How natural selection serves as a mechanism of

How natural selection serves as a mechanism of evolution Read page 459 in text!!!!!! AP Biology

§ Many of Darwin’s ideas came from § observing life on the Galapagos Islands § While travelling on the Beagle AP Biology

Darwin’s Principles He observed finches! AP Biology 2010 -2011

Darwin’s finches § Differences in beaks allowed some finches to… successfully compete u successfully feed u successfully reproduce u AP Biology § pass successful traits onto their offspring

In historical context § Other people’s ideas paved the path for Darwin’s thinking competition: struggle for survival population growth exceeds food supply land masses change over immeasurable time AP Biology

Peppered moth § What was the selection factor? u early 1800 s = pre-industrial England § low pollution § lichen growing on trees = light colored bark u late 1800 s = industrial England § factories = soot coated trees § killed lichen = dark colored bark u mid 1900 s = pollution controls § clean air laws § return of lichen = light colored bark u AP Biology _________________

Peppered Moths § Dark vs. light variants Year 1848 1895 1995 AP Biology % dark 5 98 19 % light 95 2 81

Voyage: 1831 -1836 November 24, 1859, Darwin published “On the Origin of Species by Means of Natural Selection” AP Biology

Essence of Darwin’s ideas § Natural selection heritable variation exists in populations u over-production of offspring u § more offspring than the environment can support u competition § for food, mates, nesting sites, escape predators u differential survival § successful traits = adaptations u AP Biology differential reproduction § adaptations become more common in population

Where does Variation come from? § Mutation u random changes to DNA § errors in mitosis & meiosis § environmental damage § Sexual reproduction u mixing of alleles § genetic recombination w new arrangements of alleles in every offspring § new combinations = new phenotypes AP Biology

La. Marckian vs. Darwinian view § La. Marck u in reaching higher vegetation giraffes stretch their necks & transmits the acquired longer neck to offspring § Darwin u AP Biology giraffes born with longer necks survive better & leave more offspring who inherit their long necks

§ Individuals do not evolve only § § populations. Only inherited traits can be passed on. The traits are selected by the environment! Note –Environments change AP Biology

Stick your neck out… Ask Questions! AP Biology