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Chapter 13 Biology

Darwin's main ideas can be traced back to...
Aristotle and early Judeo-Christian culture believed...
that species were fixed and designed by a creator, but there were exceptions
Charles Darwin observed here:
Galapagos Islands
Two main features of Darwin's theory of evolution:
1. diverse forms of life have arisen by descent with modification
2. natural selection
Darwin observed that organisms:
- vary in many characteristics that can be inherited
- produce more offspring than the environment can support
Evolution by Natural Selection:
1. Individuals don't evolve, populations evolve from generation to generation
2. Natural selection can amplify or diminish certain heritable traits
3. Evolution is not goal-directed
groups of individuals of the same species living in a defined area
a group of populations whose individuals can interbreed and produce fertile offspring
Artificial Selection
humans change a species over time
Examples of Natural Selection:
camouflage; development of pesticide resistance
Key Points About Natural Selection:
1. more of an editing process than a creative mechanism
2. contingent on time and place
3. significant evolutionary change can occur in a short amount of time
Evidence Supporting Evolution:
fossils, the fossil record, intermediate forms, birds, comparative anatomy, evolutionary trees
Fossil Record
an ordered array in which fossils appear within layers of sedimentary rock
Intermediate Forms
the missing links
Birds are...
living dinosaurs
Homologous Structures
features that often have different structures but are structurally similar because of common ancestry
Comparative Embryology
as developing embryos, many vertebrates have common structures
the geographic distribution of species suggest that organisms evolve from common ancestors
Molecular Biology
comparisons of DNA and amino acid sequences between different organisms reveal evolutionary relationships
the ultimate source of genetic variation that serves as raw material for evolution
Sexual Recombination
causes genetic variation that makes adaptation possible
if two or more morphs in a population are present in noticeable numbers
Natural Selection
occurs when individuals with certain traits are more likely to survive and reproduce compared to individuals with other traits
Genetic Drift
the change in the gene pool of a population due to a chance event
Gene Flow
the transfer of alleles from one population to another, as a result of movement of individuals or their gametes
Endangered species often have...
reduced variation
Natural selection can alter variation in a population in three ways..
1. stabilizing selection
2. directional selection
3. disruptive selection
Sexual Selection
differential reproductive success owing to variation in the ability to obtain mates
Sexual Dimorphism
males and females of many species are physically different; result of competition for mating partners