Características morfo-funcionais digestivas como mediadoras da frugivoria por aves
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Data
2022-12-14
Autores
Crestani, Ana Cristina Vara [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Características morfológicas digestivas parecem explicar não só o quanto da dieta de aves é composta por frutos como também quais espécies de frutos são consumidas. Sabe-se que o processo de escolha dos frutos é determinado em parte pelo conjunto de característica dos frutos carnosos, como nutrientes e compostos químicos de defesa, que interagem e influenciam a escolha e consumo por animais, e por processos digestivos que determinam a eficiência do animal em extrair e assimilar a energia dos frutos. Este trabalho buscou entender: (1) como a variação de características morfológicas do trato digestivo de espécies de aves se relaciona com o consumo de frutos com diferentes quantidades de açúcares, lipídios e compostos fenólicos e (2) a capacidade digestiva de uma espécie de ave (Euphonia violacea) com alto grau de frugivoria que consome frutos pobres em nutrientes em relação à manutenção energética e requerimentos de nitrogênio. Para isso, (1) foram realizadas medidas morfométricas do trato digestivo de nove espécies de aves com diferentes porcentagens de frutos em suas dietas (grau de frugivoria). As porcentagens de açúcares solúveis, lipídios e fenóis totais foram quantificadas para sete espécies de frutos consumidos por estas aves. Essas características, combinada com o consumo médio dos frutos pelas aves, foram utilizadas para a seleção de modelos e análises filogenéticas. O grau de frugivoria foi explicado pela área da moela e peso do fígado. Além disso, o comprimento do intestino e o peso de fígado se relacionaram com o consumo de açúcares solúveis, lipídios e fenóis totais. Como segundo capítulo (2), foram realizados experimentos contrastando indivíduos de E. violacea e uma espécie de ave frugívora menos especializada (Thraupis sayaca; Thraupidae) com dietas artificiais com diferentes porcentagens de açúcares e nitrogênio. Ambas as espécies aumentaram a ingestão de alimento ofertado conforme a diminuição da concentração de açúcar, mantendo a energia corpórea, e não foram encontradas diferenças nos consumos de nitrogênio entre as espécies. Concluiu-se que os traços fisiológicos investigados não explicam o consumo de frutos com baixo valor nutricional. Assim, este trabalho investigou como características fisiológicas digestivas e morfológicas do trato digestivo das aves se relacionam com o consumo de frutos com determinada composição nutricional e química.
Digestive morphological characteristics seem to explain not only how much of the diet of birds is composed of fruits but also what species of fruit are consumed. The fruit selection process is determined in part by the characteristic set of nutrients and chemical defense compounds present in fleshy fruits, which interact and influence the choice and consumption by animals, and by digestive processes that determine the efficiency of the animal in extracting and assimilating the energy of the fruits. In this study, we explored (1) the relationship between digestive traits and the consumption of fruits with different nutrient and chemical compounds and, (2) the digestive capacity of a bird species that exploit low-energy fruits (Euphonia violacea) regarding to energy intake and nitrogen requirement. We performed (1) morphological characterization of the digestive structures in nine species of birds whit different percentage of fruit in their diet (frugivory degree). Using seven fruit species, which are consumed by sampled birds, we analyzed the percentage of soluble sugar, lipids and total phenols. Together with the rate of consumption, we combined all this traits in multiple regressions models and phylogenetic effect. We found that frugivory degree is explained by gizzard area and liver mass, while the intestine length and liver mass also have a relationship with consumption of sugar, lipids and phenols. As a second chapter (2), we conducted trials using captive individuals of E. violacea and a less-specialized bird (Thraupis sayaca; Thraupidae), and artificial diets with distinct amounts of sugar and nitrogen. Both species were able to compensate energy intake as sugar density decreased and they did not differ in mass-corrected maintenance nitrogen requirement. Thus, this study have investigated the relationship between birds digestive structures and process with the nutritional and chemical characteristic of fruit that the birds consume.
Digestive morphological characteristics seem to explain not only how much of the diet of birds is composed of fruits but also what species of fruit are consumed. The fruit selection process is determined in part by the characteristic set of nutrients and chemical defense compounds present in fleshy fruits, which interact and influence the choice and consumption by animals, and by digestive processes that determine the efficiency of the animal in extracting and assimilating the energy of the fruits. In this study, we explored (1) the relationship between digestive traits and the consumption of fruits with different nutrient and chemical compounds and, (2) the digestive capacity of a bird species that exploit low-energy fruits (Euphonia violacea) regarding to energy intake and nitrogen requirement. We performed (1) morphological characterization of the digestive structures in nine species of birds whit different percentage of fruit in their diet (frugivory degree). Using seven fruit species, which are consumed by sampled birds, we analyzed the percentage of soluble sugar, lipids and total phenols. Together with the rate of consumption, we combined all this traits in multiple regressions models and phylogenetic effect. We found that frugivory degree is explained by gizzard area and liver mass, while the intestine length and liver mass also have a relationship with consumption of sugar, lipids and phenols. As a second chapter (2), we conducted trials using captive individuals of E. violacea and a less-specialized bird (Thraupis sayaca; Thraupidae), and artificial diets with distinct amounts of sugar and nitrogen. Both species were able to compensate energy intake as sugar density decreased and they did not differ in mass-corrected maintenance nitrogen requirement. Thus, this study have investigated the relationship between birds digestive structures and process with the nutritional and chemical characteristic of fruit that the birds consume.
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Palavras-chave
Dieta especializada, Balanço de energia, Açúcar, Lipídios, Fenóis, Diet specialization, Energy balance, Sugar, Lipids, Phenols