1,721,144 research outputs found
Mesozoic origin for West Indian insectivores
Full text linkAlfred L. Roca, Gila Kahila Bar-Gal, Eduardo Eizirik, Kristofer M. Helgen, Roberto Maria, Mark S. Springer, Stephen J. O'Brien & William J. Murph
A new species of bandicoot, Microperoryctes aplini, from western New Guinea
Full text linkKristofer M. Helgen and Timothy F. Flanner
New records of Microchiroptera (Rhinolophidae and Kerivoulinae) from Vietnam and Thailand
Full text linkThe diversity of Rhinolophidae in Thailand and Vietnam is briefly discussed and the taxonomy of Asian
Kerivoulinae, with particular reference to the genus Phoniscus, is reviewed. Four new country records are
included: Rhinolophus shameli and Kerivoula kachinensis from Vietnam and Phoniscus jagorii from Vietnam
and Thailand. A second record of Phoniscus atrox from Thailand is also discussed.Vu Dinh Thong, Sara Bumrungsri, David L. Harrison, Malcolm J. Pearch, Kristofer M. Helgen, and Paul J. J. Bate
Hybridization capture reveals evolution and conservation across the entire koala retrovirus genome
Full text linkThe koala retrovirus (KoRV) is the only retrovirus known to be in the midst of invading the germ line of its host species. Hybridization capture and next generation sequencing were used on modern and museum DNA samples of koala (Phascolarctos cinereus) to examine ca. 130 years of evolution across the full KoRV genome. Overall, the entire proviral genome appeared to be conserved across time in sequence, protein structure and transcriptional binding sites. A total of 138 polymorphisms were detected, of which 72 were found in more than one individual. At every polymorphic site in the museum koalas, one of the character states matched that of modern KoRV. Among non-synonymous polymorphisms, radical substitutions involving large physiochemical differences between amino acids were elevated in env, potentially reflecting anti-viral immune pressure or avoidance of receptor interference. Polymorphisms were not detected within two functional regions believed to affect infectivity. Host sequences flanking proviral integration sites were also captured; with few proviral loci shared among koalas. Recently described variants of KoRV, designated KoRV-B and KoRV-J, were not detected in museum samples, suggesting that these variants may be of recent origin.Kyriakos Tsangaras, Matthew C. Siracusa, Nikolas Nikolaidis, Yasuko Ishida, Pin Cui, Hanna Vielgrader, Kristofer M. Helgen, Alfred L. Roca, Alex D. Greenwoo
A new giant shrew rat (Rodentia, Muridae, Murinae) from Flores, Indonesia and a comparative investigation of its ecomorphology
No full textWe describe a new genus and species of large-bodied murine from archaeological deposits at Liang Bua, a limestone cave in western Flores, East Nusa Tenggara, Indonesia. Among a large assemblage of murine remains, several mandibular elements recovered from mostly Holocene sediments show a distinct anatomy, with a long and robust jaw, massive proodont incisors, and relatively small molars. These morphological features are unusual among murines but most similar to terrestrial and carnivorous species of the Indo-Pacific, colloquially referred to as shrew rats (Philippines, Sulawesi) or moss mice (New Guinea), and indicate a potential carnivorous dietary adaptation, perhaps specializing in a vermivorous diet. The size of the mandible indicates that this murine is the largest shrew rat yet known. Although presumed extinct, targeted field research is needed to determine if this rat still lives on Flores today.
Veatch, E. Grace, Pierre-Henri Fabre, Matthew W. Tocheri, Thomas Sutikna, E. Wahyu Saptomo, Guy G. Musser, and Kristofer M. Helgen. 2023. A new giant shrew rat (Rodentia: Muridae: Murinae) from Flores, Indonesia and a comparative investigation of its ecomorphology. In Contributions to Mammalogy and Zooarchaeology of Wallacea, ed. K. M. Helgen and R. K. Jones. Records of the Australian Museum 75(5): 741–764
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Host-parasite associations in small mammal communities in semiarid savanna ecosystems of East Africa
No full textDespite the established importance of rodents as reservoirs of vector-borne zoonoses in East Africa, there is relatively limited information regarding the infestation parameters and host associations of ectoparasites that vector many such pathogens among small mammals in this region. Between 2009 and 2013, small mammals were livetrapped in the semiarid savanna of Kenya. A subset of these individual hosts, including 20 distinct host taxa, was examined for ectoparasites, which were identified to species. Species of fleas, ticks, mites, and sucking lice were recorded. Based on these data, we calculated host-specific infestation parameters, documented host preferences among ectoparasites, conducted a rarefaction analysis and extrapolation to determine if ectoparasites were adequately sampled, and assessed nestedness for fleas to understand how pathogens might spread in this system. We found that the flea community structure was significantly nested. Understanding the ectoparasite network structure may have significant human relevance, as at least seven of the ectoparasite species collected are known vectors of pathogens of medical importance in the region, including Yersinia pestis, Rickettsia spp., and Theileria parva, the causative agents of plague, spotted fevers and other rickettsial illnesses in humans, and theileriosis, respectively.Ana Sofia Guerra, Ralph P. Eckerlin, Ashley P. G. Dowling, Lance A. Durden, Richard G. Robbins, Katharina Dittmar, Kristofer M. Helgen, Bernard Agwanda, Brian F. Allan, Tyler Hedlund and Hillary S. Youn
Historically low mitochondrial DNA diversity in koalas (Phascolarctos cinereus)
Full text linkMaria C Avila-ArcosBACKGROUND: The koala (Phascolarctos cinereus) is an arboreal marsupial that was historically widespread across eastern Australia until the end of the 19th century when it suffered a steep population decline. Hunting for the fur trade, habitat conversion, and disease contributed to a precipitous reduction in koala population size during the late 1800s and early 1900s. To examine the effects of these reductions in population size on koala genetic diversity, we sequenced part of the hypervariable region of mitochondrial DNA (mtDNA) in koala museum specimens collected in the 19th and 20th centuries, hypothesizing that the historical samples would exhibit greater genetic diversity. RESULTS: The mtDNA haplotypes present in historical museum samples were identical to haplotypes found in modern koala populations, and no novel haplotypes were detected. Rarefaction analyses suggested that the mtDNA genetic diversity present in the museum samples was similar to that of modern koalas. CONCLUSIONS: Low mtDNA diversity may have been present in koala populations prior to recent population declines. When considering management strategies, low genetic diversity of the mtDNA hypervariable region may not indicate recent inbreeding or founder events but may reflect an older historical pattern for koalas.Kyriakos Tsangaras, María C Ávila-Arcos, Yasuko Ishida, Kristofer M Helgen, Alfred L Roca and Alex D Greenwoo
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