Navegando por Palavras-chave "Toughness"

Agora exibindo 1 - 3 de 3
  • Imagem de Miniatura
    Item
    Acesso aberto (Open Access)
    A escolha do alimento por bugios-ruivo (Alouatta clamitans, Primates, Cabrera, 1940) e muriquis-do-sul (Brachyteles arachnoides, Primates, e Geoffroy, 1806): composição da dieta e resistência à fratura de itens alimentares
    (Universidade Federal de São Paulo, 2014-04-25) Andrade, Enrico Sala de [UNIFESP]; Gomes, Mauricio Talebi [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)
    Food plants have chemical and physical defence mechanisms to avoid herbivory whereas primary consumers have adaptations to cross this barrier so as to reach their specific nutritional requirements. Southern Muriquis (Brachyteles archnoides) and Brown Howlers (Alouatta clamitans) are primates essentially herbivorous and have adaptations related to folivory and frugivory. Toughness is a physical property of food that describes the difficulty of propagating a fracture on some material. It is assessed by animals during biting and when indicate the digestibility of food (fiber content) probably passively influences the food selection by primates. This study verified if toughness influenced the food choice of Southern Muriquis and Brown howlers. Behavior informations about activity patterns of the studied species was collected using the scan sampling method (sample period of 10 minutes and, sampling interval of 5 minutes). It was calculated from activity patterns data, the diet composition by time spent feeding (TSF) on each consumed food type (fruits, leaves and flowers, both immature and mature). Sampling were conducted on rainy and dry seasons over four periods (December 2012 and October 2013, rainy, and also in May 2013 and August 2013, dry) on Carlos Botelho State Park (PECB, 24°06 e 24°14 S e 47°47 e 48°07 O) (in situ). Beside, samplings of food preferences of two females of Alouatta clamitans and two males of Alouatta caraya were conducted at Fundação Parque Zoológico de São Paulo (FPZSP), São Paulo-SP. Ten specimens of each food consumed by the animals were tested to get toughness values using a portable tester. The Chapter I of this dissertation presents the activity patterns and diet in situ whereas in Chapter II are presented the toughness values of the different food types consumed by the studied primates (in situ and ex situ). For activity patterns and diet, it was observed that feeding was the second most common activity performed (33.4% Muriqui; 30.3% Howlers) and the food type ?fruit?, rather mature ones, the most often chosen for both species. The highest proportion of fruit observed, indicative of frugivory, probably reflects the high-quality habitat of the primates, with proper availability of fruits over the annual cycle. For toughness of foods, it was observed that there is no apparent preference for a specific toughness range, but toughness seems to influence Howlers (particularly leaves) more than Muriquis in their food choice: Howlers consumed leaves with higher toughness values than Muriquis. For fruits and flowers, Howlers presented a trend to avoid consume food types with high toughness values, whereas for Muriquis, some foods with this feature were consumed in high proportion. Thus, this study suggests that toughness is relevant parameter in the study of food preferences of Brown Howlers and Southern Muriquis, especially to folivory, and probably herbivory.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Membrane-plate transition in leaves as an influence on dietary selectivity and tooth form
    (Academic Press Ltd- Elsevier Science Ltd, 2016) Talebi, Mauricio G. [UNIFESP]; Sala, Enrico A. [UNIFESP]; Carvalho, Barbara [UNIFESP]; Villani, Giovanna M. [UNIFESP]; Lucas, Peter W.; van Casteren, Adam
    Primates need accurate sensory signals about food quality to forage efficiently. Current evidence suggests that they target leaf foods based on color at long-range, reinforcing this with post-ingestive sensations relating to leaf toughness evoked during chewing. Selection against tough leaves effectively selects against high fiber content, which in turn gives a greater opportunity of acquiring protein. Here we consider a novel intermediate mechanical factor that could aid a folivore: leaves may transform mechanically from membranes (sheets that cannot maintain their shape under gravitational loads and thus 'flop') early on in development into plates (that can maintain their shape) as they mature. This transformation can be detected visually. Mechanical tests on two species of leaf eaten by southern muriqui monkeys (Brachyteles arachnoides) in Southern Atlantic Forest, Brazil, support a membrane-to-plate shift in turgid leaves during their development. A measure of this mechanical transition, termed lambda (lambda), was found to correlate with both leaf color and toughness, thus supporting a potential role in leaf selection. Muriquis appear to select membranous leaves, but they also eat leaves that are plate-like. We attribute this to the degree of cresting of their molar teeth. A dietary choice restricted to membranous leaves might typify the type of 'fallback' leaf that even frugivorous primates will target because membranes of low toughness are relatively easily chewed. This may be relevant to the diets of hominins because these lack the bladed postcanine teeth seen in mammals with a specialized folivorous diet. We suggest that mammals with such dental adaptations can consume tougher leaf 'plates' than others. (C) 2016 Elsevier Ltd. All rights reserved.
  • Nenhuma Miniatura disponível
    Item
    Somente Metadadados
    Primate dietary ecology in the context of food mechanical properties
    (Academic Press Ltd- Elsevier Science Ltd, 2016) Coiner-Collier, Susan; Scott, Robert S.; Chalk-Wilayto, Janine; Cheyne, Susan M.; Constantino, Paul; Dominy, Nathaniel J.; Elgart, Alison A.; Glowacka, Halszka; Loyola, Laura C.; Ossi-Lupo, Kerry; Raguet-Schofield, Melissa; Talebi, Mauricio G. [UNIFESP]; Sala, Enrico A. [UNIFESP]; Sieradzy, Pawel; Taylor, Andrea B.; Vinyard, Christopher J.; Wright, Barth W.; Yamashita, Nayuta; Lucas, Peter W.; Vogel, Erin R.
    Substantial variation exists in the mechanical properties of foods consumed by primate species. This variation is known to influence food selection and ingestion among non-human primates, yet no large-scale comparative study has examined the relationships between food mechanical properties and feeding strategies. Here, we present comparative data on the Young's modulus and fracture toughness of natural foods in the diets of 31 primate species. We use these data to examine the relationships between food mechanical properties and dietary quality, body mass, and feeding time. We also examine the relationship between food mechanical properties and categorical concepts of diet that are often used to infer food mechanical properties. We found that traditional dietary categories, such as folivory and frugivory, did not faithfully track food mechanical properties. Additionally, our estimate of dietary quality was not significantly correlated with either toughness or Young's modulus. We found a complex relationship among food mechanical properties, body mass, and feeding time, with a potential interaction between median toughness and body mass. The relationship between mean toughness and feeding time is straightforward: feeding time increases as toughness increases. However, when considering median toughness, the relationship with feeding time may depend upon body mass, such that smaller primates increase their feeding time in response to an increase in median dietary toughness, whereas larger primates may feed for shorter periods of time as toughness increases. Our results emphasize the need for additional studies quantifying the mechanical and chemical properties of primate diets so that they may be meaningfully compared to research on feeding behavior and jaw morphology. (C) 2016 Elsevier Ltd. All rights reserved.