Everything must evolve Charles Darwin Father of Evolution

Everything must evolve…

Charles Darwin • Father of Evolution • Proposed a way how evolution works – How did creatures change over time? – by natural selection • Collected a lot of evidence to support his ideas – 1809 -1882 – British naturalist

Voyage of the HMS Beagle • Invited to travel around the world

Voyage of the HMS Beagle • Stopped in Galapagos Islands – 500 miles off coast of Ecuador

Darwin found… many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands?

Darwin found… clues in the fossils Darwin found: Evidence that creatures have changed over time present day Armadillos Darwin asked: ancient Armadillo Why should extinct armadillos & modern armadillos be found on same continent?

Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

The finches clinched it for Darwin

Darwin concluded: Each species has descended, with changes, from other species over time. Darwin called this… Descent with modifications or (change in population over time)

Data supports Evolutionary Theory

Darwin’s Theory of Evolution by Natural Selection • Species have changed through time and are related by descent from a common ancestor • The primary mechanism of Evolutionary Change is Natural Selection

Fossil Record - the history of life recorded by remains from the past. Most fossils are at least 10, 000 years old. 1. Body Fossils 2. Trace Fossils

What is found? - Fossils exist and fossil forms are unlike species living today 1. Fossil Sequence? When fossils are arranged according to their age, they show successive evolutionary change 2. Fossil Intermediates? Transitional fossils have been found between: Amphibians & reptiles, reptiles & birds, reptiles & mammals, apes and humans

The Evolution of Horses A particularly well-documented case of evolution within a group

The Fossil Record is Incomplete At the time of Darwin, the fossil record was VERY scanty. A great deal of progress has been made since, but it is far from finished. The fossil record is relatively incomplete for several reasons: 1. Soft tissues are rarely preserved 2. Movement of the earth's crust has obliterated and/or covered many fossils 3. Fossilization takes place only in certain types of habitats and favorable environments 4. Paleontologists have not dug up every place on earth

Even if there were no fossil record, the evidence from living organisms would be more than sufficient to demonstrate the historical reality of evolution

Vestigial Structures • Features that have no apparent function Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display • Typically have an important function in related species Vestigial structures Ex: Hindlimb joints in whales and snakes

Vestigial Structures in Humans Tailbone Wisdom Teeth Appendix

Evidence for the relatedness of life forms? • Hypothesis: all living organisms have descended from a common ancestor • Prediction: we should also be able to see evidence of relatedness of species -Homology -Geographic distribution

Homology • Homology: a similarity between species that is the result from the inheritance of traits from a common ancestor • The features of every creature reflect history as well as adaptation • 3 types of homologies - structural - developmental - genetic

Analogous Structures § Different structures, same function § Suggests that organisms do not share a close § common ancestor Ex. Hawk, butterfly, & bat can all fly but have different wing structure

Homologous Structures • Same structure in different animals • Suggests that organisms share common ancestor • Ex. Forelimbs of human, cat, whale, & bat Same bone structures

Homology vs. Analogy Natural selection appears to have favored similar adaptations in unrelated organisms in similar environments--> these structures are analogous Whereas homologous structures share structural similarity, but not function, analogous structures share function but not structural similarity since they evolved independently

Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display Embryos show evolutionary history Homologous structures in adults develop from homologous groups of cells in embryos --> they share developmental pathways

Comparative Embryology • Analyzing embryos with similar structures to show common ancestor

Dog Fetus Human fetus

Bat Fetus

Genetic Homologies All living organisms share the same genetic code Chromosome and gene similarities between species match evolutionary similarities This is true for both coding regions and “junk DNA”

Molecules reflect evolutionary divergence

Geographic Distributions Species that are extremely similar to one another tend to be clustered geographically (Ex. : Darwin’s finches) Living species are more similar to fossil species in the same area than they are to living species in other areas • The law of succession –general correspondence between fossil and living forms in same geographical area Darwin used this observation to predict that fossils of ancient humans should be found in Africa

That Evolution Has Occurred Is A Fact

Fossil Record - Evidence of Evolution

How to estimate how old: 1) the deeper the layer that the fossil is found in, the older it is 2) the fossils near the surface are younger and more complex 5 4 3 2 1 Which rock layer is the oldest? Which fossil is older: a fossil in layer 4 or a fossil in layer 2? What observations did you make about the organisms in layers 1 -3 and 4 -5? What does this tell you about the type of environment?

• Although scientists have a found a lot of fossils (and still continue to find them!), they still have missing pieces in the fossil records of species. • The camel however, has a nearly complete fossil record of it’s evolution How is this evidence for evolution?

Change by Chance Activity Procedures: 1. You will need a pencil for this activity. You will be working with a group of students and drawing a picture. You cannot look at anyone else’s drawing. 2. The drawing should be face down until the signal to begin is given. 3. I will signal the beginning and end of each 15 -second interval. 4. I will give the first student in each line 15 seconds to draw, not trace, the image on the colored paper onto their blank paper. 5. The first student will then pass their drawing to the next person. The second student in each row 15 seconds to draw, not trace, the first student’s drawing on his or her own paper. 6. At the end of the 15 seconds, the second students pass their drawings to the third students, and so on until all students in a group have had a chance to draw the reptile. 7. Have each group label all of their drawings with a group name, mix the order, and place them together. 8. I will collect each group’s drawings and redistribute each set to a different group. In groups, sequence the order of the drawings and then tape them on the wall. 9. Choose one person from the original group confirm the accuracy of the sequencing.

• Why was sequencing the drawings difficult? • How was this experience similar to sequencing fossil records? • How was this experience different from sequencing fossil records?

Turn to an elbow partner and answer the question below. Discuss how to determine the correct answer.

With the same elbow partner describe the changes in the fossils you see in each layer and what they tell you about that time period.

Turn to a different partner. Compare layer C to layer F in the diagram below. What evidence do these fossils provide of changes on earth?

Living or once living things share common ancestors and fossils provide evidence for common ancestry.

Changes in fossil records…. What do they mean?

Stasis - • In this picture, the color of the moths changes very little. Punctuated equilibrium is a evolutionary theory which proposes that once species appear in the fossil record they will become stable, showing little net evolutionary change.

Gradualism - suggest that organisms evolve through a process of slow and constant change. • For instance, an organism that shows a fossil record of gradually increased size in small steps, or an organism that shows a gradual loss of a structure. In the case of the moths above, they gradually change color over time.

Physical characteristics of organisms change over time and fossils provide evidence of change.

Summarizing Strategy: 3 – 2 – 1 Describe three ways in which scientists support theory of evolution. Identify two ways in which scientists know the physical characteristics of organisms change over time. Describe why the fossil record is important.