Identifying and understanding ecological preferences for habitat or prey

Patchy, non-random associations of species with habitats and of consumers with particular types of food are commonly found in the ecological literature. In many cases, these patterns are reported to show some preference by an animal making choices about its environment. Generally, however, what is reported is simply the pattern of association and the process that gives rise to this pattern is not further examined. Nevertheless, there are numerous concepts that need to be considered simply to demonstrate the pattern, including the spatial and temporal scales at which the observations are made. When animals make choices between two objects, it is difficult to separate out potential negative, neutral or positive responses to either or both of the objects, without well thought-out manipulative experiments. Apparent preference for food may be influenced by “catchability” or “acceptability” of the prey and/or the past history of the consumer and the experiments to separate these effects are naturally complex. Many experiments examining preferences are beset by problems of non-independence and lack of appropriate controls, which makes them difficult to interpret. This review introduces some of the logical, conceptual, experimental and statistical problems that beset many studies of preference and proposes important steps that must be considered in further studies to unravel this fascinating topic.     

An investigation of human-animal interactions and empathy as related to pet preference,ownership, attachment,and attitudes in children

ABSTRACT

Osgood's Semantic Differential technique was used with a sample of 12 animal names to see if they elicited responses that were distinctively characteristic, and therefore useful in uncovering connotative meaning. The 100 survey participants responded with unanimity to some species, whereas their responses to others were highly variable. Results disclosed a taxonomy of grouping animal names that differed from the normal zoological taxonomy. This suggests that the technique may be useful for discovering the connotations that animals have, and what various animal species may mean to people.     

The Life History and Host Range of Charidotis pygmaea (Col.: Chrysomelidae), a Biological Control Agent for Lantana montevidensis (Verbenaceae)

The life cycle and host range of Charidotis pygmaea Klug were investigated to assess its suitability for release as a biological control agent for Lantana camara L. and L. montevidensis (Sprengel) Briquet. Adults fed and deposited eggs on the underside of leaves of both species. They generally laid fewer eggs in the dry winter months when lantana yellows or drops its leaves. Larvae fed on the upper leaf surface and pupation occurred on the leaves or stems. Development from egg to adult took approximately 50 days. Survival to the adult stage was greater, and the development time was shorter on L. montevidensis than on all varieties of L. camara tested, suggesting that the agent would be ineffective against L. camara. Forty-two plant species were tested to determine host specificity in choice oviposition and larval feeding trials. These demonstrated that C. pygmaea did not pose a threat to non-target species. Consequently, C. pygmaea was approved for release in Australia and through its ability to survive the dry season, should assist in the control of L. montevidensis.     

Flavour preference acquired via a beverage-induced conditioning and its transposition to solid food: Sucrose but not maltodextrin or saccharin induced significant flavour preferences in pigs

When exposed to novel food during food transitions, growing pigs often elicit a neophobic response that is responsible for decreased food consumption. Flavour preference conditioning may represent an interesting way to reduce neophobia and improve food intake in growing pigs. The present series of experiments investigated the pig's conditioned preference for a flavoured beverage added with different carbohydrates and sweeteners and the possible transition of those beverage-induced preferences to flavoured solid food. In Experiment 1A, nine juvenile pigs were given three two-day conditioning sessions: they received a flavoured beverage added with 1.125% sucrose (F + S_1.125) and a second flavoured beverage with no additive (F−). In Experiment 1B, nine juvenile pigs were given six two-day conditioning sessions: they received a flavoured beverage added with 10% sucrose (F + S₁₀) and a second flavoured beverage with no additive (F−). In subsequent two-choice drinking tests, the pigs exhibited no clear-cut preference for F + S_1.125, whereas F + S₁₀ was preferred compared to F− (P < 0.05) but only during the first subsequent two-choice drinking tests, suggesting that pigs developed a short-term preference for the flavour previously paired with 10% but not 1.125% sucrose. The Experiment 2 was conducted to assess the independent effects of visceral (caloric intake) and gustative (sweet taste) reinforcement in flavour preference conditioning. Nine juvenile pigs were subjected to four three-day conditioning sessions: they received flavoured beverages added with 2.25% maltodextrin (F + m, caloric intake), 0.37% saccharin (F + s, sweet taste), or no additive (F−). During further two-choice drinking tests, no clear-cut preference emerged, but the consumption of F + m was 107% and 35% higher than that of F− and F + s, respectively. Despite pigs exhibited some conditioned flavour preferences during two-choice drinking tests in Experiments 1B and 2, no clear-cut preference was observed during two-choice feeding tests with flavoured solid food. Overall, these findings highlight the importance of the combination and/or synergy between gustative and visceral reinforcements for conditioned flavour preference and suggest that a visceral reinforcement via maltodextrin might be sufficient to condition such a preference. Moreover, the absence of clear-cut preference during two-choice feeding test illustrates the difficulty to transpose a flavour preference acquired via a sweet beverage to solid food. Further studies are needed to investigate the failure of saccharin-conditioned preference in pigs.     

Niche modification and stability of competitive systems. III. Simulation model analysis

Simulation model for niche shift in ecological time scale was constructed on the basis of the optimal foraging theory. In accordance with the previous experimental study (Shimada andFujii , 1985), the model competitive system consisted of 2 parasitoid wasp species utilizing 4 host stages. Wasps were assumed to choose host stages in the manner that they realized the maximal gain/cost values, where gain was represented by body weight of a wasp progeny emerging from each host stage and cost was expressed by time required to search for and detect an unparasitized host. The number of parasitized hosts in each host stage was calculated numerically by usingArditt 's (1983) model for avoidance of superparasitism. The model simulated well the experimental results ofShimada andFujii (1985) andShimada (1985). Sensitivity analysis of the model showed that the experimentally derived criterion for competitive coexistence (different second-best host stages between competing species even with the common best) was not necessarily the indispensable condition for niche shift and separation, but that if the criterion was not satisfied, stable competitive coexistence occurred only in the narrow range of the parametric values. Further, niche shift in ecological time scale made the competitive coexistence more stable than fixed niche on which the current niche theory stands.     

On Indifference Zone Selection with a Preference Threshold

This paper discusses a selection criterion that generalizes the well-known concept of indifference zone selection through a preference threshold. A population is preferred to another population if the difference in the sums of observed values exceeds a given nonnegative threshold value. We present an argument for this selection rule by modelling preference by imprecise previsions. We aim at guidelines to design a selection experiment, which is characterized by two numbers: the number of necessary observations per population, and the preference threshold. Next to the probability of correct selection we also need a second specification. In this paper we consider a probability of false selection that is strongly related to the minimum probability of correct selection. Based on this model the outcome of an experiment may be ‘no selection’, at least not based on strong preference of a single population. The ideas are presented through a simple selection problem for normal populations with common known variance. Although the theory has a frequentist nature, the derivation and justification of the selection rule through imprecise previsions relies on Bayesian foundations, and via this route we gain more insight into the selection criterion.     

Varietal susceptibility of certain broad bean seeds to infestation with Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) (Coleoptera: Bruchidae)

Seeds susceptibility of eight broad bean varieties to Callosobruchus maculatus (F.) and Callosobruchus chinensis (L.) infestation were studied for the first time in free- and no-choice methods in the laboratory of Plant Protection Department, Faculty of Agriculture, Zagazig University. The relation between certain seed physical characteristics and some biological and and infestation parameters of both insects in the two studied methods were evaluated. None of these varieties were resistant to both insects, showing various levels of susceptibility. Biological and infestation parameters were significantly different among varieties except the developmental period. In free- choice method, Giza 3 was the most susceptible variety to both insects, since produced the highest progeny of 246.67 and 75.67 adults and susceptibility index (SI) of 10.25 and 7.42, respectively, while the least susceptible variety was Giza 716. In no– choice method, Nubaria 5 and Sakha 1 were the most susceptible varieties to C. chinensis, while Nubaria 3 and Giza 3 to C. maculatus. Differences between physical characters of varieties were significant. Seed hardness were correlated negatively and seed coat thickness positively with laid eggs, progeny and (SI) of both insects in free-choice method. Also seed coat thickness correlated positively with weight loss and seed damage (%) of C. chinensis and negatively of C. maculatus. To reduce seed losses the cultivation of the least susceptible variety (Giza 716) is encouraged and considered for breeding purposes to avoid insecticide usage.     

Conspecific host discrimination by ovipositingEuphydryas editha butterflies: Its nature and its consequences for offspring survivorship

Ovipositing E. editha butterflies display post-alighting discrimination among patches of Collinsia torreyi, one of their major hosts in the General's Highway (GH) population at a montane site in California. Females tended to accept (i.e. oviposit on) dense patches of this host and to reject sparse patches. Possible behavioural mechanisms underlying this tendency are discussed. The consequences of this non-random pattern of oviposition for egg and larval survivorship were investigated and no differences were found in the survivorship of larvae on acceptable and unacceptable collinsias.     

Cyanide toxicity and interference with diet selection in quail (Coturnix coturnix)

Cyanide is a ubiquitous substance in the environment. Most of the cyanide absorbed by an animal is detoxified by enzymatic combination with sulfur, thus the detoxification process imposes a nutritional cost. In mammals, interactions among nutrients and toxics may influence the composition of the diet and food intake, as a function of positive or negative post-ingestive feedback. The present work aimed to describe the toxic effects of cyanide, and to determine whether cyanide interferes with diet selection in quail (Coturnix coturnix). A toxicological study was performed with 27 female quails that were assigned to three groups that received by gavage 0, 1.0 or 3.0 mg of KCN/kg/day, for 7 consecutive days. The diet selection trial was conducted with 20 female quails, that had access to two separate rations: a conventional quail ration and the same ration supplemented with 1% NaSO₄. During the toxicological study, clinical signs of poisoning and death occurred in a quail treated with cyanide. Histological changes were found only in animals dosed with cyanide, and these consisted of mild hepatic periportal vacuolation, an increased number of vacuoles in the colloid of the thyroid glands, and spongiosis in the mesencephalon. No clinical signs were found in any quail throughout the diet selection trial. There were no significant differences in food consumption or ration preference. In conclusion, exposure to cyanide promotes damage to the liver and central nervous system in quails. In contrast, the ingestion of sulfur by quail was not affected by exposure to cyanide.     

Modelling the interactions between ammonium and nitrate uptake in marine phytoplankton

An empirically based mathematical model is presented which can simulate the major features of the interactions between ammonium and nitrate transport and assimilation in phytoplankton. The model (ammonium-nitrate interaction model), which is configured to simulate a generic microalga rather than a specified species, is constructed on simplified biochemical bases. A major requirement for parametrization is that the N:C ratio of the algae must be known and that transport and internal pool sizes need to be expressed per unit of cell C. The model uses the size of an internal pool of an early organic product of N assimilation (glutamine) to regulate rapid responses in ammonium-nitrate interactions. The synthesis of enzymes for the reduction of nitrate through to ammonium is induced by the size of the internal nitrate pool and repressed by the size of the glutamine pool. The assimilation of intracellular ammonium (into glutamine) is considered to be a constitutive process subjected to regulation by the size of the glutamine pool. Longer term responses have been linked to the nutrient history of the cell using the N:C cell quota. N assimilation in darkness is made a function of the amount of surplus C present and thus only occurs at low values of N:C. The model can simulate both qualitative and quantitative temporal shifts in the ammonium-nitrate interaction, while inclusion of a derivation of the standard quota model enables a concurrent simulation of cell growth and changes in nutrient status. <br>