Decent with Modification- Darwin

May 31
05:58

2012

Elle Marie Spears

Elle Marie Spears

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What Is Theoretical about the Darwinian View of Life? • In science, a theory accounts for many observations and data and attempts to explain and integrate a great variety of phenomena

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Darwin Introduces a Revolutionary Theory

•        A new era of biology began on November 24,Decent with Modification- Darwin Articles 1859, the day Charles Darwin published On the Origin of Species by Means of Natural Selection

•        The Origin of Species focused biologists’ attention on the great diversity of organisms

•        Darwin made two major points in his book:

•        Many current species are descendants of ancestral species

•        Natural selection is a mechanism for this evolutionary process

Resistance to the Idea of Evolution

•        The Origin of Species

–       Shook the deepest roots of Western culture

–       Challenged a worldview that had been prevalent for centuries

•        The Greek philosopher Aristotle viewed species as fixed and unchanging

•        The Old Testament holds that species were individually designed by God and therefore perfect

•        Carolus Linnaeus interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose

•        Linnaeus was a founder of taxonomy, the branch of biology concerned with classifying organisms

Fossils, Cuvier, and Catastrophism

•        The study of fossils helped to lay the groundwork for Darwin’s ideas

•        Fossils are remains or traces of organisms from the past, usually found in sedimentary rock, which appears in layers or strata

•        Paleontology, the study of fossils, was largely developed by French scientist Georges Cuvier

•        Cuvier advocated catastrophism, speculating that each boundary between strata represents a catastrophe

Theories of Gradualism

•        Gradualism is the idea that profound change can take place through the cumulative effect of slow but continuous processes

•        Geologists Hutton and Lyell perceived that changes in Earth’s surface can result from slow continuous actions still operating today

•        This view strongly influenced Darwin’s thinking

Lamarck’s Theory of Evolution

•        Lamarck hypothesized that species evolve through use and disuse and the inheritance of acquired traits

•        The mechanisms he proposed are unsupported by evidence

The Voyage of the Beagle

•        During his travels on the Beagle, Darwin collected specimens of South American plants and animals

•        He observed adaptations of plants and animals that inhabited many diverse environments

•        His interest in geographic distribution of species was kindled by a stop at the Galápagos Islands near the equator west of South America

Darwin’s Focus on Adaptation

•        In reassessing his observations, Darwin perceived adaptation to the environment and the origin of new species as closely related processes

•        From studies made years after Darwin’s voyage, biologists have concluded that this is indeed what happened to the Galápagos finches

Descent with Modification

•        The phrase descent with modification summarized Darwin’s perception of the unity of life

•        The phrase refers to the view 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 branches representing life’s diversity

Survival of the Fittest

•        Individuals with characteristics that are not well suited for their environment either die or leave few offspring.

•        Darwin called this natural selection

Artificial Selection

•        In artificial selection, humans have modified other species over many generations by selecting and breeding individuals with desired traits

Summary of Natural Selection

•        Natural selection is differential success in reproduction from interaction between individuals that vary in heritable traits and their environment

•        Natural selection produces an increase over time in adaptation of organisms to their environment

•        If an environment changes over time, natural selection may result in adaptation to these new conditions

What Is Theoretical about the Darwinian View of Life?

•        In science, a theory accounts for many observations and data and attempts to explain and integrate a great variety of phenomena

•        Darwin’s theory of evolution by natural selection integrates diverse areas of biological study and stimulates many new research questions