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Variação intrapopulacional na dieta de Hoplerythrinus unitaeniatus (Spix & Agassiz, 1829) (Pisces : Characiformes) em uma planície de inundação neotropicalMamede, Angélica Francisca Mendes 13 March 2014 (has links)
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Previous issue date: 2014-03-13 / CNPq / A variação no uso de recurso é muito comum e pode ocorrer de diferentes formas dentro de uma população natural. Dentre essas se destacam a exploração de recursos
diferenciada entre machos e fêmeas, jovens e adultos, ou pode estar relacionada à
mudança na morfologia em resposta ao uso de recurso e especialização individual
(essa por sua vez pode ser afetada pela competição intra ou interespecífica). Desse
modo o objetivo desse trabalho é descrever o padrão de uso de recurso alimentar
dentro de uma população do peixe jeju (Hoplerythrinus unitaeniatus), um peixe
predador comum em ambientes lênticos, na planície de inundação do Pantanal. As
coletas foram realizadas na planície de inundação localizada na região do Pantanal de
Poconé nos anos de 2009, 2010 e 2011. De cada indivíduo foram tomadas medidas
morfológicas, tiveram seu sexo determinado e o estomago retirado. Os itens
alimentares de H. unitaeniatus e seu possível competidor Hoplias malabaricus foram
identificados. Para quantificação foi utilizado o método numérico. Verifiquei se machos
e fêmeas, e/ou jovens e adultos (classificados segundo estimativa de primeira
maturação) e/ou variações na morfologia estavam relacionadas à composição da dieta
dentro dessa população através de uma PERMANOVA. Então calculei o grau de
especialização individual na população (IS) e o aninhamento (NODF), separadamente
para grupos que diferiam na dieta. Utilizei uma PCA para reduzir a dimensionalidade
dos dados de cobertura vegetal, para então saber se existiu efeito da competição intra
ou interespecífica e cobertura vegetal no IS através de uma regressão multipla. Foram
analisados os conteúdos estomacais de 145 exemplares de H. unitaeniatus: 56
machos (CP variando entre 49,02 e 200,22 mm) e 89 fêmeas (CP variando entre 64,13
e 204,50mm). O comprimento médio da primeira maturação estimado foi de 105,8 mm.
Desta forma, 82 indivíduos foram classificados como jovens e 53 como adultos. Os
itens alimentares foram divididos em 22 categorias. Machos e fêmeas não diferiram na
composição de recursos utilizados (pseudo-F1,143=1,46; p= 0,14). No entanto, a
composição da dieta diferiu entre jovens e adultos (pseudo-F1,143= 5,26; p<0,01).
Quando confrontados com a composição da dieta, encontramos relação entre a
variação na dieta relacionada à morfologia (eixo 2, pseudo-F1,142=2,07, p<0,01; eixo 3,
pseudo-F1,142= 0,57, p=0,87). De forma geral, a amplitude de especialização individual
dentro desta população variou entre 0,22 e 0,62 e foi significativa somente na minoria
dos casos. O aninhamento só foi significativo em dois casos, e variou entre 10 e 60,83.
O modelo geral de regressão múltipla entre o IS e a abundância de jeju e de traíra e os
eixos da PCA de cobertura vegetal, representou 12,6% da variação encontrada no IS e
não foi significativo (F4,9= 1,47; R²ajustado=0,126; p= 0,29). O IS não foi afetado pela
abundância de jejus (p= 0,12), pela abundância de traíra (p= 0,53) e nem pela
cobertura vegetal (eixo 1, p= 0,94; eixo 2, p= 0,6). Em síntese, a população de
Hoplerythrinus unitaeniatus da planície de inundação do Pantanal apresentou uma
tendência em ter especialização individual em poucos casos, esta por sua vez não foi
influenciada por interações competitivas. Também encontrei variação intrapopulacional
no uso do recurso explicada pela ontogenia e por variações morfológicas. / 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.
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Effects of an Early Season Heat Wave on Ecophysiological Parameters Related to Productivity in Sugar Maple (Acer saccharum Marsh.)Filewod, Benjamin A. 07 December 2011 (has links)
Anticipated increases in the frequency, duration or intensity of high temperature events ('heat waves') have the potential to significantly impact forest form and functioning, but these events remain virtually unstudied in forest ecosystems. This thesis presents the results of an event-driven research effort into the impacts of three days of record-setting high temperatures in late May 2010 on key ecophysiological parameters in Sugar Maple (Acer saccharum. Marsh). High temperatures reduced photosynthetic capacity by ~66% versus previous years and total end-of-season leaf litter production by ~33% versus prior measurements. It is predicted that these reductions substantially reduced productivity for Sugar Maple in 2010. These results constitute the first description of the impacts of a short-duration heat wave on productivity-related parameters in a temperate forest tree. The predicted increase in high temperature events could make such impacts a significant, though so far overlooked, pathway of climate change impacts on temperate forests.
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Effects of an Early Season Heat Wave on Ecophysiological Parameters Related to Productivity in Sugar Maple (Acer saccharum Marsh.)Filewod, Benjamin A. 07 December 2011 (has links)
Anticipated increases in the frequency, duration or intensity of high temperature events ('heat waves') have the potential to significantly impact forest form and functioning, but these events remain virtually unstudied in forest ecosystems. This thesis presents the results of an event-driven research effort into the impacts of three days of record-setting high temperatures in late May 2010 on key ecophysiological parameters in Sugar Maple (Acer saccharum. Marsh). High temperatures reduced photosynthetic capacity by ~66% versus previous years and total end-of-season leaf litter production by ~33% versus prior measurements. It is predicted that these reductions substantially reduced productivity for Sugar Maple in 2010. These results constitute the first description of the impacts of a short-duration heat wave on productivity-related parameters in a temperate forest tree. The predicted increase in high temperature events could make such impacts a significant, though so far overlooked, pathway of climate change impacts on temperate forests.
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