The Evolutionary Role of Recombinational Repair and Sex

This chapter discusses the evolutionary role of recombinational repair and sex. The chapter reviews a body of work relating to the hypothesis that sexual reproduction arose very early in evolution as a way of overcoming genome damage through recombinational repair. The chapter concentrates on the second type of adaptive function, protection against physical destruction, beacuse this plays a fundamental role in the evolution of sex. Genome damage refers to physical alterations of the RNA (or DNA). The chapter discusses the nature of genome damage and the selective basis for the origin of recombinational repair and sexual reproduction because of this damage. It also discusses the further evolution of recombinational repair and sexual reproduction as it occurs in diploid multicellular organisms. The chapter considers briefly the major alternative explanations for the origin and maintenance of sex, arguing that they cannot be generally adequate. Some of the implications of sex and sexual reproduction that acts as a constraint on the optimization of adaptation are also explored in the chapter. The chapter proposes that it is the dynamics of natural selection in sexually reproducing populations that provides the fundamental explanation for the existence of species as distinct entities.