Change over Time Adaptation a characteristic that helps an organism survive in its environment Two types of adaptations Structural – physical feature Ex. Long neck, gills, striped fur Behavioral – action of organism Ex. Hibernation, hunting at night

Great Blue Heron Adaptations The Great Blue heron has adapted in many ways. They have mastered the art of hunting by standing still in shallow water waiting for their prey, then stabbing it with their extremely sharp beak. In addition, they adapted to avoid predators by building their large nests of sticks in trees so they cannot be reached easily by most predators. Lastly, it adapted to its environment by getting a grey-blue camouflage and a streaked white neck to blend in with its surroundings.

Amur Tiger Adaptations Characteristics that improves an individual’s ability to survive and reproduce in a particular environment.

Species A group of organisms that can mate with one another to produce fertile offspring Scientists believe that as Earth changes species also change or Species die out New species appear

Scientists observe that species change over time Evolution The process in which populations gradually change over time Evolution happens by Natural Selection the process of sorting individuals based on their ability to survive and reproduce within their ecosystem.

THE PRINCIPLES OF NATURAL SELECTION Organisms produce more offspring that can survive. Differences, or variations, occur among individuals of a species. Some variations are passed to offspring. (Every individual has its own combination of traits so it is similar to, but not identical to, its parents.) Some variations are helpful. Individuals with helpful variations survive and reproduce better than those without these variations. Over time, the offspring of individuals with helpful variations make up more of a population and eventually may become a separate species. THE PRINCIPLES OF NATURAL SELECTION Organisms produce more offspring that can survive. Differences, or variations, occur among individuals of a species. Some variations are passed to offspring. (Every individual has its own combination of traits so it is similar to, but not identical to, its parents.) Some variations are helpful. Individuals with helpful variations survive and reproduce better than those without these variations. What might happen to an albino lemur in its natural environment?

Examples of Natural Selection in Action – Changes in Populations Insecticide Resistance A few insects in a population may be naturally resistant to a chemical insecticide. These insects pass their resistance trait to their offspring, and an insect population gradually becomes resistant to the insecticide. Adaptation to Hunting People hunt elephants for their tusks. As a result, fewer of the elephants that have tusks survive to reproduce, and more of the tuskless elephants survive. Competition for Mates Many species have so much competition for mates that interesting adaptations result. For example, the females of many bird species prefer to mate with males that have colorful feathers.

Darwin’s Finches Darwin noticed that the finches of the Galápagos Islands were a little different from the finches in Ecuador. And the finches on each island differed from the finches on the other islands.

Natural Selection in Action - The Process of Speciation Separation Speciation often begins when a part of a population becomes separated from the rest. Adaptation Populations constantly undergo natural selection. After two groups have separated, natural selection may act on each group in different ways. Division Over many generations, two separated groups of a population may become very different until the point when they can no longer mate with one another. At this point, the two groups are no longer the same species.

Evidence of changes Fossils The remains or imprints of once-living organisms found in layers of rock Fossil record Timeline of when certain organisms existed Made by studying fossils embedded in rock Evidence #1: Fossils in newer rock layers more similar to organisms today Older fossils less similar to today’s organisms Part of fossil record is missing Fossils are rare – few organisms will become fossils

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Evidence #2: Many organisms have common characteristics (bone structure, development in womb) This indicates organisms have common ancestors

Evidence: Case Study = Whale Evidence in fossils links whales to mammals that lived on land To Organisms that partly lived on water and partly on land An organism that lived in water Modern day whales

Scientists think that the ancient ancestor of whales was probably a mammal that lived on land and that could run on four legs. The organisms shown form a sequence between ancient four-legged mammals and modern whales. Several pieces of evidence indicate that these species are related by ancestry

Evidence in skeletal structure of today’s whale Whales have hip bones!! (whales do not walk)

When comparing organisms: Evidence found : In skeletal structures Structures and order of bones are similar in organisms Evidence #3: When comparing DNA DNA in living organisms are similar More closely related organisms have a greater amount of DNA in common (chickens and dinosaurs)