BI SC 002 Lecture Notes - Lecture 34: Natural Selection, Phenotype
Document Summary
1859: darwin publishes on the origin of species. 1906: decay rates of radioactive isotopes reveal that earth is billions of years old. 1915: morgan and sturtevant map genes onto chromosomes. 1965: mendel"s laws are rediscovered, mendel discovers basic levels of inheritance. Genetic mutations create heritable variation: this variation is the raw material upon which natural selection acts. 1) most species produce more offspring than are necessary to maintain a stable population. 2) natural resources are limited: competition. Mates: not all organisms survive long enough to reproduce. 3) individuals within a species will vary in a number of physical characteristics. 4) the variations seen among individuals are the result of different alleles in a population: these traits can be passed onto offspring. 1) adaptations enhance reproductive success: advantages in environments, some individuals will have an advantage over others. Inherent variations occur within a population of individuals. Resistance to disease: the heritable traits conferring these traits are adaptations.
