Plateau pika (Ochotonidae: Ochotona curzoniae) is widespread in Qinghai-Tibetan Plateau (QTP). It is endemic to QTP and restricted to high altitude area, ranging from 3,000 to 5,200 m above sea level. In this study, I examined the genetic structure of O. curzoniae along the Qinghai-Tibetan Railway (QTR) using mitochondrial cytochrome b sequences, and investigated whether QTR had become a barrier of gene flow to populations of O. curzoniae on its two sides. In total, I found 26 haplotypes of cyt b sequences from 29 individuals, of which the mean length was 1,190 bp including 68 informative sites, and the mean genetic distance was 1.7%. Two major clades were revealed in phylogenetic trees as well as TCS haplotype network. In general, the relative positions of haplotypes in the clades were corresponded to their geographic distribution. Most haplotypes of clade I were from east side, while all the haplotypes of clade II were from west side of QTR. Significant population differentiation was revealed between populations from the opposite sides of QTR, but not the same side. Due to the far smaller geographical distances between sampling sites between opposite sides than those of the same side, the differentiation pattern was not consistent with the theory of isolation by distance. Therefore, QTR might have resulted as a barrier to gene flow between populations of O. curzoniae living on opposite sides of QTR. The degree of genetic differentiation between populations of O. curzoniae on opposite sides of QTR will probably further increase in the future.

abstract: The highly-social plateau pika (Lagomorpha: Ochotona curzoniae) excavates vast burrow complexes in alpine meadows on the Tibetan Plateau. Colonies of over 300 individuals/ha have been reported. As an ecosystem engineer, their burrowing may positively impact ecosystem health by increasing plant species diversity, enhancing soil mixing, and boosting water infiltration. However, pikas are commonly regarded as pests, and are heavily poisoned throughout their range. The underlying assumption of eradication programs is that eliminating pikas will improve rangeland quality and decrease soil erosion. This dissertation explores the link between plateau pikas and the alpine meadow ecosystem in Qinghai Province, PRC. This research uses both comparative field studies and theoretical modeling to clarify the role of pika disturbance. Specifically, these studies quantify the impact of pikas on nutrient cycling (via nutrient concentrations of vegetation and soil), hydrology (via water infiltration), local landscape properties (via spatial pattern description), and vascular plant communities (via species richness and composition). The competitive relationship between livestock and pikas is examined with a mathematical model. Results of this research indicate that pika colonies have both local and community level effects on water infiltration and plant species richness. A major contribution of pika disturbance is increased spatial heterogeneity, which likely underlies differences in the plant community. These findings suggest that the positive impact of plateau pikas on rangeland resources has been undervalued. In concurrence with other studies, this work concludes that plateau pikas provide valuable ecosystem services on the Tibetan Plateau. / Dissertation/Thesis / Ph.D. Biology 2010

L'analyse multivariée des données chez 7138 sujets a montré que l'âge, dans tous les cas, prévenirle contact des mouches avec les aliments, chez les éleveurs, le nombre de chiens par famille, résider dans le Comté de Ganzi et posséder des peaux de renards, chez les agriculteurs, le sexe féminin, l'habitude de jouer avec les chiens et de boire de l'eau des ruisseaux, chez les urbains, étaient des facteurs de risque. Par des questionnaires sur les pratiques d'élevage, des transects pour détecter les indices de présence de petits mammifères et mesurer les surfaces encloses, et la recherche du parasite dansles fèces des chiens, l'hypothèse de travail a été confirmée: le surpâturage des communaux était significativement associé à la surface des pâtures encloses ainsi qu'aux densités élevées de petits mammifères dans les communaux, elles-mêmes corrélées au niveau d'infection des chiens, susceptible d'expliquer les hautes prévalences de la maladie dans ces communautés pastoralesTibétaines