The Evolution of Living Things.

Objectives Explain how fossils provide evidence that organisms have evolved over time. Explain how organisms can be compared to support the theory of evolution.

Objectives Describe Charles Darwin and his theory of natural selection. Explain how mutations are important to evolution. Provide examples of natural selection in action. Outline the process of speciation

Evolution I. Evolution – the process by which organisms accumulate inherited changes over time. Scientists believe that all living things share a common ancestor – bacteria. Charles Darwin – determined how evolution occurred by studying finches in the Galapagos islands.

C. Adaptations – characteristics that allow or help an organism survive and reproduce. Examples – frog coloring, beak shape, ear size. Allows some organisms to survive and reproduce at a greater rate than other organisms.

Adaptations

How do we know evolution has occurred? I. Evidence of Evolution: Why do scientists believe that evolution occurs? A. Fossils: solidified remains or imprints of once living organism. Scientists use the layers of sediment to determine the relative age of fossils. B. Vestigial Structures: Remnants of once useful structures in organisms. EVIDENCE

EVIDENCE C. Comparing Organisms: Shows similarities among organisms. skeletal structures – dolphin flipper, bat wing, human arm, cat leg DNA – all organisms have DNA; many organisms have similar codes embryonic structures – chicken, rabbit, human

Layers of Sediment

Vestigial Structure

Similar Skeletal Structures

Similar DNA http://www.genome.gov/15515096

Embryonic Structures

Natural Selection – how evolution occurs Natural Selection – a process in which organisms with favorable traits survive and reproduce at a greater rate

A. Four stages Overproduction – produce more offspring than will survive to maturity. Genetic variation – all organisms within a population are slightly different than one another.

3.Struggle to Survive - organisms compete and ones with favorable traits survive and reproduce. 4.Successful Reproduction – Those individuals that are well adapted and have traits that help them survive in their environment are more likely to survive and reproduce.

Mutations B. Mutations – a change in the sequence of the DNA that causes variation within the species.

Ways it occurs… C. Natural Selection in Action 1. Insecticide Resistance - farmers use insecticide. Insects resist and reproduce.

2. Adaptation to pollution - Peppered Moth Story

How did there become so many species? 3. Speciation - Two populations become so different they can no longer interbreed. a. Separation – portion of population is physically isolated (earthquake, Pangaea, canyons, etc.) b. Adaptation - as environment changes, so does population (by natural selection) c. Division - over millions of generations, two groups are now so different that they are no longer considered the same species.

4.“Survival of the Fittest” - only organisms with favorable traits will survive and reproduce. 5.Extinction - species die out completely because they don’t have the resources or adaptations to survive.

The Big Picture How do fossils provide evidence that organisms have evolved over time? How can organisms be compared to support the theory of evolution.? Who is Charles Darwin and his theory of natural selection? How are mutations are important to evolution? Provide examples of natural selection in action. Describe process of speciation.