abstract: Social structure affects many aspects of ecology including mating systems, dispersal, and movements. The quality and pattern of associations among individuals can define social structure, thus detailed behavioral observations are vital to understanding species social structure and many other aspects of their ecology. In squamate reptiles (lizards and snakes), detailed observations of associations among individuals have been primarily limited to several lineages of lizards and have revealed a variety of social structures, including polygynous family group-living and monogamous pair-living. Here I describe the social structure of two communities within a population of Arizona black rattlesnakes (Crotalus cerberus) using association indices and social network analysis. I used remote timelapse cameras to semi-continuously sample rattlesnake behavior at communal basking sites during early April through mid-May in 2011 and 2012. I calculated an association index for each dyad (proportion of time they spent together) and used these indices to construct a weighted, undirected social network for each community. I found that individual C. cerberus vary in their tendency to form associations and are selective about with whom they associate. Some individuals preferred to be alone or in small groups while others preferred to be in large groups. Overall, rattlesnakes exhibited non-random association patterns, and this result was mainly driven by association selection of adults. Adults had greater association strengths and were more likely to have limited and selected associates. I identified eight subgroups within the two communities (five in one, three in the other), all of which contained adults and juveniles. My study is the first to show selected associations among individual snakes, but to my knowledge it is also the first to use association indices and social network analysis to examine association patterns among snakes. When these methods are applied to other snake species that aggregate, I anticipate the `discovery' of similar social structures. / Dissertation/Thesis / M.S. Biology 2012

Na cascavel Crotalus durissus terrificus ocorre o armazenamento de longo prazo do esperma (LTSS), no trato genital da fêmea, durante o intervalo entre a cópula (outono) e a ovulação (primavera). Peptídeos e peptidases estão entre os principais componentes que influenciam a atividade espermática em mamíferos. O presente estudo objetivou caracterizar a presença de peptidases em C. d. terrificus, com esta função reconhecida em mamíferos e/ou que clivam peptídeos atuantes nesta função, bem como avaliar a hipótese do envolvimento destas peptidases na preservação dos espermatozóides desta serpente. O aspecto morfo-funcional dos espermatozóides foi comparado na presença dos peptídeos angiotensina II (AngII), arginina vasotocina (AVT), bradicinina (BK), peptídeo promotor da fecundação (FPP) e hormônio liberador de tireotrofina (TRH). Caracterizamos os efeitos de agentes quelante, tiol-redutor, cofator e inibidores, bem como dos peptídeos supracitados, sobre as atividades enzimáticas relacionadas, quais sejam: aminopeptidases ácida (APA), básica (APB), alanil sensível (APN-PS) e insensível à puromicina (APN-PI), cistil (CAP), dipeptidil-peptidase IV (DPPIV), piroglutamil tipo 1 (PAP-I) e prolil-imino- (PIP), bem como da prolil endopeptidase (POP), em frações solúvel (FS) e/ou de membrana solubilizada (FM) do sêmen proveniente do ducto deferente, assim como deste próprio tecido e dos tecidos uterino e vaginal de C. d. terrificus, ou seja, tecidos por onde passam ou armazenam-se os espermatozóides. Verificamos a variação sazonal destas mesmas atividades, nestes tecidos, incluindo o sêmen armazenado no útero durante o LTSS. O sêmen coletado do ducto deferente foi fracionado para avaliação da distribuição destas atividades peptidásicas. Nossos dados mostraram características de liquefação do sêmen e movimento dos espermatozóides da cascavel que os diferenciam do padrão humano. FPP com cálcio e BK melhoraram a preservação da viabilidade espermática, similarmente ao que ocorre em mamíferos. Em todos os tecidos e no sêmen as atividades APB, PIP e POP foram detectadas apenas da FS, enquanto as demais estão presentes em FS e FM, seguindo um padrão de distribuição observado na maioria dos tecidos de mamíferos. Amastatina e bestatina inibiram APB e APN, enquanto a diprotina A foi o inibidor mais eficiente para a DPPIV em FM. PAP-I e PIP foram inibidas, respectivamente, por bestatina e puromicina. Este perfil de inibição também é similar ao encontrado para as aminopeptidases em tecidos de mamíferos. Todas as atividades peptidásicas foram influenciadas por algum dos peptídeos estudados, sugerindo que tais peptídeos são substratos potenciais e/ou moduladores destas atividades na cascavel. As atividades APB e APN foram caracterizadas como metalopeptidases. APB, CAP e DPPIV foram inibidas por MnCl2. CAP e PAP-I foram caracterizadas como enzimas sulfidril-dependentes. As atividades APB, APN-PI e APN-PS predominaram, em relação às demais peptidases, em todas as estações e na maioria dos tecidos e no sêmen, sugerindo sua maior relevância na fisiologia reprodutiva da C. d. terrificus. Os níveis de todas as atividades peptidásicas estudadas variaram sazonalmente, sugerindo que sua ação moduladora sobre peptídeos susceptíveis está integrada ao ciclo reprodutivo desta serpente. O fracionamento do sêmen do ducto deferente revelou a presença de fluido seminal e espermatozóides, bem como de uma estrutura prostassoma-símile, até então somente identificada em mamíferos. Em todas estas frações há atividade peptidásica, predominando a APN-PI no prostassoma-símile e no fluido seminal, e APN-PS e APN-PI na FS e FM dos espermatozóides, caracterizando um envolvimento com a redução da motilidade espermática, tal qual ocorre em mamíferos. Concluimos que as atividades peptidásicas estudadas apresentam características sazonais e tecido-específicas que sugerem uma atuação relevante na preservação dos espermatozóides de C.d. terrificus. / In the rattlesnake Crotalus durissus terrificus occurs the long-term sperm storage (LTSS), in the female tract, during the interval between mating (autumn) and ovulation (spring). Peptides and peptidases are among the main components that influence the spermatic activity in mammals. The present study aimed to characterize the presence of peptidases in C. d. terrificus, that are well-recognized to exert this function and/or that have the ability to hydrolyze peptides that exert this function in mammals, as well to evaluate whether these peptidases are related to the preservation of spermatozoids in this snake. The morphological and functional characteristics of spermatozoids were compared in the presence of angiotensin II (AngII), arginine-vasotocin (AVT), bradykinin (BK), fertilization promoting peptide (FPP) and thyrotropin-releasing hormone (TRH). We have checked the effect of chelating and thiol-reducing agents, cofactor and inhibitors, as well the effect of aforementionated peptides on related enzyme activities such as acid (APA), basic (APB), puromycin-sensitive (APN-PS) and puromycin-insensitive alanyl (APN-PI), cystyl (CAP), pyroglutamyl type 1 (PAP-I) and prolyl-imino (PIP) aminopeptidases, and dipeptidyl-peptidase IV (DPPIV), as well as on prolyl endopeptidase (POP), in soluble (FS) and/or solubilized membrane-bound (FM) fractions of semen from vas deferens, of this own tissue, and vagina and uterus tissues of C. d. terrificus, i.e. tissues where spermatozoids pass through or where they are stored. The seasonal variation of these peptidase activities, in all tissues, including the semen stored in uterus during the LTSS, were evaluated. The semen from vas deferens was fractioned in order to know the distribution of these peptidase activities. The features of seminal liquefaction and movement of spermatozoids were different between the rattlesnake and human. Similar to mammals, FPP plus calcium and BK improved the preservation of the viability of spermatozoids from C. d. terrificus. In all tissues and semen, the APB, PIP and POP activities were detected only in FS, while others peptidases were present in FS and FM, following a similar pattern of distribution usually observed in mammalian tissues. Amastatin and bestatin inhibited APB and APN activities, while diprotin A was the most efficient inhibitor of DPPIV in FM. PAP-I and PIP activities were inhibited by bestatin and puromycin, respectively. This inhibition profile was similar to that of mammalian tissues. All peptidase activities were influenced at least by one of the peptides under study, suggesting these peptides as potential substrates and/or modulators for these peptidases of the rattlesnake. The APB and APN activities were characterized as metallopeptidases. APB, CAP and DPPIV were inhibited by MnCl2. CAP and PAP-I were characterized as sulfhydryl-dependent enzymes. The APB, APN-PI and APN-PS activities were predominant, in relation to the other examined peptidases, in all seasons and in most tissues and semen, suggesting their great relevance in the reproductive physiology of the C. d. terrificus. The levels of all studied peptidase activities were seasonally variable, suggesting that their modulator actions on susceptible peptides are integrated to the reproductive cycle of this snake. The fractionation of C. d. terrificus semen revealed the presence of seminal fluid and spermatozoids, as well a prostasome-like structure, until then identified only in mammals. In all of these fractions, there are peptidase activities, predominating the APN-PI in prostasome and seminal fluid, and the APN-PS and APN-PI in FS and FM of spermatozoids, suggesting their involvement in the reduction of the spermatic mobility, such as in mammals. In conclusion, the studied peptidase activities present seasonal and tissue-specific characteristics, which suggest a relevant role in the preservation of the spermatozoids of C. d. terrificus.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-06-14T13:59:44Z No. of bitstreams: 1 fernandamarcondesmachadosilva.pdf: 1117035 bytes, checksum: cdd046907e5cdf700edb0af2202a0fb6 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-13T14:05:57Z (GMT) No. of bitstreams: 1 fernandamarcondesmachadosilva.pdf: 1117035 bytes, checksum: cdd046907e5cdf700edb0af2202a0fb6 (MD5) / Made available in DSpace on 2016-07-13T14:05:57Z (GMT). No. of bitstreams: 1 fernandamarcondesmachadosilva.pdf: 1117035 bytes, checksum: cdd046907e5cdf700edb0af2202a0fb6 (MD5) Previous issue date: 2016-02-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Não sendo clara a diversidade de respostas defensivas e as influências que exercem sobre estas, é vantajoso se obter cada vez mais informações sobre a espécie. Assim, elaborou-se uma relação dos comportamentos defensivos e a descrição de cada ato. Também se relacionou fatores abióticos, corporais e sociais com as respostas exibidas. Foram observados 54 espécimes adultos, divididos em grupos de cinco e mantidos por 10 dias consecutivos. Os experimentos foram realizados em três fases (Aproximação, Preensão e Manuseio), excluindo o Manuseio as fases foram repetidas em três horários e em dois recintos. Na Preensão realizou-se o pinçamento dos indivíduos em dois locais do corpo para exercer níveis diferentes de estresse. Foram identificadas 20 atos comportamentais, classificados como passivos e ativos, sendo que na fase de aproximação observou-se menor diversidade de atos defensivos (10) do que nas fases de preensão (17) e de manuseio (18). Analisando os três níveis de estresse, foi observada maior frequência de respostas ativas na Preensão do pescoço do que na Preensão do corpo e este do que na Aproximação. Com relação aos recintos, foi encontrada maior frequência de comportamentos passivos nos indivíduos inseridos em um ambiente coletivo do que quando individualizados. Havendo uma pequena influência da temperatura nas respostas exibidas, porém sem alterar a significância dos resultados dos recintos. Esse estudo caracterizou o repertório comportamental defensivo da serpente Crotalus durissus, sendo identificados e descritos dois novos atos antipredatórios (saltar e bufar). Assim, podemos compreender seus padrões de ação e também auxiliar nas precauções contra acidentes durante as atividades no campo e em laboratório. O estudo também confirmou a influência da temperatura nas respostas defensivas e registrou a diferença de comportamento quando os indivíduos estavam sozinhos e com outros espécimes. Com isso, podemos inferir algum grau de interação entre os indivíduos, não tendo sido descrito antes nessa espécie. / The variety of defensive responses and the influence they exert on these are not being clear, because of that it is advantageous to obtain more information about the species. Thus, it was elaborated a list of defensive behavior and the description of each act. We also related abiotic, physical and social factors with the displayed answers. We observed 54 adult specimens and divided into groups of five and kept for 10 consecutive days.The experiments were carried out in three phases (approach, apprehension and handling), excluding the handling, the phases were repeated three times and in two enclosures. On apprehension it held clamping of individuals in two locations of the body to exert different levels of stress. We identified 20 behavioral acts, classified by passive and active, and in the approach phase there were less diversity of defensive actions (10) than in apprehension phase (17) and handle phase (18). Analyzing the three levels of stress, we observed higher frequency of active responses at prehension of posterior region of the head follow by body prehension and the lower frequency during approach. Regard to the enclosures, it was found more passive behavior at individuals into a collective enclosure than in individualized. There was a small influence of temperature on responses, the layers analyzed set the model for the significance of the results of the enclosures. This study characterized the defensive behavioral repertoire of Crotalus durissus snake, identified and described two new anti predatory acts (jump and hiss). So, we can understand their patterns of action and also assist at preventive measures to avoid accidents during the activities in the field and in the laboratory. The study also confirmed the influence of abiotic factors on the defensive responses and recorded the difference in behavior when individuals were being individualized and with other specimens. Therefore, we can infer some interaction between the specimens, this had not been described before in this species.

No description available.

No description available.

Hydration is a critical element for many physiological processes in vertebrates, such as protein production, innate immunity, and behavioral processes such as daily activity and thermoregulation. Few studies have directly assessed the effect of hydration on these animals in nature. While it seems intuitive that drought is stressful to animals, studies examining drought are typically observational and fail to assess how the hydration state of these animals influences their physiology and behavior. We tested for an effect of hydration on several physiological and behavioral parameters in Northern Pacific rattlesnakes (Crotalus oreganus oreganus) by experimentally manipulating hydration levels in the field. Two treatment groups were created: one of these received supplemental hydration twice a month from May to September (hydrated) while the other did not (control). Pregnant females were brought to the lab before parturition to collect data on litter characteristics. We radio-tracked snakes to examine any effects on movement, measured SVL and mass of each snake throughout the study for assessment of body condition, and collected blood samples for stress hormone physiology. Finally, we used intra-coelomic temperature data loggers to track body temperature data for each individual snake every two hours. Our results suggest that supplemental water and thus hydration has a significant effect on reproduction as all four hydrated females gave birth to a litter, while no control females gave birth. We saw no effect on movement parameters; however, males had larger home ranges and moved a larger total distance than females, regardless of hydration status. Interestingly, body condition was significantly higher in hydrated snakes, suggesting that hydrated individuals were acquiring more food than control snakes. We saw no effect on stress hormone physiology. There was no influence of hydration on any behavioral parameters such as time spent above or below ground, or time spent in a particular body position. Finally, there was a significant interaction of treatment group and sex on seasonal body temperature. Hydrated females had higher mean body temperatures than all other treatment group and sex combinations. However, all hydrated females were also pregnant, which confounds this result. Similar results were seen when body temperature was analyzed by time of day. Females overall had higher body temperature than males. These results suggest that hydration may have a profound influence on reproduction and has the potential to affect body condition and thermoregulation. The lack of an effect on movement and stress physiology should not be overlooked, however. This study is the first to experimentally manipulate hydration in free-ranging rattlesnakes and one of the few to manipulate hydration in vertebrates. More studies are needed to support a pivotal role of hydration in physiology and behavior of reptiles and we encourage the use of experimental field manipulations to answer these questions.

No description available.

No description available.

Criar um ambiente experimental capaz de medir a resposta neural da visão (térmica) - em serpentes - quando estimulada por radiação infravermelha. Tratou-se da criação de estímulos dinâmicos artificiais dos quais a temperatura e a velocidade de deslocamento foram controlados. A resposta da cobra, quanto a esses estímulos, foi captada diretamente do cérebro da mesma (teto óptico), que corresponde aos processos visuais e infravermelhos do sistema nervoso central da cascavel. Mostramos que com esses estímulos criados, foi possível obter dados experimentais capazes de viabilizar analises de sensibilidade do sistema sensorial infravermelho em relação a contraste em temperatura e velocidade de movimento de presas artificiais. / The present work describe a creation of an experimental environment capable of measuring the neural response of vision (thermal) -in snakes -when stimulated by infrared radiation. There will be a creation of artificial dynamic stimuli of which the temperature and displacement velocity can be controlled. The response of the snake, when presented to these stimuli, captured directly from the brain (tecto optic), which corresponds to visual and infrared process in the central nervous system of the rattlesnake. We showed that with these stimuli created, it is possible to obtain experimental data which will allow analysis of sensitivity of the infrared sensory system in relation to contrast in temperature and speed of movement of false prey.

Criar um ambiente experimental capaz de medir a resposta neural da visão (térmica) - em serpentes - quando estimulada por radiação infravermelha. Tratou-se da criação de estímulos dinâmicos artificiais dos quais a temperatura e a velocidade de deslocamento foram controlados. A resposta da cobra, quanto a esses estímulos, foi captada diretamente do cérebro da mesma (teto óptico), que corresponde aos processos visuais e infravermelhos do sistema nervoso central da cascavel. Mostramos que com esses estímulos criados, foi possível obter dados experimentais capazes de viabilizar analises de sensibilidade do sistema sensorial infravermelho em relação a contraste em temperatura e velocidade de movimento de presas artificiais. / The present work describe a creation of an experimental environment capable of measuring the neural response of vision (thermal) -in snakes -when stimulated by infrared radiation. There will be a creation of artificial dynamic stimuli of which the temperature and displacement velocity can be controlled. The response of the snake, when presented to these stimuli, captured directly from the brain (tecto optic), which corresponds to visual and infrared process in the central nervous system of the rattlesnake. We showed that with these stimuli created, it is possible to obtain experimental data which will allow analysis of sensitivity of the infrared sensory system in relation to contrast in temperature and speed of movement of false prey.