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Our field observations on submersed macrophytes in the littoral zone of Cayuga Lake, N.Y., USA indicate that the shift in dominance from Myriophyllum spicatum L. to Elodea canadensis Michx. may be explained by the high abundance of an aquatic lepidopteran larva, Acentria ephemerella Denis & Schiffermüller. Experimental evidence for the preference of Acentria for Myriophyllum over Elodea was obtained...
The factors that promote ecological separation among closely related sympatric carnivores in tropical forests are poorly understood due to a paucity of field studies. Here, we report on community-wide food resource utilization patterns among eight co-existing carnivores in the Dzanga-Sangha Reserve, Central African Republic, based on a collection of 666 scats that were identified using a combination...
We analyzed the carbon and oxygen isotope composition of tooth enamel from mammals inhabiting marine and terrestrial ecosystems to determine whether these stable isotopes were robust indicators of foraging and habitat preferences. Consumers were separated into six habitats (offshore, nearshore, kelp beds, estuarine, freshwater, terrestrial). Consumer δ13C values were correlated with the δ13C values...
. Although the Plodia interpunctella-granulovirus system is one of the most studied models for insect-pathogen interactions, there are relatively few precise data on the dynamics of the virus in coexisting populations of these two organisms. Previous work has suggested that resource quality, in terms of the diet supplied to P. interpunctella, has a strong effect on the population dynamics of host...
Abstract. Previous studies in Fiji have shown that females of the amphibious sea-krait Laticauda colubrina are much larger than males, and have larger heads relative to body size. The dimorphism has been interpreted in terms of adaptation to a sex divergence in prey-size: females primarily eat large (conger) eels rather than smaller (moray) eels. The hypothesis that dimorphism is affected by niche...
. Previous studies in Fiji have shown that females of the amphibious sea-krait Laticauda colubrina are much larger than males, and have larger heads relative to body size. The dimorphism has been interpreted in terms of adaptation to a sex divergence in prey-size: females primarily eat large (conger) eels rather than smaller (moray) eels. The hypothesis that dimorphism is affected by niche divergence...
Abstract. The allotonic frequency hypothesis proposes that certain insectivorous bat species can prey upon moths that can hear bat echolocation calls by using echolocation frequencies outside the sensitivity range of moth ears. The hypothesis predicts that the peak frequencies of bat echolocation calls are correlated with the incidence of moths in the diets of these bats. The aim of this study was...
Hydrogen stable isotope analysis of feathers is an important tool for estimating the natal or breeding latitudes of nearctic-neotropical migratory birds. This method is based on the latitudinal variation of hydrogen stable isotope ratios in precipitation in North America (Dp) and the inheritance of this variation in newly formed feathers (Df). We hypothesized that the typically strong relationship...
The Ituri Forest, Democratic Republic of Congo (formerly Zaire) is an example of a closed canopy forest showing extreme depletion in 13C. 13C values for plants from the canopy top, from gaps in the canopy, and from the subcanopy average 29.01.7, 30.40.9, and 34.01.5, respectively. The 13C of forest mammals show these differences, with the subcanopy browsers (okapi, dwarf antelope) having 13C values...
The risk of infanticide may alter foraging decisions made by females, which otherwise would have been based on nutritional requirements and forage quality and availability. In systems where meat resources are spatially aggregated in late summer and fall, female brown bears ( Ursus arctos) would be faced with a trade-off situation. The need of reproductive females to accumulate adequate fat stores...
In biological systems, strontium (Sr) and barium (Ba) are two non-essential elements, in comparison to calcium (Ca) which is essential. The Sr/Ca and Ba/Ca ratios tend to decrease in biochemical pathways which include Ca as an essential element, and these processes are termed biopurification of Ca. The quantitative pathway of the biopurification of Ca in relation to Sr and Ba between two biological...
In an effort to understand the relationships between both the lipid content and 13C values of Collembola and their diet, isotopically labelled (C3 and C4) bakers yeasts were cultured and fed to two Collembolan species, Folsomia candida and Proisotoma minuta. The fatty acid composition of Collembola generally reflected that of the diet with the addition of the polyunsaturated components 18:2(n-6),...
Middle Miocene mammals are known from ~15 million-year-old sediments exposed along the Panama Canal of Central America, a region that otherwise has an exceedingly poor terrestrial fossil record. These land mammals, which represent a part of the ancient terrestrial herbivore community, include an oreodont Merycochoerus matthewi, small camel-like protoceratid artiodactyl Paratoceras wardi, two horses...
As more data have become available on lizard diets in the past few decades, researchers have stressed the importance of lizards as pollinators and seed dispersers. Whereas large body size has been traditionally put forward as a major biological factor allowing herbivory and frugivory in lizards, a recent review of frugivory and seed dispersal by lizards showed that frugivory might be considered to...
Seed dispersal plays a critical role in rainforest regeneration patterns, hence loss of avian seed dispersers in fragmented landscapes may disrupt forest regeneration dynamics. To predict whether or not a plant will be dispersed in fragmented forests, it is necessary to have information about frugivorous bird distribution and dietary composition. However, specific dietary information for frugivorous...
We used stable isotopes of C in breath, blood, feces and feathers to identify intra-individual changes in diet and the timescale of diet changes in free-living songbirds at a stopover site. Because accurate interpretation of differences between the δ13C of breath, plasma, and red blood cells (RBCs) relative to diet requires knowing the turnover rate of C within them, we determined the rate of change...
Cercopagis pengoi, a recent invader to the Baltic Sea and the Laurentian Great Lakes, is a potential competitor with fish for zooplankton prey. We used stable C and N isotope ratios to elucidate trophic relationships between C. pengoi, zooplankton (microzooplankton, 90–200 μm, mostly copepod nauplii and rotifers; mesozooplankton, >200 μm, mostly copepods), and zooplanktivorous fish (herring, size...
The evolutionary success of macrostomatan (enlarged-gape) snakes has been attributed to their ability to consume large prey, in turn made possible by their highly kinetic skulls. However, prey can be “large” in several ways, and we have little insight into which aspects of prey size and shape affect skull function during feeding. We used X-ray videos of broad-banded water snakes (Nerodia fasciata)...
Nitrogen isotopes have been widely used to investigate trophic levels in ecological systems. Isotopic enrichment of 2–5‰ occurs with trophic level increases in food webs. Host–parasite relationships deviate from traditional food webs in that parasites are minimally enriched relative to their hosts. Although this host–parasite enrichment pattern has been shown in multiple systems, few studies have...
The isotopic enrichment between an animal and its diet can vary among and within living systems, but the sources of variation are not yet fully understood. Some studies have found that diet quality or an animal’s nutritional status can influence the degree of trophic enrichment, while others have dismissed nutrition as a contributing factor. We evaluated the effects of nutrient and water availability...
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