PENSOFT, Sofia-Moscow, 1999.
English translation by V.S.Bogdanova (revised by G.H.Harper).
The reader is introduced to some of the most intriguing problems of evolutionary biology. Evolutionary progress remains a subject of furious debate. An intuitive notion of biological progress based on the superiority of human beings over other creatures is inadequate, and this book attempts to analyze the problem of progress from a genetic point of view. The life of an organism is maintained by a number of working structures (such as organs) supporting the vital functions. It is proposed that the capacity of a working structure is linked to the amount of genetic information underlying its development. Other conditions being equal, the amount of favourable mutations is proportional to the number of genes determining the trait under selection, that is, its genetic complexity. A species evolving in an adaptive zone can be subjected to a long-term environmental deterioration when changes in a given working structure can become limiting for its survival. Rate of change in the capacity of the working structure in response to a certain selection pressure is termed mobility. Selection favouring species with increased mobility of the limiting structure is termed 'mobilizing selection'. This not only accumulates genes for a limiting structure but also facilitates a multiplicative mode of genetic control, when any mutation changes the trait value by a certain percentage. A principle of maximum adaptability is formulated implying that a dynamic equilibrium should eventually be established among genetic complexities - and, therefore, capacities - of different working structures in accordance with how often they are limiting. This process can be considered as accumulation of knowledge by a phyletic lineage of its adaptive zone, and can be regarded as evolutionary progress. Thus the main attributes of evolutionary progress - increase in complexity and supercellular organization - are considered to be consequences of selection for species' evolutionary plasticity. These ideas are supported by analysis of some macroevolutionary trends, with special attention to complication of the suture line in Ammonoidea. Written in a popular style, the book is directed at a wide range of biologists as well anyone interested in evolution.
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