Introduction to Evolution Chapter 15 Standards 8a, 8b and 7d

15-1 The Puzzle of Life’s Diversity Evolution is a theory –Scientists have accumulated significant evidence that modern organisms were produced by changes over time.

Evolution: the process by which a species changes over time resulting from environmental pressure.

Who was Charles Darwin? Lived Educated in biology and natural history Traveled the world by sea The plant and animal life he saw on many of the remote islands he visited, peaked his curiosity. Studied live animals & fossils

Darwin’s Observations Amazed by the number of different types of plants and animals he saw on his travels…..DIVERSITY! Puzzled by where different species lived and did not live. Noticed all organisms had traits to help them survive in their environment.

Galapagos Islands Darwin visited small islands west of South America. Islands were very close, yet have very different climates. Darwin was fascinated by the diversity of animals found on each island. Famous research on the birds and tortoise populations.

15-3 Darwin’s Conclusions Famous book “On the Origin of Species” –Explained his answers to the question “Why is it that way?” –Based on research from his travels –Published 25 years after he returned Famous for theory of Natural Selection

Natural Selection Individuals that are better suited to their environment will survive and reproduce most successfully. Those that are not well suited will die off and not reproduce. “Survival of the Fittest”

What is Fitness? Fitness: An organism’s ability to survive and reproduce in a given environment based on its physical traits and behaviors. –An organism that is well suited to a certain environment has a high level of fitness.

Adaptation Adaptation: any inherited characteristic that allows an individual to better survive and reproduce in a given environment –Tiger’s camouflage stripes –Polar bear’s thick fur and fat –Eagle’s talons and beak

Diversity of Life Species – A group of similar organisms that can breed and produce fertile offspring. –Presently about million species on earth. –More than 99.9% of the species that have inhabited Earth are now extinct.

Diversity Diversity- variety of living things –Populations with many different species (diversity) are more likely to survive. –Variation within a specific species increases the likelihood that at least some members will survive. Sexual Reproduction INCREASES Diversity Asexual Reproduction DOES NOT!!