Natural Selection

A. Species overproduce offspring that may survive an environment. B. There is little variation among members of a population. C. Competition for resources, mates, and space among species leads to a struggle to survive. D. Successful individuals reproduce and pass favorable traits to the next generation. What are the 4 key components of natural selection? What kinds of limited resources can create a struggle between individuals in a population? What kinds of variable traits within a population might natural selection act upon? How does natural selection affect the genetic variation within the next generation of the same population? 4 Parts of Natural Selection

Natural Selection  The driving mechanism behind evolution, as explained in Darwin’s Origin of Species The driving mechanism behind evolution, as explained in Darwin’s Origin of Species Certain organisms survive to pass on their traits to successive generations, but most do not. Certain organisms survive to pass on their traits to successive generations, but most do not. Often summed up as “survival and reproduction of the fittest” Often summed up as “survival and reproduction of the fittest” I. Natural Selection Charles Darwin

Presented evidence that the Earth had formed by natural processes over a long period of time. II. Darwin’s Influence

Populations are limited by predators, disease, and food supply.

Selective breeding, or “artificial selection” is the same process that has led to all the variation we see in dog breeds today. In artificial selection, humans speed up the change in traits by doing the selecting themselves. In natural selection, nature itself is doing the selecting over thousands of generations.

The mechanism (driving force) for evolution, as explained by Charles Darwin. Explains changes in an entire species or population (not individuals) over time. Darwin knew this 1)Natural Selection  2) Mutations  Random changes in DNA are sometimes passed on to offspring. Some helpful; some harmful; some neutral Only traits that increase reproductive fitness will continue to be passed on. Darwin didn’t know this because he didn’t know about… III. Evolution of Species

1)Overproduction More young are produced that can survive.

2)Inherited Variation - Small differences within a population. Ex: height, color, etc. Ex: height, color, etc.

3) Struggle to Survive - Some variations are favorable and improve the ability to adapt. ability to adapt.

4) Successful Reproduction - Those that survive reproduce and pass down favorable traits. favorable traits.