The Development of Evolutionary Theory Chapter 2 The Development of Evolutionary Theory

Chapter Outline A Brief History of Evolutionary Thought The Discovery of Natural Selection Natural Selection Natural Selection in Action Constraints on Nineteenth-Century Evolutionary Theory Opposition to Evolution Today

Natural Selection The most critical mechanism of evolutionary change, first articulated by Charles Darwin; refers to genetic change or changes in the frequencies of certain traits in populations due to differential reproductive success between individuals.

Fixity of Species The notion that species, once created, can never change; an idea diametrically opposed to theories of biological evolution.

Aristotle’s Worldview This beautifully illustrated seventeenth-century map shows the earth at the center of the solar system. Around it are 7 concentric circles depicting the orbits of the moon, sun, and the 5 planets that were known at the time.

Pre-scientific View In the middle ages, the predominant world was stasis, the world was fixed and unchanging. The great chain of being held that life was arranged from simplest to most complex. It was believed that the earth was “full” and nothing new could be added. The world was seen as the result of a grand design - God’s design.

Reproductively Isolated Pertaining to groups of organisms that, mainly because of genetic differences, are prevented from mating and producing offspring with members of other groups.

Binomial Nomenclature In taxonomy, the convention established by Carolus Linnaeus whereby genus and species names are used to refer to species. For example, Homo sapiens refers to human beings. Taxonomy is the branch of science concerned with the rules of classifying organisms on the basis of evolutionary relationships.

Evolution A change in the genetic structure of a population. Also refers to the appearance of a new species. Often controversial, some religious views hold that evolutionary statements run counter to biblical teachings.

Lamarck John Baptiste Lamack was the first scientist to produce an explanation for the evolutionary process. He believed that species change was influenced by environmental change.

Cuvier Georges Cuvier introduced the concept of extinction and the theory of catastrophism.

Thomas Malthus Thomas Malthus wrote about the relationship between food supply and population increase. His essay on the Principle of Population led both Darwin and Wallace to the principle of natural selection.

Charles Lyell Charles Lyell developed the theory of uniformitarianism.

Catastrophism The view that the earth’s geological landscape is the result of violent cataclysmic events. Cuvier promoted this view, especially in opposition to Lamarck.

Uniformitarianism The theory that the earth’s features are the result of long term processes that continue to operate in the present as they did in the past. Elaborated on by Lyell, this theory opposed catastrophism and contributed strongly to the concept of immense geological time.

Mary Anning Discovered the first complete fossil of Ichthyosaurus, a large fishlike marine reptile. She became known as one of the world’s leading “fossilists” and contributed to the understanding of the evolution of marine life over 200 million years ago.

Charles Darwin Charles Darwin, photographed 5 years before the publication of Origin of Species.

Question One of the world's leading "fossilists" who contributed to the understanding of the evolution of marine life over 200 million years was: Mary Anning. Lyell. John Ray. Darwin.

Answer: a One of the world's leading "fossilists" who contributed to the understanding of the evolution of marine life over 200 million years was Mary Anning.

Question The person credited with removing the earth as the center of the universe is: Buffon. Lamarck. Copernicus. Archbishop James Ussher.

Answer: c The person credited with removing the earth as the center of the universe is Copernicus.

Evolution Is a Theory The theory has been supported by a mounting body of genetic evidence. The theory has stood the test of time. The theory stands today as the most fundamental unifying force in biological science.

The Scientific Revolution Discovery of the new world challenged fundamental views about the planet. Exposure to new plants and animals increased awareness of biological diversity.

The Scientific Revolution Copernicus challenged the idea that the earth was the center of the universe. Galileo’s work supported the idea that the universe was a place of motion. Keppler, Descartes and Newton established the laws of physics, motion and gravity.

Precursors to the Theory of Evolution John Ray provided first definition of the concept of species and genus. Carolus Linnaeus developed system of classification and the basis for taxonomy. Comte de Buffon stressed the importance of change in the universe and the environment as an agent of change.

Charles Darwin (1809-1882) Ideas were formed while serving as a naturalist on the voyage of the HMS beagle. Darwin saw the importance of biological variation within a species. Recognized the importance of sexual reproduction in increasing variation. By 1844, Darwin had complete the work that he would publish fifteen years later.

The Path of the HMS Beagle

Darwin’s Galápagos Finches Beak Variation

Domestic Dog Breeds The variation exhibited by dog breeds has been achieved in a relatively short time through artificial selection.

Alfred Russell Wallace (1823-1913) A naturalist who worked in South America and Southeast Asia. Suggested species descended from other species and new species were influenced by environmental factors. Presented paper on evolution and natural selection to the Linnean Society of London jointly with Darwin.

Contrasting Views on Evolution

Contrasting Views on Evolution

Question Darwin recognized that individuals were unique. He realized that ________ could explain how selection occurred. variation strength altitude time

Answer: a Darwin realized that variation among individuals was how selection occurred, ultimately causing change in species

Processes of Natural Selection Species can produce offspring at a faster rate than food supplies increase. There is biological variation within all species. In each generation, more individuals are produced than can survive.

Processes of Natural Selection Individuals that possess favorable traits or variations are more likely to survive and produce offspring. Environmental context determines whether a trait is beneficial. Traits are inherited and passed on to the next generation.

Processes of Natural Selection Variations accumulate over long periods of time, so later generations may be distinct from ancestral ones. As populations respond to pressures over time, they may become distinct species, descended from a common ancestor.

Natural Selection in Action Variation in the peppered moth. (a) The dark form is more visible on the light, lichen-covered tree. (b) On trees darkened by pollution, the lighter form is more visible.

Question Selective forces come from: individuals. genetics. populations. the environment.

Answer: d Selective forces come from the environment.

Evolutionary Change Through Natural Selection A trait must be inherited if natural selection is to act on it. Natural selection can’t occur without population variation in inherited characteristics. Fitness is a relative measure that changes as the environment changes. Natural selection can only act on traits that affect reproduction.

Christian Fundamentalists Adherents to a movement in American Protestantism that began in the early twentieth century. This group holds that the teachings of the Bible are infallible and are to be taken literally.