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Neotyphodium are fungal endosymbionts of grasses that reproduce asexually by infecting the hosts seed. This relationship has traditionally been considered mutualistic, with the fungus improving host fitness by alleviating important stresses. To determine the importance of biotic and abiotic stresses in mediating the endophyte-grass interaction, I investigated the relationship between grazing pressure by collared pikas and Neotyphodium sp. infection frequency in the grass Festuca altaica in an alpine meadow. I conducted a factorial design experiment combining endophyte infection, grazing history, fungicide and fertilizer. Leaf demography and herbivory damage were monitored every two weeks. In areas with chronic grazing history, infected plants were significantly less productive than uninfected tussocks, but there was no difference at low grazing history. There was no effect of infection on the likelihood of herbivory. Contrary to predictions of the mutualism theory, the Neotyphodium sp. / F. altaica symbiotum varied from parasitic to neutral across our gradient of interest. / Ecology

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

An increasing amount of evidence suggests that as temperatures increase, montane animals are moving upward in elevation (IPCC 2007, Parmesan and Yohe 2003). As suitable habitats rise in elevation and then disappear altogether, these animals could be pushed to extinction. The American pika, Ochotona princeps, is a montane mammal that lives in western North America, usually at elevations above 1500 m (Smith and Weston 1990). Recent evidence suggests that pika population numbers are dropping in response to rising temperatures (Beever et al. 2010). The pika is a small herbivorous lagomorph, a relative of hares and rabbits. Its habitat is tightly restricted to talus slopes (rockfields) and the surrounding vegetation (Grayson 2005). Pikas have a high tolerance for cold temperatures, and do not hibernate during the long montane winter. However, they have very little tolerance for even mildly warm temperatures, and have been found to die when confined above ground at 25.5˚ C (Smith 1974b). To better understand pika persistence, we resurveyed 17 historic pika sites in the Lassen Peak region of northern California in August and September, 2009. Six of the historic sites were abandoned, as well as an additional 11 of 17 new sites surveyed. At each site we collected habitat information, and analyzed the data for factors that were correlated with site occupancy. We also installed 38 iButton thermal dataloggers in abandoned and occupied pika use sites, to determine if temperature affects occupancy. The dataloggers remained in pika sites for 14 months and recorded temperature every 1.5 hours. Abandoned pika sites had higher average temperatures and more days below 0˚ C. They also had greater shrub cover, less forb and graminoid cover, and a greater percentage of litter substrate. These findings suggest that the current warming trend may be having a negative impact on pikas in the Lassen Peak Region. As temperatures rise, pikas may be declining due to unsuitable temperatures and altered vegetative communities. In addition to the Lassen surveys, I investigated pika behavior in different temperature regimes in the Sierra Nevada. If pikas are able to adapt to climate change, it is possible that populations of pikas in different temperature regimes may exhibit behavioral plasticity, or have evolved genetic differences, such that these populations have different daily activity schedules. To determine if there is a difference in pika behavior at different elevations I observed pikas in one low and one high elevation site within the Bishop Creek drainage system in the Sierra Nevada. I conducted behavioral observations of pikas in four time blocks throughout the day in August and September, 2010. I recorded specific behaviors, such as foraging and haying (vegetation collecting), and compared these activities between low and high elevation pikas at different times of day. In August, pikas in the low elevation site exhibited a different activity profile than those in the high elevation site. Low elevation pikas were significantly more crepuscular (most active at dawn and dusk) during this month. I also observed more foraging behavior in the high elevation than the low elevation site, in both August and September. Reduced activity at higher temperatures may have negative impacts on pikas as temperatures increase. Low elevation pikas may be stressed due to reduced time spent foraging and haypile (overwinter vegetation cache) gathering. However, if pikas were able to switch their activity schedules to a more nocturnal schedule, they could escape higher daytime temperatures. To detect the possibility of nocturnal behavior in low elevation pikas, I set up four infra-red remote cameras in the low elevation site. I had variable success in capturing pika behavior with the cameras, and detected no evidence of nocturnal behavior. More research on the possibility of nocturnal behavior in pikas would be worthwhile, in part to determine what chance, if any, pikas have of adapting to rising global temperatures.

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