Evidence of Change & How Change Occurs Evolution: Evidence of Change & How Change Occurs

Evolution - Change over time - Process where modern organisms have descended from ancestors with modifications

Early Evolutionary Ideas 1. Lamarck - among the first to explain how organisms change over time - later disproved

Lamarck - relied on 2 assumptions: 1. Use and disuse 2. Inheritance of acquired traits - both later disproved

2. Charles Darwin (1809-1882) - developed the theory of evolution by natural selection

- traveled around the world as a naturalist (1831-1836)

Galapagos wildlife

Darwin’s Finches & their food Small seeds Large seeds Insects Leaves

Evolution by Natural Selection - Natural Selection is the result of 3 natural processes:

Variation in Human Height 1. Natural Variation: - all organisms produced sexually are genetically different due to gene recombination and mutations Variation in Human Height

2. Adaptation This natural variation or mutation may be an adaptation that helps them outcompete others to survive and reproduce.

Male caribou competing for mates. Gazelles struggling to reach food. 2. Competition - resources (food, space, water) - mates - constant struggle for existence - winners reproduce Male caribou competing for mates. Gazelles struggling to reach food.

.Natural Selection or survival of the fittest - Those best suited will survive longer and reproduce. - Those not suited will not survive or reproduce as often.

3. Heredity - Those that survive will pass on the very traits that helped it survive.

Woodpecker

Artificial Selection - similar to natural selection - domestic crops and animals vary a lot

Artificial Selection

Artificial Selection - only the best animals or plants are allowed to produce offspring

Artificial Selection

Recent Examples of Evolution

1. Peppered Moths a. Before industrial revolution, most moths were grayish and well camouflaged.

b. During the industrial revolution, soot stained the bark black. - Rarer dark moths were then better camouflaged.

- The more common light moths were easily seen and eaten. c. Dark moths had greater fitness and became more common.

2. Resistant Diseases & Pests a. Increased resistance to antibiotic by bacteria b. Insects have become more resistant to pesticides

Resistant Pests

C. Speciation - development of one species from another species

C. Speciation Kaibab Squirrel Abert Squirrel

1. Process of Speciation a. Separation of original population by a geographic barrier b. Changed environment c. Gene pool changes d. Reproductive isolation - two populations can no longer interbreed e. New species arises

Speciation Single species; Same habitat Geographical barrier; isolated populations (c) Genetic drift; tan vs white mice (d) Barrier removed; mix but don’t interbreed

2. Divergent Evolution (Adaptive Radiation) - ancestral population evolves into several different species

Hawaiian Honeycreepers 2. Adaptive Radiation Hawaiian Honeycreepers

2. Adaptive Radiation

3. Convergent Evolution - different organisms evolve similar adaptations to survive in similar niches - develop analogous structures (similar function with different underlying anatomy)

3. Convergent Evolution

3. Convergent Evolution European Hare (lagamorph)) Patagonian “Hare” (rodent) Banded Wallaby (marsupial)

3. Convergent Evolution Tasmanian “Wolf” Coyote

Placentals Marsupials Tasmanian “Wolf” Wolf Ocelot Quoll Numbat Anteater Flying Squirrel Flying Phalanger Marmot Wombat

3. Convergent Evolution American Cactus African Euphorb

D. Evolutionary Theory Evolves 1. Genetic Drift - random changes in allele frequency produce new traits

D. Evolutionary Theory Evolves 1. Genetic Drift Masai Giraffe Rothschild Giraffe Reticulated Giraffe

D. Evolutionary Theory Evolves 2. Unchanged Gene Pools - "living fossils": sharks, horseshoe crabs, coelacanth Coelacanth Horseshoe Crab Chambered Nautilus

3. Gradualism: 4. Punctuated Equilibrium - slow change over time - periods of little change, followed by abrupt change

Gradualism Punctuated Equilibrium