5.4 Evolution IB Biology

Evolution The cumulative change in the heritable characteristics of a population Cumulative – small changes over time (many generations) Heritable – gene-controlled factors/traits Population – not an individual Life on Earth is unified by its common origins Species can evolve New species arise from preexisting ones http://www.johnkyrk.com/evolution.html

Charles Darwin Father of Evolution The Origin of the Species, 1859 HSM Beagle Studied finches in Galapagos islands

Evidence for Evolution – TOK Link

Evidence for Evolution http://www.brainpop.com/science/ecologyandbehavior/humanevolution/

Evidence for Evolution Fossil Record Remains of extinct species provide evidence that species are continuously evolving Shows a change in species over time http://www.brainpop.com/science/ecologyandbehavior/humanevolution/

Evidence for Evolution Homologous Structures Structures that may look different and perform a different function, but have a “unity” in structure (eg. bone position) Common ancestry Look different because they have adapted to perform different functions (adaptive radiation)

Pentadactyl limb (five digits) Pentadactyl limb (five digits)

Vestigial Structures Darwin called them “rudimentary organs” Reduced structures that serve no function Lost function and are gradually being lost Appendix in humans Used to be larger sac to digest cellulose Pelvic bone in baleen whales Support upright weight Walking

Evidence for Evolution Selective Breeding Humans have selected desirable traits in domesticated animals for centuries Farmer notices a favourable trait, individual allowed to breed May also influence other characteristics Farmer notices a negative characteristic, not allowed to breed Called artificial selection Eg. Cows Jersey - milk Angus - beef

Evolution Video Great Transformations

Comparative Embryology

Homework Page 184: DBQ Page 189: Thinking about science (cover the answers on the side)

Populations Populations tend to produce more offspring than the environment can support Consequence of overproduction of offspring is a struggle to survive Think back factors that limit population growth

Variation Variation - A marked deviation from the typical form or function

Variation Crossing Over (prophase I) Random Assortment (metaphase I) Creates new combinations of alleles on a chromosome Recombination Random Assortment (metaphase I) How chromosomes line up at the equator ↑ chromosome number = ↑possibilities 2n = 223= 8, 388, 608 possibilities Random Fertilization Any sperm cell can randomly fertilize the egg cell Faster swimmer!!

Evolution in response to environmental change Antibiotic Resistance in Bacteria Environmental change: methycillin antibiotic (drug)

Antibiotic resistance in bacteria Methycillin

Antibiotic resistance in bacteria Methycillin resistant Methycillin susceptible

Antibiotic resistance in bacteria Take your prescription until the very end!!!

Worms Activity

Evolution in response to environmental change Peppered Moth (Biston betularia) Environmental change: soot from pollution, industry typica stood out Predation Population declines carbonaria camoflauged Little predation Survive to pass on trait and population increases Reversing because of clean air acts http://www.techapps.net/interactives/pepperMoths.swf

Evolution in response to environmental change Galapagos finches Darwin visited Galapagos islands in 1853 Observed the size and shape of beaks many species of finches Finches on each island had different selection pressures, and over the years had adapted to suit own island – own species Common ancestry Environmental change: Food supply http://www.sepa.duq.edu/finches.html http://www.brainpop.com/science/ecologyandbehavior/naturalselection/

Natural Selection Variation produces different traits give an advantage or disadvantage Inherited characteristics affect the likelihood of an organisms survival and reproduction Traits that give an advantage are passed on to the next generation adaptations Over time, the proportion of the population with the advantageous trait will increase (and those with a disadvantage will decrease) “Survival of the fittest”

Evolution Video Evolution: Evolutionary Arms Race Fill in questions on Handout

Opposing Viewpoints Published in The Economist, 2009 Friends: http://www.youtube.com/watch?v=cXr2kF0zEgI

HW: IB Questions Explain evolution of a species by natural selection in response to evolutionary change (8 min) Explain two examples of evolution in response to environmental change (9 min) Optional: Evolution extra credit assignment Read the Survival of the Sneakiest comic on Edline. Explain it in one paragraph using ecology vocabulary