EVOLUTION Which one of these animals is a fish? Evolution is known as "the unifying theory of biology" What does that mean?

Create a list of statements regarding evolution (in your head).  Sort them into - Statements of Fact & Statements of Opinion FACT OPINION

The task is difficult.. partly because the word "fact" is a tough word. When something is a fact, it suggests it is absolute, and not subject to change.                                    Science doesn't like absolutes. Definition of fact:  an observation that has been confirmed repeatedly and is accepted as true                                               (although its truth is never final) Scientists prefer to use the term OBSERVATIONS Look at how it changes the tone of these sentences. 1.  It is a fact that the sky is blue.    (Is it?) 2.  I observe the sky is blue.

Animations like these perpetuate the myth that evolution is a linear process.

While amusing to watch, the Simpsons video illustrates a common myth about evolution.  Evolution isn't linear. Organisms aren't striving to become anything, but rather changing due to their unique environmental pressures.

More misunderstandings..... 1.  If humans evolved into monkeys, why are there still monkeys? This is also related to the misunderstanding that evolution follows a linear path...that everything is trying to be human.  - NOT SO - There are many kinds of primates, each adapted to its own environment, just like there are many kinds of felines This picture is flawed, but commonly used to illustrate human evolution.

None of these cats will evolve into a lion.

Myth 2: Scientists regularly debate whether evolution occurs. The only place debate occurs is in social settings, and is philosophical in nature.  If any debate occurs among biologists, its often regarding specifics - such as timing, or what animal is related to what, or when did a creature evolve and what is its origins.     As a THEORY, evolution is supported by a large body of evidence and is used to EXPLAIN new observations. It is also useful for making PREDICTIONS 

Myth 3: A person cannot be religious and believe in evolution. There are many scientists who have religious beliefs.   One does not necessarily preclude the other.    To say that the two are incompatible is unfair to both scientists and people of faith. 

Another myth is that  evolution encourages the strong to destroy the weak.   Remember, "strong" and "weak" are relative.   Organisms do not have to be strong to survive and cause evolution.  Cepahalopods aren’t the strongest organisms in the sea, but they do have a unique survival skill.

There are many more myths and misunderstandings about evolution There are many more myths and misunderstandings about evolution.  We will hopefully tackle those as we progress through this unit.  On a notecard, write down a question or statement you are confused about regarding evolution.  You do not need to put your name on this card.  As we cover evolution I will try to address particular questions, concerns and arguments. E V O L

Media sources that may be helpful: PBS Evolution - many resources covering the topic - videos, articles, activities and more Darwin's Dangerous Idea - 1st in a 7 part series on evolution; begins with Darwin's voyage on the Beagle and how he established the Theory of Evolution by Natural Selection Nova:  Intelligent Design on Trial  - A recent covering of a trial in Dover, Delaware, where the school board tried to establish "intelligent design" as part of its science curriculum. The Panda's Thumb - news archives about evolution and society, focuses on debunking "creation science" and "intelligent design"

“The Origin of Species” Darwin and Evolution “The Origin of Species” Question: How did the giraffe get its long neck? Why are there 9 subspecies of giraffes?

17.1 History of Evolutionary Thought In 1831, Charles Darwin, a 22-year-old naturalist, accepted a position aboard the ship HMS Beagle that began a voyage around the world; it provided Darwin with many observations.

Pre-Darwinian world-view was determined by theological beliefs. 1) The earth is young; ~10,000 years old 2) Each species was uniquely created and did not change 3) Observations can only be used to substantiate the prevailing worldview, not challenge it. Rothchilds Giraffe How would this worldview explain the giraffe’s neck? How would it explain the 9 subspecies?

Mid-Eighteenth-Century Contributions Carolus Linnaeus and Taxonomy Taxonomy is the science of classifying organisms;. Linnaeus developed a binomial system of nomenclature - two-part names for each species Homo sapiens Canis lupus Giraffa camelopardalis * with 9 subspecies

Masai Giraffe (Giraffa camelopardalis tippelskirchi) Thornicroft Giraffee Giraffa camelopardalis thornicrofti

Biogeography study of the distribution of species and ecosystems in geographic space and through geological time

One of Darwin’s ancestors suggested the possibility of common descent. The idea that species could change was not Charles Darwin’s original idea. No one could propose a MECHANISM for how these changes could occur. Paleontology was a new field, uncovering fossils of organisms that no longer exist.

Lamarck's Acquired Characteristics Lamarck mistakenly saw "a desire for perfection" as inherent in all living things; individuals could change their traits if they tried hard enough. These newly acquired traits would then be passed on. His view of giraffe evolution would have looked like this:

Experiments fail to uphold Lamarck's inheritance of acquired characteristics          

So….if that was wrong. How did giraffes come about? Also, why are there so many subspecies of giraffes?

What We Know So Far 1.  Taxonomy and classification emphasize similarities among species  (common descent) 2.  Fossils show extinct species (paleontology) 3.  Isolated species are distinct (biogeography) 4.  Organisms have adaptations to help them survive .........Enter Charles Darwin..........

The Voyage of the Beagle

Galapagos Islands off S. America Island species varied from mainland species Finches resembled mainland finches, but with more variation Tortoise Variations Shells that flare up, long necks - feed on tall plants

Figure 17.7a

Figure 17.7b

Darwin's Finches a. Finches on the Galápagos Islands resembled a mainland finch but there were more types. b.  Galápagos finch species varied by nesting site, beak size, and eating habits.

Did the animals on the islands descend from one mainland ancestor? Questions to Ponder: Did the animals on the islands descend from one mainland ancestor? What were the variations found on the finches? Why were the island finches so different from mainland finches?

Natural Selection and Adaptation Natural selection was proposed by both Alfred Russel Wallace and Darwin separately, but at the same time. The idea simply states that the organisms best suited for their environment will survive, reproduce, and pass on their desireable traits to the next generation at a higher rate than those lacking the best traits. Over many generations, the best traits will become more and more common.

Natural Selection and Adaptation It is the MECHANISM by which evolution occurs, and it would explain how giraffes got their long necks, why similar species of finches have different beaks, and why there are two different varieties of tortoises on different islands.

There are three preconditions for natural selection. 1. The members of a population have random but heritable variations. 2. In a population, many more individuals are produced each generation than the environment can support, meaning some must die. 3. Individuals have adaptive characteristics that enable some to survive and reproduce better than others.

There are two results of natural selection. 1. An increasing proportion of individuals in succeeding generations will have the “good traits”. 2. Overtime, the increase in this proportion will lead to an entire group that appears to exactly fit its specific environment.

Natural selection can only utilize random variations; therefore there is no direction to a species path or ability to predict what will change. The production of good traits is entirely trial and error. What works will stay, what doesn’t work will be eliminated. No anticipation of future needs!

Pause and think: Thinking that evolution has a direction is a common misconception. Can you think of any statements you may have heard that suggest people think that evolution is directional? Why didn’t chimpanzees evolve the ability to talk? Why aren’t other animals as intelligent as humans? Why didn’t giraffes evolve in other places?

Because evolution has no direction or control, sometimes a species doesn’t change when needed or their changes are insufficient. Extinction occurs when previous adaptations are no longer suitable to a changed  environment. Extinction is totally normal and VERY common! Over 99% of all species that ever existed on this planet are extinct. In addition, three additional species go extinct every day.

How Evolution by Natural Selection Works 1. Variations exist in a population.

2. Every individual struggles to exist.

3. Individuals differ in FITNESS (some are better, some are worse) a) fitness measures an organism’s reproductive success b) it does not necessarily mean stronger. Fully armored stickleback (ocean) Low armor (freshwater)

4. Survivors pass those “fitter” traits to offspring, and the traits become more common in the group as a whole. these fitter traits are called ADAPTATIONS

Apply these principles to the giraffes. Procamelus (ancestor)

Be careful with that word….. Adaptation is a trait, a noun. It is dangerous to use it in verb form because it suggests that an individual can adapt. They cannot. ***** POPULATIONS EVOLVE. INDIVIDUALS DO NOT.***** Fix this sentence: This Aye Aye has adapted to a life of eating insects. Its long digit is used to probe wood.

ARTIFICIAL SELECTION Proving Natural Selection as true. Dogs breeds were developed by years of artificial selection in breeding wolves. We chose the traits most desirable, then bred the organisms with those traits. Individuals with desired traits reproduce more than others, until the desired trait is very common in the group. Nature does the same with “natural selection”.

“On the Origin of Species” by Darwin 1. After the HMS Beagle returned to England in 1836, Darwin waited over 20 years to publish. 2. He used the time to test his hypothesis that life forms arose by descent from a common ancestor and that natural selection is a mechanism by which species can change and new species arise. 3. Darwin was forced to publish  Origin of Species after reading a  similar hypothesis by  Alfred Russel Wallace.

The Definition of Evolution Evolution is the change in allele frequencies, or a change in the gene pool, of a population through natural selection . A gene pool is all of the combined DNA possibilities that exist in a species group. As one gene becomes more or less common in the pool, the population is said to be evolving. Mythbuster: “No one has ever seen one animal change into another, therefore evolution isn’t true.” How would you respond to this statement?

20 Points Extra Credit - a Scenario of Evolution..... 1.  Choose a real or imaginary organism 2.  Describe 2-3 variations in that organism’s population 3.  Show how evolution would act on this population given a change in the environment (climate, predators, food change, etc.) 4.  Note which variations are beneficial and which are harmful. 5.  Show how reproduction changes the overall population (with regard to these variations) 6. Be creative!   You should draw and map your organism through a few generations and write a short essay covering all the requirements.