Evolution of Adaptive Systems

HERNÁN DOPAZO

Caracas, Venezuela

Congreso; ICTP/ICGEB Iberoamerican School of Astrobiology: Origin from the Big Bang to Civilization; 1999

ICTP/ICGEB

EVOLUTION OF ADAPTIVE SYSTEMS 1. Abstract HERNÁN J. DOPAZO Laboratorio de Biología del Comportamiento. Instituto de Biología y Medicina Experimental. (IBYME-CONICET). Vuelta de Obligado, 2490 (1428). Buenos Aires. Argentina. hdopazo@dna.uba.ar Adaptive systems are those biological and nonbiological assemblages able to evolve by natural selection. They are formed by entities with the property to replicate with errors in such a way that these variants bias directly, or indirectly, their own frequency in later generations. Neo-Darwinism focused on the study of a single adaptive system, i.e.: populations of multicellular organisms with sexual reproduction and early somatic and germ line differentiation1. Evolutionary biologists however recognize that entities like genes, chromosomes, cells, organisms, kin, animal societies, cultural characters and computer programs are indeed able to evolve by differential reproductive success of heritable variants. The objective of this paper is to overview the main ideas and con- cepts dealing with the origin and evolution of individuality at different hierarchical levels of biological organization2. First, I’ll describe the evolutionary dynamics in three abstract spaces. This will led us to distinguish replicator versus interactor concepts and codical versus material domains. This will allow us too to introduce the problem of the units of selection and the concept of organism from an evolutionary perspective. After, I’ll follow sketch the major transitions in evolution, many of them originate the compo- nents of alternative adaptive systems. Cooperation and conflicts were recurrent processes guiding the construction of alliances between units of selection. Cooperation by kin selection, trait-group selection, reciprocal altruism and byproduct mutualism will be differentiated, at the same time fraternal and egalitarian alliances will be distinguished. Exceptions to cooperation and mechanisms to avoid selfish interest of free riders are also discussed. I’ll conclude with an outline of the alternative ways by which he- reditary information was stored and transmitted during the course of biological evolution from one generation to the next. 1 Some chordates and artrophods show this kind of development. Most phyla of animals, plants, fungi and protoctista don’t. The inheritance of acquired features is possible in these last taxa [6]. 2 Life can be divided into a series of increasing levels of organization. Eldredge [21] differentiates genealogical hierarchy (genes, chromosomes, genomes, organisms, kin group, demes, species and monophyletic taxa), from ecological hierarchy (molecules, cells, tissues, organs, organisms, populations, communities and re- gional biota). This has been an important attempt to organize evolutionary theory in a rather comprehensive framework.