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The outer, middle, and inner ears were studied in the lesser bamboo rat (Cannomys badius), a subterranean rodent in Indochina. Stereoscopic dissection and micro-computed tomography were used. The middle ear of the bamboo rat was characterized by a round eardrum without pars flaccida, “freely mobile” ossicles with a reduced transversal lamina and no orbicular apophysis, an enlarged stapedial footplate, absence of the stapedial artery, no unusual inflated bulla and retention of middle-ear muscles. The inner ear exhibited an elongated and highly coiled cochlea. Some features are associated with improved low-frequency hearing but decreased hearing sensitivity, as seen in other subterranean species. Hearing frequency limits calculated based on the middle ear dimensions were 0.5–40 kHz with best sensitivity at 6–8 kHz. It seems that the ear morphology and hearing ability of the lesser bamboo rat are typically adapted for underground habitat, even though some structures deviate from the pattern of subterranean forms.
In a soil ecosystem, bottom-up control is generally considered more influential than topdown control, although some empirical studies have suggested that predators have a trophic cascade effect on soil animals at lower trophic levels. In the present study, the effects of the long-clawed shrew, a mammalian predator at a high trophic level, on the soil invertebrate community and litter decomposition were investigated in a field experiment using enclosures. In the presence of the shrew, the population densities of earthworms, isopods and spiders tended to decrease, whereas that of large springtails and centipedes appeared to increase. This result might have been caused by the shrew's direct predation on the former invertebrates and the release from predation by spiders on springtails. The reason of the increase of centipedes was unknown. Shrew had no effects on litter decomposition rates both by litter trap analysis and litter-bag test. The top-down effects of shrews on litter decomposition might have been diluted through a complex food-web and the observing period of the present study might be too short to detect litter decomposition process. Experiment for longer time might demonstrate more explicit effect of the shrew on the soil ecosystem.
Variability in the coat color of the house mouse, Mus musculus, provides an opportunity to study the evolution of phenotypes in this species. Here we associated genetic variations with coat color in seven mice from Madagascar that had identical M. m. gentilulus mitochondrial DNA sequences. The entire coding region of the 948-base pair (bp) coat-color-related gene, Mc1r, was shown to have no nonsynonymous changes. However, analyses of the two exon-1 promoter regions—termed 1A (317 bp) and 1B (499 bp)—from a second gene, Asip, which is also involved in the evolution of coat color, revealed two distinct haplotypes in each region. Associations between Asip promoter regions and dorsal color were ambiguous; however, two ventral color types—light and dark gray—were associated with the haplotypes of 1A, as determined by clustering analysis. Notably, the haplotype of the light gray animals was identical to the Asip Aw allele that is associated with white bellies.
Genetic sex identification and efficient microsatellite genotyping using non-invasive samples are important for assessing genetic diversity and structure of wild mammals. We extracted DNA from fecal samples of endangered proboscis monkeys (Nasalis larvatus) at the Yokohama Zoological Gardens, and successfully identified their sex using a DEAD-box gene marker. Using the information of 31 published microsatellite loci developed for proboscis monkeys, we redesigned the primers for 18 loci and selected microsatellite loci with high heterozygosities and then developed a multiplex PCR system, in which 19 polymorphic microsatellite loci and a sex identification marker were amplified in three multiplex sets. In our developed method, genotyping errors rarely happened using DNA extracted from feces, and we could identify individuals and estimate parent—offspring relationship with high confidence. Our developed method is applicable for genetic analysis of wild proboscis monkeys and will provide us the information of not only their ecological and social features but also conservation management.
Evolutionary history of Callosciurus squirrel species seems affected by geographical isolation by huge rivers in Southeast Asia. Geographical isolation by rivers may have influenced phylogeographical structure between and within Callosciurus species. In Sundaland, Southeast Asia, however, phylogeographical structure within Callosciurus species may be explained by geographical isolation among islands. In a test of the effects of rivers and islands, we examined phylogeographical characteristics of C. prevostii based on mitochondrial cytochrome b gene sequences. This squirrel is distributed from peninsular Thailand to Sumatra and Borneo and adjacent small islands. We collected specimens from four geographically different populations (the Malay Peninsula, central Sumatra, eastern Sumatra, and Borneo) and conducted phylogeographical analyses. Interestingly, the two Sumatra populations, geographically separated by the Batang Hari River, the longest river in Sumatra, did not show monophyly: the central Sumatra population was closely related to the Malay Peninsula population. The specimen from Borneo had clearly diverged from the others. Present geographical isolation by the ocean does not completely explain the phylogeographical structure of this species. The riverine barrier hypothesis helped explain their evolutionary history. Future studies should examine more C. prevostii specimens from more different places in Sundaland.
Little is known about the food habits of Asian elephants (Elephas maximus) in tropical rainforests of Southeast Asia. In Peninsular Malaysia, elephant habitat has been extensively modified by human intervention in the past few decades. Most of the primary forest has been logged or given way to plantations, infrastructure, and human inhabitation. Here we compare the food habits of wild elephants in three habitats of Belum-Temengor Forest Complex (BTFC): (1) primary forest, (2) selectively-logged forest, and (3) by the side of a road that bisects the forest complex. We used microhistological fecal analysis to describe elephants' diet. Elephant dung in the primary forest was mainly composed of non-grass monocotyledonous leaves (22%), woody debris (32%), and woody fiber (20%). Those in the logged forest were similar; non-grass monocotyledonous leaves accounted for 33%, woody debris for 24%, and fiber for 26%. At the roadside, elephant dung was dominated by grasses (47%). We conclude that by the road elephants shift their diet into grasses, suggesting that the road acts like a large forest gap, promoting the availability of grasses and other early succession plants. Elephant feeding by the road poses potential conservation conflicts by means of road accidents and increased contact with people.
Surveys for the occurrence, distribution, and individual identification of Indo-Pacific bottlenose dolphins Tursiops aduncus were conducted around Amami Oshima Island, Kagoshima Prefecture, Japan from 2007 to 2013. The dolphins were primarily distributed in the areas where the survey effort was concentrated, particularly in Oshima Strait and on the western coast of the Island. In total, 33 groups of dolphins were encountered with a median group size of 8 (range: 1–50 individuals). The group size in Oshima Strait was significantly smaller than that recorded off the western coast. A total of 100 individuals were identified from photographs taken by the survey cruise and local residents with the cumulative number of identified individuals increasing over time and with no indication of saturation being reached. Thus, the population size of Indo-Pacific bottlenose dolphins in the waters around Amami Oshima Island was probably larger than that indicated by the present study; hence, photo-identification needs to be continued to provide a more accurate population size estimate in the future.
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