Search results
Results from the WOW.Com Content Network
In genetics, it is sometimes useful to classify mutations as either harmful or beneficial (or neutral): A harmful, or deleterious, mutation decreases the fitness of the organism. Many, but not all mutations in essential genes are harmful (if a mutation does not change the amino acid sequence in an essential protein, it is harmless in most cases).
Adaptive mutation, also called directed mutation or directed mutagenesis is a controversial evolutionary theory. It posits that mutations, or genetic changes, are much less random and more purposeful than traditional evolution, implying that organisms can respond to environmental stresses by directing mutations to certain genes or areas of the genome.
Additionally, exposing fathers to enriching environments can reverse the effect of early life stress on their offspring. When early life stress is followed by environmental enrichment, anxiety-like behavior in offspring is prevented. [20] [37] Similar studies have been conducted in humans and suggest that DNA methylation plays a role. [38]
There are several methods, or forms, of mutation that exist including spontaneous mutation, errors during replication and repair, as well as mutation due to environmental effects. [8] These origins of mutations can cause many different types of mutations which influence gene expression on both large and small scales.
In nature, the mutations that arise may be beneficial or deleterious—this is the driving force of evolution. An organism may acquire new traits through genetic mutation, but mutation may also result in impaired function of the genes and, in severe cases, causes the death of the organism.
One example of a study was found in the 'yellow' D.melanogaster, the mating of these males was only beneficial when it was dark outside, or when they were in a dark environment. The mutation is not yet known why it occurs this way, but studies have mentioned that the females of this fly species may be turned off by the certain colour of the ...
Also, rates of epigenetic mutations, such as DNA methylation, are much higher than rates of mutations transmitted genetically [12] and are easily reversed. [13] This provides a way for variation within a species to rapidly increase, in times of stress, providing opportunity for adaptation to newly arising selection pressures. [citation needed]
A related argument against evolution is that most mutations are harmful. [118] However, the vast majority of mutations are neutral, and the minority of mutations which are beneficial or harmful are often situational; a mutation that is harmful in one environment may be helpful in another. [119]