PPG - Ecologia e Evolução

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    A influência da estrutura e complexidade vegetal sobre a riqueza, abundância e distribuição de vespas parasitoides (Hymenoptera: Ichneumonidae)
    (Universidade Federal de São Paulo, 2023-12-18) Quagliano, Juliana Abud [UNIFESP]; Püttker, Thomas [UNIFESP]; Santos, Fabiana Elaine Casarin dos [UNIFESP]; http://lattes.cnpq.br/5047065840855896; http://lattes.cnpq.br/6091761742167485; http://lattes.cnpq.br/8895302613201871
    Devido à sua relação com a abundância e variabilidade de nichos, a complexidade do habitat tem sido correlacionada positivamente com a riqueza e composição da comunidade de insetos predadores. No entanto, evidências empíricas testando a influência da estrutura do habitat em comunidades de insetos são raras, especialmente em relação a florestas tropicais. Aqui, investigamos a influência da estrutura da floresta e da abundância de hospedeiros na riqueza, abundância e composição da comunidade de vespas Ichneumonidae em um ecossistema de floresta tropical, com base em >5000 insetos individuais (com >350 vespas Ichneumonidae de 15 subfamílias) capturados durante 9240 dias de armadilhas em 20 pontos de amostragem na Mata Atlântica, com variações de idade e estrutura florestal. Encontramos uma correlação significativa entre a estrutura da floresta e a abundância das vespas Ichneumonidae, com maior riqueza e abundância observadas em áreas caracterizadas por menor complexidade e heterogeneidade. Além disso, tanto a riqueza quanto a abundância das vespas Ichneumonidae foram correlacionadas positivamente com a abundância de hospedeiros. Curiosamente, subfamílias mais abundantes responderam não apenas a diferentes componentes estruturais, mas também à abundância de diferentes ordens de hospedeiros (Coleoptera, Hemiptera e Diptera). A composição da comunidade local foi altamente variável, no entanto, nenhuma das variáveis explicativas mostrou ser um bom preditor da dissimilaridade da comunidade. Nossos resultados destacam a influência da estrutura da floresta nas comunidades tropicais de Ichneumonidae, indicando possíveis consequências de mudanças na estrutura da floresta nas funções do ecossistema.
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    Influência da distância da vegetação nativa sobre a diversidade de Himenópteros em olivais
    (Universidade Federal de São Paulo (UNIFESP), 2020-11-27) Oliveira, Christopher Henrique De [UNIFESP]; Puttker, Thomas [UNIFESP]; Universidade Federal de São Paulo
    Changes in land use caused by agropastoral activities have been the main cause of global biodiversity loss, mainly due to habitat loss of native species. With the increase in area and intensification of these activities expected for the coming years, actions that merge conservation of biodiversity with agricultural production systems become more urgent. Insects play important roles in maintaining essential ecosystem services for agriculture and Hymenoptera have a special role in providing endangered services, such as pollination and biological control. Here we investigate the effects of native vegetation on the diversity of hymenopterans around olive groves in the state of Minas Gerais, Brazil. We hypothesize that native vegetation act as a source of hymenopteran diversity for the olive groves. Therefore, we predict that the richness of families and abundance are negatively related to distance from native vegetation. In addition, we expect that the distance from native vegetation will influence the number of functional groups and the abundance per group, as well as community composition and functional group composition in olive groves. Hymenopterans were captured in 24 sampling stations during 7 capture sessions over ten months in pan-traps located at different distances from native vegetation in 3 different olive groves. The richness and abundance of families showed a negative relationship with the distance from native vegetation. The number of functional groups had no significant relationship with distance, but there was a disproportionate loss of parasitoids compared to other functional groups. The similarity of both community and functional groups between sampling stations decreased with increasing distance between stations, but only when abundance was included in the analysis. The results for richness and abundance corroborate the hypothesis that native vegetation represents a source of diversity for olive groves. The results for community composition based on abundance confirm the prediction that the distance from native vegetation has an influence on community composition, with less similarities between native vegetation and increasingly distant sampling stations. The results indicate that olive groves do not serve as habitat for many species of hymenopterans, which may have a consequence in the loss of pollination services and especially biological control, with the disproportionate loss of parasitoids. Conserve and include areas of native vegetation that allow habitat connectivity between these areas is essential for the existence of hymenopteran populations in the agricultural landscape.
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    Aumento de néctar extrafloral induzido por herbivoria não favorece interação com formigas melhores defensoras em Chamaecrista Nictitans (Fabaceae)
    (Universidade Federal de São Paulo (UNIFESP), 2020-03-31) Chinarelli, Henrique Diniz [UNIFESP]; Sousa, Laura Carolina Leal De [UNIFESP]; Universidade Federal de São Paulo
    In mutualisms involving ants and plants bearing extrafloral nectaries (EFNs), plants receive more efficient anti-herbivory defense when interacting with more aggressive ants, which also exhibit highly competitive ability. Plants tend to invest more on extrafloral nectar production after herbivory, which could increase the relative value of the plants to the ants, potentially leading to an increased probability of plant attendance by more efficient ant bodyguards. Therefore, I hypothesized that (1) plants invest more on the secretion of extrafloral nectar after herbivory, increasing (2) the relative value of the plants to ant bodyguards and, consequently, (3) the efficiency of the received anti-herbivory defense. I simulated herbivory in Chamaecrista nictitans by: Exogenous application of jasmonic acid and Leaf damage. I also kept plants which did not go through herbivory simulation. I measured nectar volume and sugar concentration and mass. Then, I identified ants with differing aggressiveness that visited the nectaries and measured their efficiency at the removal of herbivore mimics. Herbivory simulation increased, respectively, 153% and 240% the volume and sugar mass, but did not affect nectar sugar concentration or ant visitation nor defense patterns. Thus, increasing plant investment on nectar after herbivory in C. nictitans does not necessarily increase the quality of the received defense. The high frequency of interaction between plants of all treatments and the most aggressive ant defenders indicate that extrafloral nectar value on the study area was naturally high. It reinforces the importance of the environment in which the interactions are embedded in as a mediating factor of the outcome of generalized mutualisms.
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    Taxonomia e sistemática de Ceratomyxa sp. (Cnidaria: Myxozoa), parasito de Rhaphiodon vulpinus (Characiformes: Cynodontidae) da Bacia Amazônica
    (Universidade Federal de São Paulo, 2021-11-29) Franzolin, Gustavo Negrão [UNIFESP]; Adriano, Edson Aparecido [UNIFESP]; Naldoni, Juliana [UNIFESP]; http://lattes.cnpq.br/5851992242157875; http://lattes.cnpq.br/6376573741747319; http://lattes.cnpq.br/5591250868829622
    Os peixes da Bacia Amazônica são hospedeiros de diversos parasitos, como os cnidários da Classe Myxozoa (mixozoários), com aproximadamente 2600 espécies conhecidas. Dentro dos mixozoários destacam-se as espécies do gênero Ceratomyxa Thélohan, 1892, que são parasitos de peixes marinhos, mas estudos recentes vêm descrevendo novas espécies parasitando peixes de água doce na América do Sul. Neste trabalho, uma espécie de Ceratomyxa de água doce parasitando a vesícula biliar de Rhaphiodon vulpinus Spix & Agassiz, 1829 (Characiformes: Cynodontidae) do rio Tapajós, estado do Pará, Brasil foi descrita. Sua caracterização foi baseada em análises morfológicas obtidas por meio de microscopia de luz e eletrônica de transmissão, dados moleculares (sequenciamento da pequena subunidade de DNA ribossomal - SSU rDNA) e análises filogenéticas. A espécie aqui estudada desenvolve plasmódios com formato e motilidade semelhantes a vermes. Os mixosporos de Ceratomyxa sp. são alongados, com extremidades arredondadas, tendo seu interior composto por um esporoplasma binucleado e duas cápsulas polares de tamanhos iguais, as quais contêm túbulos polares com 3 espirais. A análise ultraestrutural mostrou diferentes estágios de desenvolvimento plasmodial na vesícula biliar do hospedeiro e diferentes estágios de desenvolvimento esporogônico no interior dos plasmódios. O sequenciamento da SSU rDNA resultou em uma sequência de 1448 pares de bases, que não correspondeu a nenhuma sequência de espécies de mixosporídeos disponíveis no GenBank. A análise filogenética revelou a formação de um clado composto por espécies do gênero Ceratomyxa de água doce, onde Ceratomyxa sp. parasito de R. vulpinus agrupou como espécie irmã de Ceratomyxa vermiformis. Com os dados morfológicos e moleculares aqui obtidos, pode-se concluir que Ceratomyxa sp. é uma espécie ainda não descrita na literatura.
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    Competição e persistência populacional em Acanthoscelides macrophthalmus: uma análise de estrutura populacional
    (Universidade Federal de São Paulo, 2018-03-29) Iano, Daniela Mayumi [UNIFESP]; Rossi, Marcelo Nogueira [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    The understanding of how variations in demographic processes directly influence population dynamics and persistence has been the focus of ecology for many years. It is already known that competition is one of the ecological interactions that most interfere in the biological parameters and in the abundance of the species. In this study, we have investigated how larval competition may affect the structure and population persistence of Acanthoscelides macrophthalmus, as well as its interference with the finite rate of population increase and the contribution of dispersion to the persistence of this species. Mature fruits of the host plant Leucaena leucocephala were collected from a population located in São Paulo, SP. The fruits were taken to the laboratory where they were dissected. The seeds were conditioned in six transparent plastic containers and the second generation of bruchine was established as a control population. Seeds with one or two eggs were individualized, and two treatments were established: 1) seeds without larval competition and 2) seeds with larval competition. The seeds containing eggs were individualized, and after five days 20 seeds per treatment were dissected every two days to remove the larvae. After that, the cephalic capsule of each larva was measured. The population structure was determined through the elaboration of projection matrices, from which the finite rate of increase (R), the stable distribution of stages, the sensitivity and the elasticity were estimated. Considering a single population, the simulations were done to calculate the population persistence time and the proportion of occupied patches adding 0, 5, and 10% of migration. The finite rate of population growth (R) was higher for the treatment without competition. Competition also reduced the body size of third instar larva and sensitivity results showed that the transition from the third to the fourth instar was the most important for R estimation, suggesting that this stage was mostly affected by competition. The stable stage distribution showed that the probability of populations being extinct is higher when competition is present. It was observed that competition should occur at high rates in populations to produce a significant decrease in R. Populations showed high levels of persistence (for 100 generations), even with competition, and only 5% of migration increased the persistence of populations.