University of Georgia

About: University of Georgia is a education organization based out in Athens, Georgia, United States. It is known for research contribution in the topics: Population & Gene. The organization has 41934 authors who have published 93622 publications receiving 3713212 citations. The organization is also known as: UGA & Franklin College.

Measurement of Territory and Home Range Size in Birds

Abstract: At some time during the annual cycle, most vertebrates restrict their activities to a definite area which may be termed the home range. If all or part of the home range is defended against other individuals of the same species, the guarded area is called a territory, according to current usage. Territoriality is an important mechanism which reduces intraspecific competition; it is especially pronounced in nest-building animals (birds, certain fish, insects, etc.) which have complicated behavior patterns requiring highly co6rdinated actions during reproductive periods. Establishment of territories and home ranges produces characteristic intrapopulation distribution patterns which have important bearing on the choice of census methods (See Odum, 1953, Chap. 6). Examination of the voluminous literature on territorialism in birds reveals that many qualitative details have been worked out. The "kinds" of territory, such as are listed in the comprehensive review by Nice (1941), have been classified, and the means of establishment and defense of the territory area have been described for many species. On the other hand, many quantitative aspects of territorialism have been scarcely considered. For example, the effect of various populations and habitat factors on the size and configuration of the defended or occupied areas is virtually unknown. A relation between territory size and food supply is often postulated, but we know of no case where the available food supply and the size of territory have both been accurately measured. It is true that numerous estimates made of territory size have been published, but it is evident that many are but crude approximations, often based on less than a dozen spot observations. Very little confidence can be placed in the comparison of measurements made by different investigators because of the great variation in procedures used and in the intensiveness of the observation. It is becoming quite evident that quantitative comparisons of territoriality cannot proceed until sound, consistent methods of measurement are developed. In this paper the problem of measurements of territory and home range size is critically examined, and a method for standardizing measurements is proposed. The method is illustrated by data obtained in a study of territoriality of seven southeastern species. These data are also used to test certain concepts developed by mammalogists in their parallel studies of home range.

Comparative genome sequencing of Drosophila pseudoobscura: Chromosomal, gene, and cis-element evolution

Abstract: We have sequenced the genome of a second Drosophila species, Drosophila pseudoobscura, and compared this to the genome sequence of Drosophila melanogaster, a primary model organism. Throughout evolution the vast majority of Drosophila genes have remained on the same chromosome arm, but within each arm gene order has been extensively reshuffled, leading to a minimum of 921 syntenic blocks shared between the species. A repetitive sequence is found in the A pseudoobscura genome at many junctions between adjacent syntenic blocks. Analysis of this novel repetitive element family suggests that recombination between offset elements may have given rise to many paracentric inversions, thereby contributing to the shuffling of gene order in the D. pseudoobscura lineage. Based on sequence similarity and synteny, 10,516 putative orthologs have been identified as a core gene set conserved over 25-55 million years (Myr) since the pseudoobscura/melanogaster divergence. Genes expressed in the testes had higher amino acid sequence divergence than the genome-wide average, consistent with the rapid evolution of sex-specific proteins. Cis-regulatory sequences are more conserved than random and nearby sequences between the species-but the difference is slight, suggesting that the evolution of cis-regulatory elements is flexible. Overall, a pattern of repeat-mediated chromosomal rearrangement, and high coadaptation of both male genes and cis-regulatory sequences emerges as important themes of genome divergence between these species of Drosophila.

River flows and water wars: emerging science for environmental decision making

Abstract: Real and apparent conflicts between ecosystem and human needs for fresh water are contributing to the emergence of an alternative model for conducting river science around the world. The core of this new paradigm emphasizes the need to forge new partnerships between scientists and other stakeholders where shared ecological goals and river visions are developed, and the need for new experimental approaches to advance scientific understanding at the scales relevant to whole-river management. We identify four key elements required to make this model succeed: existing and planned water projects represent opportunities to conduct ecosystem-scale experiments through controlled river flow manipulations; more cooperative interactions among scientists, managers, and other stakeholders are critical; experimental results must be synthesized across studies to allow broader generalization; and new, innovative funding partnerships are needed to engage scientists and to broadly involve the government, the private sector, and NGOs.