Theories of Evolution 15.2 pp. 282-288 Acquired trait = trait not determined by genes Theory that individuals could change their physical features over time ( like a duck stretching the skin between the toes until it gets webbed feet) Then this acquired trait could be passed on to the offspring Not possible because not genetic; Lamarck didn’t know about genes What does it mean to acquire something? What are things you have acquired that you can’t pass on to children?

Theories of Evolution 15.2 pp. 282-288 Charles Darwin = 1831 sailed around the world collecting plants and animals for comparing 1858 he published On the Origin of Species by Means of Natural Selection He realized that individuals don’t change over time, populations change over time: these changes are inherited What was Darwin’s training?

Theories of Evolution 15.2 pp. 282-288 Natural Selection = organisms that are better suited to their environment will survive better This means living longer, reproducing more, leaving more genes (nature selects) Adaptation = change in time of the genetic makeup of a population to better survive in the natural environment Examples of natural selection? Can you think of examples of artificial selection?

Theories of Evolution 15.2 pp. 282-288 Fitness = a measure of how many genes an organism passes on to the next generation The more offspring you leave behind that survive and reproduce, the more fitness you have Since your offspring have your genes, they have a better chance of inheriting the traits that allowed you to survive better, so they will survive better What does “survival of the fittest”, mean?

Theories of Evolution 15.2 pp. 282-288

Theories of Evolution 15.2 pp. 282-288