EVOLUTION Accumulation of inherited changes within a population over time

2 types of evolution Microevolution Macroevolution

Pre-Darwinian Ideas Darwin was not 1 st to propose theory of evolution Aristotle (4 th century BC) ◦ Life extended from simple to complex ◦ Imperfect but moving toward perfection ◦ No mechanism for HOW

Jean Baptiste de Lamarck ( ) ◦ 1 st to propose that organisms undergo change over time as a result of natural phenomena ◦ Use and disuse ◦ Theory of acquired characteristics ◦ LAMARCK WAS WRONG IN MECHANISM

Influences on Darwin Charles Lyell and James Hutton ◦ Earth much older than people thought

Voyage of the Beagle – 1831

Thomas Malthus Breeders - artificial selection

Darwin’s Theory of Evolution by Natural Selection In struggle for survival, favorable traits preserved, unfavorable ones eliminated ◦A◦A daptation Natural Selection – best adapted organisms survive and pass on their traits, population changes over time ◦F◦F itness

4 aspects of natural world on which Darwin based his theory: Overproduction Variation Limits on population growth Differential reproductive success

What Natural Selection is NOT: Natural Selection is not a CHOICE Natural Selection is NOT BASED ON NEED Natural Selection is not a MUST

Modern Synthesis Mendel’s work (1860s) not recognized until 20 th century 1930s-40s – biologists combined Mendelian inheritance with Darwinian Evolution ◦ Mutations are source of variation ◦ Continue to try to understand causal processes of evolution

Some new perspectives on Evolution… EvoDevo Epigenetics

What is the role of chance?? Chance is probably not much of a factor in natural selection Some scientists think chance plays a more significant role in macroevolution