Search results for "evolutionary"
showing 10 items of 4392 documents
Ancestral processes in population genetics-the coalescent.
2000
A special stochastic process, called the coalescent, is of fundamental interest in population genetics. For a large class of population models this process is the appropriate tool to analyse the ancestral structure of a sample of n individuals or genes, if the total number of individuals in the population is sufficiently large. A corresponding convergence theorem was first proved by Kingman in 1982 for the Wright-Fisher model and the Moran model. Generalizations to a large class of exchangeable population models and to models with overlying mutation processes followed shortly later. One speaks of the "robustness of the coalescent, as this process appears in many models as the total populati…
The Structural Variety and Metabolism of Proteins
1994
Individual eukaryote cells contain in the order of 104 different proteins, and each animal species contains an even greater number due to differences between the tissues of an individual and between the individuals themselves; furthermore, the protein spectrum changes during the course of development. The number of different proteins to be found in extant organisms may be as high as 1012. The description of this variety, its origin and biological significance is the most extensive theme in comparative biochemistry. This chapter will concern itself with the possibilities for structural variation and the general metabolism of proteins; further chapters will deal with comparative studies of in…
Are Neural Networks Imitations of Mind?
2015
Artificial neural networks are often understood as a good way to imitate mind through the web structure of neurons in brain, but the very high complexity of human brain prevents to consider neural networks as good models for human mind;anyway neural networks are good devices for computation in parallel. The difference between feed-forward and feedback neural networks is introduced; the Hopfield network and the multi-layers Perceptron are discussed. In a very weak isomorphism (not similitude) between brain and neural networks, an artificial form of short term memory and of acknowledgement, in Elman neural networks, is proposed.
Memetic algorithms and memetic computing optimization: A literature review
2012
Abstract Memetic computing is a subject in computer science which considers complex structures such as the combination of simple agents and memes, whose evolutionary interactions lead to intelligent complexes capable of problem-solving. The founding cornerstone of this subject has been the concept of memetic algorithms, that is a class of optimization algorithms whose structure is characterized by an evolutionary framework and a list of local search components. This article presents a broad literature review on this subject focused on optimization problems. Several classes of optimization problems, such as discrete, continuous, constrained, multi-objective and characterized by uncertainties…
The Principle of Stasis: Why drift is not a Zero-Cause Law
2016
This paper analyses the structure of evolutionary theory as a quasi-Newtonian theory and the need to establish a Zero-Cause Law. Several authors have postulated that the special character of drift is because it is the default behaviour or Zero-Cause Law of evolutionary systems, where change and not stasis is the normal state of them. For these authors, drift would be a Zero-Cause Law, the default behaviour and therefore a constituent assumption impossible to change without changing the system. I defend that drift's causal and explanatory power prevents it from being considered as a Zero-Cause Law. Instead, I propose that the default behaviour of evolutionary systems is what I call the Princ…
Biproportional Method for Analysing Interindustry Dynamics: the case of France
1990
Two elements are being presented in this paper: (1) A new and original method for analysing matrix dynamics, called the synthetical biproportional projector method (SBP), which can be used to project input–output tables and compare one with another. (2) Some results for France for the important period 1970–85. The paper starts with the observation that no systematic study of the change in the French productive structure as displayed In the input–output tables (tableaux entries-sorties in France) has ever been made. This is unfortunate, since a complete series of data is now available concerning a key period of the French economic evolution including the petroleum crisis, European integratio…
Systematic position of Dinidoridae within the superfamily Pentatomoidea (Hemiptera: Heteroptera) revealed by the Bayesian phylogenetic analysis of th…
2012
Mitochondrial 12S and 16S rDNA sequences of five species of Dinidoridae Stål, 1868, a largely Paleotropical family, and 16 other shield bugs (Pentatomoidea) were studied. This was the first molecular examination of the systematic position of this family within the superfamily Pentatomoidea using more than a single dinidorid species. Phylogenetic trees obtained from the Bayesian inference of 12S and 16S sequences of these mitochondrial DNA, identified Dinidoridae as the monophylum and a sister group to the Tessaratomidae. Moreover, results of the study suggested a close molecular affinity of the genus Eumenotes to representatives of the subfamily Dinidorinae, which contradicts all previous m…
Evolutionary relationships among the members of an ancient class of non-LTR retrotransposons found in the nematode Caenorhabditis elegans.
1998
We took advantage of the massive amount of sequence information generated by the Caenorhabditis elegans genome project to perform a comprehensive analysis of a group of over 100 related sequences that has allowed us to describe two new C. elegans non-LTR retrotransposons. We named them Sam and Frodo. We also determined that several highly divergent subfamilies of both elements exist in C. elegans. It is likely that several master copies have been active at the same time in C. elegans, although only a few copies of both Sam and Frodo have characteristics that are compatible with them being active today. We discuss whether it is more appropriate under these circumstances to define only 2 elem…
Genetic Variability and Taxonomical Considerations about Six Species of European Cardueline Finches (Aves, Passeriformes)
1997
Abstract Electrophoretic patterns of seven enzyme systems and two nonenzymatic proteins, albumin and haemoglobin, representing 13 loci, have been investigated in six species of cardueline finches with Palearctic distribution. A new locus, SOD-3, has been characterized in this subfamily. The two nonenzymatic proteins turned out to be the best genetic markers. From the analysis of the genetic distances it emerges that the mean values between species are higher than those reported for other groups of birds. However, the same results were obtained for other species of the same subfamily native to North America. In both cases this result is probably due to a classification that disagrees with th…
Pretarsal structures in the family Parastrachiidae (Hemiptera: Heteroptera: Pentatomoidea)
2010
Parastrachiidae, for a long time regarded as a subfamily within the Cydnidae (e.g., Schaefer et al. 1988; Schuh and Slater 1995; Gapud 1991), was raised to family level by Sweet and Schaefer (2002), and this position was then accepted by many heteropterists (e.g., Lis and Heyna 2001; Lis and Schaefer 2005; Hironaka et al. 2007; Schaefer and Kikuhara 2007; Lis 2010).