EARTH 7 Lecture Notes - Lecture 5: Common Descent, Genetic Drift, Mesozoic
10/12/17
● Amniotes
○ Form eggs inside a protective membrane and reproduce vio internal fertilization
●Mass extinction 250 ma
○ Boundary between paleozoic and mesozoic
● First flowering plants early cretaceous
● Second mass extinction 65 MA
○ Mesozoic from cenozoic
● Evolution and the Organization of life
● Darwin
○ Common Descent and Natural Selection
●Species: A group of viably interbreeding organisms
●Lineage: a species through time
●Divergence: when lineages split
● Jean-baptiste Lamarck
○ Evolution
■ Change of species over time
● NOT DARWIN’S IDEA
● Lamarck’s ideas on evolution were already well-known in Darwin’s
day
● Darwin
○ The origin of species by means of natural selection
● Most important ideas
1. Common Descent with modification
a. All living organisms are related, descending from a single common
ancestor
b. Diversity is the result of the bifurcation of lineages (divergence)
c. Similarity is the result of close ancestry
Document Summary
Form eggs inside a protective membrane and reproduce vio internal fertilization. Species : a group of viably interbreeding organisms. Lamarck"s ideas on evolution were already well-known in darwin"s day. The origin of species by means of natural selection. Most important ideas: common descent with modification, all living organisms are related, descending from a single common ancestor, diversity is the result of the bifurcation of lineages (divergence, similarity is the result of close ancestry. Natural selection is one (very important) mechanism explaining evolution. Sexual selection, genetic drift, historical contingency, structural and developmental processes and constraints, group selection, etc. One source of genetic variation: sexual reproduction. One source of genetic variation: changes in dna. Darwin"s very bold predictions: fossil record should include transitional forms , age of earth and life must be immense. Earth rocks/minerals, moon rocks, and meteorites all suggest that the earth and solar system formed 4. 5 billion years ago. History of humans does not = history of life.
