Natural Selection

Evolution Descent with modification or Change in a population over time

Natural Selection Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Some factor in the Environment selects those individuals that are best suited to their environment to survive and reproduce, thus changing the population over time.

Overproduction of Offspring Organisms tend to produce more offspring than can survive.

Inherited Variation Offspring are born with different traits (phenotype) because of different gene combinations. Differences are the result of : mutations, crossing over, and/or independent assortment.

Competition to survive There is a finite supply of environmental resources like… Food, shelter, mates, water, avoiding predation, sunlight, oxygen, etc.

Adaptation Those individuals who are born with variations that help them to survive are said to have an adaptation. Variation is random and so an individual cannot choose to have an adaptation An advantage in one environment is sometimes a disadvantage in another.

Reproduction “Differential Reproductive Success” Survival of the fittest – those individuals who are better suited to their environment will survive and reproduce most successfully. It is the individual who leaves behind the most offspring who “wins”

Result Over time traits that lead to more offspring accumulate in the environment and the population becomes better suited to their environment.

Industrial melanism

Activities Read survival of the sneakiest article and answer the questions http://evolution.berkeley.edu/evolibrary/article/sneakermales_01 Make a cartoon showing overproduction, variation, finite resources/competition, natural selection/differential survival and reproduction Peppered moth simulation http://www.biologycorner.com/worksheets/pepperedmoth.html http://peppermoths.weebly.com/

Ideas for your cartoon…

Coevolution