Despite much theoretical work, the molecular-genetic causes and evolutionary consequences of asexuality remain largely undetermined. Asexual animal species are rare, evolutionarily short-lived, and thought to suffer mutational meltdown as a result of lack of recombination. Whole-genome analysis of 11 sexual and 11 asexual genotypes of Daphnia pulex indicates that current asexual lineages are in...

Previous studies have demonstrated that certain pesticides, including carbaryl and endosulfan, can modulate the expression of predator-induced morphology in Daphnia. These pesticides affect the transmission of nervous impulses in vertebrates and invertebrates. The aim of this study was to determine the role of two neurotransmitter systems, excitatory cholinergic transmission and inhibitory gamm...

The origin and maintenance of sex remains one of the most debated topics in evolutionary biology. Investigations of the molecular genetic consequences of asexuality, such as direct estimation of mutation and recombination rates in asexual lineages, are critical for explaining the prevalence of sex in nature. In this study, we use long-term mutation accumulation lines of asexually propagating Da...

The anthelmintic activity of the eugenol against the fish parasite Gyrodactylus sp. was evaluated. After 1-h exposure to 5 and 10 mg/L eugenol, mortality of the parasites was near 80 and 90%, respectively. The concentrations used in the antiparasitic test were not toxic to Daphnia pulex (LC50 42.5 mg/L).

To estimate costs and benefits of antipredator defenses in the Chaoborus–Daphnia system, we employed lake enclosures wherein controls (C) had no predators, the predation (P) treatment had freely swimming Chaoborus, and the kairomone (K) treatment predators were sequestered in a mesh tube apart from the Daphnia. Population growth (r) of two Daphnia pulex clones, one responsive (RC) and the other...

Recent studies have indicated that nitrogen availability can be an important determinant of primary production in freshwater lakes and that herbivore growth can be limited by low dietary nitrogen availability. Furthermore, a lack of specific essential nitrogenous biochemicals (such as essential amino acids) might be another important constraint on the fitness of consumers. This might be of part...