Presentation is loading. Please wait.

Presentation is loading. Please wait.

The Theory of Evolution

Similar presentations

Presentation on theme: "The Theory of Evolution"— Presentation transcript:

1 The Theory of Evolution
Honors Biology Chapter 16

2 Build you biology muscle by exercising you QUADs!
What environmental factor determined the beak shape of the finches? Explain why.

3 16.1 The Theory of Evolution by Natural Selection
Evolution: Change in a population over time. Natural Selection: Process in which organisms well suited to the environment survive and reproduce to a greater extent than organisms less suited to the environment. Adaptation: An inherited trait that has become more common in a population because the trait provides a selective advantage

4 A. Darwin’s Voyage 1. Charles Darwin: English scientist
a. In 1831, he set sail around the world on the ship Beagle. He spent five years collecting plants, animals, and fossils. b. He found evidence that challenged the traditional belief that species are unchanging. c. When he observed finches on the Galapagos Islands, he noticed both similarities and differences to finches on South America


6 Build you biology muscle by exercising you QUADs!
How did Malthus contribute to Darwin’s theory of Evolution by natural selection? Be as specific as possible.

7 16.2 Ideas that shaped Darwin's Thinking
A. Hutton (Geologist) 1780’s 1. Forces beneath the Earth’s surface can push rock layers and move them in the process B. Lyell (Geologist) 1780’s 1. laws of nature are constant over time 2. scientists must explain the past by looking at processes they can observe in the present ***Both agreed that Earth is extremely old & that the processes that changed the Earth in the past are still present today.

8 C. Lamarck 1. Proposed that organisms can change over time by selectively using or not using body parts 2. parents could pass these acquired traits down to their offspring causing changes in species over time D. Malthus 1. population size is limited by the resources available E. Artificial Selection 1. Humans breed plants and animals based on the traits that are desirable

9 16.3 Darwin makes his case 1. Darwin’s Theory of Evolution by Natural Selection: a. Inherited variation exists within the genes of every population or species descent with modification b. In a particular environment, some individuals are better suited to survive and will have more offspring. c. Over time, the traits that make certain individuals of a population able to survive and reproduce tend to spread in that population natural selection d. In 1859, Darwin published the book called The Origin of Species.


11 16.4 Evidence of Evolution A. The Fossil Record –
1. Fossils provide evidence for evolution. a. Fossils provide a record of the Earth’s past life forms. b. They provide “links” between living species and tell us when and where certain organisms lived. Earliest Bat Fossil Icaronycteris sp.


13 B. Anatomy and Development
1. Vestigial Structures: Structures that are no longer used, but provide clues about their past, reduced in size ex. the hind limbs of whales 2. Homologous Structures: Structures that share a common ancestry, but are modified in different species. Example: forelimbs of vertebrates. 3. Embryos (early stages in an organism’s development) are difficult to tell apart.

14 C. Biological Molecules
1. Similarities between amino acids, proteins, and nucleic acids help to identify species that may be closely related 2. The fewer the differences in them, the closer the relationship will be.

15 Vestigial Structure

16 Homologous Strucutre

17 Molecular Similarities


19 D. We must remember that not all features are inherited from a common ancestor.
a. Convergent Evolution occurs when similarities evolve in organisms that are not closely related to one another, but they live in similar habitats Ex. Such as wings on birds and insects b. The characters that arise through convergent evolution are called analogous characters.

20 Analogous Structures

21 E. Example of Evolution: The beaks of finches
1. dry weather: beaks will be more-massive to eat the large tough seeds. 2. wet weather: smaller beaks to gather the small seeds that are available. The population of finches evolves to survive in the changing environment (See page 472, Fig 16-17).

Download ppt "The Theory of Evolution"

Similar presentations

Ads by Google