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Satellite telemetry and stable isotope analysis were used to confirm that oceanic areas (where water depths are >200 m) are alternative feeding habitats for adult female green sea turtles (Chelonia mydas), which have been thought to be obligate herbivores in neritic areas (where depths are <200 m). Four females were tagged with satellite transmitters and tracked during post-nesting periods from...
Young leaves of most species experience remarkably higher herbivore attack rates than mature leaves. Considerable theoretical effort has focused on predicting optimal defense and tradeoffs in defense allocation during leaf expansion. Among others, allocation to secondary chemistry may be dependent on growth constraints. We studied flavanoid production during leaf development in two species of Inga...
Diapause allows insects to temporally avoid conditions that are unfavorable for development and reproduction. However, diapause may incur a cost in the form of reduced metabolic energy reserves, reduced potential fecundity, and missed reproductive opportunities. This study investigated a hitherto ignored consequence of diapause: trade-offs involving sequestered chemical defense. We examined the aristolochic...
As trees grow tall and the resistance of the hydraulic pathway increases, water supply to foliage may decrease forcing stomata to close and CO2 uptake to decline. Several structural (e.g. biomass allocation) and physiological adjustments, however, may partially or fully compensate for such hydraulic constraints and prevent limitations on CO2 uptake and growth. The degree to which trees compensate...
Empirical studies on bat assemblages have shown that richness is not appreciably influenced by local processes such as ecological interactions. However, most of these studies have been done in large areas that include high heterogeneity, and they analyse all bat species within such areas, and thus they may be not reflecting local but supra-community conditions. We followed an ecomorphological approach...
Extreme weather events can lead to immediate catastrophic mortality. Due to their rare occurrence, however, the long-term impacts of such events for ecological processes are unclear. We examined the effect of extreme winters on barn owl (Tyto alba) survival and reproduction in Switzerland over a 68-year period (∼20 generations). This long-term data set allowed us to compare events that occurred only...
The hypothesis that migratory bird populations are limited during the non-breeding season is increasingly supported by empirical studies that also suggest consequences that carry-over into subsequent seasons. Although variation in food supply is the best supported explanation for non-breeding season limitation, the ecological mechanisms and physiological consequences are not well understood. We both...
Predators have the potential to limit the spread of pathogens not only by selecting infected prey but also by shaping prey demographics. We tested this idea with an epidemiological experiment in which we simulated variable levels of size-selective predation on zooplankton hosts and monitored the persistence of host and parasite populations. In the absence of simulated predation, the virulent protozoan...
Conspecific attraction is the preferential settlement into habitat patches with conspecifics. To be a good proximate strategy, fitness gains from settling with conspecifics must outweigh the costs of higher conspecific densities, such as intraspecific competition. Two types of benefits have been proposed to explain conspecific attraction: Allee effects (i.e., positive density dependence) and conspecific...
Solar ultraviolet-B radiation (UV-B) can have large impacts on the interactions between plants and herbivorous insects. Several studies have documented effects of UV-B-induced changes in plant tissue quality on the feeding performance of insect larvae. In contrast, the effects of UV-B-induced plant responses on the behavior of adult insects have received little attention. We carried out a series of...
C and N stable isotope ratios of red deer (Cervus elaphus) bone collagen (154 individuals) from five modern populations occupying geographically different habitats are reported. No significant difference was observed between deer occupying forested and non-forested environments subject to similar climatic conditions suggesting a simple “canopy effect” is not observed. Mean population δ13C is negatively...
Repercussions of species loss on ecosystem processes depend on the effects of the lost species as well as the compensatory responses of the remaining species in the community. We experimentally removed two co-dominant plant species and added a 15N tracer in alpine tundra to compare how species’ functional differences influence community structure and N cycling. For both of the species, production...
Forest soils and streams receive substantial inputs of detritus from deciduous vegetation. Decay of this material is a critical ecosystem process, recycling nutrients and supporting detrital-based food webs, and has been attributed, in part, to leaf litter species composition. However, research on why speciose leaf litter should degrade differently has relied on a bottom-up approach, embracing interspecific...
Interspecific brood parasitism in birds presents a special problem for the host because the parasitic offspring exploit their foster parents, causing them to invest more energy in their current reproductive effort. Nestling brown-headed cowbirds (Molothrus ater) are a burden to relatively small hosts and may reduce fledgling quality and adult survival. We documented food-provisioning rates of one...
While known to be uniformly non-feeding, short-lived, and potentially short dispersing, sponge larvae display different behaviours (swimming ability and taxis). Our aim was to show whether sponge larvae with different behaviours exhibit different dispersal strategies under variable intensity of water movements. We first assessed the distribution of larvae of six taxa: Dictyoceratida spp., Dysidea avara...
Experimental research has identified many putative agents of amphibian decline, yet the population-level consequences of these agents remain unknown, owing to lack of information on compensatory density dependence in natural populations. Here, we investigate the relative importance of intrinsic (density-dependent) and extrinsic (climatic) factors impacting the dynamics of a tree frog (Hyla arborea...
Although both environment and genetics have been shown to affect the mycorrhizal colonization of host plants, the impacts of these factors on hosts that can be dually colonized by both ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) fungi are less understood. We examined the influence of environment and host crosstype on the EM and AM colonization of cottonwoods (Populus angustifolia and natural...
The pathways linking consumer effects to primary productivity (PPR) are likely to vary among taxa because of species-specific trophic and functional differences. Thus, it is necessary to understand the dynamics of consumer–PPR interactions so that effects of species loss on ecosystem function can be addressed from a mechanistic approach. In this study, I used three fish taxa (orangethroat darter,...
Nitrogen (N) and carbon–nitrogen (C:N) ratio are key foliar traits with great ecological importance, but their patterns across biomes have only recently been explored. We conducted a systematic census of foliar C, N and C:N ratio for 213 species, from 41 families over 199 research sites across the grassland biomes of China following the same protocol, to explore how different environmental conditions...
Community structure is the observable outcome of numerous processes. We conducted a laboratory experiment using a microbial model system to disentangle effects of nutrient enrichment, dispersal, and predation on prey species richness and predator abundance at local and metacommunity scales. Prey species included: Chilomonas sp., Colpidium striatum, Colpoda cucullus, Paramecium tetraurelia, P. caudatum...
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