Variação intrapopulacional na dieta de Hoplerythrinus unitaeniatus (Spix & Agassiz, 1829) (Pisces : Characiformes) em uma planície de inundação neotropical

• Ano de defesa: 2014
• Autor(a) principal: Mamede, Angélica Francisca Mendes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Biociências (IB); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Ecologia e Conservação da Biodiversidade
• Palavras-chave em Português: Uso do recurso; Variação ontogenética; Especialização intrapopulacional; Hoplerythrinus unitaeniatus; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA; Resource use; Ontogenetic variation; Individual specialization
• Link de acesso: http://ri.ufmt.br/handle/1/659

The variation in resource usage is very common and can occur in different ways in a natural population. Among these, I highlight the differentiated exploitation of resources between males and females, young and old, or can be related to change in morphology in response to resource usage and individual specialization (that in turn can be affected by intra-or interspecific competition). Thus the aim of this study is to describe the standard of food resources usege within a population of jeju fish (Hoplerythrinus unitaeniatus), a predator fish common in lentic environments) on the floodplain of the Pantanal. The collections were made in the floodplain located in the Pantanal region of Poconé in the years 2009, 2010 and 2011. The measures of morphology of each individual were taken and they had their sex determined and their stomach removed. The food itens of H. unitaeniatus and its possible competitor Hoplias malabaricus were identified. To quantify the numerical method was used. I checked if males and females, and/or adults (classified according to estimate of first maturity), and/or variations in morphology were related to the composition of the diet within that population through a PERMANOVA. Then I calculated the degree of individual specialization in the population (IS) and nestedness (NODF), separately for groups that differed in the diet. I used a PCA to reduce the dimensionality of the data of vegetation cover, and then whether there was effect of intra and interspecific competition or vegetation cover in IS through a multiple regression. The food itens of 145 especims of H. uniteniatus were analized: 56 males (Standard Length between 49.02 and 200.22 mm) and 89 females (SL between 64.13 and 204.50mm). The average length of the first maturation estimated is 105.8 mm. Thus, 82 individuals were classified as young and 53 as adults. The food itens were divided into 22 categories. Males and females did not differ in the composition of resource used (pseudo-F1.143=1.46; p= 0.14). However, diet composition differed between young fishes and adults (pseudo-F1.143= 5.26; p<0.01). When confronted with the composition of the diet, we found relashionship between variation in diet linked to morphology (axis 2, pseudo-F1.142=2.07, p<0.01; exis 3, pseudo-F1.142= 0.57, p=0.87). In general, the amplitude of individual specialization within this population ranged from 0.22 and 0.61 and was significant only in a minority of cases. The nestedness was significant only in two cases, and range between 10 and 60.83. The general model of multiple regression between the IS and the abundance of jeju and traíra and the PCA axes of vegetal cover, represented 12.6% of the variation found in the IS and was not significant (F4.9= 1.47; R²adjusted=0.126; p= 0.29). The IS was not affected by the abundance of jeju (p= 0.12), by the abundance of traíra (p= 0.53) and not by the vegetation cover (axis 1, p= 0.94; axis 2, p= 0.6). In summary, the population of Hoplerythrinus unitaeniatus of floodplain of Pantanal, presented a tendency to have individual specialization in a few cases, this turn was not influenced by competitive interactions. I also found intrapopulation variation in resource use explained by ontogeny and morphological variations.