The ambient temperature of an environment has potential to influence many aspects of the behavior and physiology of small-bodied ectotherms, including brush-legged Wolf spiders Schizocosa ocreata (Hentz, 1844) (Araneae: Lycosidae). Temperature varies significantly, and often unpredictably, in their habitat throughout the spring breeding season, and is known to influence male Schizocosa courtship behavior. Currently unknown is what effect fluctuations in ambient temperature alone might have on critical, non-behavioral sexual signals such as female silk and chemical cues. We collected cues from mature, virgin females and subjected each sample to one of three thermal treatments (40°C, 20°C, or -12°C), at constant humidity. We presented treated female cues to mature males and recorded male response across treatment types as a behavioral indicator of signal degradation. There were no significant differences across treatments in the frequency or duration of male behaviors, including critical courtship and exploratory behaviors. Our results suggest that thermally induced degradation of female sexual signals is negligible for this species and likely has little or no influence on male behavior.

No description available.

The chemosensory abilities of fishes, are important in order to understand how prey can perceive and avoid predators. Predator-naïve Channel catfish were exposed to four extracts over eight sessions (naïve bass water (NBW), bass that were fed catfish water (BFCW), catfish skin extract (CS), and naïve bass water paired with catfish skin extract (CO)) to determine whether they have an innate predator response to potential chemical cues indicating possible predation risk. Movement was quantified as grid squares crossed, directional changes, and tail beats. Response increased during the first minute following stimulus injection and decreased during the second minute. Channel catfish increased movement upon exposure to stimuli from NBW, CS and CO but not to BFCW. Increased response to bass odor while habituating to catfish skin extract, which presumably contains alarm pheromone, suggests that catfish learned to recognize bass odor without external reinforcement.

The thesis results of two laboratory experiments focusing on the impacts of predation risk, prey density and habitat complexity on predator-prey interaction strengths and predator metabolic rates, complemented by a brief review of the subject. The experimental system used in the first experiment consisted of cladoceran prey, larvae of three dragonfly species (Sympetrum sanguineum, Libellula quadrimaculata, Ischnura cf. elegans) as intermediate predators, and larvae of a large dragonfly species (Aeshna sp.) as a top predator. The second experiment of investigated how predation risk influences metabolic rates of the intermediate predators.

The dissertation thesis focuses on predator ecology in artificial water bodies. Paper I deals with the importance of chemical cues for predator-prey interactions in an aquatic environment. Here, I demonstrate that the ability to detect chemical cues represents a survival benefit for prey species. Paper II points out gillnet methodological bias, which may have subsequent repercussions in field evaluation of a predator's presence and assessment of larger fish abundance in general. Papers III and IV focus on asp Leuciscus aspius spawning grounds. In Paper III, I demonstrate how males maximize their spawning chances by early arrival and in Paper IV, I evaluate the predation pressure of asp prey, Alburnus alburnus, directed on asp eggs.

No description available.

Rodent commensal species produce great damage in agriculture and urban areas. As invasive species they can endanger local species and are carriers and vectors of several important zoonoses. Control methods rely mainly on the use of warfarins, which can be inadvertently be taken up by untargeted species. Warfarins have also lost their efficacy in rodents due to the development of genetic resistance. In addition, these methods are considered inhumane as they cause a slow and painful death due to haemorrhages. Olfaction is a main source for environmental risk assessment by rodents, and it can be used to modify their use of space. My aim in this thesis was to identify behavioural reactions of the house mouse (Mus musculus), using laboratory strains as models of wild animals, to ecologically meaningful chemical messages, including predator and plant chemical olfactory cues. My results showed that mice avoided complex ferret olfactory cues and ethanol which is a ubiquitous chemical related to fruit rotting and ripening. The feline protein Fel d 1, which belongs to the secretoglobin family and is a major cat allergen in humans, did not elicit significant avoidance or alter foraging behaviour in mice. However, Trimethylthiazoline purified from fox faeces, elicited clear avoidance behaviour and stress responses. I carried out a bibliographic review to evaluate and discuss rodent pest control methods from an ethical standpoint. This literature showed that many of the current methods of pest control are considered inhumane, and do not tally with current society concerns and welfare standards in other domains such as farms or laboratory animals. These results raise new research questions to identify ferret and plant chemical compounds that can induce rodent avoidance, and to carry out next stage of research with wild animals both under laboratory and field conditions.

Throughout their lives, prey organisms must balance the tradeoff between fitness-related activities and the risk of predation. To successfully mediate such tradeoffs, prey must have an accurate method to gauge current predation risk. For many aquatic organisms, the use of chemosensory information has been shown to be a ubiquitous and useful tool in mediating predation risk. The chemical cues to which aquatic organisms respond include the odour of known predators and the odour of a damaged conspecific or known or closely related heterospecific. In fishes, the response to damage-released cues from conspecifics or closely related heterospecifics has been shown to be innate, while the response to distantly related unknown heterospecific cues are likely learned. In a series of laboratory and field studies I examined the role of learning in the ability of fathead minnows to respond to damage-released cues of brook stickleback as an indication of predation risk. My results indicate that minnows from a population without stickleback do not recognize stickleback cues as dangerous. However, following the introduction of stickleback, minnows learn to recognize stickleback cues as dangerous. Further study indicated a low ratio of stickleback to minnows in a given population will decrease the likelihood of learning when compared with a similar sized population containing a higher ratio of stickleback to minnows. I also demonstrated that an increase in habitat complexity decreases the ability of minnows to learn to recognize stickleback cues. Studies have further demonstrated that in the face of predation (as indicated by chemical cues from minnows and stickleback) minnows will decrease their antipredator response when in the presence of a fish shoal, especially a shoal of conspecifics. Finally, an examination of the effects of a minnows length, body condition and breeding status indicate that morphological parameters can play a significant role in the intensity of response to heterospecific and conspecific damage-released cues. Previous works have demonstrated that behavioural responses to heterospecific damage-released cues increase the probability of the receiver surviving a predation event. This has important implications for predator/prey interactions and consequently factors affecting the learning and use of such cues deserve increasing attention from ecologists.

Throughout their lives, prey organisms must balance the tradeoff between fitness-related activities and the risk of predation. To successfully mediate such tradeoffs, prey must have an accurate method to gauge current predation risk. For many aquatic organisms, the use of chemosensory information has been shown to be a ubiquitous and useful tool in mediating predation risk. The chemical cues to which aquatic organisms respond include the odour of known predators and the odour of a damaged conspecific or known or closely related heterospecific. In fishes, the response to damage-released cues from conspecifics or closely related heterospecifics has been shown to be innate, while the response to distantly related unknown heterospecific cues are likely learned. In a series of laboratory and field studies I examined the role of learning in the ability of fathead minnows to respond to damage-released cues of brook stickleback as an indication of predation risk. My results indicate that minnows from a population without stickleback do not recognize stickleback cues as dangerous. However, following the introduction of stickleback, minnows learn to recognize stickleback cues as dangerous. Further study indicated a low ratio of stickleback to minnows in a given population will decrease the likelihood of learning when compared with a similar sized population containing a higher ratio of stickleback to minnows. I also demonstrated that an increase in habitat complexity decreases the ability of minnows to learn to recognize stickleback cues. Studies have further demonstrated that in the face of predation (as indicated by chemical cues from minnows and stickleback) minnows will decrease their antipredator response when in the presence of a fish shoal, especially a shoal of conspecifics. Finally, an examination of the effects of a minnows length, body condition and breeding status indicate that morphological parameters can play a significant role in the intensity of response to heterospecific and conspecific damage-released cues. Previous works have demonstrated that behavioural responses to heterospecific damage-released cues increase the probability of the receiver surviving a predation event. This has important implications for predator/prey interactions and consequently factors affecting the learning and use of such cues deserve increasing attention from ecologists.

Orientador: Paulo Sergio Moreira Carvalho de Oliveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-13T21:02:13Z (GMT). No. of bitstreams: 1 Rodrigues_PedroAugustodaPos_M.pdf: 3475275 bytes, checksum: 8ba90669e5ed880eab0fca20ec5bb371 (MD5) Previous issue date: 2009 / Resumo: Em matas de restinga da Ilha do Cardoso (SP), forrageadoras da formiga arborícola crepuscular/noturna Odontomachus hastatus podem caçar a > 8 m do ninho. O forrageamento se dá principalmente no dossel, em uma intricada rede de galhos, onde esta formiga deve ser capaz de aprender o caminho de retorno ao ninho. O ambiente do dossel e seu hábito noturno tornam esta espécie um interessante modelo para pesquisa em orientação espacial. Para investigar os mecanismos de orientação empregados por O. hastatus, realizamos experimentos sob condições controladas em laboratório, usando uma arena circular onde marcas visuais e químicas poderiam ser manipuladas. Testamos a influência de: (i) um padrão de dossel artificial; (ii) pistas visuais horizontais; (iii) uma pista tridimensional (cilindro); e (iv) pistas químicas na superfície do chão da arena. Nossos resultados demonstram que O. hastatus se guia principalmente por pistas visuais (pistas do dossel e pistas horizontais), o que está de acordo com o encontrado em formigas diurnas. A luminosidade noturna (lua/estrelas) é aparentemente suficiente para produzir silhuetas contrastantes do dossel e vegetação circundante, e podem ser importantes referenciais de orientação. Por outro lado, substâncias químicas não funcionaram como pistas para o retorno de forrageadoras. Ao contrário do chão plano da arena circular, é possível que marcas químicas sejam importantes na marcação de rotas arbóreas bifurcadas de O. hastatus. O uso de pistas químicas por formigas é geralmente considerado importante para orientação noturna e este trabalho é a primeira demonstração experimental do uso de pistas visuais por uma formiga noturna e arborícola. O presente estudo contribui para o desenvolvimento de estudos comparativos sobre a evolução da orientação espacial em formigas e outros insetos. / Abstract: In the 'restinga' sandy plain forest of Ilha do Cardoso (SP), foragers of the crepuscular/nocturnal arboreal ant Odontomacus hastatus may hunt > 8 m away from their nests. Foraging takes place mainly in the canopy amongst the intricate net of branches and bifurcations, where ant foragers must be able to learn the way back to the nest. The canopy environment together with the nocturnal habit makes this species an interesting model for research on spatial orientation. In order to investigate orientation mechanisms employed by O. hastatus, we performed controlled laboratory experiments using a circular arena where chemical and visual cues could be manipulated. We tested the influence of: (i) an artificial canopy pattern; (ii) horizontal visual cues; (iii) a tridimensional cue (cylinder); (iv) chemical cues on the ground surface. Our results demonstrate that O. hastatus is guided mainly by visual cues (canopy and horizontal cues), which is in accordance with other diurnal arboreal ants. Nocturnal luminosity (moon/stars) is apparently sufficient to produce contrasting silhouettes from the canopy and surrounding vegetation, which may be important as orientation references. On the other hand, chemical substances provided no cues to returning foragers. Contrary to the plain floor of the circular arena, it is possible that chemical cues are important for marking bifurcated arboreal routes of O. hastatus. The use of chemical cues by ants is generally considered / Mestrado / Ecologia / Mestre em Ecologia