Chapter 13 Theory of Evolution High School Biology

Chapter 13 – Theory of Evolution High School Biology Class

What is EVOLUTION? A textbook definition of evolution… “…evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next. " - Helena Curtis and N. Sue Barnes, Biology, 5 th ed. 1989 Worth Publishers, p. 974

What is EVOLUTION? Put a simpler way… n The change in a species over time.

I. What evidence is there for Evolution? A. Fossil records B. Transitional species C. Geological time and dating D. Anatomical trends E. Embryology F. Biochemical/Molecular data

A. Fossil Record n What is a Fossil? Preserved remains, imprints, or traces of an organism that has survived.

i) Types of fossils n n Mold: sediment hardens around an organism preserving the outside shape. Cast: sediments enter a mold and harden.

Fossils (cont. ) n n Petrifaction: atoms in living tissues are replaced by minerals. Imprint: footprints, tracks, or tunnels made by an organism.

B. Transitional Fossils n Fossils that show a relationship or evolutionary link between two different species of a family of organisms.

Archaeopteryx

Archaeopteryx 1) Reptile features: n Trunk region vertebrae are free. In birds the trunk vertebrae are always fused together. n Neck attaches to skull from the rear. As in dinosaurs not from below as in birds.

Archaeopteryx 2) Bird features: n Feathers. n Opposable hallux (big toe). n Pubis (hip bones) are elongated and directed backward.

Protospinax

Protospinax 1) Ray features: n Flattened body. n Primitive teeth. n Spent large amounts of time on the sea and ocean floors.

Protospinax 2) Shark Features: n 5 foot long body. n Had a detached upper jaw.

Other transitional fossils 1) 2) 3) 4) 5) 6) 7) Acanthostega Canobius Ichthyostega Karaurus Panaderichthys Trematops Vieraella And Many More…

C. Geologic time dating n The Earth is 4. 5 Billion Years Old! If the Earth’s history was just one year long then… n Each day would be about 12 million years! n First bacteria = about the middle of March. n Dinosaurs don’t show up until late November. n Humans haven’t even been around a ½ day.

How do we know the earth is that old? By using the technique of radioactive dating of different isotopes! (Example: Carbon dating)

Other radioactive isotopes Isotopes Dating Key Fission Sample Product Lutetium. Hafnium-176 Uranium. Lead-206 238 Uranium. Lead-207 235 Rubidium. Strontium-87 87 Potassium. Argon-40 40 Carbon-14 Nitrogen-14 Half-life (years) Effective Dating Range (years) 37 billion early Earth 4. 51 10 million to origin of billion Earth 0. 704 10 million to origin of billion Earth 48. 8 10 million to origin of billion Earth 1. 25 100, 000 to origin of billion Earth 5730 ± 40 0 -100, 000

D. Anatomical Trends 1. Homologous structures: structures with the same general form and originating from the same region of the embryo. 2. Vestigial structures: a structure that has been greatly reduced with no apparent function. (thought to at one time have a purpose)

1. Homologous structures

2. Vestigial structures Examples: a. Whales have a pelvis yet no feet. b. Cave salamanders have eyes although they are blind. c. Humans have a tailbone but no tail.

E. Embryological development n n Embryos of certain species develop almost identically especially in early stages. The embryos of all vertebrates (animals with backbones) have gill slits and a tails, which indicates that all vertebrates may have common ancestry.

F. Biochemical/Molecular 1) DNA and RNA are made of the same nucleotides in ALL organisms. 2) ATP is the energy molecule of all life systems.

Biochemical/Molecular 3) The metabolism of different organisms is based on the same complex biochemical compounds. 4) Certain blood proteins are found in almost every organisms. 5) The protein (cytochrome c) is essential for all organisms that perform aerobic respiration.

II. Developing the “Theory of Evolution” n Theory of Evolution is a carefully reasoned and tested hypothesis about how evolutionary change occurs.

Theories of Evolution A. Jean Baptiste de Lamarck (1809) His theory was eventually disproved but it was the first attempt to support evolution. B. Charles Darwin & Alfred Wallace (1858) Came up with an almost identical theory on evolution although each worked separately. (Basis for our current theory of evolution. )

A. Theory of Acquired Characteristics (Lamarck) Also known as “Theory of Use and Disuse” n Organisms acquired traits during their lifetime and then passed those traits to their offspring. Example: If giraffes stretched their necks to reach leaves higher on the trees, then their offspring would have longer necks.

Lamarck vs. Darwin said: n Giraffes with long necks survived and those with short necks died because they had to compete for food that was higher up in trees. Consequently, they then passed on the stretched (acquired) long-necks to n Consequently, the long neck genes were passed their offspring. on and over time the average giraffe had a longer neck. Lamarck said: n Giraffes STRETCHED their short necks to reach food. n

B. Charles Darwin n n Charles Darwin was born on February 12, 1809 in Shrewsbury, England. Contrary to popular belief, Darwin was not the first person to describe the concept of evolution, but he was the one who gave it its popularity.

Charles Darwin n Darwin set sail on the H. M. S. Beagle (1831 -1836) to survey the south seas (mainly South America and the Galapagos Islands) to collect plants and animals. On the Galapagos Islands, Darwin observed species that lived no where else in the world. These observations led Darwin to write a book in 1859 called “The Origin of the Species by Means of Natural Selection”.

Galapagos Islands

Galapagos Islands: Darwin’s Finches

Darwin’s Finches 1. All of the finches came from the same 2 parent finches. 2. The birds reproduced and some of their offspring flew to different islands. 3. Each population adapted to their unique environment. 4. Finches prefer not to fly long distances. Thus, reproductive isolation occurred. 5. Birds that lived on the same island evolved in their own unique ways leading to formation of new species of finch.

Darwin’s Finches There are 13 different species of finches on the Galapagos Islands all evolved from a single ancestor.

Each species of finch live on a different island they have adapted to that particular environment.

Consequently, each species has developed their own set of behavioral and physical differences. Example: The Galapagos finches can vary greatly. Some eat small seeds while others prefer large seeds, and some eat ticks all because of differences in their beaks.

III. Natural Selection Darwin knew nothing of genes, but what he did have were many observations and a little foresight that provided the driving force for evolution.

Darwin’s Field Observations 1. Organisms produce more offspring than can survive which creates competition.

Darwin’s Field Observations 2. Not all members of a species are exactly alike.

Darwin’s Field Observations 3. The members with the most favorable traits to their environment will survive (survivial of the fittest). 4. Survivors with the favorable traits will pass them on to their offspring.

Darwin’s Field Observations 5. In time, the most favorable traits may become adaptations for the survival of that species. 6. If the new species is different enough from its ancestors we say a new species is created

Modern Theory of Evolution n Same as what Charles Darwin and Alfred Wallace described, AND adding the new information that: “Mutations are a way of producing changes in members of a species. ”

Modern Theory of Evolution “Population isolation leads to the formation of new species because they become so different from one another that they cannot interbreed. ”

Modern Theory of Evolution “Mass and minor extinctions lead to the replacement of that species by other species that are better suited to the environment. ”

General rules about Evolution “When facing a constantly changing environment a species must get M. A. D. ” (Migrate, Adapt, or Die)

IV. Types of Evolution n Evolution is not unidirectional. Some species grow less alike, some grow more alike, and some change in response to changes in others. These are the “Patterns in Evolution”.

A. Divergent Evolution n The process where two or more related species become more and more dissimilar. Example: 1. The color of the Red Fox helps it blend in with the trees in its environment while sandy color of the Kit Fox helps it blend into the desert.

B. Convergent Evolution n Species from different evolutionary branches may come to resemble one another if they live in very similar environments. Example: 1. The Ostrich (Africa) and Emu (Australia) look alike due to the similar environments in which they live.

C. Coevolution n Evolutionary change, in which one species act as a selective force on a second species, inducing adaptations that in turn act as a selective force on the first species. Example: 1. Humming Birds have a beak relative to the length of the plants with flowers that have longer or shorter tubes.

Any Questions? n n “It is the mark of an educated mind to be able to entertain a thought without accepting it. ” – Aristotle “It is not the strongest of the species that survives, nor the most intelligent, but the most responsive to change. ” –Darwin