Slide 1 / 101 Slide 2 / 101 New Jersey Center for Teaching and Learning Progressive Science Initiative AP BIOLOGY This material is made freely available at www.njctl.org and is intended for the non-commercial use of students and teachers. These materials may not be Big Idea 1 used for any commercial purpose without the written permission of the owners. NJCTL maintains its Part A website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course August 2012 materials to parents, students and others. www.njctl.org Click to go to website: www.njctl.org Slide 3 / 101 Slide 4 / 101 Big Idea 1 The following is the AP's explanation of the first Big Idea: Big Idea 1: "Evolution is a change in the genetic makeup of a population over time, with natural selection its major driving mechanism. Darwin’s theory, which is supported by evidence from many The process of evolution drives scientific disciplines, states that inheritable variations occur in individuals in a population. Due to competition for limited the diversity and unity of life. resources, individuals with more favorable variations or phenotypes are more likely to survive and produce more offspring, thus passing traits to future generations... Slide 5 / 101 Slide 6 / 101 Big Idea 1 Big Idea 1: Part A In addition to the process of natural selection, naturally occurring catastrophic and human induced events as well as Click on the topic to go to that section random environmental changes can result in alteration in the gene pools of populations. Small populations are especially sensitive to these forces. A diverse gene pool is vital for the survival of species because environmental conditions change. · Darwin Helped Define Biological Evolution Mutations in DNA and recombinations during meiosis are · Darwin's Evidence sources of variation. Human-directed processes also result in new genes and combinations of alleles that confer new · Natural Selection phenotypes. Mathematical approaches are used to calculate · Mutations & Hardy-Weinberg changes in allele frequency, providing evidence for the occurrence of evolution in a population." · Evidence for Evolution
Slide 7 / 101 Slide 8 / 101 Darwin Helped Define Evolution Defined Biological Evolution ev·o·lu·tion Biology- a. Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species. Return to Table of Contents Slide 9 / 101 Slide 10 / 101 Evolution Defined Charles Darwin Upon graduation from Cambridge University, Charles "Change in the genetic composition of a population during Darwin took a position as a naturalist on a ship called the successive generations, as a result of natural selection acting H.M.S. Beagle. The main purpose of the Beagle was to on the genetic variation among individuals, and resulting in map out the coastline of South America. the development of new species." Darwin was on board the Beagle from 1831 to 1836. The person most responsible for this current definition of biological evolution is Charles Darwin and his theories presented in his book " The Origin of Species " Slide 11 / 101 Slide 12 / 101 The Galapagos Islands Journey of the H.M.S. Beagle 1831-1836 In the 4th year of the voyage, the H.M.S Beagle reached the Galapagos Islands off the coast of Equador. Darwin found many plant and animal species that were very similar to the species on the mainland of South America. He compared the island and mainland species and found that the island varieties had different adaptations from the same mainland species.
Slide 13 / 101 Slide 14 / 101 Darwin in South America Darwin's Observations As we go over the 5 major observations that Darwin made As the ship's crew surveyed the coast of South America, in South America, write down some of your own theories. including the Galapagos Islands, Darwin spent most of his time The question we need to answer: inland collecting thousands of living plants and animals as well as old bones. Why do living things do what Darwin observed? During his 5 year voyage Darwin made many observations that led to his published theories. Slide 15 / 101 Slide 16 / 101 Darwin's Observations Darwin's Observations 1st Observation 2nd Observation In the majority of species observed by humans, more There are a limited amount of resources (food, water, offspring are born than can survive to become adults. shelter) available to any given species. These resources Female fish can hatch thousands of offspring, but usually limit the amount of offspring that can survive, yet species only one or two survive to become adults. The same is would quickly exceed that limit if all of their offspring true for the bugs, turtles, birds and plant species Darwin survived. observed. WHY? Species would go extinct if their numbers outgrew WHY? Producing offspring uses a lot of energy. Why the available resources. Why do individuals have the ability would individuals make so many if only a few can survive? to produce enough offspring to easily deplete resources? Think about it for a minute Think about it for a minute Slide 17 / 101 Slide 18 / 101 Darwin's Observations Darwin's Observations 4th Observation 3rd Observation Individuals of a species vary in almost all of their The number of individuals in a group of the same species characteristics. He observed beak sizes in birds, shells of remains relatively constant over the long term. tortoises, spotting patterns of beetles, color of flowers and many more variations of common features. WHY? Given the 1st and 2nd observation, why do we not see an increase in the overall number of individuals? Why WHY? It must be important to have these variations, but does the overall number of individuals not decrease due to why? the limitations of resources? Think about it for a minute Think about it for a minute
Slide 19 / 101 Slide 20 / 101 Darwin's Observations Darwin's Observations 5th Observation Now take 2 minutes and look over your thoughts regarding Each mating season parents produce more offspring. The the previous questions. Can you put your reasons for these variations that are present in the successful parents are observations of life into a few clear statements. Compare passed to their offspring. This process of heredity is your statements with other students' statements. repeated generation after generation. WHY? It must be important to the species to have the specific variations of the successful parents, but why? Think about it Think about it for a minute Slide 21 / 101 Slide 22 / 101 Darwin's Inferences Darwin's Inferences In the previous activity you were producing inferences . 1st Inference These are statements made taking into account past A population is a group of individuals of the same observations. This is how a hypothesis is created. species living in the same geographic area that are capable of interbreeding. The individuals of a Darwin did the same. Compare your inferences with population are in constant competition with one Darwin's... another for the limited resources available. This inference is based on the first three observations. It accounts for why populations remain relatively constant in number of individuals even though there is a high number of offspring in each new generation. Slide 23 / 101 Slide 24 / 101 Darwin's Inferences Darwin's Inferences 2nd Inference 3rd Inference The variations in the individuals of a population help Individuals that survive the competition are able to the individual to survive or can lead to its death in the breed and produce offspring. Since these individuals competition for survival. pass their traits on and the losers do not, over many generations the different rates of survival based on This inference is based on the fourth observation. It variation causes the population to transform. The explains the purpose of variation. They give an "good" traits survive, the "bad" traits are weeded out. individual more or less chance at survival. Any variation that consistently helped individuals survive This inference is based on the fifth observation. It would be beneficial to the entire population. explains that heredity is the key to an evolving population. This inference has become know as survival of the fittest .
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