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Catalyst:Which of the choices below is an appropriate representation of commensalism?+/+c. -/-+/-d. +/0
How were the activities yesterday connected to evolution?
What is the difference between microevolution and macroevolution?
Evolution: A Darwinian View of Life
Overview: Darwin Introduces a Revolutionary Theory
A new era of biology began on November 24, 1859The day Charles Darwin published: On the Origin of Species by Means of Natural Selection
The Origin of SpeciesFocused biologists attention on the great diversity of organisms
Darwin made two major points in his book
He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral speciesHe proposed a mechanism for the evolutionary process, natural selection
The Origin of Species
Shook the deepest roots of Western culture
Challenged a worldview that had been prevalent for centuries
Darwin: from childhood to publicationAs a boy and into adulthood, Charles DarwinHad a consuming interest in nature
Soon after Darwin received his B.A. degreeHe was accepted on board the HMS Beagle, which was about to embark on a voyage around the world
Darwins interest in the geographic distribution of species was kindled by the Beagles stop at the Galpagos Islands near the equator west of South America
As Darwin reassessed all that he had observed during the voyage of the Beagle
He began to perceive adaptation to the environment and the origin of new species as closely related processes
Darwin developed two main ideas:
1. Evolution explains lifes unity and diversity
2. Natural selection is a cause of adaptive evolution
The phrase descent with modification
Summarized Darwins perception of the unity of life
States that all organisms are related through descent from an ancestor that lived in the remote past
In the Darwinian view, the history of life is like a tree
With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms
Observation #1: For any species, population sizes would increase exponentially if all individuals that are born reproduced successfully
Observation #2: Nonetheless, populations tend to be stable in sizeExcept for seasonal fluctuations
Observation #3: Resources are limited
Inference #1: Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving
Observation #4: Members of a population vary extensively in their characteristicsNo two individuals are exactly alike
Observation #5: Much of this variation is inheritable
Inference #2: Survival depends in part on inherited traitsIndividuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals
Inference #3: This unequal ability of individuals to survive and reproduceWill lead to a gradual change in a population, with favorable characteristics accumulating over generations
Natural selection can produce an increase over time in the adaptation of organisms to their environment
Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits, this is called artificial selection