8/11 • Good Afternoon • Please turn in your Natural Selection Simulation… don’t forget to turn in the packet, 2 graphs, 2 paragraph summaries, and 3 discussion questions. • Please remove all hats and put electronics away.
Good morning • Please pick up an iRespond remote. • Turn in your evidence for evolution webquest. • Get ready for your quiz!
Evolution and Natural Selection How did life evolve on Earth?
What is Evolution? -Evolution is the gradual change in a POPULATION over a long period of time.
Evidence of Evolution 1) Fossils • Found in sedimentary rock layers (strata) • Fossils found deeper very different from fossils found closer to surface • Relative dating- idea that fossils found deeper are older • Radiometric dating- A fossil’s carbon14 can be measured to determine actual age • Fossils have revealed changes in organisms over time and provide clues to changes in climate.
Evidence for Evolution 2) Biogeography • We can compare island species with their mainland ancestors • Ex: Darwin’s discovery of a species of finches in the Galapagos Islands
Evidence of Evolution 3) Homology- Similarity in characteristics of different species resulting from common ancestor -homologous structures: same structure, different function
Evidence for Evolution 4) Vestigial structures: structures that have a reduced or no function today, but had a function in a common ancestor
Evidence for Evolution 5) Embryological- if the embryonic development was similar then this may indicate a close relationship and common ancestor
Evidence of Evolution 6) Biochemical Evidence: if two species have similar DNA sequences then they may have common ancestor (most reliable source)
What is Natural Selection? • A process in nature that only the organisms best adapted to their environment tend to survive and pass on the surviving traits to their offspring. • It is a key mechanism of evolution.
Natural Selection • Individuals within a population vary in their traits. • Moreoffspring are produced than can survive. Many will get eatenor will not be able to compete for resources. • There is competitionfor limited resources that creates a struggle for existence. • Individuals with advantageous traitswill survive and reproduce. Those with bad traits will die, taking those bad traits with them. • Concept was called survival of the fittest by Herbert Spencer after Spencer read Darwin’s book, On the Origin of Species. • Natural Selection of “the best” traits leads to EVOLUTION.
What an Adaptation IS and IS NOT… • An adaptation is a trait that an organism is born with/has genetically that better enables it to survive in an environment. • Ex: webbed feet on a duck • An adaptation is NOT acquired during an organism’s lifetime.
What are two types of evolution? Divergent Evolution: • When a species diverges into 2 or more descendant species which results in once related species becoming more and more dissimilar.
What are two types of evolution? Convergent Evolution • Unrelated species evolve similar traits even though they live in different parts of the world. • Similarity in environment has led to evolution of similar traits. • EX: Madagascar aye-aye and New Guinea striped opossum both have elongated middle fingers. Live separately but have same structure
What is Speciation? • Species: group of individuals that actually or potentially interbreed in nature. • Speciation: process of one species splitting into two species. Usually due to a geographic divide that separates the species. • Ex: Kaibab squirrel and Abert squirrel were once the same species but were divided by creation of Grand Canyon. • Phylogenetic Trees show evolutionary relationships among organisms. • They also show how they evolved from a common ancestor