Studies of biogeographic variation in species abundances are fundamental to understanding and predicting the impacts of invasive exotic species. We quantified the abundance of the introduced and now invasive biocontrol weevil, Rhinocyllus conicus, on a newly adopted native host plant, Cirsium canescens (Platte thistle), across the plant's distributional range. We used regression and structural ...

Abstract Aims Grassland-to-shrubland transition is a common form of land degradation in drylands worldwide. It often attributed to changes disturbance regimes, particularly overgrazing. A myriad direct and indirect effects (e.g., accelerated soil erosion) grazing may favor shrubs over grasses, but their relative importance unclear. We tested the hypothesis that topsoil “winnowing” by wind erosi...

The alteration in gene expression that occurs in plants subjected to water shortage has been documented extensively (Skriver and Mundy, 19901, and gene cloning and sequencing has shed some light on the molecular processes that may protect cells from the harmful effects of osmotic stress (Bray, 1991, 1993). Since plant hormones such as ABA and jasmonate are in some cases capable of causing expre...

North Bangkok. ** Department of Chemistry, Faculty of Science, Ramkhamhaeng University. Abstract A new ecdysteroid, P5, has been isolated from the stem bark of aged trees (with flower) of vitex canescens. 20-Hydroxyecdysone, makisterone A, 24-epi-makisterone A, and canescensterone have also been isolated from both young trees (without flower) and aged trees (with flower) of vitex canescens. The...

1. Soil characteristics influence plant communities in part through water relations. Hypothetically, finer textured soils in arid climates should be associated with more negative plant and soil water potentials during drought, greater resistance of xylem to cavitation, and shallower root systems than coarse soils. 2. These hypotheses were tested by comparing the water relations of Great Basin s...

Premise of the study Microsatellite primers were developed to characterize the genetic diversity and structure of the annual herb Atriplex tatarica (Amaranthaceae) and to facilitate ecological and evolutionary studies of A. tatarica and its relatives. Methods and Results Sixteen novel microsatellite primers were developed for A. tatarica based on high-throughput sequencing of enriched librari...