There is considerable variation in cannibalism between different species and also between individuals of different species, although relatively little is known about what creates this variation. We investigated the degree of cannibalism in guppy (Poecilia reticulata) populations originating from high and low predation environments in Trinidad, and also how cannibalism was affected by the presence of refuges. Females from two populations were allowed to feed on juveniles from two populations in aquaria trials. The cannibalism was size-dependent and varied depending on both juvenile and female origin. Low predation females were more efficient cannibals and low predation juveniles were better at avoiding cannibalism compared to high predation guppies when no refuges were present. The high predation females were superior cannibals and the high predation juveniles were better at escaping cannibalism than the low predation guppies when refuges were present. We discuss whether the differences in cannibalism and response to refuge addition relate to predation-induced habitat shifts and differences in the guppies' natural environment.

Aim To assess habitat filtering and dispersal limitation in spore plant community assembly using bryophytes on recently emerged land uplift islands as study system. Location Gulf of Bothnia, northern Europe. Taxa Bryophytes, including the spore plant phyla Bryophyta (mosses) and Marchantiophyta (liverworts). Methods The species compositions of 20 coastal land uplift islands differing in age, area, connectivity and habitat composition were recorded in the field. In addition, we compiled a list of the regional species pool (446 species) and gathered data on species traits related to habitat affiliations (substrate, light, moisture, and pH) and dispersal capacity (regional abundance, spore size, sporophyte frequency, sexual system, vegetative propagules). For the 420 species with available trait data, we used multivariate generalized linear models to compare trait effects on species occurrence probabilities on the islands. Results Occurrence probabilities depended strongly on habitat affiliations. In addition, occurrence probabilities were lower for predominantly asexual species than for sexual species and for regionally rare than for regionally abundant species. Having specialized asexual propagules increased occurrence probabilities, but compensated only partly for the reductions in asexual species. No effect of the size of sexually produced spores was detected. Comparison of trait effects across island size and connectivity gradients revealed (a) reduced habitat filtering on larger islands and (b) decreasing negative effects of being predominantly asexual with increasing island connectivity. Conclusions Both habitat filtering and dispersal capacities affect the community assembly of spore plants on land uplift islands. Asexual mosses and liverworts show landscape scale (≤10 km) dispersal limitation. The weak or absent relationships between island connectivity and the effects of dispersal traits suggest that colonization is regulated mainly by habitat availability and the abundance of each species in a “regional spore rain” from which colonists are recruited.