Introduction to Evolution Pre-AP Biology

Bellwork Ancestors of the polar bear had a brown coat but today they have a white coat. Why? What initiated the change?

Objectives Explain how Lyell and Malthus contributed to Darwins Theory of Evolution. Define descent with modification and natural selection

Key Terminology Inheritance of acquired characteristics Descent with modification Natural selection

Important Dates Darwin – published his theory of evolution 1859 Mendel –published that parents pass on their offspring discrete heritable factors 1866 Hershey and Chase Experiment – discovery DNA genetic material-1952 Watson and Crick discovery of DNA structure -1953

Jean Lamarck’s Ideas One of first to develop a theory of evolution Reasoned that organisms must adapt to their environment Inheritance of acquired characteristics organisms develop certain characteristics during their lifetime and pass them on to their offspring. Example: Giraffe’s long neck due to stretching to reach leaves

Ideas from Geology Charles Lyell-geologist-suggested Earth far older than originally thought. Evidence: Slow and gradual geological processes occur over long periods of time cause enormous changes to Earth Examples building of mountains creation of canyons

Malthus and Population Dynamics Observed more babies born than people dying Suggests human population growing at a rapid rate Maintain this pace, eventually run out of food and living space

PROPERTY OF PIMA COUNTY JTED, 2010 Think-Pair-Share How might Malthus ideas be applied to plants and animals? 3. Think-pair-share teacher presents a question teacher gives wait time for student to form answer teacher instructs students to share their answer with a partner teacher calls on non-volunteers to share with the class PROPERTY OF PIMA COUNTY JTED, 2010 3

Darwin influenced by Malthus ideas Applied Malthus ideas to plant and animal populations Plant and animal populations typically do not become overpopulated. Ex. Orange trees Suggests certain factors keep population in check disease availability of food and other resources

Charles Darwin Darwin took a voyage on the HMS Beagle in 1831 Purpose of voyage was to map the topography of South American coastline As a naturalist, his job was to record and collect the plants and animals of South America From these observations developed his theory of evolution which was published in “Origin of Species” in 1859

Two key ideas published in the Origin of Species Descent with modification Natural Selection

Descent with modification Originated from common ancestor Descendants of that ancestor spread into various habitats and accumulated modifications Modifications were adaptations that allowed them to live successfully in that environment Occurred over millions of years Descent with modification was driven by natural selection

Natural Selection Individuals better suited for the environment Are more fit Survive and successfully reproduce Passing those desirable traits onto their offspring

Natural Selection requires several factors Genetic variation within the population Environmental selection pressures Ability of the organism to reproduce

PROPERTY OF PIMA COUNTY JTED, 2010 Think-Pair-Share Why is reproduction critical to natural selection and descent with modification? 3. Think-pair-share teacher presents a question teacher gives wait time for student to form answer teacher instructs students to share their answer with a partner teacher calls on non-volunteers to share with the class PROPERTY OF PIMA COUNTY JTED, 2010 3

Example: Darwin’s Finches

PROPERTY OF PIMA COUNTY JTED, 2010 Think-Pair-Share Examining the picture of finches, what was the 1. genetic variation 2. environmental pressure 3. Think-pair-share teacher presents a question teacher gives wait time for student to form answer teacher instructs students to share their answer with a partner teacher calls on non-volunteers to share with the class PROPERTY OF PIMA COUNTY JTED, 2010 3

PROPERTY OF PIMA COUNTY JTED, 2010 Think-Pair-Share Why is the statement “She has evolved into a fine pianist” not biologically accurate? 3. Think-pair-share teacher presents a question teacher gives wait time for student to form answer teacher instructs students to share their answer with a partner teacher calls on non-volunteers to share with the class PROPERTY OF PIMA COUNTY JTED, 2010 3

2 Minute Summary Over millions of years, the average length of the giraffes’ necks has increased. During the time that this change was taking place, food close to the ground became relatively scarce, but there were always plenty of leaves on the higher branches of trees. Provide the most likely explanation for the giraffes’ long neck a) according to Lamarck b) according to Darwin