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31.
32.
Body growth and life history in wild mountain gorillas (Gorilla beringei beringei) from Volcanoes National Park,Rwanda 下载免费PDF全文
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Justin Roy Mimi Arandjelovic Brenda J. Bradley Katerina Guschanski Colleen R. Stephens Dan Bucknell Henry Cirhuza Chifundera Kusamba Jean Claude Kyungu Vince Smith Martha M. Robbins Linda Vigilant 《Biology letters》2014,10(11)
Compared with other African apes, eastern gorillas (Gorilla beringei) have been little studied genetically. We used analysis of autosomal DNA genotypes obtained from non-invasively collected faecal samples to estimate the evolutionary histories of the two extant mountain gorilla populations and the closely related eastern lowland gorillas. Our results suggest that eastern lowland gorillas and mountain gorillas split beginning some 10 000 years ago, followed 5000 years ago by the split of the two mountain gorilla populations of Bwindi Impenetrable National Park and the Virungas Massif. All three populations have decreased in effective population size, with particularly substantial 10-fold decreases for the mountain gorillas. These dynamics probably reflect responses to habitat changes resulting from climate fluctuations over the past 20 000 years as well as increasing human influence in this densely populated region in the last several thousand years. 相似文献
36.
Pascale Sicotte 《Primates; journal of primatology》2000,41(1):93-101
In mountain gorillas (Gorilla g. beringei), male immigration in bi-sexual units is rare. This paper presents the case of a nearly weaned male infant gorilla who followed
his mother in her transfer. This case was recorded in the study population at the Kariske Research Center in 1988. The data
come from observation in Group B (on 12 days just prior to the transfer and on 54 days after the transfer over a period of
6 months). The situation of the infant did match the conditions in which infanticide occurs in gorillas, but he was not killed,
despite receiving male aggression and being wounded twice. In fact, both the mother and the infant received male aggression
more frequently than the long term residents in the group. The aggression received by the mother decreased after she mated
with the males and after she weaned the infant. The aggression received by the infant, however, did not decrease after his
mother mated with the males, and increased in intensity. The infant reacted fearfully to male aggression, in marked contrast
to his mother, who reacted either with indifference, or by simply avoiding the males. The aggression eventually stopped, and
the infant became a blackback in Group B. Evolutionarily, the death of the infant would not have markedly accelerated the
mother's return to estrus, but the death of the infant could still have benefitted the males, by decreasing the reproductive
output of a competitor. Adult male gorillas are also presumably selected to resist male immigration. Proximately, the aggression
directed towards the infant was not related to mating access to the mother. The sex of the infant may contribute to explain
the post-transfer male aggression, but data on the integration of old female infants in a new group is needed to test whether
the sex of the infant has an effect on their vulnerability to infanticide. Also, the intense fear displayed by the infant
may have played a role in prompting male aggression. 相似文献
37.
Juichi Yamagiwa Ndunda Mwanza Takakazu Yumoto Tamaki Maruhashi 《Primates; journal of primatology》1994,35(1):1-14
Details are presented of the composition of the diet of eastern lowland gorillas, derived mainly from a study of their fresh
trails and fecal analysis, during the course of an entire year in the tropical lowland forests of the Itebero region, Zaire.
Gorillas ate 194 plant foods from 121 species and 45 families. They consumed 48 species of fruits; and 89% of fecal samples
contained fruit seeds, but fruits were a relatively small part (25%) of the total number of food items. The composition of
their diet changed seasonally. When consumption of fruit decreased in the long rainy and the long dry seasons, the gorillas
ate, in addition to Zingiberaceae and Marantaceae, many kinds of leaf and bark, which may be an important buffer against the
shortage of fruits. Gorillas also fed regularly on ants (Ponerinae), and the frequency of consumption showed small seasonal
variations. From a comparison of diet composition, eastern lowland gorillas appeared to be intermediate between the other
two subspecies. The choice of food showed differences in preference of fruits and insects between subspecies and may reflect
high similarities within subspecies in lowland and montane forests. 相似文献
38.
Habituation of western gorillas to human presence is generally an expensive, lengthy and difficult process. Here we describe the habituation process for two groups of western gorillas at the Mondika Research Center, with the hope that the lessons we learned will facilitate future gorilla studies. We expand upon earlier studies by describing the process through complete habituation for both males and females, and for more than one group. The major obstacle to habituation was developing sufficient tracking skills to follow gorilla trail on a daily basis. Once this was achieved, the silverback became semi-habituated (i.e. ignoring human presence during half of contacts) within a year, although the majority of group females continued to avoid humans. As female presence at contacts increased, a period of male recidivism followed, requiring an additional year before his complete habituation was reached. Habituating the females took longer than the male, but we found, contrary to earlier studies, that it consisted of the same stages, including avoidance, aggression, and curiosity before habituation. We compare results between groups and across sites and discuss how factors such as tracking abilities, group size and cohesion, population density and home range overlap, and the manner of approaching gorillas during contacts influence the habituation process. 相似文献
39.
Juichi Yamagiwa 《Primates; journal of primatology》1986,27(3):273-282
To clarify the advantages of solitary life in gorilla males, a lone silverback mountain gorilla (Gorilla gorilla beringei) was studied for nine months in the natural habitat of the Virunga volcanoes. While the time budget for each activity and
daily activity cycle were similar to those of groups, his daily journey distance and ranging patterns differed from those
of groups. His movements were little influenced by the distribution and abundance of foods, which strongly influence the movements
of groups. He notably increased his day journey distances when he encountered neighboring groups. He persistently followed
the groups for days and went out of his usual range area. These encounters shifted his monthly range from his natal group's
range to that of other groups. When the silverbacks of the encountered groups noticed his presence, they usually gave hoots
and chest-beats and sometimes fought violently with him, while females and immatures did not show positive responses towards
him. Lone males could have more chance to contact females and to lure them away from their groups than silverbacks within
groups. The lone male stage, accompanied by frequent contacts with different groups, probably provides maturing males with
useful knowledge of neighboring groups and areas. 相似文献
40.
We examined the pattern and possible functions of social interactions between adult males and immatures in three free-ranging, multi-male groups of mountain gorillas (Gorilla beringei beringei). Previous studies conducted during the 1970s when groups contained one to three adult males concluded that male-immature relationships were likely to be a form of low-cost paternal investment [Stewart, Mountain gorillas: three decades of research at Karisoke. Cambridge, UK: Cambridge University Press, 2001]. We evaluated whether this hypothesis still held in groups containing six to nine adult males, or if male-immature relationships might serve other functions (e.g. mating effort, kin selection, or alliance building). Overall, we found that immatures spent the most time near, and interacted most with, the alpha silverback. These behaviors peaked during the period when infants were still quite vulnerable but increasing their independence from their mothers. Such findings suggest that parenting effort remains the primary function of male-immature relationships; however, there is some evidence for the mating effort hypothesis as well. 相似文献