Warm Up Contrast homologous and analogous characteristics.

What is fitness?

Darwin on the HMS Beagle Evolution  His job was to collect biological and geological specimens during the ship’s travel.  The Galápagos Islands Darwins Theory of Natural Selection

Evolution  Darwin began to collect mockingbirds, finches, and other animals.  He noticed that the different islands seemed to have their own, slightly different varieties of animals.

 Almost every specimen that Darwin had collected on the islands was new to European scientists. Evolution  Populations from the mainland changed after reaching the Galápagos.

Evolution  Darwin hypothesized that new species could appear gradually through small changes in ancestral species. evolution/videos/darwin-evolution-natgeo

There is variation in traits. There is differential reproduction. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. There is heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis. End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown.

Natural Selection Evolution  Individuals in a population show variations.

Natural Selection  Variations can be inherited.

 Organisms have more offspring than can survive on available resources.

 Variations that increase reproductive success will have a greater chance of being passed on.  Traits with higher fitness will be passed on. hill.com/sites/ /student_view0/unit4/chapter1 5/concepts_in_motion.html# More Brown Beatles Survive More Brown Offspring

Evolution Chapter 15 hill.com/sites/ /student_view0/unit4/ch apter15/concepts_in_motion.html#

 Darwin’s theory of natural selection is a means of explaining how evolution works. The Origin of Species Evolution  Darwin published On the Origin of Species by Means of Natural Selection in 1859.

A. Individuals show variations. B. Variations can be inherited. Which is not a principle of Darwin’s theory about the origin of species? Evolution D. Offspring always inherit the best traits. C. Organisms have more offspring than available resources will support. Chapter 15 Chapter Diagnostic Questions

D. Natural selection explains how evolution works. A. They mean the same thing. B. Evolution works against natural selection. What is the relationship between the terms natural selection and evolution? Evolution Chapter Formative Questions C. Evolution explains how natural selection works.

A. mutations B. natural selection C. nonrandom mating D. small population size Which of these conditions can act on phenotypes to provide adaptive advantages to a population? Evolution Chapter Formative Questions

Closing Quiz How could natural selection cause changes in organisms.