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20 Cards in this Set

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  • Back
natural selection
population of organisms can change over the generations if individuals having certain heritable traits leave more offspring than other individuals
evolutionary adaptation
-result of natural selection
-a population's increase in the frequency of traits that are suited to the environment
evolution
-genetic composition of the population has changed over time (descent with modification)
-genetic changes in populations over time
fossils
imprints or remains of organisms that lived in the past
Jean-Baptiste de Lamarck
proposed that acquired characteristics are inherited

--proved wrong, but helped set stage for Darwin by proposing that species evolve as a result of interactions between organisms and their environments
Major points of darwin's theory
1. organisms display variations
2. many are heritable variations
3. more offspring produced than survive to reproduce (struggle for existence)
4. Survivors have variations favored by the environment (adaptations)
5. Survivors will leave more offspring with those adaptations (natural selection)
6. Adaptations will accumulate over time (descent with modification)
fossil record
ordered sequence of fossils as they appear in the rock layers, marking the passing of geologic time
prokaryotes
oldest known fossils from about 3.5 bya.
--ancestors of all life
eukaryotic organisms
fossils in younger layers of rock
general beliefs/views about natural world in 18th century
1. a young earth
2. catastrophism
3. special creation
4. immutability of species
biogeography
today's organisms evolved from ancestral forms

--closely related species found in some places (marsupials in australia)
comparative anatomy
comparison of body structures between different species
homologous structures
common structures modified for different functions in different species
homology
anatomical similarity due to common ancestry
transitional forms
species with primitive traits indicating ancestry
vestigial organs
remnants of structures that served important functions in the organism's ancestors

--structures that are nonfunctional in some species but functional in others
comparative embryology
comparison of anatomical structures that appear during the early stages of development of different organisms
molecular biology
provided strong evidence that all life forms are related through branching evolution from earliest organisms.

--all forms of life use DNA and RNA
--genetic code (how RNA triplets are translated into amino acids) is universal
important point to darwin's theory
evolution is the process

natural selection is the mechanism
modern synthetic theory
1. integration of Darwin's theory with Mendelian genetics
2. natural selection is the primary mechanism of evolution
3. other mechanisms also cause evolutionary change: mutation, gene flow, genetic drift