Lesson Overview

1. Lesson Overview 16.1 Darwin’s Voyage of Discovery

2. Darwin’s Epic Journey • Evolution: process of change over time • Darwin developed a scientific theory of biological evolution that explains how modern organisms evolved over long periods of time through descent from common ancestors. • Darwin published his first complete work on evolution: On the Origin of Species • He sailed on the HMS Beagle’s for five-years , mapping the coastline of South America.

3. Common descent! • Common descent – all species (living and extinct) descended from a common ancestor! • Over many generations, adaptations caused a successful species to evolve into a new species! • The fossil record provides evidence for this descent with modification!

4. Evidence of descent from common ancestors: • 1. Geographic distribution of species • 2. Fossils • 3. Anatomy (homologous structures) • 4. Physiology (analogous structures) • 5. Embryology • 6. Universal genetic code

5. Species Vary Locally- Finches • Adapted from one original species. Due to different food availability.

6. Artificial selection • Nature provides variation in organisms’ traits, but • humans choose to breed those organisms • that have the most useful traits. • n Example: humans breed cows that produce the • most milk. • N  Example: humans breed trees that create the • most fruit.

7. Natural Selection • Natural selection is the process by which organisms with variations most suited to their local environment survive and reproduce. • By surviving, these attributes can be passed onto their children, causing an increase of these traits in the species population, thus causing a gradual change in the characteristics of the population. • Individuals whose characteristics are not well-suited to • their environment die or leave few offspring. • Because natural selection favors a certain trait over • others, more individuals in the population carry the • genes for that trait. • survival of the fittest • .

9. The scarlet king snake exhibits mimicry—an adaptation in which an organism copies, or mimics, a more dangerous organism. Although the scarlet king snake is harmless, it looks like the poisonous eastern coral snake, so predators avoid it, too. • A scorpionfish’s coloring is an example of camouflage—an adaptation that allows an organism to blend into its background and avoid predation.

10. Fitness describes how well an organism can survive and reproduce in its environment. • Individuals with adaptations that are well-suited to their environment can survive and reproduce and are said to have high fitness.

12. PHYSIOLOGY • Analogous structures Body parts that share a common function, but not structure. • Examples: a bat’s wing and a moth’s wing--both are wings and both are used for flight, but a bat has bones and a moth does not. • Vestigial Structures- body structures that have reduced or no body function • As species adapt to environments the change in form and behavior and continue to inherit these structures as part of the body even though they • have no function. • Examples: A human’s appendix, a whale’s pelvis!

13. ANATOMY • Homologous structures – similar in structure but differ in function! • parts of different organisms (that are often quite dissimilar) that developed from the same ancestral body parts! • Forelimbs of whales, bats, crocodiles, and chickens have similar anatomy but are modified for different functions – common • Ancestry!