Drought Monitoring and Assessment: Status and Trends in the United States

Drought is a normal, recurring feature of climate. The characteristics of this hazard, along with its far-reaching impacts, make its effects on society, economy, and environment difficult to identify and quantify. A national drought watch system has been recommended as a necessary component of drought assessment and management. The National Drought Mitigation Center, in collaboration with others, has undertaken a number of drought watch activities for the past few years, using a variety of resources available over the Internet. These resources include tools such as the Standardized Precipitation Index, a new drought index that is more reliable for detecting emerging drought conditions

O-chromosome lethal frequencies in Serbian and Montenegrin Drosophila subobscura populations

Lethal chromosomal frequencies were obtained from three Drosophila subobscura samples from the Mt. Avala (Serbia) population in September 2003 (0.218), June 2004 (0.204) and September 2004 (0.250). These values and those from other Balkan populations studied previously (Petnica, Kamariste, Zanjic and Djerdap) were used to analyze the possible effect of population, year, month and altitude above sea level on lethal chromosomal frequencies. According to ANOVAS no effect were observed. Furthermore, the lethal frequencies of the Balkan populations did not vary according to latitude. This is probably due to the relative proximity and high gene flow between these populations. From a joint study of all the Palearctic D. subobscura populations so far analyzed, it can be deduced that the Balkan populations are located in the central area of the species distribution. Finally, it seems that lethal chromosomal frequencies are a consequence of the genetic structure of the populations