Presentation is loading. Please wait.

Presentation is loading. Please wait.

Evolution A population changes over time. Charles Darwin (1809- 1882)

Similar presentations

Presentation on theme: "Evolution A population changes over time. Charles Darwin (1809- 1882)"— Presentation transcript:

1 Evolution A population changes over time

2 Charles Darwin ( )

3 A. Published Origin of Species in 1859

4 - 22 years old, HMS Beagle - Voyage of 5 years

5 2. Galapagos Islands

6 B. Darwin’s Influences 1. 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

7 Kayan “giraffe” women

8 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

9 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

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

11 C. Fossils: found on Darwin’s trip. Shows earth is old – there is enough time for descent with modification to occur

12 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








20 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.

21 Only swimming marine iguana


23 Blue Footed Boobie Bblue feet and dancing to impress the female.mating ritual


25 Frigatebird- Do this to distract others and take their prey



28 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)

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


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

32 Evidence for Evolution A. Fossils B. Biogeographical C. Anatomical D. Biochemical E. Embryology F. Examples- Antibiotic

33 Fossils

34 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


36 “Lucy” 3.2 million year old hominid fossil Australopithecus afarensis Significant because skeleton shows evidence of small skull capacity like that of apes and of upright bipedal posture like humans

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

38 C. Anatomical Evidence 1. Homologous Structure: Structures that are similar because they are inherited from a common ancestor

39 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.


41 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





46 D. Biochemical 1. 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

47 E. Embryology ( Development) 1. Embryos of closely related organisms often have similar stages in development.

Download ppt "Evolution A population changes over time. Charles Darwin (1809- 1882)"

Similar presentations

Ads by Google