EQ:

What evidence supports the

theory of evolution?

SB5.c Explain how fossil evidence and biochemical evidence

support the theory.

KEY CONCEPT 10.4

Evidence of common ancestry among species comes

from many sources.

SOURCE #1: Fossils• Fossils in older/lower layers are more primitive/simple than

those in the newer/upper layers.

• Provided strongest evidence for the theory (before DNA

analysis)

Remember the Tortoises and Finches: similar but distinctly different from one another on Galapagos.

Also different from species on mainland of South America

Darwin decided they were descendents from a common mainland ancestor

Pinta IslandIntermediate shell

Pinta

Isabela IslandDome-shaped shell

Hood IslandSaddle-backed shellHoodFloreana

Santa Fe

Santa Cruz

James

Marchena

Fernandina

Isabela

Tower

The study of geography provides evidence of evolution.

– island species most closely resemble nearest

mainland species

– populations can show variation from one island to

another

SOURCE #3 - Embryology.

Larva

Adult barnacleAdult crab

– identical larvae = different adult body forms

– similar embryos = diverse organisms

Look the same as larva

Early stages of embryos hard to tell different organisms apart

(vertebrates especially)

Groups of cells develop in same order forming the homologous structures

Homologous Body Structures: structures with different mature form but develop from same tissues

Some organisms (especially vertebrates) have limbs constructed from same basic bones even though vary in function

Wings, legs, and Flippers all similar in structure & vary in function

ALL = Evidence for a common ancestor

Human hand Bat wingMole foot

– Homologous structures are similar in

structure but different in function.

– Homologous structures are evidence of a

common ancestor.

Turtle Alligator Bird Mammals

Typical primitive fish

Bat wingFly wing

Analogous structures are NOT evidence of a common ancestor.

– Analogous structures have a similar

function.

• Vestigial structures are remnants of organs or

structures that had a function in an early ancestor.

• Ostrich wings are examples of vestigial structures.

Vestigial Organs: structures that have reduced in size so no longer functioning.

Examples include tailbone at the end of the spine, appendix in humans, hip bones in whales, and wings on the Ostrich

Still there but do not affect organisms ability to survive & reproduce

The skeleton of a baleen whale, a representative of the

group of mammals that contains the largest living species,

contains pelvic bones. These bones resemble those of

other mammals, but are only weakly developed in the

whale and have no apparent function.

KEY CONCEPT 10.5

New technology is furthering our understanding of

evolution.

EQ:

What modern evidence supports

the theory of evolution?

Paleontology is the study of fossils or extinct organisms.

Paleontology provides evidence to support evolution.

#1 Two closely-related organisms will have similar DNA sequences.

#2 Pseudogenes are sequences providing evidence of evolution.

– no longer function

– carried along with functional DNA

– can be clues to a common ancestor

Disabled genes, molecular relics scattered

across the human landscape, have a story

of their own to tell. And it is still unfolding.

-Mark Gerstein and Deyou Zheng, (2006)

Scientific American

#3 Homeobox genes (Hox genes) indicate a very distant common ancestor.

– control the development of specific structures

– found in many organisms #4 Protein comparisons, or molecular fingerprinting reveals

similarities among cell types of different organisms. (lab tomorrow comparing protein sequences)

• Scientist from many fields contribute to the understanding

of evolution.

• The basic principles of evolution are used in many

scientific fields (such as medicine, agriculture, geology,

biochemistry, and ecology).

10.4 Evidence of Evolution

1. With your assigned partner, read the Scientific American (published Jan. 11, 2015).

2. On a separate sheet of notebook paper, list 8 tetrapod species and their adaptations that are described in the article.

3. Describe how these adaptations give these species an advantage in their environment.

4. List any scientific terms that you do not understand (excluding species names).

5. Write using complete sentences!