EVOLUTION HSLS 4 1 COMMUNICATE SCIENTIFIC INFORMATION THAT

HSLS 4 -1: COMMUNICATE SCIENTIFIC INFORMATION THAT COMMON ANCESTRY AND BIOLOGICAL EVOLUTION ARE SUPPORTED

FOSSIL RECORD • Fossils provide snapshots of what life looked like throughout time. By

MORPHOLOGY • Organisms with anatomical similarities must have come from a common ancestor •

MORPHOLOGY • Vestigial Structures: Vestigial structures are body parts that seemingly have no purpose

DNA ANALYSIS • All living things have the same DNA code with the same

EMBRYOLOGY • During some stages of development, organisms exhibit ancestral features in whole or

HSLS 4 -2 CONSTRUCT AN EXPLANATION BASED ON EVIDENCE THAT THE PROCESS OF EVOLUTION

INDIVIDUAL VARIATION • Organisms in a population vary • Everyone is different • Ex:

OVERPRODUCTION • Organisms in a population have more offspring than will survive • Not

STRUGGLE FOR EXISTENCE • Organisms struggle to survive • Compete with each other and

SURVIVAL OF THE FITTEST • Organisms that best fit the environment are more likely

KEY TERMS • Fitness-ability of an individual to survive and reproduce in a specific

NATURAL SELECTION • Organisms that are the “fittest” are more likely to survive and

–Natural selection can occur in 3 different ways

DIRECTIONAL SELECTION: • The trait on one end becomes more common, so the graph

DIRECTIONAL SELECTION: EXAMPLE • After a volcanic eruption the landscape becomes darker in color,

STABILIZING SELECTION: • The medium trait becomes more common, so the graph becomes skinnier

STABILIZING SELECTION: • After excessive logging, the landscape becomes dusty and desert like. Mouse

DISRUPTIVE SELECTION: • The traits on both sides become more common, so the graph

DISRUPTIVE SELECTION: • The female mice prefer male fur color to be either very

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EVOLUTION

HSLS 4 -1: COMMUNICATE SCIENTIFIC INFORMATION THAT COMMON ANCESTRY AND BIOLOGICAL EVOLUTION ARE SUPPORTED BY MULTIPLE LINES OF EMPIRICAL EVIDENCE.

FOSSIL RECORD • Fossils provide snapshots of what life looked like throughout time. By studying fossils, you can see how life has changed through time. • Example: Dinosaur fossils are found throughout the world, but no dinosaurs exist today. At the same time, human fossils do not occur before a certain date. This shows that life has certainly changed over time.

MORPHOLOGY • Organisms with anatomical similarities must have come from a common ancestor • Example: Hummingbirds and whales both have 4 legged skeletons, with nearly every bone in one correlating to a bone in the other. This could only occur if they had descended from a common ancestor.

MORPHOLOGY

MORPHOLOGY • Vestigial Structures: Vestigial structures are body parts that seemingly have no purpose or function. Perhaps they once did, but somewhere along the way they lost their functions and are now basically useless.

DNA ANALYSIS • All living things have the same DNA code with the same four bases that provides the instructions for everything about them. This means we all must have a common ancestor. • Example: Roundworms and humans share 25% of their genes. Somewhere back in time, we must have had a common ancestor.

EMBRYOLOGY • During some stages of development, organisms exhibit ancestral features in whole or incomplete form. This shows that these organisms most likely have a common ancestor. • Example: Some snakes have hind limb buds as embryos, but lose them as they develop. This shows that these snakes must have an ancestor with hind

HSLS 4 -2 CONSTRUCT AN EXPLANATION BASED ON EVIDENCE THAT THE PROCESS OF EVOLUTION PRIMARILY RESULTS FROM FOUR FACTORS: (1) THE POTENTIAL FOR A SPECIES TO INCREASE IN NUMBER, (2) THE HERITABLE GENETIC VARIATION OF INDIVIDUALS IN A SPECIES DUE TO MUTATION AND SEXUAL REPRODUCTION, (3) COMPETITION FOR LIMITED RESOURCES, AND (4) THE PROLIFERATION OF THOSE ORGANISMS THAT ARE BETTER ABLE TO SURVIVE AND REPRODUCE IN THE ENVIRONMENT.

INDIVIDUAL VARIATION • Organisms in a population vary • Everyone is different • Ex: Some cows give more milk than others. Some plants have larger fruit than others. • Heritable variation -> Can lead to artificial selection

OVERPRODUCTION • Organisms in a population have more offspring than will survive • Not everyone lives

STRUGGLE FOR EXISTENCE • Organisms struggle to survive • Compete with each other and other organisms • Depend on non-living factors • Food, living space, etc. • Predators who are faster can catch more prey; prey that are faster avoid being caught

SURVIVAL OF THE FITTEST • Organisms that best fit the environment are more likely to survive • Not necessarily the strongest or the best

KEY TERMS • Fitness-ability of an individual to survive and reproduce in a specific environment • Is a result of adaptations • Adaptations-inherited characteristic that increases an organism’s chance of survival • Ex. Structure, processes or behavior

NATURAL SELECTION • Organisms that are the “fittest” are more likely to survive and reproduce to pass those beneficial genes on. • Based on random mutation and the environment. • Environment “selects” for traits that are better suited or help with survival. • Over time, natural selection results in changes in the inherited characteristics of a population.

–Natural selection can occur in 3 different ways

DIRECTIONAL SELECTION: • The trait on one end becomes more common, so the graph shifts to one side.

DIRECTIONAL SELECTION: EXAMPLE • After a volcanic eruption the landscape becomes darker in color, so dark fur color becomes more common.

STABILIZING SELECTION: • The medium trait becomes more common, so the graph becomes skinnier and taller in the middle.

STABILIZING SELECTION: • After excessive logging, the landscape becomes dusty and desert like. Mouse fur color becomes mostly medium brown.

DISRUPTIVE SELECTION: • The traits on both sides become more common, so the graph splits in the middle.

DISRUPTIVE SELECTION: • The female mice prefer male fur color to be either very light or very dark. After time, light brown and dark brown become more common.