This page has been archived and is no longer updated. Charles Darwin proposed that all living species were derived from common ancestors. The primary mechanism he proposed to explain this fact was natural selection: that is, that organisms better adapted to their environment would benefit from higher rates of survival than those less well equipped to do so. However he noted that there were many examples of elaborate, and apparently non-adaptive, sexual traits that would clearly not aid in the survival of their bearers. He suggested that such traits might evolve if they are sexually selected, that is if they increase the individual's reproductive success, even at the expense of their survival Darwin
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Sexual reproduction can increase genetic variation but reduce species diversity
SEXUAL VS. ASEXUAL REPRODUCTION: SCIENTISTS FIND SEX WINS | The UCSB Current
The evolution of sexual reproduction is an adaptive feature which is common to almost all multi-cellular organisms and also some single-cellular organisms with many being incapable of reproducing asexually. Prior to the advent of sexual reproduction , the adaptation process whereby genes would change from one generation to the next genetic mutation happened very slowly and randomly. Sex evolved as an extremely efficient mechanism for producing variation, and this had the major advantage of enabling organisms to adapt to changing environments. Sex did, however, come with a cost. In reproducing asexually, no time nor energy needs to be expended in choosing a mate. And if the environment has not changed, then there may be little reason for variation, as the organism may already be well adapted. Sex, however, has evolved as the most prolific means of species branching into the tree of life.
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SEXUAL VS. ASEXUAL REPRODUCTION: SCIENTISTS FIND SEX WINS
Figure S2. Experimental data do not support yearly variation in the cost of sex. Table S2. The sex ratio of diploid sexual lineages in the parental generation of experimental mesocosms.
Sex can be a costly endeavor—biologically, that is. Combining genetic material can of course bring beneficial new combinations, but even for tiny organisms that are barely visible to the naked eye, mating is fraught with all kinds of hazards, such as a long wait for offspring, sexually transmitted diseases, and the risk of getting eaten during or after sex. So why , if many of these bitty beasts can produce asexually , do some of them do it anyway? Evolutionary theory has suggested that the nature of the environment might have something to do with the mode of reproduction.