Charles Darwin English Naturalist Darwin made numerous observations

Charles Darwin • English Naturalist • Darwin made numerous observations and collected evidence that led him to propose the Theory of Evolution

What is an adaptation? Adaptations are body features and behavior habits that help a living thing survive and reproduce in its natural environment.

Structural Adaptation An organism has special body parts, or structures, which help the organism survive in its environment.

Behavioral Adaptation Special ways that an organism behaves that help the organism survive in its environment.

Physiological Adaptation Organisms are able to perform certain body functions that help the organism survive in its environment.

Survival of the Fittest AKA Natural Selection Individuals with characteristics well-suited to the environment will survive and reproduce.

Descent with Modification Each living species has descended, with changes, from an ancestor from the past.

Fossil Record Comparing fossils from older rock layers with fossils from younger layers shows that life on Earth changed over long periods of time.

Geographic Distribution Beaver Muskrat Capybara Coypu Similar but unrelated species living in different locations were products of different lines of evolutionary descent.

Homologous Body Structures Anatomical similarities among the body structures of animals with backbones

Vestigial Organs A structure that has lost all or most of its original function through the process of evolution.

Similarities in Embryology The early stages, or embryos of animals with backbones are similar, providing evidence that they shared a common ancestor.

Sources of Genetic Variation Father has big nose Mother has Bushy eyebrows Son has big nose and bushy eyebrows Mutations Gene Shuffling

Single-Gene Trait A single-gene trait is controlled by a single gene that has two alleles. Only two phenotypes.

Polygenic Trait Polygenic trait - trait controlled by two or more genes, each with two or more alleles. Many phenotypes.

Directional Selection Original Population Individuals at one end of the bell curve have higher fitness than individuals in the middle or at the other end.

Stabilizing Selection Evolved Population Original Population Individuals near the center of the bell curve have higher fitness than individuals at either end

Disruptive Selection Original Population DISRUPTIVE SELECTION Individuals at the upper and lower ends of the bell curve have higher fitness than individuals near the middle.

Camouflage is a trait that makes it hard to see an organism in its natural habitat.

Concealing Coloration The organism has the same color as the background in the environment.

Disruptive Coloration The organism has a pattern like stripes or spots that help break up its body outline.

Disguises The organism looks like something in its environment.

Counter Shading The organism has a dark upper body and a light underside. Blends in when viewed from above or below.

Mimicry The organism mimics or copies a trait in another organism.

Speciation - formation of a new species

Behavioral Isolation Occurs when two populations are capable of interbreeding but have differences in courtship rituals or other behavioral strategies.

Geographic Isolation Two populations are separated by geographical barriers such as rivers, mountains or bodies of water.

Temporal Isolation Fowler’s Toad American Toad Mates late summer Mates early summer Two or more species reproduce at different times.

Relative Dating The age of the fossil is determined by comparing its placement with that of fossils in other layers of rock

Radioactive Dating Half-life: Length of time it takes for half of the radioactive atoms to decay The age of a sample is based on the amount of remaining radioactive isotopes it contains

Break Time!