Hows does evolution take place? I understand that its an accumulation of changes to adapt to an environment, but how does it change generation to generation? Is the set of traits that will be passed down to an offspring predetermined or does it change depending on how my environment is? Its seems too fascinating that my environment may change the set of dna that is passed down, or is that not the case?
In: Biology
DNA mutations are at the heart of evolution. That’s how you get variety, and natural selection requires there to be variation in traits among organisms. Mutation is random. Mutation rates can be increased by stresses to the body/cells, but in general DNA mutations will be random and usually have a neutral impact, but occasionally will cause a harmful or beneficial change for the organism. When it DOES result in beneficial traits, it may give the organism a higher chance of having offspring and passing those genes down. The “mutated” DNA will become more prevalent through the population over generations as a result.
The environment can’t change DNA with any “intention” but it can put selective pressure on the variety of life that is currently living there. With competition for resources, organisms with better traits will be more likely to survive, reproduce, and pass down those traits. There is some luck involved too, of course, and “drift” is another mechanism of evolution that accounts for the luck/lottery component of how genes get passed down (for example if a population is small and spread out, luck may play a bigger role in which mating pairs find each other).
The set of genes that will be passed down isn’t really “predetermined”, but environmental stressors can influence which genes are turned on/off. So a gene might become dormant and functionally inactive, and that “on/off setting” can get passed down to the offspring. We’re only just barely starting to understand this process (epigenetics), but it’s a way for traits to change quickly between generations without the actual DNA itself necessarily being altered. Even small tweaks to gene expression can have large effects on how an organism looks/functions.
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