EvolutionA population changes over time

Charles Darwin (1809- 1882)

A. Published Origin of Species in 1859

- 22 years old, HMS Beagle- Voyage of 5 years

2. Galapagos Islands

B. Darwin’s Influences1. Lamarck (early 1800s)

i. Believed that animals change over time- contrary to popular belief! ii. Inheritance of Acquired

Characteristics: characteristics can be gained through use and

passed on to offspring

Kayan “giraffe” women

Traits Must be Genetic to Pass On!

You cannot “ force” yourself to have a characteristics Example #1: You cannot force yourself to

be lactose tolerant Example #2: Bacteria CANNOT acquire resistance to antibiotics

Note: New traits cannot be created during your lifetime Only genes can be passed on

2. Lyell

• Previously, idea was that Earth itself is less than 10,000 years old

• Proposed that gradual and observable geologic processes such as erosion could explain the physical features of today's Earth taking place over thousands or millions of years

i. Earth 4.5 billion years old 3.5 billion years first life (single celled)

C. Fossils: found on Darwin’s trip.

Shows earth is old – there is enough time for descent with modification to occur

II. Darwin’s Finches A. Biogeography- geographic distribution of life forms

B. Galapagos Islands- Volcanic islands off the coast of South America 1. Species were slightly different than the ones on the mainland

C. Finches- different beaks depending on the food available

i. Cactus-eating finch:more point beak ii. Insect-eating finch: sharp ( trees) iii. Types of seeds D. All descended from one mainland Finch

DESCENT WITH MODIFICATION from a COMMON ANCESTOR

VIDEO: https://www.youtube.com/watch?v=flDL2ZQtK8I

• The Galápagos tortoise or Galápagos giant tortoise the largest living species of tortoise and 10th-heaviest living reptile, reaching weights of over 400 kg (880 lb) and lengths of over 1.8 meters (5.9 ft). Shell size and shape vary between populations- humidity, dryness etc.

Only swimming marine iguana

Blue Footed Boobie

Bblue feet and dancing to impress the female.mating ritual

Frigatebird- Do this to distract others and take their prey

III. Natural Selection A. Definition: mechanism for evolutionary

change

B. Components:1. Inherited variations:

Mutations- changes in DNA Meiosis

2. Struggle for existence 3. Adaptations (traits that help an organism be

more suited to the environment) increase survival and reproductive success

4. Reproduction- Genes for adaptations increase in each generation – (Fitness- reproductive success)

IV. Artificial Selection

Breeder choices which traits to perpetuate (dogs descended from wolves). Canis familiaris comes from Canis lupis domesticated 14,000 years ago.

The result of Natural Selection is a population adapted to the local environment

Evidence for Evolution

A. Fossils B. Biogeographical C. Anatomical D. Biochemical E. Embryology F. Examples- Antibiotic

Fossils

8 million years ago humans chimpanzees : dozen human-like species called hominids The modern form of Homo sapiens first appeared about 100,000 years ago. This species is distinguished by large brain size, mouth not as protruding. Begin with bipedal ancestor- skulls begin when humans began to walk on two feet

“Lucy”

3.2 million year old hominid fossilAustralopithecus afarensis

Significant because skeleton shows evidence of small skull capacity like that of apes and of upright bipedal posture like humans

B. Biogeography

A mammal of an order (Marsupialia) whose members are born incompletely developed and are typically carried and suckled

C. Anatomical Evidence1. Homologous Structure: Structures that are

similar because they are inherited from a common ancestor

C. Anatomical Evidence

2. Analogous Structures: features are similar in function but not in structure. They do not derive from a recent common ancestor but in response to a similar environment.

ANALOGOUS STRUCTURES

C. Anatomical Evidence

3. Vestigial structures: no longer have function. occur because organism inherit anatomy from their ancestors.

Examples: Some snakes have small hindlimbs Humans: Appendix, wisdom teeth, tail bone

THE APPENDIX

VESTIGIAL STRUCTURE

KOALA

EUCALYPTUS

D. Biochemical1. Living organisms use DNA, and many identical

enzymes (same 20 amino acids)

2. Degree of similarity of DNA sequence or amino acid structure based on how closely related

E. Embryology ( Development)

1. Embryos of closely related organisms often have similar stages in development.