Chapter 8 Review

What is the difference between a homologous structure and analogous structure?

Homologous Structure - A physical characteristic in different organisms that is similar because it was inherited from a common ancestor. Analogous Structure - developed from different original structures.

How does migration promote evolutionary change?

May change allele frequencies. The movement of some individuals of a species from one population to another

What are the four mechanisms of evolution and how does each one work?

Mutation, Genetic Drift, Migration, and Natural Selection Mutation: An alteration of the base pair sequence of an individual's DNA. Mutations that are found in GAMETES are the only ones that are passed on to the next generation. Genetic Drift: Random change in allele frequencies in a population due to chance alone. Ex. would be dimple in chin. Unrelated to the alleles' influence on reproductive success. Migration: leads to a change in allele frequencies in a population as individuals move into or out of the population. Natural Selection: is a mechanism of evolution that occurs when there is heritable variation for a trait and individuals with one version of the trait have greater reproductive success than do individuals with a different version of the trait. In order for natural selection to occur, three conditions must be met: •There must be variation for the particular trait within a population. •The variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring). •Individuals with one version of the trait must produce more offspring than those with a different version of the trait.

What is the Hardy-Weinberg equation used for? What does each variable stand for?

Predicts how common each genotype in the population will be. p2=frequency of homozygous dominant AA q2=frequency of homozygous recessive aa 2pq=frequency of heterozygotes Aa p2 + 2pq +q2 = 1

Which mutations are inherited? The ones in somatic cells or reproductive cells?

Reproductive cells

Be sure you know the general information on Darwin's voyage and the Galapagos Islands.

Voyage was a 5 year round the world survey on the HMS Beagle. At each stop the boat made, Darwin would investigate the new worlds. In Brazil, he loved the tropical forests. In Patagonia, near the southern most part of South America, he explored beaches, and cliffs, finding spectacular fossils from huge extinct mammals. He also explored coral reefs and barnacles. Darwin only brought one book with him which was Lyell's Principles of Geology.

Fixation

the point at which the frequency of an allele in a population is 100% and, therefore, there is no more variation in the population for this gene

What are the 3 potential outcomes of natural selection?

•Directional Selection - natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals. •Stabilizing Selection - occurs when individuals with intermediate phenotypes are the most fit. •Disruptive Selection - individuals with extreme phenotypes have the highest fitness.

What is fitness?

•Fitness is reproductive success. •How many offspring you produce compared to others. •Your contribution to the gene pool of next generation. •How many of your offspring survive and reproduce. •Depends on the demands of a stable or changing environment.

What conditions must be met for a population to be at equilibrium?

•No natural selection. •No mutations. •No migration. •No genetic drift. •Random mating.

What 3 conditions of natural selection must be satisfied for evolution to occur?

•There must be variation for the particular trait within a population. •The variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring). •Individuals with one version of the trait must produce more offspring than those with a different version of the trait.

What are the five primary lines of evidence for natural selection?

1.The fossil record - physical evidence of organisms that lived in the past. 2.Biography - patterns in the geographic distribution of living organisms. 3.Comparative anatomy and embryology - growth, development, and body structures of major groups of organisms. 4.Molecular Biology - the examination of life at the level of individual molecules. 5.Laboratory and field experiments - implementation of the scientific method to observe and study evolutionary mechanisms.

Founder Effect

A new population with dominating features > A small number of individuals may leave a population and become the founding members of a new, isolated population. > The founders may have different allele frequencies than the original source population, particularly if they are a small sample .

Who was the other naturalist who came up with the same ideas as Darwin?

Alfred Russel Wallace

Be sure to know Darwin's education and influences. Why did he come up with the ideas about natural selection and what made him write the Origin of Species?

At the age of 16 he attended the University of Edinburgh, pursued medical studies. He then studied Theology at Cambridge University where he met Professor Henslow who taught botany. His real love was the study of nature. Henslow is the person who gave the recommendation for Darwin to get on the HMS beagle and sail around the world.

What were the major ideas of evolution and species before Darwin?

Before Darwin, most people believed that all species had been created separately and were unchanging. • Georges Buffon - suggested that the earth was much older than previously believed. • Georges Cuvier - documented fossil discoveries which showed that extinction had occurred. • Jean-Baptiste Lamarck - suggested that living species might change over time. Proposed evolution by acquired characteristics. Traits acquired during lifetime passed down to offspring. Example: Giraffe. • Charles Lyell - argued that geological forces had gradually shaped the earth and continue to do so. 1830 book: Principles of Geology. Played a large factor in how Darwin thought.

8. How did beliefs change after the Origin of Species?

Before: -Organisms were all put on earth at the same time a creator. -Organisms are fixed, no additions or subtractions. -Earth is about 6,000 years old. -Earth is mostly unchanging. After: -Organisms change over time. -Some organims have become extinct. -Earth is more than 6,000 years old. -The geology of earth is not constant but always changing,

What is natural selection?

Certain individuals in a population are born with characteristics that enable them to survive better. They can reproduce more than offspring of other individuals in the population.

What did Darwin observe on his voyage?

Darwin noted unexpected patterns among fossils he discovered and living organisms her observed. Fossils resembled but were not identical to the living organisms in the same area in which they were found. Also finch species on each of the Galapagos Islands differed from each other in small but significant ways.

What causes mutations? Can they be benefictial?

Environmental phenomena called mutagens. Radiation/chemicals. Mutations are random. Nearly all mutations reduce an organism's fitness by causing its early death or by reducing its reproductive success. Is the only way that new alleles can be created within a population, and so generates the variation on which natural selection can act. Very rarely can they be beneficial.

What is evolution at the population level?

Evolution is a genetic change in the population.

Why is evolution and natural selection not the same thing?

Evolution is a process; natural selection is a tool by which it works. Evolution is the fact that organisms change through time, while Natural Selection is one of the mechanisms describing how/why this change occurs.

What do alleles have to do with evolution?

Evolution occurs when the allele frequencies in a population changes.

Genetic drift

Genetic drift is a random change in allele frequencies in a population. Genetic drift is a significant agent of evolutionary change primarily in small populations.

Bottleneck Effect

Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population.