Evolution view.php?id=5741
Intro to Evolution Essential Questions 1.What is evolution? 2.Isn’t evolution just a theory that remains unproven? 3.Who is Charles Darwin? 4.What is natural selection and how does it work? 5.What are the requirements for natural selection? 6.What is an adaptation?
Evolution: the gradual change in a species through adaptations over time -All living species are the modified descendants of earlier species -All modern species share a common ancestor in the distant past
-Evolution explains why there is so much diversity among Earth’s 5 million living species -“Nothing in biology makes sense except in the light of evolution.” - Theodosius Dobzhansky, evolutionary biologist -Evolution ties together the facts generated by the fields of geology, paleontology, biology, biochemistry, and more.
Charles Darwin: -English scientist -Originally published the theory of evolution (1859) -Gathered evidence in the Galapagos Islands
Alfred Russell Wallace: -English scientist -Independently conceived the same idea as Darwin -Gathered evidence in the Malay Archipelago
Scientists of Evolution: Not just Darwin! Greek philosophers Anaximander, Empedocles, and Aristotle John Ray (England 1627) Carl Linnaeus (Sweeden 1707) Pierre Louis Maupertuis (France 1698) Georges-Louis Buffon (France 1707) Jean-Baptiste Lamarck (1744) William Paley (England 1743) Charles Darwin (England 1809) Alfred Russell Wallace (England 1823) Thomas Henry Huxley (England 1825) Gregor Mendel (Germany 1822) Hugo de Vries (Dutch 1848) Ronald Fisher (England 1890) Theodosius Dobzhansky (Ukraine 1900) Now, evolutionary research is being carried out in most major American colleges and universities!
Evolution is not just a “theory”- it’s a scientific theory Scientific theory: a rigorously tested explanation for an observation that has never been proven wrong As science advances, data from a range of scientific disciplines (geology, physics, chemistry, molecular biology) have not only supported evolutionary theory, but expanded it Theory of evolution = theory of gravity
What is evolution? Evolution is the biological model for the history of life on earth Small modifications occur within the DNA of each generation; these genetic changes can affect how the creature interacts with its environment Over time, the accumulation of these genetic changes can alter the characteristics of the whole population, creating a new species
Natural selection: the mechanism by which evolution takes place
Natural selection is the idea that those organisms who are more fit to survive in their environment will pass on their genes to future generations
Natural selection: the mechanism by which evolution takes place Natural selection is the idea that those organisms who are more fit to survive in their environment will pass on their genes to future generations Over time, the population will begin to resemble the organisms that are more fit
Similarly, harmful traits are quickly eradicated as individuals that possess them are less likely to reproduce.
Natural selection works to create a population that is highly suited to its environment and can adapt over time to environmental changes.
Requirements for Natural Selection 1.Variation within one trait in a population These variations may involve body size, hair color, facial markings, voice properties, or number of offspring.
Requirements for Natural Selection 2. The trait must be heritable, not created by environmental conditions Heritable Not Heritable
Requirements for Natural Selection 3. The population must have a high growth rate so that traits will be passed on frequently enough
Requirements for Natural Selection 4. The trait must affect how an organism can or cannot compete for resources. Individuals possessing traits well suited for the struggle for local resources will contribute more offspring to the next generation.
Requirements for Natural Selection In order for natural selection to operate on a trait, the trait must: 1. Possess variation 2. Be heritable 3. Create an advantage in the competition for resources. If one of these requirements does not occur, then the trait does not experience natural selection.
Adaptation: a trait that gives an organism an advantage when it comes to surviving and reproducing
Intro to Evolution Essential Questions 1.What is evolution? 2.Isn’t evolution just a theory that remains unproven? 3.Who is Charles Darwin? 4.What is natural selection and how does it work? 5.What are the requirements for natural selection? 6.What is an adaptation?
2. Isn't evolution just a theory that remains unproven? -In science, a theory is a rigorously tested statement of general principles that explains observable and recorded aspects of the world. A scientific theory therefore describes a higher level of understanding that ties "facts" together. A scientific theory stands until proven wrong -- it is never proven correct. -The Darwinian theory of evolution has withstood the test of time and thousands of scientific experiments; nothing has disproved it since Darwin first proposed it more than 150 years ago. Indeed, many scientific advances, in a range of scientific disciplines including physics, geology, chemistry, and molecular biology, have supported, refined, and expanded evolutionary theory far beyond anything Darwin could have imagined.