Section KEY CONCEPT There were theories of biological and geologic change before Darwin.

Transcription

1 Section 10.1 KEY CONCEPT There were theories of biological and geologic change before Darwin.

2 Early scientists proposed ideas about evolution. Evolution is the biological change process by which descendants come to differ from their ancestors.

3 Early scientists proposed ideas about evolution. A species is a group of organisms that can reproduce and have fertile offspring.

4 There were many important naturalists in the 18th century. Carolus Linnaeus: classification system from kingdom to species

5 There were many important naturalists in the 18th century. Jean-Baptiste Lamarck: environmental change leads to use or disuse of a structure

6 Theories of geologic change set the stage for Darwin s theory. Catastrophism: natural disasters such as floods and volcanic eruptions have happened often during Earth s long history Can lead to mass extinctions

7 Theories of geologic change set the stage for Darwin s theory. Gradualism: the changes observed in landforms resulted from slow changes over a long period of time

8 Section 10.2 KEY CONCEPT Darwin s voyage provided insight on evolution.

9 I. Darwin observed differences among island species. 1. Variation is a difference in a physical trait.

10 I. Darwin observed differences among island species. 1. Variation is a difference in a physical trait. 2. Galápagos tortoises that live in areas with tall plants have long necks and legs.

11 I. Darwin observed differences among island species. 1. Variation is a difference in a physical trait. 2. Galápagos tortoises that live in areas with tall plants have long necks and legs. 3. Galápagos finches that live in areas with hard-shelled nuts have strong beaks.

12 II. Darwin realized species could adapt to their environment. 1. An adaptation is a feature that allow an organism to better survive in its environment. Species are able to adapt to their environment. Adaptations can lead to genetic change in a population.

13 III. Darwin observed fossil and geologic evidence supporting an ancient Earth. 1. Fossil evidence included: - Found fossils of extinct animals that resemble modern animals. - Found fossil shells high up in the Andes mountains.

14 III. Darwin observed fossil and geologic evidence supporting an ancient Earth. 2. Geological evidence included: - Saw land move from underwater to above sea level due to an earthquake.

15 Section 10.3 KEY CONCEPT Darwin proposed natural selection as a mechanism for evolution.

16 Several key insights led to Darwin s idea for natural selection. Artificial selection is the process by which humans select traits through breeding. Darwin noticed a lot of variation in domesticated plants and animals. neck feathers crop tail feathers

17 Several key insights led to Darwin s idea for natural selection. Heritability is the ability of a trait to be passed down.

18 Several key insights led to Darwin s idea for natural selection. There is a struggle for survival due to overpopulation and limited resources.

19 Several key insights led to Darwin s idea for natural selection. Darwin proposed that adaptations arose over many generations. Natural selection is a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals.

20 There are four main principles to the theory of natural selection. Variation The differences among individuals that result from differences in the genetic material of the organisms Can be inherited from a parent or occur from a mutation VARIATION

21 There are four main principles to the theory of natural selection. Overproduction While having many offspring raises the chance that some will survive, it also results in competition between offspring for resources. OVERPRODUCTION

22 There are four main principles to the theory of natural selection. Adaption Allows an individual to survive better than other individuals it competes against in its environment. ADAPTATION

23 There are four main principles to the theory of natural selection. Descent with Modification More individuals will have the trait in every following generation, as long as the environmental conditions continue to remain beneficial for that trait.

24 Fitness The measure of survival ability and ability to produce more offspring.

25 Natural selection acts on existing variation. Natural selection can act only on traits that already exist. Structures take on new functions in addition to their original function. five digits wrist bone

26 Section 10.4 KEY CONCEPT Evidence of common ancestry among species comes from many sources.

27 Evidence for evolution in Darwin s time came from several sources. Fossils provide evidence of evolution. Fossils in older layers are more primitive than those in upper layers.

28 Evidence for evolution in Darwin s time came from several sources. The study of geography provides evidence of evolution. island species most closely resemble the nearest mainland species populations can show variation from one island to another

29 Evidence for evolution in Darwin s time came from several sources. The study of anatomy provides evidence of evolution. Homologous structures are similar in structure but different in function. Homologous structures are evidence of a common ancestor. Human hand Mole foot Bat wing

30 Evidence for evolution in Darwin s time came from several sources. The study of anatomy provides evidence of evolution. Human hand Analogous structures have a similar function. Mole foot Analogous structures are not evidence of a common ancestor. Fly wing Bat wing

31 Structural patterns are clues to the history of a species. Vestigial structures are remnants of organs or structures that had a function in an early ancestor. Ostrich wings are examples of vestigial structures.

32 Evidence for evolution in Darwin s time came from several sources. Embryology studies the embryo of different species Developmental similarities provide evidence of evolution.