This lecture begins with a history of the theory of evolution, from Aristotle to Lamarck and Darwin. Natural selection is one mechanism that can increase the frequency of beneficial alleles in a population. Essentially, genetic variations that increase survival and the production of offspring will be passed on. Genetic variation arises from mutations, independent assortment, crossing over, and random fertilization. There are three types of natural selection: stabilizing selection, directional selection, and disruptive selection. Sexual selection can influence the traits that increase an individuals chance of mating. Evidence for evolution can be found in paleontology and biogeography, as well as comparative anatomy. Comparative anatomy examines homologous structures which look similar but have different functions and analogous structures which have the same function but a different structure to find common ancestry.
While studying species during
his voyage on the HMS Beagle, Darwin observed that:
Individuals within a population
vary in the traits that they possess.
Species produce more offspring
than can be supported by the environment and the offspring must
compete for survival.
Offspring inherit traits from
Darwin concluded that the
offspring who possess favorable traits will have a higher
probability of surviving and producing more offspring. Over many
generations, these favorable traits will increase in the population.
Stabilizing selection selects
for intermediate phenotypes and decreases the frequency of extreme
Directional selection results
in an increase in the frequency of a phenotype at one extreme of a
Disruptive selection results in
an increase in the frequency of phenotypes at both extremes.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
The book and CD package include two full length practice exams that are presented with all questions answered and explained. The author also presents detailed reviews of all test topics and includes multiple-choice and free-response questions with answers at the end of each topic's chapter.
This book includes a review of the AP Biology exam format and scoring, proven strategies for answering multiple-choice questions, and hints for tackling the essay questions. The practice tests include answers and explanations and there is also proven test-taking strategies for both the multiple choice and essay parts.