Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: " Theoretical size distribution of fossil taxa: analysis of a null model | Theoretical Biology and Medical Modelling BioMed Central Research Theoretical size distribution of fossil taxa analysis of a null model William J Reed 1 and Barry D Hughes2 Open Access Address Department of Mathematics and Statistics University of Victoria Victoria British Columbia V8W 3P4 Canada and 2Department of Mathematics and Statistics University of Melbourne Parkville Victoria 3010 Australia Email William J Reed - reed@ Barry D Hughes - hughes@ Corresponding author Published 22 March 2007 Received II December 2006 Theoretical Biology and Medical Modelling 2007 4 12 doi 1742-4682-4-12 Accepted 22 March 2007 This article is available from http content 4 1 12 2007 Reed and Hughes licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract_ Background This article deals with the theoretical size distribution of number of sub-taxa of a fossil taxon arising from a simple null model of macroevolution. Model New species arise through speciations occurring independently and at random at a fixed probability rate while extinctions either occur independently and at random background extinctions or cataclysmically. In addition new genera are assumed to arise through speciations of a very radical nature again assumed to occur independently and at random at a fixed probability rate. Conclusion The size distributions of the pioneering genus following a cataclysm and of derived genera are determined. Also the distribution of the number of genera is considered along with a comparison of the probability of a monospecific genus with that of a monogeneric family. Background Mathematical .
