Made available in DSpace on 2014-06-11T19:22:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-12Bitstream added on 2014-06-13T20:09:25Z : No. of bitstreams: 1 borges_ff_me_jabo.pdf: 2088766 bytes, checksum: 5403ba70f285528d3490e9444e9af9fd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O estudo foi realizado no Setor de Ranicultura do Centro de Aquicultura da Universidade Estadual Paulista, Câmpus Jaboticabal/SP em dois períodos distintos, compreendendo uma fase de girinagem e uma fase de engorda no ciclo de criação de rã-touro. Os objetivos foram verificar as características físicas, químicas e microbiológicas da água de entrada e de saída dos tanques em cada fase do ciclo. Os resultados obtidos foram comparados com a legislação ambiental CONAMA 357 de 2005, para verificar se o manejo utilizado em cada fase causa alterações na qualidade da água. Foram analisadas as variáveis temperatura, pH, oxigênio dissolvido, condutividade elétrica, turbidez, nitrogênio amoniacal, nitrato, fósforo total, DBO5, DQO e Escherichia coli em cada etapa do ciclo. O delineamento experimental foi o Inteiramente Casualizado, com dois tratamentos, água de abastecimento e efluente e seis repetições (tanques) em um esquema de parcelas subdivididas, sendo as sub-parcelas as coletas no tempo. As coletas das amostras foram realizadas a cada quinze dias no período da manhã. Na fase de girino o experimento foi realizado entre novembro de 2008 e janeiro de 2009 e teve duração de 76 dias, até os animais completarem a metamorfose. Não foi observada diferença significativa (p>0,05) entre os tratamentos para temperatura, condutividade, turbidez, DQO e E. coli. Entretanto, esses parâmetros variaram nas diferentes coletas. As variáveis pH, oxigênio dissolvido, fósforo total, amônia, nitrato e DBO5 tiveram diferença significativa (p<0,05) entre os tratamentos. Porém, somente as concentrações de fósforo total e DBO5 encontraram-se acima da recomendada pela legislação. A fase de recria teve duração de 77 dias, compreendendo o período de novembro de 2009 a janeiro de 2010, até os animais atingirem o peso de abate. Todas as análises apresentaram diferença significativa... / The study was performed at the frog culture Sector, Aquaculture Center, Sao Paulo State University, Campus Jaboticabal, SP in two different periods, including a tadpole and growout phase in the cycle of creation of the bullfrog. The objectives were to verify the physical, chemical and microbiological water inlet and outlet of the tanks at each stage of the cycle. The results were compared with environmental legislation CONAMA 357, by 2005, to verify whether management used at each stage cause changes in water quality. The variables temperature, pH, dissolved oxygen, electrical conductivity, turbidity, ammonia nitrogen, nitrate, total phosphorus, BOD5, COD and E. coli at each stage of the cycle. The experimental design was completely random, with two treatments, water supply and sewage and six repetitions (tanks) in a split plot, and the sub-plots samples collected over time. The collections of samples were taken fortnightly during the morning. At tadpole phase, the experiment was conducted between November 2008 and January 2009 and lasted 76 days until the animals complete metamorphosis. There was no significant difference (p> 0.05) among treatments for temperature, conductivity, turbidity, COD and E. coli. However, these parameters varied in different samples. The pH, dissolved oxygen, total phosphorus, ammonia, nitrate and BOD5 were significantly different (p<0.05) among treatments. But, only the concentrations of total phosphorus and BOD5 were found above the recommended legislation. The growing phase lasted 77 days, including the period November 2009 to January 2010, until the animals reach slaughter weight. All analysis showed significant differences (p<0.05) among treatments and between collections. The variables, dissolved oxygen, total phosphorus, ammonia, BOD5 and E. coli had their values above those permitted by law... (Complete abstract click electronic access below)

The concept of maximal oxygen consumption (VO2 max) implies that there is a limit to the amount of oxygen that can be consumed by an organism in a given time. Many attempts have been made to delineate exactly what factor or factors are limiting to VO2 max. Current models focus on the steps over which oxygen must traverse in order to get from the ambient air to the mitochondria. However, no model has addressed the issue of whether or not carbon dioxide flux may impose a limit to VO2 max. Impedance of carbon dioxide flux may have a deleterious effect on intracellular pH, which in turn, may effect mitochondrial oxidative performance.

Resumo: Estudar o sangue significa monitorar a saúde dos animais reduzindo, desta forma, as perdas por doenças ou injúrias, seja frente a um determinado tipo de estressor, por sistemas de criação não apropriados, por manejos inadequados ou ainda por alterações ambientais. O objetivo deste trabalho foi avaliar a resposta fisiológica de girinos de rã-touro (Rana catesbeiana) em diferentes densidades e após exposição aérea. O experimento foi realizado em duas etapas utilizando-se de animais entre os estágios 31 a 39, na fase de pró-metamorfose; na primeira etapa, realizada no CAUNESP - UNESP/SP, avaliou-se somente a exposição aérea nos tempos de 0, 15, 30,45,60 e 90 minutos. Na segunda etapa, realizada no Instituto de Pesca - APTA/ SP foi avaliada a densidade de estocagem sendo testados 1 girino/L (Tratamento I), 5 girinos/L (Tratamento 2) e 10 girinos/L (Tratamento 3), conduzidos em 3 réplicas simultâneas, e a exposição aérea nos dias 0,14(6 horas), 4, 8 e 12 dias. O sangue foi retirado por rompimento do vaso caudal na condição de Normóxia - N (tempo zero) e Hipóxia - H (tempo de 15 minutos de exposição ao ar). Avaliou¬se, na primeira etapa, somente o cortisol plasmático e na segunda etapa, cortisol plasmático, glicemia, hematócrito, hemoglobina, número de eritrócitos, os índices hematimétricos absolutos ¬VCM, HCM e CHCM, contagem diferencial de leucócitos e contagem total de leucócitos e trombócitos. Foi observado um aumento nos valores de cortisol, aos 4 e 8 dias de exposição aérea retomando aos valores basais ao final do experimento, apesar de não haver diferenças significativas. A glicemia foi influenciada no tratamento com 10 girinos/L mostrando forte correlação com a hipóxia. Os parâmetros hematológicos, principalmente, o número de linfócitos, neutrófilos e eosinófilos mostraram diferença significativa aos 12 dias de experimentação ...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Studying blood means monitoring animals health reducing, losses by disease or injury caused by certain kinds of stress related to improper rearing systems, handling or alterations in the environment. The aim of this study was to evaluate bullfrog's tadpole physiological answer (Rana catesbeiana) to different densities and air exposition. The experiment was carried out in two parts using animals, at the pro-metamorphosis phase, on the first part carried out at CAUNESP - Aquaculture Center, São Paulo State University was evaluated only air exposition, which animals were sampled on zero, fifteen, thirty, forty five, sixty and ninety minutes and on second part, carried out at Fisheries Institute - APTA/SP was evaluated different densities and air exposition, which stocking densities was 1 tadpole/L (treatment one), 5 tadpoles/L (treatment two) and 10 tadpoleslL (treatment three) with three simultaneous replicates and animals were sampled on zero, 114 (six hours), four, eight and twelve experimental days. Blood was collected by breaking tail blood vessel at norrnoxic (zero time) and hipoxic (fifteen minutes by air exposition) conditions. Only cortisol was evaluate on the first part and on second, cortisol, glicemy, hematocryts, haemoglobin tax, couting of erytrocyte's number, absolute hematimetrycs indices -MCV, MCH and MCHC, differenctial couting of leucocytes, total counting of leucocytes and trombocytes were evaluated. An increase in plasmatic cortisol was observed at four and eight days of the experiment, retuming to initial values after 12 days. Glicemy values increased at treatrnent. three, showing strong correlation with hypoxia. Hematological parameters as linphocytes, neutrophils and eosinophils numbers at the 12th day of the experiment showed differences comparing to zero day; concluding that stocking densities until 10 tadpoles/L and air exposition ...(Complete abstract, click electronic access below) / Orientadora: Maria José Tavares Ranzani de Paiva / Coorientadora: Claudia Maria Ferreira / Banca: Elisabeth Criscuolo Urbinati / Banca: Maria Isabel Mataqueiro / Mestre

Thyroid hormones (THs) are essential signaling molecules for the postembryonic development of all vertebrates. THs are capable of initiating a diverse set of developmental programs across multiple tissues. The role of TH in regulating gene expression is well-known, but the initiation of TH signaling is still not fully understood. In amphibians, THs are the sole hormones required for the metamorphosis from tadpole to juvenile froglet. Amphibians are a useful model for studying TH signaling, as they undergo extensive, tissue-specific response programs in response to exogenous TH. The metamorphosis of the American bullfrog, Rana [Lithobates] catesbeiana is temperature sensitive. R. catesbeiana tadpoles do not undergo metamorphosis at cold temperatures (4-5 °C) even in the presence of THs that should otherwise prompt it. However, tadpoles undergo metamorphosis at an accelerated rate when returned to warm temperatures (24-25 °C) forty days after their initial TH exposure. R. catesbeiana tadpoles possess a “molecular memory” of TH exposure which establishes the TH signal at cold temperatures and prompts accelerated metamorphosis after a return to warmer temperatures. The mechanisms of the molecular memory which allow it to uncouple the initiation of TH signaling from the execution of the TH response program are not fully understood. Previous research has established that transcripts encoding transcription factors are a substantial component of the TH-dependent transcriptomic response of cultured tailfin (C-Fin) at cold temperatures. However, not all of these putative transcripts encoding transcription factors required active transcription and translation for their induction, which suggests that the initiation of a TH signal involves mechanisms other than regulating gene expression. Herein, we used quantitative polymerase chain reaction (qPCR) and RNA-Sequencing (RNA-Seq) to investigate the TH-dependent transcriptomic response of the back skin, a tissue that undergoes extensive remodeling during metamorphosis. Cultured back skin (C-Skin) was TH-responsive in warm, cold and temperature shift conditions. Forty-four transcripts underwent significant changes in abundance in response to TH in cold temperatures under which the molecular memory is established. Seven of these transcripts encoded putative transcription factors. Surprisingly, the only TH-responsive transcript significantly changed at 4 °C in both the C-Skin and the previously studied C-Fin was thyroid hormone-induced basic leucine zipper-containing protein (thibz). Thibz has been found to be TH-responsive at cold temperatures in the liver, lung, liver, brain, tailfin and back skin of whole animals, which suggests it may be an important regulator of initiating TH signaling. The lack of overlap in the transcriptomic responses of C-Skin and C-Fin may suggest that even the early initiation of TH signaling has tissue-specificity. Alternately, the molecular memory may include mechanisms that do not require active transcription and translation. Transcripts associated with epigenetic modifications and post-transcriptional changes to mRNA stability were also significantly expressed at 4 °C within the C-Skin. Previous investigation of the putative transcription factors in C-Fin revealed that active transcription and translation was not always required for changes in transcript abundance. Multiple mechanisms may be at play in the TH response at different temperatures. In cold temperatures, TH may modulate mRNA stability to influence transcript abundance as a part of initiating TH signaling without executing metamorphosis. Further research is needed to explore potential alternative mechanisms of establishing the molecular memory and the accelerated metamorphic response. The temperature sensitivity of R. catesbeiana’s TH response is incredibly valuable in investigating mechanisms of early TH signaling during postembryonic vertebrate development. / Graduate

The decline of the Oregon Spotted Frog (Rana pretiosa), a Pacific Northwest endemic now federally listed as threatened, has been attributed to several aspects of ecosystem alteration, primarily habitat degradation and loss. The introduced American Bullfrog (Rana (Aquarana) catesbeiana) has been widely implicated in those declines, but the basis of that contention has been difficult to characterize. The bullfrog occurring at every site of recent Oregon Spotted Frog extirpation has focused concern about its impact. Here, I present a suite of interconnected studies that examine the behavioral ecology of both species to better understand the potential for bullfrog-mediated Oregon Spotted Frog extirpation. I quantified Oregon Spotted Frog anti-predator behavior from the only known population successfully co-occurring with bullfrogs (Conboy Lake) and a population devoid of bullfrog impact (Big Marsh), and compared these behaviors to the predatory traits of the bullfrog. The initial study revealed that captive-reared individuals from the Oregon Spotted Frog population that has successfully co-occurred with bullfrogs respond faster to a predatory stimulus (measured as latency to response) than Oregon Spotted Frogs from a population not to exposed to bullfrogs. Subsequent field investigations of the approach distance allowed by a predator stimulus before taking evasive action (termed the flight initiation distance: FID) conducted with the Oregon Spotted Frog population co-occurring with bullfrogs first demonstrated that FID of recently metamorphosed bullfrogs is consistently greater than that of recently metamorphosed Oregon Spotted Frogs. Further, examination of FID across all post-metamorphic age classes of Oregon Spotted Frogs revealed that older frogs do not allow as close approach as recently metamorphosed Oregon Spotted Frogs. This age class shift in FID did not occur in the Oregon Spotted Frog population not exposed to bullfrogs. In the latter population, FID did not differ among age classes. Since the bullfrog might be driving this age-based change in anti-predator behavior, I explored the variation in strike distance of bullfrogs from the site of co-occurrence in both the field and laboratory to determine the extent of overlap with Oregon Spotted Frog FID. I found that the bullfrog strike distance significantly overlaps the FID of all ages of Oregon Spotted Frogs from the bullfrog-free site but only that of youngest (recently metamorphosed) frogs at the site of co-occurrence. Older Oregon Spotted Frogs from the site of co-occurrence generally escaped at distances greater than the strike distance of bullfrogs. I also collected > 880 bullfrogs from the site of co-occurrence and analyzed the stomach contents to assess their dietary trends. I found that bullfrogs consume Oregon Spotted Frogs at the site, but do not eat the larger (older) frogs. Moreover, the body size ratio between Oregon Spotted Frogs as prey and bullfrogs as predators suggests that nearly all of the adult size distribution of bullfrogs at Conboy would be incapable of preying on adult Oregon Spotted Frogs. Collectively, these studies strongly suggest that bullfrogs have altered the escape behavior of Oregon Spotted Frogs at Conboy Lake and that most adult Oregon Spotted Frogs at Conboy may have a size-based release from predation by bullfrogs. Implicit in this finding is that bullfrogs may pose a real threat via predation to other Oregon Spotted Frog populations with which they might come into contact where the distribution of bullfrog body sizes differ substantially from that at Conboy Lake.

Resumo: O estudo foi realizado no Setor de Ranicultura do Centro de Aquicultura da Universidade Estadual Paulista, Câmpus Jaboticabal/SP em dois períodos distintos, compreendendo uma fase de girinagem e uma fase de engorda no ciclo de criação de rã-touro. Os objetivos foram verificar as características físicas, químicas e microbiológicas da água de entrada e de saída dos tanques em cada fase do ciclo. Os resultados obtidos foram comparados com a legislação ambiental CONAMA 357 de 2005, para verificar se o manejo utilizado em cada fase causa alterações na qualidade da água. Foram analisadas as variáveis temperatura, pH, oxigênio dissolvido, condutividade elétrica, turbidez, nitrogênio amoniacal, nitrato, fósforo total, DBO5, DQO e Escherichia coli em cada etapa do ciclo. O delineamento experimental foi o Inteiramente Casualizado, com dois tratamentos, água de abastecimento e efluente e seis repetições (tanques) em um esquema de parcelas subdivididas, sendo as sub-parcelas as coletas no tempo. As coletas das amostras foram realizadas a cada quinze dias no período da manhã. Na fase de girino o experimento foi realizado entre novembro de 2008 e janeiro de 2009 e teve duração de 76 dias, até os animais completarem a metamorfose. Não foi observada diferença significativa (p>0,05) entre os tratamentos para temperatura, condutividade, turbidez, DQO e E. coli. Entretanto, esses parâmetros variaram nas diferentes coletas. As variáveis pH, oxigênio dissolvido, fósforo total, amônia, nitrato e DBO5 tiveram diferença significativa (p<0,05) entre os tratamentos. Porém, somente as concentrações de fósforo total e DBO5 encontraram-se acima da recomendada pela legislação. A fase de recria teve duração de 77 dias, compreendendo o período de novembro de 2009 a janeiro de 2010, até os animais atingirem o peso de abate. Todas as análises apresentaram diferença significativa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The study was performed at the frog culture Sector, Aquaculture Center, Sao Paulo State University, Campus Jaboticabal, SP in two different periods, including a tadpole and growout phase in the cycle of creation of the bullfrog. The objectives were to verify the physical, chemical and microbiological water inlet and outlet of the tanks at each stage of the cycle. The results were compared with environmental legislation CONAMA 357, by 2005, to verify whether management used at each stage cause changes in water quality. The variables temperature, pH, dissolved oxygen, electrical conductivity, turbidity, ammonia nitrogen, nitrate, total phosphorus, BOD5, COD and E. coli at each stage of the cycle. The experimental design was completely random, with two treatments, water supply and sewage and six repetitions (tanks) in a split plot, and the sub-plots samples collected over time. The collections of samples were taken fortnightly during the morning. At tadpole phase, the experiment was conducted between November 2008 and January 2009 and lasted 76 days until the animals complete metamorphosis. There was no significant difference (p> 0.05) among treatments for temperature, conductivity, turbidity, COD and E. coli. However, these parameters varied in different samples. The pH, dissolved oxygen, total phosphorus, ammonia, nitrate and BOD5 were significantly different (p<0.05) among treatments. But, only the concentrations of total phosphorus and BOD5 were found above the recommended legislation. The growing phase lasted 77 days, including the period November 2009 to January 2010, until the animals reach slaughter weight. All analysis showed significant differences (p<0.05) among treatments and between collections. The variables, dissolved oxygen, total phosphorus, ammonia, BOD5 and E. coli had their values above those permitted by law... (Complete abstract click electronic access below) / Orientador: Marta Verardino de Stéfani / Coorientador: Luiz Augusto do Amaral / Banca: Laudicéia Giacometti Lopes / Banca: Lúcia Helena Sipaúba Tavares / Mestre

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Bullfrogs (Rana catesbeiana) have been introduced in many continents causing impact on native species. We have studied the influence of bullfrogs on the native anuran fauna through the diet analysis of 291 specimens, collected between May 2002 and June 2003, in an area in the South of Brazil. In order to check the feeding importance of the food items, the Pinkas index was used, classifying them by their relative importance (IRI). To analyze ontogenetic changes in the diet, we compared the variation among weigh classes. The most important item found in the bullfrog diet was the anuran (IRI=2157.71) from the Leptodactylidae, Hylidae, Microhylidae and Ranidae families, totalizing nine preyed species. Anurans were found in all weight classes. These results show a potentially strong predation pressure on the native anuran fauna. A control program for this invasive species in natural environments in the South of Brazil is suggested to be undertaken urgently. / A rã-touro (Rana catesbeiana) vem sendo introduzida em vários continentes causando impactos nas espécies nativas. Em uma área no sul do Brasil, com altas densidades de rã-touro, estudamos a predação desta espécie sobre a anurofauna nativa através da análise da dieta alimentar de 291 espécimes, coletados entre maio de 2002 e junho de 2003. Para verificar a importância alimentar dos itens encontrados utilizou-se o índice de Pinkas, classificando os itens através da sua importância relativa (IIR). Para avaliar a mudança ontogenética na dieta, comparamos a variação entre classes de pesos. O item mais importante encontrado na dieta da rã-touro foi Anura (IIR=2157.71), das famílias Leptodactylidae, Hylidae, Microhylidae e Ranidae, totalizando nove espécies predadas. O item Anura foi encontrado em todas as classes de peso. Estes resultados demonstram uma forte pressão de predação sobre a anurofauna nativa. Um programa de controle desta espécie, em ambientes naturais no sul do Brasil demanda urgência.

Made available in DSpace on 2014-12-17T15:36:36Z (GMT). No. of bitstreams: 1 AlexPC_TESE.pdf: 1908145 bytes, checksum: 643f86df6b9e5e514de6656ebc92ff08 (MD5) Previous issue date: 2010-06-07 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The behavior of bullfrogs reared in captivity must be well understood to support management practices that use efficient feeding regimes. In general, bullfrogs reared in captivity have normal pigmentation, but to develop an enhanced product, some studies have investigated the introduction of albino individuals in frog farms. The present study characterized the behavior of both pigmented and albino bullfrogs reared in captivity. In an initial experiment, 48 bullfrogs (70.5 ? 25.6 g) housed in small stalls were fed once a day at random times. Frogs were filmed and the images showed that both the pigmented and albino varieties behaved similarly: food intake was more frequent at dawn followed by light periods; moving and resting in dry areas may be associated to feeding events; frogs appeared to anticipate feeding time and to rest in the water more frequently in periods other than feeding time; daylight is the recommended period for feeding both pigmented and albino frogs. In a second experiment, 72 albino bullfrogs were fed at fixed times (10 a.m. or 4 p.m.) in small stalls. An initial weight of 23.8 ? 7.6 g was considered to evaluate frog performance, and after the animals reached 60.0 ? 20.0 g, they were filmed for behavior analyses. Food intake varied as a function of feeding time, and frogs were more likely to eat during the early hours of the day and immediately after receiving fresh food. Frogs fed only in the afternoon changed their behavior. Food supplied twice a day stimulated the albino frogs to eat at different times, but did not increase growth. Although fresh food stimulated feeding behavior, food intake was more frequent at dawn. Food supplied at this time of day should therefore be further investigated. The results did not indicate a more suitable feeding time (10 a.m. or 4 p.m.) for albino bullfrogs, or any advantage in using two feedings per day. The results provide xvi important information about bullfrogs in terms of food supply regime and activity preferences throughout the day. This novel information will contribute to future studies in this area / O entendimento das atividades comportamentais de r?s-touro em cativeiro ? de grande import?ncia para a indica??o de caminhos adequados no manejo da esp?cie, visando o uso racional do alimento fornecido. A r? de pigmenta??o normal ? atualmente usada nos ran?rios, mas a introdu??o de animais albinos vem sendo pesquisada com o objetivo de se obter um produto diferenciado. Assim, esse estudo objetivou caracterizar as atividades comportamentais de r?s-touro de pigmenta??o normal e albinas em cativeiro. No primeiro experimento foram utilizadas 48 r?s-touro (70,5 ? 25,6 g) alimentadas uma vez ao dia, em hor?rios aleat?rios em minibaias. As atividades comportamentais, obtidas atrav?s de filmagens dos animais, foram semelhantes entre os de pigmenta??o normal e albinos, sendo destacados os seguintes comportamentos: a atividade de ingest?o que foi mais frequentemente observada no amanhecer, seguido dos hor?rios da fase de claro; o deslocamento e o descanso no seco mostraram haver uma rela??o com a alimenta??o; houve ind?cios de antecipa??o do hor?rio de alimenta??o e que o descanso na ?gua acontece com maior frequ?ncia em fase oposta ao da alimenta??o; e a fase de claro pode ser recomendada para a oferta de alimentos aos animais pigmentados e albinos. J? no segundo experimento, foram fixados os hor?rios de alimenta??o (10 h ou 16 h), sendo utilizadas 72 r?s-touro albinas em minibaias. Para a an?lise de desempenho, o peso inicial foi de 23,8 ? 7,6 g, e quando os animais atingiram 60,0 ? 20,0 g foram feitas as filmagens das atividades comportamentais. Foram encontradas diferen?as significantes entre os diferentes hor?rios de oferta de alimento testados, para a atividade de ingest?o, havendo uma tend?ncia dos animais se alimentarem no amanhecer e logo ap?s a oferta de alimento fresco. Ficou evidenciado que os animais, que recebiam alimento somente pela tarde, tiveram xiv suas atividades comportamentais alteradas. O uso de dois parcelamentos di?rios estimula a r?-touro albina a consumir alimento em diferentes hor?rios do dia, mas isso n?o resultou em maior crescimento do animal. O alimento fresco ? um est?mulo para os animais se alimentarem, mas a ingest?o ocorreu com maior frequ?ncia ao amanhecer, portanto recomendam-se estudos sobre o fornecimento de alimentos nesse hor?rio. N?o foram constatadas evid?ncias de um hor?rio (10 h ou 16 h) mais adequado para o manejo alimentar dos animais albinos, nem vantagens de se usar duas ofertas di?rias de alimento. Os resultados aqui apresentados trazem importantes informa??es sobre o manejo de oferta de alimento e a prefer?ncia de hor?rios das atividades dos animais, ajudando, com informa??es in?ditas, as futuras pesquisas direcionadas nessa ?rea

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L’expansion agricole ne cesse d’agir sur la perte d’habitats essentiels et nécessaires au développement des espèces. Bien que plusieurs espèces réussissent à survivre dans ces habitats peu adéquats, la persistance et la santé de plusieurs populations semblent compromises par l’utilisation souvent intensive de polluants chimiques agricoles et de fertilisants. Cette étude a pour but de déterminer l’impact des contaminants et de l’écologie du paysage sur la diversité génétique des populations de ouaouarons retrouvées en milieu agricole. Notre hypothèse de départ stipule qu’une exposition chronique aux polluants agricoles induira des différences génétiques au niveau des populations exposées. Le bassin versant de la rivière Yamaska a été désigné comme site d’étude puisqu’il fait partie de la région agricole la plus importante du Québec et parce qu’on y retrouve un gradient d’utilisation des terres pour l’agriculture (faible, moyen, élevé). Le ouaouaron a été choisi à titre de modèle biologique puisque ses caractéristiques physiologiques et écologiques en font une espèce sentinelle capable de rendre compte de l’état de santé global des écosystèmes. La caractérisation génétique des populations a été effectuée à partir de marqueurs d’AFLP (Amplified Fragment Length Polymorphism). Les résultats montrent que la diversité génétique est liée à la colonisation à partir de l’embouchure de la rivière Yamaska et que quelques populations sont génétiquement différenciées. De plus, nous avons démontré une relation positive entre le nombre de locus polymorphes et l’atrazine, l’indice de contamination et le métolachlore et la concentration en azote ainsi qu’entre l’hétérozygotie attendue et la concentration en phosphate. / Agricultural expansion continues to act on the loss of critical habitats for the development of species and affects the integrity of remaining habitats. Although several species manage to survive in such inadequate ecosystems, persistence and health of many populations seem compromised by the intensive use of pesticides and fertilizers. This study aims at determining the impact of pollutants and landscape ecology on the genetic diversity of bullfrog populations inhabiting an agricultural area. Our hypothesis states that chronic exposure to agricultural pollutants induces genetic differences in exposed populations. The watershed of the Yamaska River was designated as the study site because it is part of the largest agricultural region in Quebec and because the sampling sites represent a gradient of land use for agriculture (low, moderate, high). The bullfrog was chosen as the biological model, since its physiological and ecological characteristics make it a sentinel species, which can reflect the overall health of an ecosystem. Population genetic characterization has been conducted from AFLP (Amplified Fragment Length Polymorphism) markers. The results show that genetic diversity is correlated to colonization from the mouth of the Yamaska River and that some populations are genetically differentiated. Furthermore, we demonstrated a positive relationship between the number of polymorphic loci and the atrazine, the contamination index and the nitrogen concentration as well as between expected heterozygosity and phosphate concentration.