Genetic differentiation of rare and common varieties of Eriogonum shockleyi (Polygonaceae) in Idaho using ISSR variability

Idaho populations of Eriogonum shockleyi are divided taxonomically into 2 varieties: E. shockleyi var. packardae , which is endemic to Idaho, and the typical variety, which is widespread in the western United States. Recent morphological investigations of E. shockleyi in Idaho have identified potentially reliable morphological characters for field identification of the subspecific taxa. This paper investigates the genetic basis for the separation of the 2 varieties of E. shockleyi using inter simple-sequence repeats (ISSR) markers. Although we found some morphological differences between the populations that correlated with the 2 varieties, we identified no molecular markers in this study to distinguish between them. Morphological measurements obtained in the field indicate that although a population may have an overall average morphology that defines the variety, some individuals in nearly all populations have putative diagnostic characters that define the other variety. The morphological characters used to distinguish the 2 varieties are most likely the result of environmental variability and could result from differences in precipitation and soil water retention. Alternatively, high levels of outcrossing through pollen flow could be obscuring selection for morphological characters at particular sites.     

Diel use of water by reintroduced bighorn sheep

Water sources are an important habitat component for populations of bighorn sheep ( Ovis canadensis ), and the technique of sampling at water sources has been used extensively to study behaviors and estimate parameters of bighorn populations. Little is known, however, concerning the time of day at which groups of bighorns visit water. Understanding when bighorns visit water sources will allow wildlife investigators to conduct sampling when bighorns are most likely to be present at this resource. We quantified use of 7 water sources by reintroduced bighorn sheep during summer 2005 and 2006 on Antelope Island State Park, Utah. Our purpose was to determine if female, male, or mixed-sex groups visited water at a particular time and if visits to this resource by all bighorns differed in time during drought conditions compared with nondrought conditions. The mean time that all bighorns visited water was 14:22 ( s = 3:08 hours). No time differences existed among female, male, or mixed-sex groups or between drought and nondrought conditions. Our results provide wildlife investigators with a time frame for activating motion-sensor cameras or sampling at water sources, which will increase the likelihood of photographing or observing reintroduced Rocky Mountain bighorn sheep at water sources in portions of the Great Basin Desert.     

Perceptions of Utah alfalfa growers about wildlife damage to their hay crops: implications for managing wildlife on private land

We conducted a survey of Utah alfalfa ( Medicago sativa ) growers in 1993 to identify wildlife damage problems to bay crops. Such surveys can provide wildlife managers with important insights regarding landowners' wildlife damage management concerns and needs. Pocket gophers ( Thomomys spp.) and mule deer ( Odecoileus hemionus ) were perceived by growers as causing the most damage. Respondents reported a total annual loss of $350,000 or $24.79/ha (2.8% of the total crop value) because wildlife damage in alfalfa crops. Decreased hay quantity was the most frequently cited problem caused by wildlife. Compensation and incentive programs were preferred over assistance and information programs for managing wildlife damage in alfalfa crops.     

Reproduction and demography of Townsendia aprica (Asteraceae), a rare endemic of the Southern Utah Plateau

Townsendia aprica (Asteraceae: Astereae), a rare pulvinate perennial of the Southern Utah Plateau, was listed as threatened under the U.S. Endangered Species Act in 1985. Here we report on the reproductive biology and pollination of this little-known species and provide an estimate, for a single site-year, of size-specific reproductive effort. Last Chance townsendia appears a short-lived perennial that begins reproducing in its 2nd year (1.5-2.0 cm diameter). Maximum reproductive effort is attained with the 2.5-4.0 cm diameter size class: 38% of these plants produced 84% of the flower heads. Few plants survived past the 4-cm size class. The species is primarily self-incompatible: neither autogamous nor geitonogamous breeding system treatments produced a significant number of achenes. Unlike some populations of some congeners, the Ivie Creek population was not apomictic. Outcrossing is the primary means of reproduction and native solitary bees are the most important pollinators. Paramount are several species in the genus Osmia , and the ground-nesting species Synhalonia fulvitarsis , which nests among the T. aprica plants. Synhalonia fulvitarsis also visits a contemporaneous blooming phlox ( P. austromontana ), which may facilitate pollination of the rare townsendia. The Townsendia-Phlox-Synhalonia interaction may represent another example of why we must consider communities rather than individual species in our conservation efforts.     

Large temperature drop across the Eocene-Oligocene transition in central North America

The Eocene-Oligocene transition towards a cool climate (approximately 33.5 million years ago) was one of the most pronounced climate events during the Cenozoic era. The marine record of this transition has been extensively studied. However, significantly less research has focused on continental climate change at the time, yielding partly inconsistent results on the magnitude and timing of the changes. Here we use a combination of in vivo stable isotope compositions of fossil tooth enamel with diagenetic stable isotope compositions of fossil bone to derive a high-resolution (about 40,000 years) continental temperature record for the Eocene-Oligocene transition. We find a large drop in mean annual temperature of 8.2 +/- 3.1 degrees C over about 400,000 years, the possibility of a small increase in temperature seasonality, and no resolvable change in aridity across the transition. The large change in mean annual temperature, exceeding changes in sea surface temperatures at comparable latitudes and possibly delayed in time with respect to marine changes by up to 400,000 years, explains the faunal turnover for gastropods, amphibians and reptiles, whereas most mammals in the region were unaffected. Our results are in agreement with modelling studies that attribute the climate cooling at the Eocene-Oligocene transition to a significant drop in atmospheric carbon dioxide concentrations.     

一种基于种群熵估计的自适应遗传算法

为获得运行过程中对搜索空间勘探和开采的平衡 ,该文提出了一种基于种群熵估计的参数自适应遗传算法。该算法每一进化代的新种群由保留、繁殖和随机 3部分子种群组成 ,其数量则由相应的参数进行控制。通过引入种群熵的概念对种群内个体的多样性进行度量并使用一种简单的方法对其进行估计以确定各控制参数 ,该算法实现了参数的自适应调节。试验结果表明该算法能够有效协调勘探和开采 ,在处理复杂问题时表现出较高的性能     

Arctic microorganisms respond more to elevated UV-B radiation than CO2

Surface ultraviolet-B radiation and atmospheric CO2 concentrations have increased as a result of ozone depletion and burning of fossil fuels. The effects are likely to be most apparent in polar regions where ozone holes have developed and ecosystems are particularly sensitive to disturbance. Polar plant communities are dependent on nutrient cycling by soil microorganisms, which represent a significant and highly labile portion of soil carbon (C) and nitrogen (N). It was thought that the soil microbial biomass was unlikely to be affected by exposure of their associated plant communities to increased UV-B. In contrast, increasing atmospheric CO2 concentrations were thought to have a strong effect as a result of greater below-ground C allocation. In addition, there is a growing belief that ozone depletion is of only minor environmental concern because the impacts of UV-B radiation on plant communities are often very subtle. Here we show that 5 years of exposure of a subarctic heath to enhanced UV-B radiation both alone and in combination with elevated CO2 resulted in significant changes in the C:N ratio and in the bacterial community structure of the soil microbial biomass.     

Recovery of 16S ribosomal RNA gene fragments from ancient halite

During the last decade, sensitive techniques for detecting DNA have been successfully applied to archaeological and other samples that were a few hundred to a few thousand years old. Nevertheless, there is still controversy and doubt over claims of exceptionally ancient DNA. Additional accounts stretching back nearly a century suggest that microorganisms may survive over geological time in evaporite deposits. There is, however, often doubt over the age relationship between evaporite formation and the incorporation of microorganisms. Here, we have used petrographic and geochemical techniques (laser ablation microprobe inductively coupled plasma mass spectrometry) to verify the estimated geological age of halite (NaCl) evaporite samples. Fragments of 16S ribosomal RNA genes were detected by polymerase chain reaction amplification of DNA extracted from halite samples ranging in age from 11 to 425 Myr (millions of years). Haloarchaeal 16S rDNA amplicons were present in one sample (11 16 Myr), whereas other samples (65 425 Myr) yielded only bacterial 16S rDNA amplicons. Terminal restriction fragment length polymorphism analyses indicate complex and different populations of microorganisms or their free DNA in ancient halites of different ages.