Warm-Up: page 32 How is the evolution of earth’s surface related to the evolution of living organisms? Be very specific in your answer and use vocabulary 5pts Date Session # Activity Page # 1/13-14 Principles of Evolution Stations Review 30 Evidence of Evolution 31 1/15-16 Evidence of Evolution Notes 32 Genotype vs Phenotype Quick Write 33 h/w: complete on p33 of your notebook Complete phenotype and genotype compare and contrast activity

8.L.4 Understand the evolution of organisms and landforms based on evidence, theories and processes that impact the earth over time. 8.L.4.1 Summarize the use of evidence drawn from geology, fossils, and comparative anatomy to form the basis for biological classification systems and the theory of evolution

TLW identify the evolutionary relationship between organisms by comparing and contrasting structures, DNA and embryology then summarize how evidence is used to support evolution in a quick write.

Contents, Covers and the stories they tell Part 1 Carefully examine the bone structures on Lab Sheet 1. (Note: bones are not drawn to scale.) All are forelimbs of mammals. Look for key structural features that give tell-tale clues about which mammal the bones are from. Bone Set Key Structural Features Proposed Animal Source A B C D Five separate digits or fingers; hand-like structure; long, thin upper and lower arm segments Human E

MOLE SEAL ELEPHANT OPOSSUM WOLF 7 BAT

Evidence of Evolution p.32 Comparative Anatomy Homologous structures (divergent evolution) Analogous structures (convergent evolution) Vestigial Structures Embryological Similarities Cellular/Molecular Similarities Similar DNA Similar Biochemistry Fossils

Homologous Structures Traits inherited by two different organisms from a common ancestor Similar anatomy, different function

Example of Homology: the tetrapod limb The tetrapod limb In an evolutionary tree, traits are passed from ancestor to decendent

The wing of a dragon fly and the wing of a butterfly are homologous – they were both inherited from an ancient flying insect

Not all homologous structures are obvious if they have been adapted for different roles. For example, the chomping front teeth of a beaver look quite different than the tusks of an elephant. Each is a modification of the basic incisor tooth structure

Homologous structures show that Divergent Evolution takes place Divergent Evolution creates Homologous structures: A common ancestor evolves into new species, which continue to evolve and become less and less alike over time due to differences in their environments

Brown bears and polar bears illustrate divergent evolution Brown bears and polar bears illustrate divergent evolution. Scientists think that a long time ago a group of brown bears became geographically separated from the rest. This isolated group acquired new characteristics, such as the ability to eat meat, blubber to keep warm in snowy weather, and a white coat for camouflage. They slowly evolved into polar bears.

So what about ANALOGOUS STRUCTURES?? Consider the following example….. Thylacosmilus Smilodon

Both are extinct animals and both of them have saber-teeth…but are they homologous structures? (Consider that Australia had separated from the Supercontinent a loooooong time ago)

They are Analogous structures They are Analogous structures! Similarity due to convergent evolution (evolved to the same environment) Not common ancestry CONVERGENT Evolution creates Analogous Structures: When two separate groups of animals evolve to have similar structures because they have evolved in a similar environment Similar function, different anatomy

How do analogous structures evolve? Often, two species face a similar selection pressure. Natural selection may then shape both of them in similar ways – resulting in analogous structures…...like the saber teeth.

So there you have it….. HOMOLOGY vs ANALOGY Similar due to inheritance Similar due to other factors

Apply your knowledge p32 For each of the 4 example3, write: Organisms’ names and structure we are comparing Are they homologous or analogous structures? In one sentence, explain your answer

1. Sugar Glider & Flying Squirrel “cape”

Placental reproduction Marsupial reproduction Squirrel Glider Placental reproduction Marsupial reproduction Large eyes Fur

While sugar gliders (marsupials) superficially resemble the placental flying squirrels of North America, the ability to glide through the air evolved independently in these mammals.

2. Shark and Dolphin body shape Streamlined body Triangular Dorsal Fin Skeleton made of cartilage Skeleton made of bone Use gills to get oxygen from the water in which they swim Go to the surface and breathe atmospheric air through their blowholes Don’t nurse their young Do nurse their young Don’t have hair Do have hair –they are born with hair around their “noses” Propels through water in side-to-side motion Propels through water in up and down movement

They have ANALAGOUS structures Sharks are closely related to rays, and dolphins are closely related to other mammals. Streamlined bodies and fins are traits that dolphins and sharks evolved separately, both as adaptations from swimming.

3. Leaves of oak trees and the leaves of gingko trees Oak Leaves Ginko Leaves Photosynthesis Cell walls Multi lobed shape leaf Single lobed shape leaf Large leaf surface area

4. Pointed Snout and Sharp Claws Anteater Echidna Fur Placental Mammal Egg Laying Mammal Eats from Anthills Latin & South America Australia Long, Sticky Tongue

Vestigial structures/organs Structures or organs that seem to serve no useful function. Vestigial organs are often homologous to organs that are useful in other species For example: snakes have tiny pelvic bones and limb bones eyes on cave salamanders (blind) leg bones in whales Organisms having vestigial structures probably share a common ancestry with organisms in which organisms in which the homologous structure is functional.

Hind limbs in Whales Pelvis & Hind limbs in Snakes

Embryology Similar early development Developmental similarities can be see in comparing the early embryos of many species

Embriological Evidence Similar early development Embryos are very similar Early in development

Cellular/Molecular Evidence Related organisms have similar chemical processes, chemicals and proteins. Examples: photosynthesis, hemoglobin in mammals vs hemocyanin in mollusks DNA (gene codes) Related organisms share large % of similar DNA sequences (lots of genes in common)

Fossil Evidence Preserved remains of ancient organisms….these allow us to compare anatomies and trace change….how?

Fossils provide evidence of: Other organisms that lived at the same time Progression of life Geological Events that changed the environment and changed selective pressures

Tape onto page 33

30-30-30 Turn and talk to your partner for 30 seconds…you will summarize the evidence of evolution and how we use it

Quick Write page 33 Summarize 2 types of evidence we have learned and how it is used to classify organisms and support the theory of evolution