

Background: Female only unisexual vertebrates that reproduce by hybridogenesis show an unusual genetic composition. They are of hybrid origin but show no recombination between the genomes of their parental species. Instead, the paternal genome is discarded from the germline prior to meiosis, and gametes (eggs only) contain solely unrecombined maternal genomes.

Food supply modifies the trade-off between past and future reproduction in a sexual parasite-host system (Rana esculenta, Rana lessonae).

Life history theory is concerned with the costs of survival, growth and reproduction under different ecological conditions and the allocation of resources to meet these costs. Typical approaches used to address these topics include manipulation of food resources, followed by measures of subsequent reproductive traits, and measures of the relationship between current and future reproductive investment. Rarely, however, do studies test for the interaction of past investment, present resource availability and future investment simultaneously.

Patterns of natural selection on size at metamorphosis in water frogs.

Strategies for optimal metamorphosis are key adaptations in organisms with complex life cycles, and the components of the larval growth environment causing variation in this trait are well studied empirically and theoretically. However, when relating these findings to a broader evolutionary or ecological context, usually the following assumptions are made: (1) size at metamorphosis positively relates to future fitness, and (2) the larval growth environment affects fitness mainly through its effect on timing of and size at metamorphosis. These assumptions remain poorly tested, because data on postmetamorphic fitness components are still rare.

The Effect of Assortative Mating on the Coexistence of a Hybridogenetic Waterfrog and Its Sexual Host.

In central Europe, the hybridogenetic waterfrog Rana esculenta, a hybrid between Rana ridibunda and Rana lessonae, lives in sympatry with one of its parental species, the poolfrog Rana lessonae. As R. esculenta has to backcross constantly with R.

Nestling provisioning in water pipits (Anthus spinoletta): do parents go for specific nutrients or profitable prey?

In this study, we investigated whether free-living insectivorous water pipits (Anthus spinoletta) choose prey according to biochemical quality as measured by protein, lipid, carbohydrate, energy and water contents and/or according to profitability as measured by density, size and catchability. Food preference - expressed in relation to availability - is estimated for 22 arthropod taxa (families and orders). Uni- and multivariate statistics detected no relationships between food preference and nutrient contents, but revealed that more larger prey items are fed to nestlings than smaller ones, both for all prey taken together and within individual taxa.

PERFORMANCE OF TADPOLES FROM THE HYBRIDOGENETIC RANA ESCULENTA COMPLEX: INTERACTIONS WITH POND DRYING AND INTERSPECIFIC COMPETITION.

The performance of three genotypes (LL, LR, RR) of tadpoles resulting from the hybrid mating system of Rana lessonae (phenotype L, genotype LL) and Rana esculenta (phenotype E, genotype LR) was determined in artificial ponds. The effects of interspecific competition and pond drying on growth, development, and survival of tadpoles were used to measure the performance of genotypes and the relative fitness of offspring. Among the three genotypes, tadpoles from the homogametic mating RR had the lowest survival, growth, and development under all environmental conditions.