Chapter 16 Darwin

Evolution Game Play the game “Who wants to live a million years” on Miss D’s wikispace If you finish before time is called, click around on the other links (Quiz, Natural Selection, or Darwin’s Bio)

With your partner… Was the game easy or hard? Explain. Was there a trick to the game? Explain. What mechanism of evolution is this game explaining? What types of forces cause evolution to occur?

Darwin’s Theory of Evolution Darwin is the father of evolution Evolution = the process of change over time, descent from common ancestors Evidence: 1. Species vary globally 2. Species vary locally 3. Species vary over time

Why study tropical areas?

Species vary Globally Rheas = flightless birds that look and act a lot like ostriches, yet rheas lived in South America Ostriches lived in Africa Emu lived in Australia Darwin noticed that different, yet ecologically similar, animal species inhabited separate, but ecologically similar, habitats around the globe.

Species vary locally Two species of Rhea’s living in South America Species = population that can breed and produce fertile offspring Different shell shapes in tortoises of Galapagos Darwin noticed that different, yet related, animal species often occupied different habitats within a local area

Species vary over time Darwin collected fossils (preserved remains of animals) Some fossils of extinct animals were similar to living species.

Ideas that Shaped Darwin’s Thinking Hutton and Lydell proved that Earth is extremely old and that the processes that changed Earth in the past are the same processes that operate in the present. Examples? Darwin - If Earth changed over time, could life too?

Lamarck’s Evolutionary Hypthesis Read p. 456 with a partner and explain why Lamarck’s ideas were not correct

Malthus’s view If human population grew unchecked, there would not be enough living space and food for everyone.

Artificial Selection Artificial selection: the selective breeding of domesticated plants and animals Shows convincing evidence that humans were playing the role of the environment in nature

Natural Selection Natural selection the basic mechanism of evolution 1. Struggle for existence 2. Variation and adaptation 3. Survival of the fittest (fitness = survival and reproduction)

Struggle for Existence Members of a population must compete for food, living space, etc.

Variation and Adaptation Some variants are better suited than others Faster, longer claws, camouflage, sharper teeth Adaptation = heritable characteristic that increases organisms ability to survive and reproduce Bowerbird display

Survival of the Fittest Differences in adaptation affect fitness (how well an organism can survive and reproduce Different in rates of survival and reproduction= survival of the fittest

Natural selection Process by which organisms with variations most suited to their local environment survive and leave offspring Similar to artificial, but nature is controlling When does it occur? More individual are born than can survive (struggle for existence) Natural heritable change (variation and adaptation) Variable fitness among individuals (survival of the fittest)

Natural Selection Myths Does not make organisms better But does enable them to pass on their genes Does not move in a fixed direction No one perfect way of doing something, ex pollination Not the only mechanism that drives evolution

Common descent According to the principal of common descent, all species – living and extinct – are descended from ancient common ancestors Evidence?

Evidence of Evolution Biogeography (distribution) The Age of Earth and Fossils Comparing Anatomy and Embryology (homologous, analogous and vestigial structures) Genetics and Molecular Biology (amino acid sequences) Lab – Evidence of Evolution