Evolution Chapter 15

What is Evolution? Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms.

Who is Charles Darwin? Charles Darwin – born in England Joined the crew of the H.M.S. Beagle Sailed around the world Made numerous observations and collected evidence that led him to propose his hypothesis.

What did Darwin Observe during his voyage? Patterns of Diversity: Puzzled by where different species lived and did not live He Asked: * Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them? * Why were there no kangaroos in England? * Why do they look so similar?

What did Darwin observe during his voyage? Living Organisms & Fossils Darwin collected and preserved fossils Fossils resembled organisms that were still alive – other looked completely unlike any creature he had ever seen. He Asked: Why had so many of these species disappeared? Looks nothing like any living species Looks LIKE a Kangaroo

What did Darwin Observe? The Galapagos Islands Most influential place Darwin visited Although islands were so close together, the islands had very different climates. Fascinated by the land tortoises, marine iguanas, & finches.

Where are the Galapagos Islands? Clicker Question: Where are the Galapagos Islands? D A C B

What did Darwin observe on the Galapagos Islands? Click to zoom into Galapagos Islands

What did Darwin observe on the Galapagos Islands? Galapagos Tortoises * Domed shell w/ short neck * Live on wetter islands * Have short necks that can reach grasses and vegetation on the ground

What did Darwin observe on the Galapagos Islands? * Flatter shell compared to domed * Live on slightly drier islands * Have longer necks than domed to reach short bushes and trees

What did Darwin observe on the Galapagos Islands? * “Saddle” w/ VERY long necks * Live on dry islands * Dry climates have less vegetation on the ground * Long neck used to reach vegetation up in bushes & trees growing off the ground

Galapagos Tortoises

What did Darwin observe on the Galapagos Islands? All tortoises resemble a species living in South America Saw that giant tortoises varied in predictable ways from one island to another. The shape of a tortoise’s shell could be used to identify which island a particular tortoise lived.

Natural Selection Questions (Bill Nye) A young man that walked out was __ ___. He quit medical school to become a ___. How long did the Beagle stay in the Galapagos Islands? __ days Finches had different shaped ___: varied by the environment they inhabited. What was the mechanism that made evolution occur? ___ ____ When did he publish his book? Now, every where we look at today, we see something that came from ___.

Natural Selection Clip (Bill Nye)

Who influenced Darwin’s ideas? James Hutton and Charles Lyell Recognized that Earth is many millions of years old. And the processes that changed Earth in the past are the same processes that operate in the present.

Wild/Crazy Idea: Earth changes over time Hutton and Lyell said… Volcanoes release hot lava and gases now, just as they did on an ancient Earth. Erosion continues to carve out canyons, just as it did in the past. Also said that awesome geological features could be built up or torn down over long periods of time. (examples: earthquakes and volcanoes) Wild/Crazy Idea: Earth changes over time

So……Because of Hutton & Lyell’s work….. Hutton and Lyell So……Because of Hutton & Lyell’s work….. Darwin then asked: If the Earth could change over time, might life change as well?

Who else influenced Darwin’s Ideas? Malthus (an economist) – Studied population growth - observed that babies were being born faster than people were dying. He reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone.

Lamarck’s Theory of Evolution Who else was thinking about evolution? Lamarck’s Theory of Evolution Proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in a species Was he “right”? Lets break it down….

How did Lamark think organisms changed? Fiddler Crabs: An Example 1. The male crab uses its small front claw to attract mates and ward off predators 2. Because the front claw has been used repeatedly, it becomes larger (acquired). 3. A larger claw, is then passed on to the crab’s offspring. He was WRONG! He did not realize that the large claw traits were inherited

Lamark’s Theory Another Example: According to Lamarck's theory, a given giraffe could, over a lifetime of straining to reach high branches, develop an elongated neck. The long neck is ACQUIRED

The Origin of Species by Means of Natural Selection Darwin’s Book The Origin of Species The actual title of his book is: The Origin of Species by Means of Natural Selection The book proposed a mechanism for evolution that he called natural selection. He presented evidence that demonstrates the process of evolution has been taking place for millions of year. Darwin was 50 when it was published!

What were Darwin’s arguments in his book? Natural Variation and Artificial Selection Argued that species were NOT perfect and unchanging. Natural Variation: There are differences among individuals of a species.

What is Natural Variation? White Version/Morph Peppered moths come in two versions Black Version/Morph If trees in an area have dark bark, the black version blends in better and is less likely to be eaten by predators. If trees in an area have white bark, the white version blends in better and is less likely to be eaten by predators.

What is Natural Variation? Bessie Elsie * Elsie’s natural variation is to produce more milk than Bessie * Which cow would the farmer use to reproduce offspring? Why?

What were Darwin’s arguments in his book? Artificial Selection: Nature provided the variation among different organisms, and humans selected those variations that they found useful. * Only the largest hogs, fastest horses, and the cows that gave the most milk were selected to breed and produce offspring.

Darwin’s Evolution by Natural Selection The Struggle for Existence: Means that members of each species compete regularly to obtain food, living space, and other necessities of life. A predator that is the fastest or has a particular way of catching prey can catch more prey. Prey that are faster, better camouflaged, or better protected avoid being caught.

Darwin’s Evolution by Natural Selection Survival of the Fittest: Process by which individuals that are better suited to their environment survive and reproduce most successfully; also called Natural Selection. Darwin called the ability of an individual to survive AND reproduce in its specific environment fitness. An adaptation is any inherited characteristic that increases an organism’s chance of survival.

Darwin’s Discoveries Video Clip

Survival of the Fittest The concept of fitness, Darwin argued, was central to the process of evolution by natural selection. Example: Baby birds compete for food in the nest. The stronger bird may take food from the weaker siblings.

Evolution by Natural Selection Descent with Modification: Principle that each living species has descended, with changes, from other species over time. Implies that all living organisms are related to one another. Common Descent: The principle that says all species – living and extinct – were derived from common ancestors.

Evidences of Evolution There are 4 categories

Evidence #1: FOSSIL RECORD

What are some evidence of Evolution? Fossil Record Fossils that had formed in the different layers of rock were evidence of gradual change over time. One could view how a species had changed and produced different species over time.

Evolution of Horses Horses do not look the same as they did many years ago - Fossil Record shows evidence that animals have changed over time and that they share a common ancestor based on similarities in their skeletons.

Evidence #2: COMPARATIVE ANATOMY

What are some evidence of Evolution? Homologous Structures: Structures that have different mature forms in different organisms but develop from the same embryonic tissues. Shows that the organisms are RELATED!

What are some evidence of Evolution? Analogous structures can be superficially similar in construction, but are NOT inherited from a common ancestor. Example: The wing of an eagle & the wing of a insect have the same function (both enable the organism to fly) – but are constructed in different ways & from different materials.

What are some evidence of Evolution? * While analogous structures do not indicate close evolutionary relationships, they do show that functionally similar features can evolve independently in similar environments.

Vestigial Structures Vestigial Structures are structures that are the reduced forms of functional structures in different species. Examples: 1. Snake Pelvis: The pelvis is the attachment point for legs and is therefore nonfunctional in an animal without legs

Vestigial Structures 2. Kiwi Wing: The wings of kiwis are too small to be of any use in flight 3. Human Appendix: Important for digestion in many mammals, but of limited use in humans & some apes

Evidence #3: COMPARATIVE EMBRYOLOGY

Similarities in Early Development What are some evidence of Evolution? Similarities in Early Development In their early stages of development, chickens, turtles, and rats look similar, providing evidence that they shared a common ancestry.

Evidence #4: COMPARATIVE BIOCHEMISTRY

What we know… All cells rely on DNA to make proteins. Using new technologies, biologists are able to determine the amino acid sequences in proteins to determine evolutionary relationships among various species of organisms.  The more closely related two species are, the greater the similarity in amino acid sequences of their proteins. 48

For example: 49

Evolution Video

Types of Evolution There are 5 main types

Divergent Evolution: When two species move away from the traits that they share with a common ancestor as they adapt to their own environments Also called Adaptive Radiation… Has homologous structures, And are CLOSELY related!

Convergent Evolution: When two distinct species with differing ancestries evolve to display similar features. Sugar Glider: Has analogous structures, Australian marsupial And are NOT closely related! Flying Squirrel A GA squirrel

Geographic Distribution of Living Species - Species now living on different continents had each descended from different ancestors. - Because some animals on each continent were living under similar ecological conditions, they were exposed to similar pressures of natural selection. They ended up evolving certain striking features in common… but are NOT related! This is called Convergent Evolution

Punctuated Equilibrium Evolution that has long periods of stability/unchange followed by short periods of rapid change.

Gradualism A change that is very slow over time. Its hard to notice a difference over a short period of time…it is slow and gradual.

Adaptations: A body part, body covering, or behavior that helps an organism survive its environment.

Biological Resistance Some organisms have a mutation that makes them resistant to a toxin (antibiotic or pesticide). Over use of antibiotics & pesticides create populations of “super bugs”. This is why you need to take your antibiotics for the entire time… You expose the bacteria to the toxin, if you don’t kill them all (take all your medicine), then you taught them how to resist the antibiotic!

Adaptations: Mimicry: Adaptation in which one species evolves to resemble another species for protection or other advantages.

Adaptations: Camouflage: Adaptation that allows organisms to blend into their surrounds.

Plants: Tropisms (Responses): 1) Phototropism: Responds to light

Plants: Tropisms (Responses): 2) Thigmotropism: Responds to touch

Plants: Tropisms (Responses): 3) Gravitropism: Responds to gravity Video Here/Turn volume off!

Plants: Tropisms (Responses): 4) Hydrotropism: Responds to water

Cactus Waxy Covering: Prevent water loss Ridges: Expand to store more water when it rains Thorns: Protect against being eaten No Leaves: Prevent water loss

Catching prey/digging Polar Bear Thick Blubber: Keep warm Short/small Ears: Save Heat Large Paws: Walking on snow White/clear Fur: Blend in with snow Long Claws: Catching prey/digging

Adaptation Poster Adaptations: 1.) Animal must be drawn, in color, & neat 2.) Must include background environment 3.) Must have at least 5 adaptations w/ explanation Not adaptations: * How long they live * Where they live * How many babies the have * What they eat Adaptations: * Large paws, thick beak, bright colored feathers, skinny legs, large ears, sharp teeth, fur thickness….

The End