S&T: 3 pg. 310 give examples of types of evidence that Darwin gathered to develop the theory of evolution;

1. Structural similarities among organisms.2. Geographic distribution of organisms.3. The embryological similarities among organisms.4. The pattern of organism groupings.5. The direct observation of evolutionary changes in

the laboratory and in the wild.6. The molecular similarities among organisms- were

found after Darwin (more to come ).7.Transitional species found in fossil record.-bonus

Evidence for Evolution

Key Idea

• Evidence for evolution comes from many sources.

1. Fossils2. Vestigial structures3. Biogeography4. Homologous structures5. Embryology6. DNA/protein sequences

Fossils• Fossils provide evidence of

evolution.• Fossils in older layers are

more primitive than those in the upper layers.

• Extinct Fossils resemble modern animals. This shows a common ancestry.

Dating Fossils

– Relative dating estimates the time during which an organism lived.

– It compares the placementof fossils in layers of rock.

– Scientists infer the order inwhich species existed.

Transitional species found in fossil record – fish-amphibian (Tiktaalik)

• 375 million years old• Discovered in

Canada in 2004

Transitional fossil: bird/reptileArchaeopteryx

150 million yrs old.7 specimens found

Fossil Evidence for Whale Evolution

Whale Video

2. Vestigial Structures• Vestigial structures are remnants of

organs or structures that had a function in an early ancestor.

• Examples include ostrich wings, human appendix, and wisdom teeth, whale and snake pelvis/hind legs.

Pythons have tiny femurs (leg bone)

3. BiogeographyBiogeography: the study of past and present distribution of species.• 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

4. Homologous Structures• Homologous structures- Similar anatomical

features that originated in a shared ancestor.• Homologous structures are similar in structure

but may be different in function.

Homologous Structures vs. Analogous Structures

• Analogous structures have a similar function.• Analogous structures are not evidence of a common

ancestor.

Human hand

Bat wing

Mole foot

Fly wing

Analogous Structures look similar on the outside same function different structure & development on the inside different origin no evolutionary relationship

Solving a similar problem with a similar solution

Homologies: at the cellular levelReview from IS 1: What cellular structures are

shared by all eukaryotic organisms?

5. Embryology• Embryology- studying the early stages of

development of an organism (inside the womb or inside the egg)

all vertebrate embryos have a “gill pouch” at one stage of development all vertebrate embryos have a “gill pouch” at one stage of development

Hox genes control body development in many organisms. They help control head to tail organization.

6. DNA/Protein Sequences

• Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences.

• This also gives evidence of a common ancestor.

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

Comparing DNA & protein structure everyone uses the same genetic code!

DNA

compare common genes compare common proteins

compare common genes compare common proteins

number of amino acids different from human hemoglobinnumber of amino acids different from human hemoglobin

DNA (cont)

• DNA code itself is a homology that links all life on Earth to a common ancestor.

• In some cases, if we were to transfer genetic material from the cell of one living thing to the cell of another, the recipient would follow the new instructions as if they were its own.

• Useful in genetic engineering

GFP traditionally refers to the protein first isolated from a gene found in the jellyfish

Aequorea victoria which glows in the dark.

• This gene can be transferred to other organisms which will express this same trait

GloFish, the first genetically modified animal to be sold as a pet

Building “family” trees - PhylogeniesClosely related species are branches on the tree — coming from a common ancestorClosely related species are branches on the tree — coming from a common ancestor

Cladograms

• diagram that depicts evolutionary relationships among groups.

• based on PHYLOGENY, which is the study of evolutionary relationships.

• Uses traits/characteristics that are common between organisms to organize them

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=alEDLH8Z3HHLFM&tbnid=1jCpfkxHmTyrNM:&ved=0CAUQjRw&url=http://357163546355864778.weebly.com/process.html&ei=AAClUd2AF-aniQKjmoCgAg&bvm=bv.47008514,d.cGE&psig=AFQjCNHB5VEsYejs3x4d2y7ZtqLQqI2KJA&ust=1369854322696125

You try: Match each point on the cladogram with the trait.

1. ______ Wings2. ______ 6 Legs3. ___ Segmented Body4. ___ Double set of wings5. ____ Jumping Legs6. __ Crushing mouthparts7. ____ Legs8. ______ Curly Antennae

Phylogenetic trees• Very similar to a cladogram• Tends to use genetic information and physical

traits to construct• Root of the tree represents the ancestral

lineage, and the tips of the branches represent the descendants of that ancestor.

• As you move from the root to the tips, you are moving forward in time.

Speciation

• Species: a group of organisms that can interbreed in nature

• Speciation: When two groups of organisms can no longer interbreed – they have become too different through evolution

• When a lineage splits (speciation – forming a new species), it is represented as branching on a phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or more daughter lineages.

• Phylogenies trace patterns of shared ancestry between lineages. Each lineage has a part of its history that is unique to it alone and parts that are shared with other lineages.

• Each lineage also has ancestors that are unique to that lineage and ancestors that are shared with other lineages — common ancestors

• Nodes represent common ancestors