Dlaczego rozmnażanie płciowe jest tak rozpowszechnione w przyrodzie? Jakie są korzyści hermafrodytyzmu? Badanie stułbi zdolnych do dwóch typów rozrodu może ułatwić znalezienie czynników wpływających na ewolucję strategii rozrodczych.

Why is the sexual mode of reproduction so common in nature? What are the advantages of hermaphroditism? Studying water hydra, capable of both sexual and asexual reproduction, may help us better understand the evolution of different reproductive strategies.

Przedstawiciele gatunku, którzy podczas ewolucji nie podlegają ograniczeniom, powinni rozmnażać się zaraz po urodzeniu, produkować maksymalną liczbę potomstwa i fyć wiecznie. Ewolucjoniści nazywają takie hipotetyczne istoty demonami Darwina. Wydaje się, że niektóre organizmy zbliżają się do tego demonicznego ideału...

If evolution of species was not confined by any restńctions, organisms would reproduce right after being born, produce the maximum number of offspring, and live indefinitely. Such hypothetical organisms are dubbed "Darwinian demons" Certain organisms do resemble this "demonic" ideal...

We compared different net sampling methods for microplastic quantitative collection by sampling different water volumes with nets of different mesh sizes. Sampling covered freshwater lake and reservoir with a significant degree of eutrophication located in Central Poland. The fibres were the main type of plastic collected from sampling sites and constituted 83% of all microplastic particles. Fibres of 700–1900 μm dominated in the samples. The size of mesh affected the amount of fibres collected. Small fibres of 10–200 μm in length were collected using only a fine net of 20 μm mesh size. The total amount of fibres depended on sample volumes; concentrations of microplastics were higher for smaller water volumes. It is likely that clogging with phytoplankton and suspended particles reduced the filtration capacity of the finest nets when large volumes were sampled, which led to an underestimation of microplastic. To our knowledge, this is the first study to provide evidence that the amount of small microfibres depends on mesh size and that the total microplastic abundance in freshwaters in Poland depends on the sample volume. We suggest sampling rather larger than smaller water volumes to assess the level of microplastic contamination more accurately, but clogging, which reduces the filtration capacity of finest nets, should be taken into account when eutrophic freshwater environments are studied.