Optimal Foraging Research Papers - Academia.edu (original) (raw)

�� he status of cheetahs Acinonyx jubatus in West Africa is poorly documented. In the literature, the species is reported to range in Gambia, in the South of Mauritania, West of Mali in the Boucle du Baoule complex, in the North and South... more

�� he status of cheetahs Acinonyx jubatus in West Africa is poorly documented. In the literature, the species is reported to range in Gambia, in the South of Mauritania, West of Mali in the Boucle du Baoule complex, in the North and South of Mali, and West of Burkina Faso at the western border and in a region extending on the border between eastern Burkina Faso, northern Togo, northern Benin and South West of Niger (Marker 1998, Nowell & Jackson 1996).

Summary of the resource density-dependent occurrence (time budgets) of each behaviour of nauplii of the copepod species <i>Temora longicornis</i>, <i>Centropages hamatus</i>, <i>Oithona nana</i> and... more

Summary of the resource density-dependent occurrence (time budgets) of each behaviour of nauplii of the copepod species <i>Temora longicornis</i>, <i>Centropages hamatus</i>, <i>Oithona nana</i> and Acartia tonsa. All data are means ±SD for each resource concentration. ´N.ó means the behaviour is not observed.

Our traditional view of the interactions between marine organisms is conceptualized as food webs where species interact with one another mainly via direct consumption. However, recent research suggests that understudied non-consumptive... more

Our traditional view of the interactions between marine organisms is conceptualized as food webs where species interact with one another mainly via direct consumption. However, recent research suggests that understudied non-consumptive interactions, such as behaviourally mediated indirect interactions (BMIIs), can influence marine ecosystems as much as consumptive effects. Here, we show, to our knowledge, the first experimental evidence and quantification of bottom-up BMIIs in plankton food webs. We used observational, modelling and experimental approaches to investigate how behavioural responses to resource availability influence predation mortality on grazers with different foraging strategies (ambushing versus active foraging). A three-level food chain was used: phytoplankton as resource, copepod nauplii as grazers of phytoplankton and a large copepod as a predator. Ambushers showed little change in foraging activity with resource availability, whereas active foragers decreased t...

1. Bark beetles and their predators are useful systems for addressing questions concerning diet breadth and prey preference in arthropod natural enemies. These predators use bark beetle pheromones to locate their prey, and the response to... more

1. Bark beetles and their predators are useful systems for addressing questions concerning diet breadth and prey preference in arthropod natural enemies. These predators use bark beetle pheromones to locate their prey, and the response to different pheromones is a measure of prey preference.2. Trapping experiments were conducted to examine geographic variation in the response to prey pheromones by two bark beetle predators, Thanasimus dubius and Temnochila virescens. The experiments used pheromones for several Dendroctonus and Ips prey species (frontalin, ipsdienol, and ipsenol) and manipulated visual cues involved in prey location (black vs. white traps). The study sites included regions where the frontalin‐emitter Dendroctonus frontalis was in outbreak vs. endemic or absent.3. There was significant geographic variation in pheromone preference for T. dubius. This predator strongly preferred a pheromone (frontalin) associated with D. frontalis at outbreak sites, while preference was...

Drongos are well known to participate in mixed-species bird flocks, but it is not clear whether they are mostly commensalists, catching insects that other species disturb, or kleptoparasites, stealing food directly from other species. We... more

Drongos are well known to participate in mixed-species bird flocks, but it is not clear whether they are mostly commensalists, catching insects that other species disturb, or kleptoparasites, stealing food directly from other species. We studied the foraging ecology ...

Summary 1. Optimal foraging theory assumes that a predator preys selectively to maximize fitness gain. The associated model assesses predator’s fitness gain by estimating prey profitability in terms of appropriate foraging costs and... more

Summary 1. Optimal foraging theory assumes that a predator preys selectively to maximize fitness gain. The associated model assesses predator’s fitness gain by estimating prey profitability in terms of appropriate foraging costs and benefits. While model developing, unsuccessful foraging was included in the model because it is inevitable and costly for a predator. However, it has rarely been taken into account in previous studies, nor has the consumption success been included in the estimation of prey profitability. Thus, although such model may successfully predict prey selection of many predators, it is inadequate in explaining prey selection of predators with highly variable consumption success. 2. In this study, we tested the prediction of optimal foraging model by accounting for consumption success in prey profitability for the prey selection of Whitmania laevis (Hirudinida: Hirudinidae), a shell‐invading leech with highly variable consumption success in different prey. Five sn...

The first peopling of Sahul (Australia, New Guinea and the Aru Islands joined at lower sea levels) by anatomically modern humans required multiple maritime crossings through Wallacea, with at least one approaching 100 km. Whether these... more

The first peopling of Sahul (Australia, New Guinea and the Aru Islands joined at lower sea levels) by anatomically modern humans required multiple maritime crossings through Wallacea, with at least one approaching 100 km. Whether these crossings were accidental or intentional is unknown. Using coastal-viewshed analysis and ocean drift modelling combined with population projections, we show that the probability of randomly reaching Sahul by any route is <5% until ≥40 adults are ‘washed off’ an island at least once every 20 years. We then demonstrate that choosing a time of departure and making minimal headway (0.5 knots) toward a destination greatly increases the likelihood of arrival. While drift modelling demonstrates the existence of ‘bottleneck’ crossings on all routes, arrival via New Guinea is more likely than via northwestern Australia. We conclude that anatomically modern humans had the capacity to plan and make open-sea voyages lasting several days by at least 50,000 year...

Predators can play important roles in structuring their communities through top‐down effects on the distribution and abundance of their prey. Sharks are top predators in many marine communities, yet few studies have quantified those... more

Predators can play important roles in structuring their communities through top‐down effects on the distribution and abundance of their prey. Sharks are top predators in many marine communities, yet few studies have quantified those factors influencing their distribution and hunting behaviour. Here, we use location data from 340 predatory interactions between white sharks Carcharodon carcharias (Linnaeus), and Cape fur seals Arctocephalus pusillus pusillus (Schreber), data on associated environmental factors, and spatial analysis, including a novel application of geographic profiling – a tool originally developed to analyse serial crime – to investigate spatial patterns of shark attack and search behaviour at Seal Island in False Bay, South Africa. We found that spatial patterns of shark predation at this site are nonrandom. Sharks appear to possess a well‐defined search base or anchor point, located 100 m seaward of the seal's primary island entry–exit point. This location is n...

One of the major alterations observed in mealybug Planococcus citri parasitized by Leptomastix dactylopii is a strong reduction of laid eggs, which is evident soon after parasitization. Venom injection in unparasitized hosts determines a... more

One of the major alterations observed in mealybug Planococcus citri parasitized by Leptomastix dactylopii is a strong reduction of laid eggs, which is evident soon after parasitization. Venom injection in unparasitized hosts determines a drastic reduction of fecundity indicating that this female secretion injected at the oviposition plays a key-role in host regulation. In order to assess the impact of parasitism and venom injection on host reproductive tissues, ovaries were dissected at different time intervals after these treatments and observed by light and transmission electron microscopy. The developing eggs showed clear symptoms of degeneration, already half an hour after parasitization or venom injection. Heat and protease treatments of venom nearly suppressed its effects on host reproduction, indicating that proteins are likely responsible for the observed alterations. The electrophoretic profile of venom proteins covers a wide range of molecular masses between 15 to 200 kDa ...

The movement of limbless terrestrial animals differs fundamentally from that of limbed animals, yet few scaling studies of their locomotor kinematics and morphology are available. We examined scaling and relations of morphology and... more

The movement of limbless terrestrial animals differs fundamentally from that of limbed animals, yet few scaling studies of their locomotor kinematics and morphology are available. We examined scaling and relations of morphology and locomotion in sidewinder rattlesnakes (Crotalus cerastes). During sidewinding locomotion, a snake lifts sections of its body up and forward while other sections maintain static ground contact. We used high-speed video to quantify whole-animal speed and acceleration; the height to which body sections are lifted; and the frequency, wavelength, amplitude and skew angle (degree of tilting) of the body wave. Kinematic variables were not sexually dimorphic, and most did not deviate from isometry, except wave amplitude. Larger sidewinders were not faster, contrary to many results from limbed terrestrial animals. Free from the need to maintain dynamic similarity (because their locomotion is dominated by friction rather than inertia), limbless species may have gre...

Summary 1. Optimal foraging theory assumes that a predator preys selectively to maximize fitness gain. The associated model assesses predator’s fitness gain by estimating prey profitability in terms of appropriate foraging costs and... more

Summary 1. Optimal foraging theory assumes that a predator preys selectively to maximize fitness gain. The associated model assesses predator’s fitness gain by estimating prey profitability in terms of appropriate foraging costs and benefits. While model developing, unsuccessful foraging was included in the model because it is inevitable and costly for a predator. However, it has rarely been taken into account in previous studies, nor has the consumption success been included in the estimation of prey profitability. Thus, although such model may successfully predict prey selection of many predators, it is inadequate in explaining prey selection of predators with highly variable consumption success. 2. In this study, we tested the prediction of optimal foraging model by accounting for consumption success in prey profitability for the prey selection of Whitmania laevis (Hirudinida: Hirudinidae), a shell‐invading leech with highly variable consumption success in different prey. Five sn...