Bean, C.W. and I.J. Winfield. 1995. Habitat use and activity patterns of roach ( Rutilus rutilus (L.)), rudd ( Scardinius erythrophthalmus (L.)), perch ( Perca fluviatilis L.) and pike ( Esox lucius L.) in the laboratory: the role of predation
Authors:M. Ferrante, G. Barone, M. Kiss, E. Bozóné-Borbáth, and G. L. Lövei
Lepidoptera is one of the most diverse orders of insects, their larvae are very abundant in many habitats, and frequent prey of various predators. To decrease predation risk, caterpillars developed several means of defence, among them timing their activity to avoid predators (seeking enemy-free time). Although the enemy-free time hypothesis is often invoked to explain caterpillar behaviour, empirical evidence for it is scarce. We tested whether such enemy-free time exists in a temperate forest by comparing predation pressure on artificial caterpillars during day and night on the ground in forest fragments in Denmark. We found a high predation rate, 23.9%d-1, and higher predation rate at night (30.9%d-0.5) than during the day (17.0%d-0.5), both by invertebrate (23.3%d-0.5 vs. 12.4%d-0.5) and vertebrate (8.5%d-0.5 vs. 3.3%d-0.5) predators. The most important predators were chewing insects (73.4% of all attacks) and small mammals (19.0%). Attack rates on red caterpillars were higher (30.0%d-1) than on green ones (19.5%d-1). Overall, these data do not support the idea that night activity can provide enemy-free time for solitary caterpillars on the temperate forest floor.
Authors:S. Fanfard, F. Charles, J. Coston-Guarini, C. Nozais, and J.-M. Guarini
The ecological process of community assembly is described as the succession of three phases: colonization, regulation and segregation. Early colonization remains the least studied and quantified phase of assembly. In order to fill this gap, an approach combining in situ experiments and modelling was proposed to study colonization by a benthic macrofauna community in open microcosms containing a single, non-limiting resource. The experiment was three months long. A total of 51 taxa were observed in the microcosms, but data analyses of the species composition and abundances revealed that five species, Capitella spp., Gammaropsis maculata, Erichtionus punctatus, Nereiphylla paretti and Harmothoe mariannae, explained most of the observed variation in the assembly process. The population dynamics of these species were simulated taking into account functional traits that govern individual interactions. The dynamic model simulated a demographic stochasticity due to low population densities that result from the small size of the experimental microcosms. Using this combined approach of experiments and modelling, we showed that predation interactions alone can account for the abundances and species composition of primary consumers during the transient phase of early colonization.
. Organization of the New England rocky intertidal community: role of predation, competition, and environmental heterogeneity. Ecological Monographs 46:355-393.
Organization of the New England rocky intertidal community: role of