2All of these frogs live in the same area. What differences are there?
3Differences among organisms Each organism has a different adaptation to help it survive.Adaptation – a characteristic that helps an organism survive and reproduce in its environmentExamples: structures to find food, protection, or moving from place to place.
4SpeciesA group of organisms that can mate with one another to produce fertile offspring.Ex: giraffe, lion, rhino
5Species over timeThe Earth is a very old planet that scientists estimate to be 4.6 Billion years old.Life has existed on this planet almost as long.Living things have changed with time.Some died, some survived,and some changed.What caused the change?
6EvolutionThe process by which populations accumulate inherited changes over time.Because of evolution, scientists believe all living things come from a common ancestor.
7Evolution EvidenceThe largest piece of evidence for evolution is the fossil record.Fossils – the solidified remains or imprints of once-living organismsFossils are made when an organism dies or leaves an imprint that gets covered by sediment layers.
8Fossil RecordThe fossil record supplies evidence about the order in which evolutionary changes have occurred.Older fossils are found indeeper layers, while newerfossils are found in layersnear the surface.
9Gaps in the Fossil Record We do not have a complete fossil record of all organisms.Fossils are rare and not easily preserved.Conditions for making fossils are not always present.
11Vestigial structures The remnants of once useful structures. Ex: WhalesWhales are mammals that need air to breathWhy are they living in the water?There are remnants of what used to be hip bones and leg bones in whales todayWhales might have ancestors that walked on land
13More EvidenceIf we look at similar structures on different organisms, we see how similar the structures are.Humans, cats, dolphins and bats come from a common ancestor
14DNA ComparisonWith the development of genetic engineering, we are able to look at DNA from several species and compare how similar they are.All organisms share some genetic material.Scientists look at matching sequences of base pairsEx: Chimpanzees and gorillas are close relatives, while chimpanzees and turtles are distant relatives.
16Comparing Embryonic Structures Early in development of any species, an individual goes through embryonic stages.In the early stages, organisms with a common ancestor look very similar.As organisms grow, they develop the features that make them different.