Navegando por Assunto "Alouatta"

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Acesso aberto (Open Access)
Efeito do sexo, dieta e tamanho de sementes sobre o tempo de retenção em Guariba preto cativo
(Universidade Federal do Pará, 2015-01-30) SANTOS NETO, Raymundo Tomaz Melo dos; MUNIZ, José Augusto Pereira Carneiro; http://lattes.cnpq.br/4993290160435067; LOPES, Maria Aparecida; http://lattes.cnpq.br/3377799793942627
The effectiveness of a seed disperser depends on the time in which the seeds are retained in their digestive tract and involves several factors such as characteristics of the animals (physiology, morphology, health, age, sex, diet, body mass) and characteristics of the seeds (size , weight and rigidity). These are still largely unknown parameters for A. caraya. In this study we tested the influence of sex, diet, and seed size on the seed retention time (RT) in the digestive tract of howler monkeys using analysis of variance (ANOVA) for repeated-measurements. We used six captive individuals of Alouatta caraya (three of each sex), six seed species (two small, two medium, and two large), and three types of diet (composed of 15, 30, and 60% of leaves). The General Retention Time Mean (RTM) was 1.152 ± 639 min (range: 315-2.050 min) and the General Standard Deviation of the Retention Time (SDRT) was 577 ± 166 (range: 158-1.039 min). Significant influence was observed between the type of diet and the interaction between seed size and diet on RTM. RT was higher for diets comprised of 30% leaf and this effect varied for males and females dependent on seed size, which indicates that diet is an important factor in determining the effectiveness of the species as a seed disperser.
Acesso aberto (Open Access)
Ontogenia e dimorfismo sexual nas espécies de guaribas vermelhos, gênero Alouatta lacépède, 1799 (Primates, Atelidae)
(Universidade Federal do Pará, 2007) AVELAR, Áderson Araújo; SILVA JÚNIOR, José de Sousa e; http://lattes.cnpq.br/4998536658557008
Sexual dimorphism in red howlers is relatively well documented for adult specimens and in all species of the genus Alouatta adult males are larger than females. However, sexual dimorphism among these species is not homogeneous and A. seniculus is considered the more dimorphic species. Moreover, sexual dimorphism among non adult ages is poorly known. The aim of this work is to evaluate the ontogeny of sexual dimorphism in five closely related species of howler monkeys: Alouatta seniculus, A. juara, A. macconnelli, A. puruensis, and A. nigerrima, and establish a method for identification of more accurate age classes in these taxa. A total of 28 cranial and hyoidean dimensions were extracted from 329 crania, and pelage color of 192 skins was examined. Sexual dimorphism in each age class was verified using Student’s t Test, and Discriminant Function Analysis (DFA) was employed to verify the consistence of the age groups. Analysis of Variance (ANOVA), followed by Tukey’s pairwise comparisons test, was applied to analyze growth in some adult cranial dimensions in A. macconnelli. Five adult age classes were recognized through the evaluation of oclusal wear and cranial suture closure; however, these classes were not recognized by cranial dimensions only. Non adult age classes did not exhibit sexually dimorphic measurements on cranium, and sexually dimorphic characters appeared at the first adult age class. A. macconnelli was the more dimorphic species, and sexually dimorphic characters arose earlier in this species. In contrast, A. nigerrima exhibited a smaller number of sexual dimorphic characters, suggesting that differences in behavior of this species play an important role on dimorphism development. Among all cranial dimensions, the canine length was the most sexually dimorphic. In females, this dimension ranged about 60% of that in males. The sexual dimorphism was not evident in the neurocranium. In A. macconnelli, seven cranial dimensions in females and five in males exhibited variation among the adult age classes. Ontogenetic differences in pelage color were very subtle and refer to bleaching of chromatic fields in different degrees. Ontogenetic modifications on the cranium are more intense in males than females, leading to a narrower and more flattened cranium in adult specimens of the former. Some age classes could not be tested for some species due to the inadequate number of specimens in the collections analyzed.