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Natural Selection. Mutation. All genetic variation is the result of mutation. . Mutations occur for a variety of reasons and are quite often negative . However on occasion a beneficial mutation will occur such as venom, coloring, or the ability to access a new resource .
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Mutation • All genetic variation is the result of mutation. • Mutations occur for a variety of reasons and are quite often negative • However on occasion a beneficial mutation will occur such as venom, coloring, or the ability to access a new resource • These beneficial mutations may become more common via natural selection
Overview • Natural Selection- The process by which organisms die and reproduce at different rates based on how well they are adapted to their environment. • This is seen in nearly all environments • This idea has been around for centuries • It is important to know that this is not the same thing as Evolution
An Example • You Have a species of mice half the members are brown the other half are white • These mice live in the desert and are eaten by foxes
Example Continued • Over time the white mice will become less common as they die and are unable to reproduce • Eventually there may only be brown mice left because they were better adapted to their environment. • Now imagine the same mice in a snowy environment
Examples of Natural Selection • Predation- some members of a species may have slightly better defenses, these individuals will pass that trait on • Competition- some members of a species may be better at exploiting a resource, these individuals will survive and reproduce better. • Sexual Competition- Competition for a mate
Example of Intraspecific Competition • Intraspecific means within a species • Two squirrels trying to get the same acorn • A cow eating all the grass which deprives the other cows of that resource.
Examples of Sexual Competition • Two Lions fighting to the death for a mate. • Peacocks plumage and dance. • Bird songs • In nearly every species it is the male that competes for the female • However this is usually determined by which gender has the greater number of individuals
Genetic Drift • Genetic Drift is a term used by biologists to refer to any event that changes the ratio traits in a given species • These are random things like fires, storms, and earthquakes • These events can lead to certain traits being wiped out.
Gene Flow • This is the process of different populations of the same species sharing genetic material • For example two birds populations come together, one population is red, the other is blue • If blue is the dominant trait the red coloration will become less common and may eventually disappear. • This process is due to immigration and emigration
Speciation • Some or all of these factors may eventually lead to new species. • This occurs when differences become so extreme that the two groups cannot or will not reproduce. • There are some situations where species can come back together and begin reproducing however the offspring are often sterile.
