The mosquitofish Gambusia affinis, globally introduced to fight mosquitos, is a threat for freshwater ecosystems and a model for sex chromosome evolution. Cyto-/genomics reveals aneocentromere to shield parts of its evolutionary young female sex chromosome (W) that actively differentiates by expansion of transcribed transposons, while major sequence divergence or gene decay are missing.
The dryness in the Atacama Desert led to fracture networks of salt-poor sand wedges outlining salt-rich polygons as potential microbial habitats. Mineral composition, pH, electrical and thermal conductivity, water activity and content were analyzed for their relevance to habitability. The results emphasize the relevance of polygonal networks as microbial habitats in extreme environments.
Empirical studies show divergent impacts of alien populations on ecosystems which hinders the creation of a unified theory. The authors propose a synthesis that categorizes hypotheses along a timeline of invasion considering population, community and ecosystem levels. For any given case study, this framework provides a guide to choose the appropriate concepts according to the stage of invasion.
The study investigated the oxygen budget of 4 arctic lakes using high-frequency data. Incubation experiments measured sediment metabolism. Volume-averaged oxygen depletion in situ was independent of water temperature and duration of ice-cover. Modeling under ice-oxygen dynamics requires consideration of optical properties, biological and transport processes modifying oxygen.
Study of the effects of macrophyte removal on phytoplankton, zooplankton and macroinvertebrates at five sites with highly variable characteristics repeating the same Before-After-Control-Impact design to disentangle general from site-specific effects. Macrophyte removal had negative effects on biodiversity, esp. on zooplankton and macroinvertebrates. It had positive effects on phytoplankton.
