Evolution Review! Part I

This man was the first person to propose a reasonable theory for how and why life changes. His explanation of how giraffes got their long neck was insightful, but ultimately incorrect. Name the two mechanisms for evolution Lamarck presented (next two slides may help)

Lamarck Idea #1 ______________ How did the giraffe get his long neck? A giraffe stretches his neck up to reach the last leaves available on the highest branches. Eventually, its neck gets just a bit longer. He passes that on to the next generation. Over time giraffes’ necks grow gradually longer.

Cave Dwelling Eyeless Organisms ______________________________________ If parts were useful and needed, then they would be modified to help If parts were not needed, then they were lost Lamarck was no dummy.: Correct: changes were related to the interaction of the organism with its environment Didn’t Know: that we can only form structures as our DNA allows us to Lamarck Idea #2 Cave Dwelling Eyeless Organisms

Darwin noticed that the tortoises had variations on different islands. On the well-watered islands, the tortoises had normal shells like at left. On dry islands, the tortoises had a notch in their shell allowing them to feed on vegetation higher, by craning their necks up to reach the leaves (bottom left and right). 2) What main mechanism for evolution did Darwin present? 3) Explain the differences between Lamarck and Darwin’s mechanisms for evolution.

Alfred Russell_______ ______ independently came up with an almost identical set of ideas to Darwin’s Knowing that Darwin was working on his own theory of evolution, in 1858 Wallace sent his ideas to Darwin. This was Darwin’s final prod to get him to publish his work _______ never resented that Darwin – what a great guy! 4) What other scientist came to about the same conclusions as Darwin did about evolution?

Darwin’s world-changing book, outlining his theory. Hey, remember this guy? KNOW HE WROTE ON THE ORIGIN OF SPECIES!

Darwin’s Theory 1) 2) 3) 4) 5) 6) 7) 5) Give an outline of the main points in Darwin’s theory of evolution.

More long ear alleles (LL) in the next generation If natural selection chooses certain traits in an organism, in reality it is really choosing particular alleles that code for the trait long ear alleles (LL) survives Babies with L short ear alleles (ll) dies No Babies  More long ear alleles (LL) in the next generation LL LL LL 6) What did Darwin mean by “natural selection”. What does it have to do with variations? LL ll LL LL

Beetles! 7) What are the environments’ “selective pressures” and how do they cause natural selection?

8) Explain the difference between punctuated equilibrium and gradualism as ideas about the pace of evolution. Two models for evolutionary change focused on the pace of evolution. The left model sees evolution as a slow, incremental, gradual change. The right model views the pace of evolution as periods of little or no change, followed by periods of rapid change.

Deposited last, _____fossils deposited first, _____ fossils Rocks formed by layers (sediments) settling on top are called ________. ______ Layers Deposited last, _____fossils 9) What kind of rock do we find most fossils in ? 10) How does the depth of the fossils in the layers indicate something about the age of the fossils?   ______ Layers deposited first, _____ fossils

Evidence for Evolution 11) Give 7 different evidences of evolution. Describe each briefly. There are some hints for these 7 in the next 7 slides! You should be able to fill in the blanks!

The___________ A story we piece together as we find new fossils Clearly, the fossil record tells us of times when life on Earth was very different than it is today The story tells us life has gradually become more complex. Evidence for Evolution #1 (describe briefly) Fossil of cells that resemble modern cyanobacteria (3.5 billion years old) a very scary salamander

The distribution of different organisms around the planet _____________ The distribution of different organisms around the planet Evidence for Evolution #2 (describe briefly)

_______________ Structures used for different purposes that indicate a common ancestry Why would appendages used for different purposes have the same underlying bone structure? Evidence for Evolution #3 (describe briefly)

___________Structures? These are structures that have no function in the organism --- like nipples on males, the tail bone of humans, leg “spurs” on snakes, and hips in whales. The only explanation is that they are remnants of evolution. Evidence for Evolution #4 (describe briefly)

Comparative__________ Turtle Mouse Human Chick Pig Can you tell which is which? mouse, turtle, chick, pig, and human Evidence for Evolution #5 (describe briefly) Why would all these very different organisms need to develop the same way?

_________ Evidence Compare DNA sequences of different organisms to see how similar they are! Evidence for Evolution #6 (describe briefly) KNOW HOW TO READ THIS CHART! % Similarity Between Species

_________ of Adaptations The Panda’s Thumb Eats bamboo, not meat Developed thumb grasp bamboo Not a perfect solution, but it works! Evidence for Evolution #7 (describe briefly)

Evolution acts on _____________ Individual organisms do not improve themselves 12) Evolution acts on __________ not individuals. Explain Nature selects the best of the members of a population to survive and produce the next generation

Mutations may produce such unique features but selection enhances them Evolution does not produce ___________ It amplifies (increases) or diminishes (decreases) variations that are already present 13) Evolution does not produce _______________ Mutations may produce such unique features but selection enhances them

14) What is this an example/definition of? All of the alleles for all of the traits for all of the members of a population

A New Definition for Evolution: Evolution is any change in the proportion (frequency) of alleles in a population, from one generation to the next YOU SHOULD KNOW THIS It’s all about Passing on your awesome alleles!

Mechanisms for Evolution 1) 2) 3) 4) 5) 15) Identify five different factors that can cause the proportion of alleles in a population to change (hint, the next few slides may help!)