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Coexistence among ecologically similar species is often facilitated through temporal or spatial partitioning mechanisms that reduce or eliminate direct interaction. However, in many communities exhibiting guild structure, wherein potential competitors may also prey on one another, sympatric relationships persist despite species' similar life history strategies, spatial and temporal restrictions imposed by ephemeral habitats, and resource limitations that promote competition and predation. To identify the ecological roles of species-specific behavioral patterns within aquatic guilds, I quantified larval intraspecific agonistic behavior among two species of intraguild (IG) predators, Ambystoma opacum and A. tigrinum, and their shared intraguild prey, A. maculatum. All species exhibited similar ontogenetic patterns of aggression, characterized by peaks of aggression early in development and subsequent gradual decreases through metamorphosis. However, the intensity of aggression varied considerably among guild species through development, as did behavioral responses to varying levels of ambient water temperature, invertebrate prey density, and presence of predatory odonate naiads. The observed patterns suggest that guild species, despite morphological and physiological similarities, exhibit unique behavioral responses through ontogeny and in response to habitat variables, suggesting that temporally staggered breeding phenologies have contributed to behavioral divergence among these sympatric congeners. However, in situ observations of larval behavior, although largely in agreement with laboratory results on timing of increased aggression, indicated that IG predators exhibited pond-level species partitioning and do not necessarily co-occur despite being regarded as sympatric. These results, taken together with observed species-specific impacts of IG predators on IG prey, suggest that ecologically similar IG predators exert widely differing predatory pressure on shared prey, and that similarities among guild species may ultimately result in habitat partitioning across local scales.

Orientador: Célio Fernando Baptista Haddad / Banca: Rogério Pereira Bastos / Banca: Anne Taffin D'Heursell Baldisseri / Banca: Ricardo Jannini Sawaya / Banca: Itamar Alves Martins / Resumo: Até a presente tese, a informação sobre predação e estratégias defensivas em anuros estava fragmentada e desconexa na literatura científica. Na ausência de uma revisão sobre o tema, algumas especulações foram geradas baseadas nas impressões pessoais de diversos pesquisadores. Por exemplo, existem muitos ou poucos relatos de anuros sendo apresados? Um determinado comportamento defensivo já foi descrito em algum lugar, ou é inédito? Qual a relação entre os predadores e os mecanismos de defesa dos anuros? Essas e outras perguntas estavam em aberto. Mesmo em livros texto, os quais geralmente revisam os assuntos abordados de forma abrangente, nota-se o parco conhecimento sobre o tema, sendo estes sempre os menores capítulos dos livros e de conteúdo razoavelmente superficial. Todavia, muita informação já foi gerada e muita ainda está por vir. É nesse sentido que idealizamos e realizamos o presente estudo, visando reunir grande parte do conhecimento atual e gerar novas previsões e hipóteses testáveis. Assim, relacionamos os predadores atuais e naturais dos anfíbios anuros (incluindo as desovas e pós-metamórficos) e revisamos as principais estratégias defensivas dos adultos (pós-metamórficos). Muitos dados apresentados são inéditos e outros compilados da literatura, mas ambos analisados de maneira integrada e sempre dando enfoque evolutivo nas discussões apresentadas. Consideramos este estudo um ponto inicial para compreendermos mais profundamente as estratégias defensivas dos anuros e sua relação com os predadores naturais. / Abstract: Until the present moment, the information about defensive strategies and predation upon anurans was fragmented and disconnected in the scientific literature. In the absence of an overview of the subject, some speculations have been raised based on personal points of view of several scientists. For example, are there many or few reports of predation upon anurans? A specific defensive behavior has already been described or not? How is the relationship between the defensive strategies and predator mechanisms? These and odder questions were hard to answer. Even in text books, where the subjects are treated in a broad way we can notice the poor knowledge of the subject and these are always the shorter and superficial chapters. However, many information is already available and many is about to come. Therefore, we idealized and did the present thesis, aiming to joint a large part of the current knowledge and promoting some previsions and testable hypotheses. So, we related the actual and natural predators of anurans (including eggs and post-metamorphics) and reviewed the main defensive strategies of the adults (post-metamorphics). A great amount of the data presented is novel and other set of data were found in the available literature, but both were analyzed simultaneously with an evolutive approach. We consider this thesis a starting point of a deeper comprehension of the anurans’ defensive strategies and their relationship with natural predators. / Doutor

Orientador: Nilza Maria Martinelli / Coorientador: Ana Lúcia Benfatti Gonzalez Peronti / Banca: Valmir Antonio Costa / Banca: Arlindo Leal Boiça Junior / Resumo: A agricultura é de suma importância para o desenvolvimento do Brasil. O estado de São Paulo, com significativa produção e produtividade de diversas culturas, é o maior produtor de cana-de-açúcar e citros, e o terceiro em café. No entanto, grandes perdas econômicas e ambientais ocorrem pelo uso indiscriminado de agrotóxicos para controlar insetos-praga, incluindo cochonilhas. Informações sobre insetos benéficos atualmente presentes nas regiões produtoras são fundamentais para o manejo integrado de pragas. Este estudo teve como objetivo fazer um levantamento de inimigos naturais associados a espécies de cochonilhas consideradas pragas, primárias ou secundárias, para as culturas de cana-de-açúcar, citros e café no estado de São Paulo, relacionando à origem de cada espécie; especificidade a presa; e as possíveis adaptações a predação ou parasitismo em relação às características morfológicas macroscópicas das cochonilhas. O levantamento de inimigos naturais associados com dez espécies de cocóideos frequentemente associados a estas plantas foi realizado em 15 municípios, situados nas mesorregiões de São José do Rio Preto, Ribeirão Preto, Araraquara e Campinas. As coletas foram realizadas entre agosto de 2016 e agosto de 2017, de maneira aleatória, em áreas urbana e rural. Nesse período, foram coletadas 52 espécies de inimigos naturais. Para cochonilhas da cana-de-açúcar, todas as associações são novos relatos para o estado de São Paulo; e, Anagyrus saccharicola Timberlake,... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Agriculture is of great importance for the development of Brazil. The state of São Paulo, with significant production and productivity of several crops, is the largest producer of sugarcane and citrus, and the third in coffee. However, major economic and environmental losses occur through the indiscriminate use of pesticides to control pest insects, including scale insects. Information on beneficial insects currently present in producing regions is essential for integrated pest management. The objective of this study was to survey natural enemies associated with scale insects species considered as primary or secondary pests for sugarcane, citrus and coffee crops in the state of São Paulo, relating to the origin of each species; specificity prey; and the possible adaptations to predation or parasitism in relation to the macroscopic morphological characteristics of scale insects. The survey of natural enemies associated with ten coccoid species frequently associated with these plantations was carried out in 15 municipalities located in the mesoregions of São José do Rio Preto, Ribeirão Preto, Araraquara and Campinas, in the main sugarcane producing regions, citrus and state coffee. The collections were carried out between August 2016 and August 2017, in a random manner, in urban and rural areas. During this period, 52 species of natural enemies were collected. For sugarcane scale insects, all associations are new reports for the state of São Paulo; and, Anagyrus saccha... (Complete abstract click electronic access below) / Mestre

The effects of habitat complexity and predation risk on community assembly in small standing waters are reviewed. Both lethal and nonlethal predator effects are discussed. Emphasis is put on the role of omnivorous predators which do not fit into the standard food chain model. The review is complemented by a manuscript intended for publication in Freshwater Biology. It reports the results of a mesocosm experiment focusing on the effects of both lethal and nonlethal predation risk, induced by the invasive crayfish species Orconectes limosus, and habitat complexity on the abundance and biomass of macroinvertebrates in a naturally assembled community.

xiii, 141 p. : ill. (some col.) / The small trochid gastropod <italic>Lirularia succincta</italic> occurs in rocky intertidal habitats along the Pacific coast of North America. Strong escape responses of adult <italic>L. succincta</italic> were elicited by the predatory seastars <italic>Leptasterias hexactis</italic> and <italic>Pycnopodia helianthoides</italic> but not by the nonpredatory seastar <italic>Henricia</italic> sp. Escape responses to juvenile <italic>L. hexactis</italic> were not observed in newly-hatched <italic>L. succincta</italic>. The snails exhibited weak avoidance responses to water-borne chemical stimuli from <italic>L. hexactis</italic>. The vertical distribution of a population of <italic>L. succincta</italic> was described, and changes in the size-frequency distribution of the population in the spring and summer were documented. Finally, factors that may affect oviposition in <italic>L. succincta</italic> were investigated in the laboratory. The snails deposit egg masses year round with a peak in reproductive output in the summer. In the laboratory and in the field, egg masses are preferentially deposited in crevices. / Committee in charge: Dr. Craig M. Young, Chair; Dr. Richard B. Emlet, Member; Dr. Alan L. Shanks, Member

This thesis deals with the role of species traits in predator-prey interactions and food web structure. I conducted laboratory experiments with predatory aquatic insects and their prey to reveal the traits determining who eats whom in small standing waters. I also focused on the possibility of incorporating the observed dependence of predator-prey interactions on body mass into existing food web models. Further, I developed a simple simulation model to explore the consequences of body mass dependent feeding and dispersal for food web assembly. Last, I show that four common methods for sampling aquatic insects differ in their selectivity, especially on the basis of body mass of sampled insects. In conclusion, I combined laboratory experiments, field work and mathematical models to evaluate the importance of body mass and other species traits, such as foraging behaviour and microhabitat selectivity, in predator-prey interactions and explored selected food web level consequences.

abstract: In desert riparian ecosystems, rivers provide free water but access to that water diminishes with distance producing a steep gradient in the relative importance of water for growth and reproduction of riparian animals and hence, their biodiversity. Previous work suggests that water limited riparian predators eat more prey to meet their water demand where free water is not available. Here I explore the effect of water limitation on prey selection and per capita interaction strengths between a predatory spider ( Hogna antelucana) and two prey species occupying different trophic levels using a controlled field experiment conducted in the riparian forest of the San Pedro River, Cochise County, AZ. Lab measurements of water and energy content revealed that intermediate predators (smaller spiders in the genus Pardosa) had 100-fold higher energy: water ratios than an alternate prey species more basal in the food web (crickets in the genus Gryllus). Given this observation, I hypothesized that water-stressed predatory wolf spiders would select more water-laden crickets but switch to more energy rich Pardosa when water stress was experimentally eliminated. Additionally, I hypothesized that switching by quenched Hogna to Pardosa would reduce predation by Pardosa on Gryllus leading to increased abundance of the basal resource. Finally, I hypothesized that water mediated switching and release of basal prey would be stronger when male Hogna was the apex predator, because female Hogna have higher energetic costs of reproduction and hence, stronger energy limitation. Experimental water additions caused both sexes of Hogna to consume significantly higher numbers of Pardosa but this difference (between water and no-water treatments) did not vary significantly between male and female Hogna treatments. Similarly, strong negative interaction strengths between Hogna and Pardosa led to release of the basal prey species and positive interaction strengths of Hogna on Gryllus. Again strong positive, indirect effects of Hogna on Gryllus did not depend on the sex of the Hogna predator. However, water mediated indirect effects of Hogna (either sex) on Gryllus were the strongest for male Gryllus. These results suggest that water and energy co-dominate foraging decisions by predators and that in managing water-energy balance; predators can modify interaction pathways, sex-ratios of prey populations and trophic dynamics. / Dissertation/Thesis / Masters Thesis Biology 2015

abstract: Many animals thermoregulate to maximize performance. However, interactions with other animals, such as competitors or predators, limit access to preferred microclimates. For instance, an animal may thermoregulate poorly when fighting rivals or avoiding predators. However, the distribution of thermal resources should influence how animals perceive and respond to risk. When thermal resources are concentrated in space, individuals compete for access, which presumably reduces the thermoregulatory performance while making their location more predictable to predators. Conversely, when thermal resources are dispersed, several individuals can thermoregulate effectively without occupying the same area. Nevertheless, interactions with competitors or predators impose a potent stress, often resulting in both behavioral and physiological changes that influence thermoregulation. To assess the costs of intraspecific competition and predation risk during thermoregulation, I measured thermoregulation, movement, and hormones of male lizards (Sceloporus jarrovi) in experiment landscapes, with clumped to patchy distributions of microclimates. I found lizards aggressively competed for access to microclimates, with larger males gaining priority access when thermal resources were aggregated. Competition reduced thermoregulatory performance, increased movements, and elevated plasma corticosterone in large and small males. However, the magnitude of these responses decreased as the patchiness of the thermal environment increased. Similarly, under simulated predation risk, lizards reduced thermoregulatory performance, decreased movements, and elevated plasma corticosterone. Again, with the magnitude of these responses decreased with increasing thermal patchiness. Interestingly, even without competitors or predators, lizards in clumped arenas moved greater distances and circulated more corticosterone than did lizards in patchy arenas, indicating the thermal quality of the thermal landscape affected the energetic demands on lizards. Thus, biologists should consider species interactions and spatial structure when modeling impacts of climate change on thermoregulation. / Dissertation/Thesis / Doctoral Dissertation Biology 2017

Orientador: Carlos Camargo Alberts / Banca: Fernando Frei / Banca: Beatriz M. Beisiegel / Resumo: O conflito entre humanos e carnívoros silvestres devido à predação exercida sobre rebanhos domésticos tem sido um dos precursores mundiais que tornam os carnívoros um dos grupos com espécies mais ameaçados de extinção. No Brasil, a predação por onças-pardas tem sido documentada em diversas regiões e como consequência a perseguição desses animais é fortemente observada. A fim de identificar os fatores que poderiam estar associados a predações aos rebanhos domésticos por onças-pardas no oeste do Estado de São Paulo, realizamos entrevistas com produtores rurais, utilizando questionários semi-estruturados, abordando características das propriedades, do manejo e da paisagem. Realizamos 71 entrevistas e identificamos propriedades que passaram por eventos de predação na última década. Ovinos e bovinos foram os grupos de animais mais frequentemente predados. Através da Regressão Logística foi possível obter um modelo de previsão de ataques com 81% de concordância entre estimado e observado, do qual o número de ovinos e a quantidade de vegetação natural presentes em cada propriedade foi positivamente relacionado aos casos de predação, porém o manejo das criações de risco como ovinos e bezerros pode contribuir significativamente para a redução de perdas de animais domésticos e assim reduzir possíveis conflitos com a fauna silvestre / Abstract: The conflict between humans and wild carnivores due the predation on domestic livestock has been a reason that made the Carnivora one of the groups with most threatened species. In Brazil, predation by pumas has been recorded in various regions and result in a harsh persecution on these animals. In order to identify factors that might be associated with predation on domestic livestock by pumas in the west of São Paulo, we did interviews with farm owners and their regular employees using a semi structured questionnaire, addressing characteristics of the property, the management and landscape. We conducted 71 interviews and identified properties that had gone through predation events in the last decade. Sheep and cattle were the most often attacked species. Using logistic regression it was possible to obtain a predictive model of attacks with 81% agreement between estimated and observed, in which the number of sheep and amount of natural vegetation present in each property was positively related to cases of predation. However, a proper management of individuals under risk for both sheep and calves showed to be effective and can contribute significantly to reduce livestock losses and thus to reduce potential conflicts with wildlife / Mestre