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Schistosomes are parasitic flatworms that cycle between humans and freshwater snails, infecting more than 200 million humans. Many schistosome-endemic sites are invaded by non-native plants that snails cannot consume. Inedible plants could suppress snail growth, reproduction, and schistosome production by outcompeting edible resources. Alternatively, their decomposition could create edible detritus that fuels snail growth, reproduction, or schistosome production. We evaluated the nutritional effects of detritus from four widespread invasive plants on human schistosomes, Schistosoma mansoni, and snail intermediate hosts, Biomphalaria glabrata. We predicted that water hyacinth, which is fibrous and waxy, would cause poor growth, reproduction, and parasite production. In contrast, we predicted water lettuce, water fern, and duckweed would enable rapid growth, reproduction, and parasite production via better nutrient content and digestibility. Infected snails consuming water fern and water lettuce grew ~ 100% larger and produced ~ ninefold more cercariae than those consuming water hyacinth or duckweed. We then tested whether extended decomposition of water hyacinth could improve snail and schistosome performance but found negligible effects. Managers should prioritize removal of plants that produce nutritious detritus, because in situ destruction could increase schistosome transmission. Characterizing interactions among plant invasions, management, and parasites could facilitate solutions that improve human and environmental health. [ABSTRACT FROM AUTHOR]

Animal movement and resource use are essential considerations for effective environmental management, but they are challenging to quantify in expansive natural ecosystems such as oceans.We used a novel combination of fish tracking with expansive acoustic telemetry networks, stable isotope analysis and integrated modelling techniques to characterize the spatial and trophic ecology of a marine fish species, permit Trachinotus falcatus, and to address specific resource management needs in the Florida Keys.Tracking‐based movement patterns indicated that permit remained primarily within the designated fisheries management unit (92% of individuals), but they moved frequently among distinct habitat types and fisheries. Movement metrics from 109 individuals were integrated into Bayesian isotope mixing models, revealing variable reliance on seagrass‐ versus offshore/pelagic‐based energy channels amongst individuals. Variance was driven mainly by fish habitat use and home range size (km2).A telemetry‐based regional isoscape, informed by individual‐level estimates of resource use (% seagrass reliance; median = 70%, 29%–100% range), illustrated connectivity among habitats and fisheries. Specifically, seagrass flats were highly connected with the Florida reef tract, with frequent movements between these habitat types and a high reliance on seagrass‐based prey. There was a distinction between these fish and those occupying artificial reefs, with the latter showing high use of pelagic/offshore (i.e. planktonic) energy channels.Synthesis and applications. This study used a novel combination of telemetry, stable isotope analysis and integrated modelling techniques to identify two distinct ecotypes of a nearshore fish species, permit, in the Florida Keys. Of the two ecotypes, nearshore Florida Keys permit support multiple valuable fisheries; for these fish management should prioritize conservation of seagrass flats as a key permit food source, as well as fisheries protection measures at spawning sites on the Florida reef tract. This study highlights the capacity for integrated telemetry‐isotope models to provide key insights into animal ecology that has direct implications for applied environmental management. [ABSTRACT FROM AUTHOR]

Resource value assessment, in which competitors adjust behaviours according to the perceived value of a contested resource, is well described in animal contests. Such assessment is usually assumed to be categorical or linear; for example, males fight more aggressively when females are present than absent, or as female fecundity increases. Here, to our knowledge for the first time, we show quadratic resource value assessment, in which resource value is highest at a certain level and decreases in either direction. The mantis shrimp Neogonodactylus bredini occupies coral rubble burrows in a size-assortative manner: individuals of a certain body size inhabit burrows of a certain size. Using mock burrows of various sizes, we tested whether mantis shrimp (1) chose burrows predicted to be the best fit for their body size and (2) were more aggressive during, endured higher costs during and were more likely to win contests over burrows predicted to be best fit. Individuals chose burrows larger than their predicted best fit burrows. In contests, intruders without burrows were more likely to evict burrow residents when the burrow was slightly smaller than the intruder's predicted best fit size. Intruder success decreased as relative burrow size increased or decreased from this value. Intruders won by delivering more strikes and by being aggressive first. In contrast to intruders, burrow residents showed little evidence of resource value assessment. A literature review revealed that quadratic resource value assessment may play a role in contests over resources from territories to parasite hosts. Therefore, our results impact theoretical models of contest behaviour and may lend insight to how contests affect resource distributions. • Mantis shrimp inhabit protective coral rubble burrows in a size-assortative manner. • Intruders without burrows won fights over burrows smaller than the predicted ideal size. • Intruders won by delivering more high-force strikes and by being aggressive first. • Burrow residents showed no evidence of burrow size assessment. • The quadratic resource value assessment we describe may inform other systems. [ABSTRACT FROM AUTHOR]

In this paper, the resource programming ecology is pioneered. The limit nature of GLERP is developed into both limits: zero limit and ε limit, which is conducive to obtaining the programming results. The novel notions such as matrix operator, comb matrix, and rare matrix are available for resource programming. [ABSTRACT FROM AUTHOR]

The unambiguous recognition of a species’ habitat is a matter of debate. For terrestrial species, habitat is often defined as physical patches of a certain vegetation type in a matrix of non-habitat. Ecological resources that make up the habitat of a species may, however, only cover subsets of vegetation types or can be spatially dispersed in a complex way over different vegetation types. Here we present and test a procedure to recognize and delineate habitat according to a resource-based approach instead of a vegetation-based approach. We used the green hairstreak butterfly (Callophrys rubi) in a heathland landscape as a study case. Our resource-based habitat approach selects those zones that comprise essential resources and conditions within an appropriate spatial window. Variables that were retained in a logistic regression model were used to calculate larval, adult and combined habitat indices in a GIS, taking into account thermal constraints on resource-use, as this is a key habitat aspect for this heliothermous insect. To group different (and sometimes scattered) ecological resources into functional habitat zones, we derived a measure of space-use from mark-release-recapture data. By least-cost modelling this spatial window was adapted to the nature of the vegetation between sets of resources. The habitat zones that were delineated using this approach matched the observed distribution of butterflies significantly better than did a classic approach based on vegetation types with host plants only. Our approach provides concrete output for conservation purposes, like recognizing zones with the highest potential for habitat restoration. [Copyright &y& Elsevier]

A dynamic model of the functional response is a first prerequisite to be able to bridge the gap between local feeding ecology and grazing rules that pertain to larger scales. A mechanistic model is presented that simulates the functional response, growth and grazing time of ruminants. It is based on results of studies on voluntary food intake and animal production of ruminants. Physiological requirements and food quality are key factors that determine the intake. The model is also based on the results of studies on the functional response of grazers. Quantitative aspects of vegetations i.e. bulk density and height, and the animals’ mouth dimensions are the main factors that determine how much a grazer can swallow. The structure of the model applies to ruminants under tropical conditions. The model parameters are set and validated for the African buffalo, Syncerus caffer. Three variants of the model are elaborated: a non-reproducing female, a reproducing female and a male ruminant. The similarity between the results of the simulation runs and field data are considered to be satisfactory. The results suggest that the quality of the vegetation i.e. the crude protein content, together with the animal''s energy requirements, govern the daily intake of food. However, the quantitative characteristics of the vegetation, especially height, can be critical. The model aims to be a tool in the interpretation of empirical field data and in the development of grazing theory. Transparency, concision and a robust empirical basis were therefore striven after in the construction of the model. [Copyright &y& Elsevier]

1. Nitrogen (N) and phosphorus (P) availabilities are important ecological determinants of resource use in nature. Despite the wide range of hosts used by species of the genus Drosophila, elemental composition of natural resources of these flies has never been investigated. 2. Total body N and P contents were determined in seven species of wild-caught Drosophila, their natural hosts, and artificial diets routinely used to rear these flies in the laboratory. The flies tested included D. hydei, D. arizonae, D. simulans and D. pseudoobscura collected from rotting fruit (melons), and the cactophilic D. nigrospiracula, D. mojavensis and D. pachea collected from their specific host plants, Saguaro, Organpipe and Senita cactus, respectively. 3. Natural hosts varied in elemental composition, with fruit showing higher N (2·8–4·3% dry mass) and P (0·50–0·67%) levels compared with cacti (0·5–1·6% N; 0·01–0·29% P). No consistent differences in N and P levels were found between healthy and necrotic cactus tissue. 4. Total body N and P also varied among Drosophila species. This variation mirrored the levels of N and P found in the respective hosts and laboratory diets. N:P ratios were consistently lower in female flies compared with conspecific males suggesting phosphorus demands during oogenesis are high. 5. Potential mechanisms by which Drosophila deal with N or P limitation in nature are discussed. [ABSTRACT FROM AUTHOR]

Two populations (salt marsh and seagrass bed) of the hermit crab Pagurus longicarpus were sampled to examine associations between shell characteristics and egg production. Multivariate statistical analyses controlled for crab size and time of year, variables that otherwise could be confounded with shell effects. Although correlations between shell characteristics and reproduction existed in both populations, generalizations could not be made because associations varied within and between populations. Shell species was not associated with a female's reproductive state (i.e., whether or not she was barren when sampled) in either population. In the seagrass population, medium-large and large females occupying severely damaged or fouled shells were half as likely to be reproductive as females occupying other shell conditions. However, there was no association between shell condition and reproductive state for small and small-medium females in the seagrass population or among all females in the salt marsh population. In the seagrass population, small through medium-large reproductive females occupied shells more similar to their predicted shell size, regardless of whether the occupied shell was relatively small or large, than nonreproductive females. In contrast, relative shell sizes of reproductive and nonreproductive females were similar for large females in the seagrass population and all females in the salt marsh population. Clutch sizes were enhanced for females occupying Polinices duplicatus shells or shells larger than their predicted shell size in the seagrass population. Relative shell size also was associated with clutch size in the salt marsh population, but crabs occupying shells similar to their predicted shell size had the largest clutches. [ABSTRACT FROM AUTHOR]

When foraging in a social group, individuals are faced with the choice of sampling their environment directly or exploiting the discoveries of others. The evolutionary dynamics of this trade-off have been explored mathematically through the producer-scrounger game, which has highlighted socially exploitative behaviours as a major potential cost of group living. However, our understanding of the tight interplay that can exist between social dominance and scrounging behaviour is limited. To date, only two theoretical studies have explored this relationship systematically, demonstrating that because scrounging requires joining a competitor at a resource, it should become exclusive to high-ranking individuals when resources are monopolisable. In this study, we explore the predictions of this model through observations of the natural social foraging behaviour of a wild population of chacma baboons ( Papio ursinus ). We collected data through over 800 h of focal follows of 101 adults and juveniles across two troops over two 3-month periods. By recording over 7,900 social foraging decisions at two spatial scales we show that, when resources are large and economically indefensible, the joining behaviour required for scrounging can occur across all social ranks. When, in contrast, dominant individuals can aggressively appropriate a resource, such joining behaviour becomes increasingly difficult to employ with decreasing social rank because adult individuals can only join others lower ranking than themselves. Our study supports theoretical predictions and highlights potentially important individual constraints on the ability of individuals of low social rank to use social information, driven by competition with dominant conspecifics over monopolisable resources., Competing Interests: The authors declare there are no competing interests.

Organisms may reduce uncertainty regarding how best to exploit their environment by collecting information about resource distribution. We develop a model to demonstrate how competition can facilitate or constrain an individual's ability to use information when acquiring resources. As resource distribution underpins both selection on information use and the strength and nature of competition between individuals, we demonstrate interdependencies between the two that should be common in nature. Individuals in our model can search for resources either personally or by using social information. We explore selection on social information use across a comprehensive range of ecological conditions, generalizing the producer-scrounger framework to a wide diversity of taxa and resources. We show that resource ecology--defined by scarcity, depletion rate and monopolizability--determines patterns of individual differences in social information use. These differences suggest coevolutionary processes linking dominance systems and social information use, with implications for the evolutionary demography of populations., (© 2016 The Authors.)