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Little Correspondence (little + correspondence)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

PERSPECTIVE: PURGING THE GENETIC LOAD: A REVIEW OF THE EXPERIMENTAL EVIDENCE

EVOLUTION, Issue 12 2002
Peter Crnokrak
Abstract., Inbreeding depression, the reduction in fitness that accompanies inbreeding, is one of the most important topics of research in evolutionary and conservation genetics. In the recent literature, much attention has been paid to the possibility of purging the genetic load. If inbreeding depression is due to deleterious alleles, whose effect on fitness are negative when in a homozygous state, then successive generations of inbreeding may result in a rebound in fitness due to the selective decrease in frequency of deleterious alleles. Here we examine the experimental evidence for purging of the genetic load by collating empirical tests of rebounds in fitness-related traits with inbreeding in animals and plants. We gathered data from 28 studies including five mammal, three insect, one mollusc, and 13 plant species. We tested for purging by examining three measures of fitness-component variation with serial generations of inbreeding: (1) changes in inbreeding depression, (2) changes in fitness components of inbred lines relative to the original outbred line, and (3) purged population (outcrossed inbred lines) trait means as a function of ancestral outbred trait means. Frequent and substantial purging was found using all three measures, but was particularly pronounced when tracking changes in inbreeding depression. Despite this, we found little correspondence between the three measures of purging within individual studies, indicating that the manner in which a researcher chooses to estimate purging will affect interpretation of the results obtained. The discrepancy suggests an alternative hypothesis: rebounds in fitness with inbreeding may have resulted from adaptation to laboratory conditions and not to purging when using outcrossed inbred lines. However, the pronounced reduction in inbreeding depression for a number of studies provides evidence for purging, as the measure is likely less affected by selection for laboratory conditions. Unlike other taxon-specific reviews on this topic, our results provide support for the purging hypothesis, but firm predictions about the situations in which purging is likely or the magnitude of fitness rebound possible when populations are inbred remain difficult. Further research is required to resolve the discrepancy between the results obtained using different experimental approaches. [source]

Linnaeus' sexual system and flowering plant phylogeny

NORDIC JOURNAL OF BOTANY, Issue 1-2 2007
Birgitta Bremer
Carl Linnaeus brought order to the knowledge of plants and animals by arranging all known species in encyclopaedic works. He proposed a system of plants, the sexual system, based on the number and arrangement of male and female organs. His artificial sexual system has since long been replaced by ,natural' or phylogenetic systems but there has never been a comprehensive comparison of the sexual system with modern plant classification. The currently most often used classification of flowering plants is the APG-system. It is based on comprehensive phylogenies of flowering plants, reconstructed by analyses of DNA data. The APG-system covers all flowering plants which are classified in 453 families and these are classified in 45 orders. Most of the species were not known at time of Linnaeus. Families and orders in the APG-system are arranged in larger informal groups representing major branches in the flowering plant phylogenetic tree. Three such groups are the monocots, the rosids, and the asterids. I have examined all genera published in Species plantarum (1753) and classified them according to order and major groups in the APG-system. All classes except one, number 15 Tetradynamia, comprises groups of unrelated plants. Not surprisingly, the sexual system does not display what we know today about plant relationships. As is evident from this analysis, there is little correspondence between the sexual system and the APG-system. This does not mean that the sexual system has been useless or misleading. When it was introduced, it formed the basis for much intensified research and increased knowledge of plants. [source]

COMPARISON OF SITUATIONAL AND BEHAVIOR DESCRIPTION INTERVIEW QUESTIONS FOR HIGHER-LEVEL POSITIONS

PERSONNEL PSYCHOLOGY, Issue 3 2001
ALLEN I. HUFFCUTT
Based on a study of federal investigative agents, Pulakos and Schmitt (1995) hypothesized that situational interviews are less effective for higher-level positions than behavior description interviews. To evaluate their hypothesis we analyzed data from 2 new structured interview studies. Both of these studies involved higher-level positions, a military officer and a district manager respectively, and had matching SI and BDI questions written to assess the same job characteristics. Results confirmed that situational interviews are much less predictive of performance in these types of positions. Moreover, results indicated very little correspondence between situational and behavior description questions written to assess the same job characteristic, and a link between BDI ratings and the personality trait Extroversion. Possible reasons for the lower situational interview effectiveness are discussed. [source]

Variability of Broca's area homologue in African great apes: Implications for language evolution

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003
Chet C. Sherwood
Abstract The cortical circuits subserving neural processing of human language are localized to the inferior frontal operculum and the posterior perisylvian region. Functional language dominance has been related to anatomical asymmetry of Broca's area and the planum temporale. The evolutionary history of these asymmetric patterns, however, remains obscure. Although testing of hypotheses about the evolution of language areas requires comparison to homologous regions in the brains of our closest living relatives, the great apes, to date little is known about normal interindividual variation of these regions in this group. Here we focus on Brodmann's area 44 in African great apes (Pan troglodytes and Gorilla gorilla). This area corresponds to the pars opercularis of the inferior frontal gyrus (IFG), and has been shown to exhibit both gross and cytoarchitectural asymmetries in humans. We calculated frequencies of sulcal variations and mapped the distribution of cytoarchitectural area 44 to determine whether its boundaries occurred at consistent macrostructural landmarks. A considerable amount of variation was found in the distribution of the inferior frontal sulci among great ape brains. The inferior precentral sulcus in particular was often bifurcated, which made it impossible to determine the posterior boundary of the pars opercularis. In addition, the distribution of Brodmann's area 44 showed very little correspondence to surface anatomy. We conclude that gross morphologic patterns do not offer substantive landmarks for the measurement of Brodmann's area 44 in great apes. Whether or not Broca's area homologue of great apes exhibits humanlike asymmetry can only be resolved through further analyses of microstructural components. Anat Rec Part A 271A:276,285, 2003. © 2003 Wiley-Liss, Inc. [source]