Coyote capture vulnerability relative to space use and trap density

Coyotes (Canis latrans) are reported to be less vulnerable to capture in familiar areas of territories, however, most studies do not control for trap density across the territory. We determined if accounting for trap density provided a better explanation of observed capture rates. Based on a sample of 24 captured coyotes (6 inside core areas and 18 on peripheries of occupied areas) the best fitting model describing capture location only accounted for trap density and not relative time spent in each region. Our results suggest that coyote capture rates are a function of trap density in an area and not novelty avoidance. Placing traps in core areas of territories can increase the probability of capturing individuals from specific territories to increase the effectiveness of management or research activities. © 2011 The Wildlife Society.     

Resolving abbreviations to their senses in Medline

MOTIVATION: Biological literature contains many abbreviations with one particular sense in each document. However, most abbreviations do not have a unique sense across the literature. Furthermore, many documents do not contain the long forms of the abbreviations. Resolving an abbreviation in a document consists of retrieving its sense in use. Abbreviation resolution improves accuracy of document retrieval engines and of information extraction systems. RESULTS: We combine an automatic analysis of Medline abstracts and linguistic methods to build a dictionary of abbreviation/sense pairs. The dictionary is used for the resolution of abbreviations occurring with their long forms. Ambiguous global abbreviations are resolved using support vector machines that have been trained on the context of each instance of the abbreviation/sense pairs, previously extracted for the dictionary set-up. The system disambiguates abbreviations with a precision of 98.9% for a recall of 98.2% (98.5% accuracy). This performance is superior in comparison with previously reported research work. AVAILABILITY: The abbreviation resolution module is available at http://www.ebi.ac.uk/Rebholz/software.html.     

Microhabitat use by a post-settlement stage estuarine fish: evidence from relative abundance and predation among habitats

Seagrass beds provide food and shelter for many fish species. However, the manner in which fishes use seagrass bed habitats often varies with life stage. Juvenile fishes can be especially dependent on seagrass beds because seagrass and associated habitats (drift macroalgae) may provide an effective tradeoff between shelter from predation and availability of prey. This study addressed aspects of habitat use by post-settlement pinfish, Lagodon rhomboides (Linneaus), an abundant and trophically important species in seagrass beds in the western North Atlantic and Gulf of Mexico. Abundance of post-settlement fish in seagrass beds was positively related to volume of drift macroalgae, but not to percent cover of seagrass, indicating a possible shelter advantage of the spatially complex algae. Tethering experiments indicated higher rates of predation in seagrass without drift macroalgae than in seagrass with drift macroalgae. Aquarium experiments showed lower predation with higher habitat complexity, but differences were only significant for the most extreme cases (unvegetated bottom, highest macrophyte cover). Levels of dissolved oxygen did not differ between vegetated and unvegetated habitats, indicating no physiological advantage for any habitat. Seagrass beds with drift macroalgae provide the most advantageous tradeoff between foraging and protection from predation for post-settlement L. rhomboides. The complex three-dimensional shelter of drift macroalgae provides an effective shelter that is embedded in the foraging habitat provided by seagrass. Drift macroalgae in seagrass beds is a beneficial habitat for post-settlement L. rhomboides by reducing the risk of predation, and by providing post-settlement habitat within the mosaic (seagrass beds) of adult habitat, thus reducing risks associated with ontogenetic habitat shifts.     

Environmental influences on DNA curvature

DNA curvature plays an important role in many biological processes. To study environmental influences on DNA curvature we compared the anomalous migration on polyacrylamide gels of ligation ladders of 11 specifically-designed oligonucleotides. At low temperatures (25 degrees C and below) most of the sequences exhibited a degree of anomalous migration. Increased temperature had a significant effect on the anomalous migration (curvature) of some sequences but limited effects on others; at 50 degrees C only 1 sequence migrated anomalously. Mg2+ had a strong influence on the migration of certain sequences, whilst spermine enhanced the anomalous migration of a different set of sequences. Sequences with a GGC motif exhibited greater curvature than predicted by the presently-used angles for the nearest-neighbour wedge model and are especially sensitive to Mg2+. The data have implications for models for DNA curvature and for environmentally-sensitive DNA conformations in the regulation of gene expression.     

Sea lice escape predation on their host

Parasites seldom have predators but often fall victim to those of their hosts. How parasites respond to host predation can have important consequences for both hosts and parasites, though empirical investigations are rare. The exposure of wild juvenile salmon to sea lice (Lepeophtheirus salmonis) from salmon farms allowed us to study a novel ecological interaction: the response of sea lice to predation on their juvenile pink and chum salmon hosts by two salmonid predators-coho smolts and cut-throat trout. In approximately 70% of trials in which a predator consumed a parasitized prey, lice escaped predation by swimming or moving directly onto the predator. This trophic transmission is strongly male biased, probably because behaviour and morphology constrain female movement and transmission. These findings highlight the potential for sea lice to be transmitted up marine food webs in areas of intensive salmon aquaculture, with implications for louse population dynamics and predatory salmonid health.     

Habitat overlap between predatory benthic fish and their invertebrate prey in streams: the relative influence of spatial and temporal factors on predation risk

1. The spatial heterogeneity of ecosystems as well as temporal activity patterns of organisms can have far‐reaching effects on predator–prey relationships. We hypothesised that spatiotemporal constraints in mesohabitat use by benthic fish predators would reduce habitat overlap with benthic invertebrates and lead to mesohabitat‐specific predation risks. 2. We analysed the spatiotemporal activity patterns of two small‐bodied benthivorous fishes, gudgeon (Gobio gobio) and stone loach (Barbatula barbatula), and of benthic invertebrates in a small temperate stream during three 24‐h field experiments. By applying a novel method of field video observation, we monitored the spatiotemporal foraging behaviour of the fish in their natural environment. A parallel analysis of invertebrate mesohabitat use by means of small area Hess sampling allowed a direct estimation of habitat overlap at a pool–riffle scale. 3. Gudgeon showed a dominant spatial activity pattern preferring pools at all times of day, whereas stone loach used both mesohabitats but with a distinct temporal (nocturnal) activity pattern. The patterns of residence were not identical with those of active foraging. Invertebrate community composition differed significantly between mesohabitats but not between times of day. More than half of the total dissimilarity between pools and riffles was accounted for by six invertebrate taxa. Five of these were subject to higher fish predation in pools than in riffles. The total prey consumption of the two fish species together in pools was about three times as high as in riffles. Trophic niche breadth of stone loach and thus its predation range was broader than that of gudgeon. 4. These results indicate that the potential predation risk for stream invertebrates depends on the combination of spatial and temporal patterns of both predator and prey. Given the distinct differences in predation risk found between pools and riffles, we conclude that spatial heterogeneity at the mesohabitat scale can influence mechanisms and consequences of selective predation. We also suggest that the analysis of spatiotemporal predator–prey relationships should not be based on the premise that the main residence habitat and active foraging habitat of a predator are identical.     

Environmental influences on long-term variability in marine plankton

The major patterns of geographical and seasonal variability of the plankton of the north-east Atlantic and the North Sea are described to provide the background to a presentation of the dominant patterns of year-to-year fluctuations in the abundance of the plankton of the area for the period 1948 to 1984. A feature of the variability is a marked similarity both between species and between areas. The main pattern of year-to-year change has the form of a quasi linear downward trend in abundance with, superimposed on this, an element of variability with a periodicity of about three years. There is a complex relationship between the plankton and an estimate of changes in the frequency of westerly weather which can be interpreted in terms of influences acting over limited periods of the seasonal cycle coupled with persistence in the stocks of zooplankton. Relationships between year-to-year variations in the abundance of phytoplankton and zooplankton can be interpreted in terms of a response by the zooplankton to variations in food supply coupled with feed-back to the phytoplankton involving in situ nutrient regeneration.     

Environmental influences on fish assemblages in irrigation ponds

Ponds are common features of the landscape and are considered important for freshwater biodiversity conservation. Although fish have a significant impact on the lentic ecosystems, the environmental factors that regulate fish assemblages in human-created water bodies, such as irrigation ponds, remain unclear. We evaluated the relationship between environmental factors and the fish assemblage structure in 31 ponds located in northern Japan. Species richness (range: 1–9) was positively correlated with the size of the inflow channel. Multivariate analyses revealed that the size of the inflow channel was a better predictor for species richness than lake morphology (surface area and maximum depth), vegetation coverage, water quality (turbidity, pH, DO, and EC), distance to the main channel, and distance to an adjacent pond. Species richness was significantly different between ponds with and without an inflow channel. Furthermore, three of the four most commonly observed species are thought to be relatively tolerant to low oxygen. Given that ponds have a relatively high local extinction rate resulting from exposure to stressful conditions, such as low oxygen and/or small population sizes, our results suggest that immigration from surrounding water bodies plays an important role in maintaining species richness of pond-dwelling fish.     

Environmental influences on neural crest cell migration

Neural crest cells migrate extensively and interact with numerous tissues and extracellular matrix components during their movement. Cell marking techniques have shown that neural crest cells in the trunk of the avian embryo migrate through the anterior, but not posterior, half of each sclerotome and avoid the region around the notochord. A possible mechanism to account for this migratory pattern is that neural crest cells may be inhibited from entering the posterior sclerotome and the perinotochordal space. Thus, interactions with other tissue may prescribe the pattern of neural crest cell migration in the trunk. In contrast, interactions between neural crest cells and the extracellular matrix may mediate the primary interactions controlling neural crest cells migration in the head region. © 1993 John Wiley & Sons, Inc.     

Environmental influences on mountain gorilla time budgets

Data on the time budgets of mountain gorillas (Gorilla gorilla beringei) were collected during field studies in the Virunga Volcanoes region of Rwanda and Zaire. Focal sampling was used to determine the proportion of time that individuals of different age/sex classes spent in several mutually exclusive activity states. The gorillas spent the majority of daylight hours feeding; most of the rest of the day was devoted to resting, with little time spent moving or engaged in social activity. The time budget varied among the different subhabitats used by the gorillas, and the gorillas satisfied subsistence needs more quickly when in areas where food was more abundant and/or of better nutritional quality. Silverbacks spent more time feeding than all other age/sex classes, but age/sex class differences were not great. All age/sex classes responded to variability in habitat quality in similar fashion. Unlike the case for many other primates, there was no significant seasonal variation in time budgets. There was a direct relationship between group size and time spent feeding, although variation in relation to group size was lower than that in relation to variation in habitat quality. These results are consistent with the relationship of feeding time to body size in primates. They are also consistent, with other evidence that social foraging entails a cost to gorilla females, but that this cost is low in comparison to those faced by many other primates. Permanent association with males apparently offers little ecological disadvantage to females, who are likely to be more than compensated by mutualistic benefits.     

Sire coloration influences offspring survival under predation risk in the moorfrog

When breeding, male moor frogs Rana arvalis develop a bright blue dorsal coloration which varies in intensity between males. We tested whether this colour acts as a potential signal of a male's genetic quality to female moor frogs by artificially crossing pairs of males differing in the extent of the blue coloration to the same female. Maternal half-sibships provide a powerful means to detect paternal genetic effects on offspring as they control for other potentially confounding variables. We assayed the ability of offspring to survive an ecologically realistic test of fitness by exposing them to predation by the larvae of the predatory water beetle Dytiscus marginalis. Although sire's coloration did not influence tadpole body size, it did affect their ability to survive the predation trial. Offspring of bright blue males had higher survival than those of dull males when exposed to large predators, which were more voracious predators than smaller ones. Our results indicate that paternal secondary sexual traits provide information about genetic effects on offspring fitness in this species, but suggest that these effects may be context-dependent. Variable selection caused by contextual dependence may have important consequences for the evolution of female choice rules, and for the maintenance of genetic variation for both male trait and female preference.     

Ultraviolet light influences habitat preferences in a fish under predation risk

Environmental light conditions are of general importance in predator–prey interactions. In aquatic systems, prey individuals experience different levels of predation risk depending on the properties of the visual environment, such as structural complexity or water transparency. To reduce the threat of predation, prey should move to habitats providing better protection against visual predators. We studied the role of UV wavelengths in habitat choice behaviour under predation risk in a fish, the three-spined stickleback (Gasterosteus aculeatus) that uses UV signals in different contexts of intraspecific communication. In a laboratory experiment sticklebacks were exposed to a predatory threat and given the choice between two escape habitats, one providing full-spectrum conditions including UV light (UV+) and one without UV wavelengths (UV−). Fish from two rearing treatments were tested, one group had been raised under natural lighting conditions (UV+), the other group under UV-deficient lighting conditions (UV−). Sticklebacks from the UV+ group preferred the UV− habitat as a refuge which suggests that predator avoidance behaviour is UV-related in this species with UV− conditions presumably being advantageous for prey fish. However, individuals from the UV− treatment group were equally attracted to both presented light habitats. It is possible that these fish could not discriminate between the two light habitats due to physiological limitations caused by their rearing conditions. Further control trials with neutral-density filters revealed that the UV− habitat preference of UV+ fish in the main experiment was rather not influenced by a difference in achromatic brightness between the UV+ and UV− habitat.     

Environmental diversity: on the best-possible use of surrogate data for assessing the relative biodiversity of sets of areas

The conservation goal of representation of biodiversity (in the broad sense of all species) in protected areas requires best-possible use of available surrogate information. One standard approach is based on indicator groups of taxa. A minimum set of areas having at least one representation of each indicator species is taken to be representative of other organisms. This same minimum-set approach is adapted to other attributes of biodiversity, for example, derived environmental clusters. A weakness of these approaches is that useful information is lost; for example, for environmental clusters, there is no distinction made either among or within clusters. A more powerful surrogate approach can use some expression of environmental and/or biotic pattern so that variation among areas is seen as part of a continuum rather than partitioned into arbitrary clusters/attributes. The challenge in using pattern effectively is to adopt a robust model for the relationship between pattern and the underlying units of biodiversity, i.e. species. An environmental space (a continuum or ordination pattern), combined with the standard ecological continuum model relating species to environmental space, has advantages over other patterns based on hierarchy or distance matrices. Because an environmental space can be estimated either directly (observed environmental data) or indirectly (data on indicator groups), the corresponding surrogate-measure of biodiversity, environmental diversity (ED) makes best-possible use of either kind of data. We conclude that the arbitrariness of the attribute approach can be replaced by a robust surrogate pattern approach that is flexible and avoids unwarranted assumptions.     

Environmental noise reduces predation rate in an aquatic invertebrate

Noise is one of a wide range of disturbances associated with human activities that have been shown to have detrimental impacts on a wide range of species, from montane regions to the deep marine environment. Noise may also have community-level impacts via predator–prey interactions, thus jeopardising the stability of trophic networks. However, the impact of noise on freshwater ecosystems is largely unknown. Even more so is the case of insects, despite their crucial role in trophic networks. Here, we study the impact of underwater noise on the predatory functional response of damselfly larvae. We compared the feeding rates of larvae under anthropogenic noise, natural noise, and silent conditions. Our results suggest that underwater noise (pooling the effects of anthropogenic noise and natural noise) decreases the feeding rate of damselflies significantly compared to relatively silent conditions. In particular, natural noise increased the handling time significantly compared to the silent treatment, thus reducing the feeding rate. Unexpectedly, feeding rates under anthropogenic noise were not reduced significantly compared to silent conditions. This study suggests that noise per se may not necessarily have negative impacts on trophic interactions. Instead, the impact of noise on feeding rates may be explained by the presence of nonlinearities in acoustic signals, which may be more abundant in natural compared to anthropogenic noise. We conclude by highlighting the importance of studying a diversity of types of acoustic pollution, and encourage further work regarding trophic interactions with insects using a functional response approach.     

Environmental influences on the monoterpene variation in Hedeoma drummondii

Samples of leaves were taken from clonal stock of Hedeoma drummondii to determine the effect of light and temperature variations on the monoterpenes. Low light intensity and cold conditions caused significant differences in quantitative levels of some of the major monoterpene constituents, as well as total yield. The changes are discussed in relation to photosynthate availability and implications for taxonomy.