Evolutionary history

These results are compatible with an evolutionary history in which the new enzyme activity of mandelate racemase has evolved from a preexisting enzyme that catalyzes the basic chemical reaction of proton abstraction and formation of an intermediate. Subsequent mutations have modified the... 

The Earth is a highly unusual planet because life did evolve on it and it thrived to the extent that the surface and atmosphere of the planet were greatly modified. The Earth is unique in this respect relative to all known astronomical bodies (Taylor, 1999). The Earth s location, composition, and evolutionary history are all significant factors in the planet s success in nurturing life. Critical factors include its temperature, its atmosphere, its oceans, its long-term stability and its "just right" abundance of water and other light element compounds. 

Ortells MO, Lunt GG Evolutionary history of the ligand-gated ion-channel superfamily of receptors. Trends Neurosci 18 121—127, 1995 Overall JE, Gorham DR The Brief Psychiatric Rating Scale. Psychol Rep 10 799—812,1962 Payne JP The criminal use of chloroform. Anaesthesia 53 685—690, 1998... 

C.K. 1988 New information from the Swartkrans cave of relevance to robust australop-ithecines. In Grine, F.E., ed.. Evolutionary History of the Robust Australopithecines. New York, Aldine de Gruyter 405 26. 

There can be little doubt that certain stresses have characteristic demographic consequences both for populations and for plant parts and it is also evident that, according to taxonomic and evolutionary history, species and genotypes may differ in their responses to the same stress. Thus, demographic study is often a useful preliminary to analysis of the causation and evolutionary origins of particular stress responses. However, some demographers go further and advocate long-term field observation as the only reliable way forward ... 

As explained in Chapter 1, the toxicity of natural xenobiotics has exerted a selection pressure upon living organisms since very early in evolutionary history. There is abundant evidence of compounds produced by plants and animals that are toxic to species other than their own and which are nsed as chemical warfare agents (Chapter 1). Also, as we have seen, wild animals can develop resistance mechanisms to the toxic componnds prodnced by plants. In Anstralia, for example, some marsupials have developed resistance to natnrally occnrring toxins produced by the plants upon which they feed (see Chapter 1, Section 1.2.2). 

Chemokines are small chemotactic cytokines that act as important messenger molecules between cells of the immune system. Chemokines produce their effects by activating a family of G-protein-coupled receptors. Chemokine receptors are all seven-transmembrane glycoproteins that are structurally related. They may be characterized into those that bind to specific ligands, or those that bind several chemokine ligands. There are also virally encoded (viral) chemokine receptors that represent shared receptors that have been transduced into the viral genome during evolutionary history (Premack and SchaU 1996). 

In order to gain a better understanding of the relationships and evolutionary history of Dactylis, Lumaret and colleagues have undertaken extensive studies of various biochemical markers. The first of these that can be examined is the flavonoid analysis of the Atlantic part of the subtropical group (Jay and Lumaret, 1995). In all. 

Bayer, R. J. 1990. Investigations into the evolutionary history of the Antennaria rosea complex (Asteraceae Inuleae) polyploid complex. Plant Syst. Evol. 169 97-110. 

The evolutionary history of symbiotic nitrogen fixers is therefore a tale of coevolution, which occurred in the shadow of their hosts, chasing their growing roots, and striving for adaptation. It is an example of how bacterial genetics has managed to keep pace with the creative power of eukaryotic sexual recombination. Mobile replicons, insertion elements, and symbiotic islands prone to move have helped rhizobia to succeed in their pursuit. The race, naturally, is not over and, looking at it from a distance, what we have. seen, compared to what we have yet to see, is probably just a cloud of dust. 

As a guide to the evolutionary history of the continents, Patterson decided to measure the lead isotope ratios of Earth s crust as a whole. As rocks erode, their minerals are collected and mixed in the oceans, where they eventually settle in layers of sediment. Patterson organized a formidable series of experiments to measure the lead isotopes on land, in various layers of ocean water, and in sediments on the sea floor. 

Fossilized primates, especially fossilized humans, are, unfortunately, particularly rare, and this partly explains why the evolutionary history of human beings is incomplete and continuously being revised. Still, the few fossilized human remains that have been preserved provide the main foundations for modem human evolution theories (Reader 1981). 

The problem of evolutionary transition is to formulate a coherent theory that can explain these transitions and guide evaluation of empirical evidence for each. Part of this work involves describing units of evolution adequate to explain the evolutionary origin of new levels and not merely evolution at levels (Griesemer, 2000c). The key insight into the units problem afforded by consideration of evolutionary transition is that units of evolution themselves have an evolutionary history. Differently put, there is a temporal or processual dimension to the units problem as well as spatial and functional dimensions. Because the spatial and functional perspectives on units mentioned above were not articulated with the evolutionary transition problem in mind, they are not clearly suited to its theoretical solution. In particular, if a perspective assumes the existence of levels of organization or embeds assumptions about these products of evolution in their analysis of units, then it has assumed what is to be shown by a theory of evolutionary transition. 

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