Evolution Sections 15-1 & 15-2

Life’s Diversity On Earth there are millions of different types of organisms  = biodiversity

What is a Theory? In science, the word theory takes on a new and very different meaning. A scientific theory is… Testable Well-supported Based on facts, observations, and hypotheses

Evolution Why is there so much biodiversity?  evolution = change over time Process of by which modern organisms have descended from ancient organisms

Lamarck First person to propose a theory of evolution. Law of use and disuse  An organism can lose or change a body feature during its life time and passes it on to their children 1. Using it -improves 2. Not using it - disappear

short-neck giraffes stretched their necks to reach higher into trees for food = acquired longer necks this acquired characteristic was passed on to (inherited by) their off-spring

Charles Darwin Disproved Lamarck’s theory of evolution Darwin’s new theory was based on … natural selection Not a chance, Lamarck!

Charles Darwin sailed on the Beagle around the world.

Voyage of the Beagle made observations, collected fossils, living organisms, and studied the Earth Some fossils looked like living organisms while others looked foreign

The Importance of Fossils Darwin asked important questions as he collected the fossils. Why had so many species disappeared? Are these fossilized species related to living species? What other important info do fossils hold?

The Galapagos Islands Islands were close together but had very different climates Darwin studied the animals on the islands

Darwin evolution affects populations  Not just individual environmental changes cause evolution  Same as Lamarck organisms with certain features are naturally selected  hummingbirds with slightly longer beaks are naturally selected for certain organisms survive  hummingbirds with the longer beaks will survive.

Darwin explained evolution by NATURAL SELECTION

Mutations A change in the DNA code, that forms a new trait Can be good = increase survival Can be bad = decrease survival

Darwin’s Findings Adaptation  A beneficial trait (good mutation) that helps an organism survive and reproduce Adaptations evolve (develop or change over time) (1000’s years)  Anatomical - Teeth, body covering  Physiological - movement, camouflage, mimicry

Adaptation? My partially webbed hind feet help me to swim. My flattened tail acts as a rudder. My teeth help me to shred cattails and other plants to build my lodge. Sea otter

Adaptation? My hard outer shell helps to protect my soft body from predators. I can make my own cement to attach myself to stationary objects. I have feathery legs for trapping plankton and other food. Barnacles

Adaptation? My long beak helps me to drink the nectar from plants. My wings help me to hover in one place. My small body is lightweight. Hummingbird

Behavior adaptations can be learned or instinctive. 1. Social behavior - some animals live by themselves, while other live in groups. 2. Behavior for protection - can help to protect the animal. For instance the opossum plays dead. A rabbit freezes when it thinks it has been seen. Migration (birds, whales) Hibernation (bats, snakes, bears)

Artificial Selection Aka selective breeding  humans choose attractive mates  cattle ranchers choose biggest and healthiest cows  Farmers choose biggest tomatoes

Natural Selection Nature selects the best traits best traits survive Survive and reproduce = fitness “survival of the fittest”

4 points of Natural Selection "survival of the fittest" 1. Variations exist among members of a population 2. Many more individuals are produced than will survive 3. Members of a population compete for food, space, mates Individuals that are better adapted survive & reproduce

Stop talking, Goodnight.

Evidence of Evolution 1. Fossils 2. Bio-geographical 3. Anatomical 4. Embryological 5. Biochemical

1. Fossils

2. Biogeographical Geographic Distribution of Living Species ? why similar species lived in different locations?

3. Anatomical Homologous Body Structures (definition) different mature forms, but develop from the same embryonic tissues. means they all had a common ancestor.

4. Embryology In the early stages of development, the embryos of many different species look very similar. Means = a common ancestor!

5. Biochemical same basic biochemical molecules  DNA, ATP, enzymes... Similarities in amino acid sequences (DNA codes) means = a common ancestor