Browsing by Author "Struhsaker, TT"

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    A pilot study of genetic and morphological variation in the muriqui (Brachyteles arachnoides)
    (Prim. Conserv, 1990) Sa, Lemos de; M, R; Pope, TR; Glander, KE; Struhsaker, TT; Fonseca, GAB da
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    Dietary Variability in Redtail Monkeys (Cercopithecus ascanius schmidti) of Kibale National Park, Uganda: the Role of Time, Space, and Hybridization
    (International Journal of Primatology, 2017-10-01) Struhsaker, TT
    © 2017, Springer Science+Business Media, LLC. Studies of the diet of different groups of the same species allow us to understand intraspecific dietary variability. I collected dietary data from six neighboring groups of redtail monkeys (Cercopithecus ascanius schmidti) and three hybrid monkeys over 12 years at Ngogo and from one group at Kanyawara in Kibale National Park, Uganda and compared these results with previous studies of redtail diets elsewhere in Kibale and from the Kakamega Forest of Kenya. I scored feeding as a particular monkey ingesting a species-specific plant part, or catching insects from a species-specific substrate. A new feeding score was tallied for the same combination of parameters only after a 30-min interval or if the identity of one of the three parameters changed. I counted trees along transects in the home ranges of the two main study groups to calculate food selection ratios. I used chi-square tests to compare diets between groups and time periods and Spearman rank correlation coefficient tests for dietary correlates. These comparisons reveal considerable variation in plant parts and species eaten by redtails between months, years, and neighboring groups with overlapping ranges. Selection ratios show that some tree species are important sources of plant food, while others are more important as sources of invertebrates. The high incidence of insectivory by redtails demonstrates another ecological role they play in addition to seed dispersal. The intrademic variation in diets I describe for Kibale was often as great as and sometimes greater than the interdemic variation. The diets of the hybrid monkeys at Ngogo differed in some ways from their parental species, particularly in their greater consumption of invertebrates. Introgression may have led to some of these differences within and between redtail demes. The pronounced variability in redtail diets demonstrates why a typological perspective of species is unwarranted and that the validity of interspecific comparisons requires a thorough understanding of intraspecific variation.
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    Sexual dimorphism in canine length of woolly spider monkeys (Brachyteles arachnoides, E. Geoffroy 1806)
    (International Journal of Primatology, 1993-10-01) Lemos de Sá, RM; Pope, TR; Struhsaker, TT; Glander, KE
    We measured canine teeth from 28 woolly spider monkeys (Brachyteles arachnoides) to assess sexual dimorphism and population differences. The specimens are from the Brazilian states of Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro, and São Paulo. We found strong sexual dimorphism in canine length for individuals belonging to populations south of 22°00′ latitude but no sexual dimorphism in canine length from individuals of populations north of 21°00′ latitude. Canine length did not vary among females of northern and southern populations. However, southern males had significantly longer canines than northern males. This geographical difference in canine morphology, together with the presence or absence of thumbs and published accounts of differences in genetics and social structure between northern and southern populations, suggests that Brachyteles arachnoides may be composed of at least two subspecies, which appear to be separated by the rivers Grande and Paraiba do Sul and the Serra da Mantiqueira. © 1993 Plenum Publishing Corporation.