Covell, who is likewise new to illustrating children's books, draws his Rat and Roach halfway between adorable and creepy, in brushy computer ink.
At WwTW A, measured concentrations of effluent during the roach exposures between fertilization and 60 dph were 0±0%0% (tap water control), 0 ± 0% (river water control), 15.0 ± 1.3%, 24.9 ± 1.4%, 42.6 ± 2.2%, and 100 ± 0% (mean ± SEM).
We cannot exclude that variation in roach morphology between the lakes reflects differences in swimming activity (in response to differing predation risk); however, roach from Döllnsee, where predation risk was highest, had morphologies that appear better adapted to rapid and extended swimming, which contrasts the conclusion that predation risk always induces reduced swimming activity of prey.
The presence of such a continuous morphological distribution between roach and bream would indicate that successful reproduction between hybrids is widespread in the systems examined.
In four cases (two fish with a morphology intermediate between roach and hybrid in Lough Ramor and two fish intermediate between bream and hybrids in Ross Lake), DFA was not able to correctly assign the specimens to the a priori identified groups.
Furthermore, inter-species differences in toxicokinetics between roach and rainbow trout might also influence concentrations of PAH metabolites in bile measured after exposure to contaminated sediment.
Our hypotheses were that by crossing low and high algal resource treatments with a gradient of predation pressure from juvenile roach, interaction effects between bottom-up and top-down forces on zooplankton would arise.
Hybridisation represents a viable conduit for introgression of genes between roach and bream.
Average pairwise FST between roach samples from different catchments was 0.028 and comparisons were consistently highly significant (Table 3, Additional file 4).
Morphometric analysis in Lough Ramor identified two fish with morphologies intermediate between roach and roach × bream hybrids, one of these was heterozygous and the other was not available for genetic analyses.
