What Is Evolution? I. What is Evolution? A. Evolution is the process of change over time B. Evolution occurs not only in living populations but in all sorts of other areas. *communication *technology *entertainment

What Is Evolution? C. The theory of evolution is NOT necessarily an explanation for the origin of life, it simply means that existing species are constantly changing. D. Evidence for evolution comes from many fields of science

Evidence from Fossils II.Evidence from Fossils Fossils allow us to view changes that have occurred in organisms over time (evolution) In the geologic fossil record, the oldest fossils are found at the bottom and the youngest are found at the top.

Evidence from Fossils C. By looking at the fossil record, several things can be concluded: 1st - the earliest organisms were small and simple in structure 2nd- over millions of years organisms became larger and more complex

Evidence from Fossils 3rd - the number of different types of organisms has increased over time   4th - many species of organisms have disappeared and been replaced by different species

Evidence from Structure III. Evidence from Structure   Much of the evidence for evolution comes from the observations of the body structure of different organisms

Evidence from Structure B. Homologous Structures - structures in different species that have the same evolutionary origin Ex. The forelimb of a bat, human, and whale; these all have different functions and are found in different species but they have the same bone structure.

                                                    WHALE HUMAN BAT

Evidence from Structure C. Vestigial Organs - small incomplete organs which have no apparent function   - Ex. vestigial leg bones in snakes are evidence that the ancestors of snakes were reptiles with legs. Vestigial pelvis bones in whales are evidence that their ancestors once walked on land

Natural Selection IV. The Theory of Natural Selection Up until the 1800’s people believed that species were fixed and unchanging. B. Darwin provided the theory of Natural Selection and provided evidence to support this theory in his book On the Origin of Species (1859).

Natural Selection C. Darwin devoted most of his life to studying living things and went on a 5yr expedition to the Galapagos Island where he observed and collected many specimens.

Natural Selection D. Darwin also drew from his observations on controlled breeding of domestic plants and animals. He realized that variations were the basis on which organisms were selected for breeding. He hypothesized that a similar kind of selection occurred in nature. E. Natural selection depends on the environment.

Natural Selection F. Darwin’s theory of evolution by means of Natural Selection can be summarized in 4 statements 1) Organisms produce more offspring than can survive (so there is competition for resources)

Natural Selection 2) Variations exist within populations 3) Some variations give individuals a better chance for survival and reproduction

Natural Selection 4) Over time, the offspring of parents with favorable characteristics will make up a greater portion of the population.  REMEMBER !!!! EVOLUTION OCCURS IN POPULATIONS, NOT IN INDIVIDUALS.

Classification

Millions of years New World Monkeys Old World Monkeys Apes

Human Tree Show video

The Peppered Moth Does the Peppered Moth example illustrate Darwin’s ideas? True or False: 1. Organisms produced more offspring than survived. 2. There were variations in the population.

The Peppered Moth Some variations gave individuals a better chance for survival and reproduction Over time, the offspring of parents with favorable characteristics made up a greater portion of the population.