Chapter 4: Organization of Life 4.2 Evolution

Evidence of Evolution Comparative Anatomy –Atavisms A recurrence of a trait from ancestral origin –Small tail in human babies –Legs in snakes –Homologous Structures A body part with similar structure and origin –Forelimbs in mammals –Vestigial Structures A body part that has lost all or most of its function –Hind legs in whales –Appendix/wisdom teeth in humans

Evidence of Evolution Physiology/Biochemistry –DNA sequences are similar Chimpanzees: 1.2% difference Gorillas: 1.6% difference –Embryonic development begins nearly identical across classes of vertebrates Distribution –Common animals found on different continents Monkeys: S & Central America/Africa/Asia Observation –Experimentation and artificial selection

Natural Selection Proposed by Darwin in the Origin of Species Sequence of Ideas: –1. Overpopulation 1-4 Polar Bear Cubs; Average: 2 –2. Competition Arctic is cold and void of food/water –3. Survival of the Fittest 43% Survival rate in Beaufort Sea –4. Reproduction Survivors reproduce –5. Speciation Further reproduction promotes “fit” organisms

Adaptations An anatomical, physiological, or behavioral change that improves the ability to survive –Anatomical Physical features of an organism –Size, Color, Jaw structure –Physiological Specialized body functions –Digestion, Reproduction, Venom –Behavioral Inherited or learned actions –Migration, Mating, Predator Fear –Many adaptations are interconnected

Convergent Evolution –Organisms of uncommon ancestry develop similar traits Wings: Birds, mammals, fish, insects Fins: Fish and mammals Long, sticky tongues: Anteaters, pangolins, armadillos. Echolocation: bats and whales Divergent Evolution –Organisms of common ancestry develop different traits Darwin’s Finches

Coevolution –Change in the genetics of one organism in response to another Flowers and Pollinators –Hummingbirds & Flowers »Curved beak ideal for corolla »Vision is centered on red –Long-nosed Bats and Saguaros Evolutionary arms race –Predator vs. Prey Speed –Venom vs. Anti-venom

Artificial Selection Selective breeding of organisms by humans for specific desirable characteristics –Domestic dogs are descendents of wolves –Broccoli, Brussels Sprouts, Cauliflower, Cabbage are all engineered from wild mustard seed –All modern corn is genetically engineered –All wheat/grains are genetically engineered

Resistance Ability of an organism to tolerate a chemical or disease- causing agent –Studies indicate bacteria are becoming more resistant to antibiotics over time MRSA –Highly resistant “Staph” infection Strep is becoming more resistant over time –Responsible for Pneumonia and Meningitis –Studies indicate that insects are becoming more resistant to pesticides over time House Flies are becoming resistant to DDT DDT is also becoming limited in malaria prevention English Rats can consume 5x rat poison of US rats before showing signs of fatality Potato Beetle is immune to >52 insecticides

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