Charles Darwin
Charles Darwin 1937
writes down ideas on the transmutation of species in a notebook
Charles Darwin 1839
marries his first cousin, 10 children, only 7 survived childhood
Charles Darwin 1841
writes to a friend that they will work on a book titles “varieties and species”
Charles Darwin 1842
makes a pencil outline of his theory of “descent with modification”
Charles Darwin 1844
expands his sketch into an essay on the origin of species and natural selection
- Rejected scala naturae hierachy/ fixity of species
- relationship between the origin of new species and environmental adaptation
Charles Darwin 1859
published ideas about natural selection in a book titled the origin of species
- had been thinking about for a long time
Charles Darwin 1858
alfred russel wallace sends “on the tendancy of varieties to depart indefinitely from the original type” to darwin
- darwin thinks his lifes work is getting stolen
- papers by him and wallace were presented at the linnean society
alfred russel wallace
natural selection
fundamentals of natural selection
speciation
evolutionary process that results in the formation of new species
- ex. natural selection where variants accumulate in a population and groups become extinct from ancestors
geographical isolation
as groups become isolated, they adapt to different environmental contexts, responses to diverse selective pressures may result in distince species
favourable traits
traits that help a species be more likely to survive and create offspring for next generation
environmental context
determines if trait is beneficial in that environment
what happens if more offspring are produced than resources
competition
examples of natural selection
types of selection
directional, stabilizing, disruptive
directional selection
the change in a phenotype or genotype of a population in one direction away from the mean (average) in a particular environment over time
stabilizing selection
a type of natural selection that favors individuals with average or moderate phenotypes, while selecting against extremes
disruptive selection
when more extreme phenotypes (or genotypes) within a population have a fitness advantage over intermediate individuals
sexual selection
selection in relation to sexual reproduction
- traits that don’t enhance survival but enhance reproduction
misconceptions of natural selection
consequences of misconceptions of natural selection