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Evolutionary Path (evolutionary + path)
Selected AbstractsDEFINED ORDER OF EVOLUTIONARY ADAPTATIONS: EXPERIMENTAL EVIDENCEEVOLUTION, Issue 7 2008Erez Oxman Organisms often adapt to new conditions by means of beneficial mutations that become fixed in the population. Often, full adaptation requires several different mutations in the same cell, each of which may affect a different aspect of the behavior. Can one predict order in which these mutations become fixed? To address this, we experimentally studied evolution of Escherichia coli in a growth medium in which the effects of different adaptations can be easily classified as affecting growth rate or the lag-phase duration. We find that adaptations are fixed in a defined and reproducible order: first reduction of lag phase, and then an increase of the exponential growth rate. A population genetics theory explains this order, and suggests growth conditions in which the order of adaptations is reversed. We experimentally find this order reversal under the predicted conditions. This study supports a view in which the evolutionary path to adaptation in a new environment can be captured by theory and experiment. [source] A review of the theories of corporate social responsibility: Its evolutionary path and the road aheadINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 1 2008Min-Dong Paul Lee This study aims to trace the conceptual evolutionary path of theories on corporate social responsibility (CSR) and to reflect on the implications of the development. The retrospection has revealed that the trend has been a progressive rationalization of the concept with a particular focus on tighter coupling with organizations' financial goals. Rationalization involves two broad shifts in the conceptualization of CSR. First, in terms of the level of analysis, researchers have moved from the discussion of the macro-social effects of CSR to organizational-level analysis of CSR's effect on profit. Next, in terms of theoretical orientation, researchers have moved from explicitly normative and ethics-oriented arguments to implicitly normative and performance-oriented managerial studies. Based on the retrospection, the limitations of the current state of CSR research that places excessive emphasis on the business case for CSR are outlined, and it is suggested that future research needs to refocus on basic research in order to develop conceptual tools and theoretical mechanisms that explain changing organizational behavior from a broader societal perspective. [source] Land and Social Change in a Tanzanian Village 1: Kinyanambo, 1920s,1990JOURNAL OF AGRARIAN CHANGE, Issue 3 2005Elizabeth Daley This article (in two parts) traces the historical development of land tenure in Kinyanambo village, Mufindi District, Tanzania. It suggests a gradual commoditization of land and the evolution of a predominantly individualized land market, processes influenced by the long-term commoditization of agriculture and social reproduction more generally. Local land tenure practices evolved more or less independently of national land tenure policy until 1974, when villagization altered the evolutionary path of local land tenure, marking a fundamental turning point in people's understandings of their land rights. Together with the simultaneous establishment of Mafinga town, it created conditions for the rapid and more spatially concentrated growth of the local population, for urbanization, and for associated changes in livelihoods, land use, and relations between people and land. As a result, and following the economic reforms of the current period of structural adjustment and liberalization, by 2000 Kinyanambo had a deep-rooted, widespread and socially legitimate market in land. [source] Tornaria of hemichordates and other dipleurula-type larvae: a comparison,JOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2000L. P. Nezlin The evolutionary origin of phylum Chordata is the subject of intensive discussion, with the most conflicting views prevalent. One popular theory advocates the separation of chordates from a dipleurula-like ancestor. Thus the dipleurula-type larvae (tornaria of enteropneusts, auricularia and bipinnaria of echinoderms) are considered to recapitulate the ancestral features and the direct evolutionary path from Echinodermata and Hemichordata to Chordata (i.e. Garstang 1894 Zool. Anzeiger 27, 122,125; Grobben 1908 Verh. Zool.-Bot. Ges. Wien 58, 491,511; Dillon 1965 Evolution 19, 436,446; Jollie 1973 Acta Zool. (Stockholm) 54, 81,100; Ivanova-Kazas and Ivanov 1987 Sov. J. Mar. Biol. 13, 67,80; Crowther and Whittaker 1992 J. Neurophysiol. 23, 280,292; Lacalli 1994 Am. Zool. 34, 533,541; Lacalli et al. 1999 Proc. R. Soc. Biol. Series B 266, 1461,1470; Nielsen 1999 Dev. Genes Evol. 209, 198,205). Comparison of the nervous system in enteropneust tornariae and echinoderm larvae has revealed however, striking differences in distribution of biogenic amines and cholinesterase activity. In tornariae, monoamine-containing cells concentrate in the aboral and oesophageal ganglia. In echinoderms, they are located along the ciliary bands throughout their length. The difference in distribution of cholinesterase activity in each group reasonably suggests that acetylcholine-dependent control of locomotion also differs. Our data do not support the homology of the dipleurula-type larvae. Therefore we believe in the course of adaptive evolution, larvae of certain marine invertebrates acquired a set of common morphological and behavioural characteristics, yet retained different physiological mechanisms of behavioural regulation. Thus, similarities in the dipleurula-type larvae (tornaria, auricularia or bipinnaria, and actinotrocha) may have originated from convergence rather then from a common dipleurula-type predecessor. In consequence we must call into question any attempt to trace the ancestors of Chordata to the dipleurula-type animal. [source] | ||||||||||