Essay on Evolution and Natural Selection

Submitted By j94princess
Words: 5101
Pages: 21
Open Document
Biology Final Exam  Notes
Chapter 16
• Microevolution: Heritable change in the genetic makeup of a population
• Population: all individuals of a single species that lives together in the same place or time
• Polymorphism: the existence of discrete variants of a character
• Gene pool: the sum of all alleles at all gene loci in all individuals
• Genotype Frequencies: the percent og individuals possessing each genotype
• Phenotype Frequencies: The ratio of individuals with a particular phenotype to the total number of individuals in the population
• Allele Frequencies: the proportion of all copies of a gene that is made up of a particular gene variant (allele).
• Diploid: 2 basic sets of chromosomes
• Haploid: 1 basic set of chromosomes
• Null Model: predict what they would see if a particular factor had no effect o Serve as theoretical reference points against which observations can be evaluated
• Genetic Equilibrium: describes the condition of an allele or genotype in a gene pool (i.e. population) where the frequency does not change from generation to generation.
• Neutral Mutation: mutation that has no effect on fitness
• Gene flow: when organisms or their gametes sometimes move from one population to another. o If immigrants reproduce, they may introduce novel alleles into the population they’ve joined.
• Genetic Drift: chance events sometimes causing allele frequencies in a population to change unpredictably o Most common in smaller populations because only few individuals contribute to the gene pool and because any given allele is present in very few individuals o Generally leads to loss of alleles and reduced genetic variability
• Natural Selection: process by which such beneficial, heritable traits become more common in subsequent generations
• Sexual Selection: a form of natural selection established by male competition for access to females and by the females choice of males
• Sexual Dimorphism: differences in the size or appearance of males and females
• Inbreeding: a special form of nonrandom mating in which individuals that are genetically related, mate with each other.
• Balanced Polymorphism: 2 or more phenotypes are maintained in fairly stable proportions over many generations.
• Frequency Dependent Selection: term given to an evolutionary process where the fitness of a phenotype is dependent on its frequency relative to other phenotypes in a given population.
• Neutral Variation Hypothesis: some of the genetic variation at loci coding for enzymes and other soluble proteins is selectively neutral
• Relative Fitness: the # of surviving offspring that an individual produces compared with the number left by others in the population
• Directional Selection: When individuals near 1 end of the phenotypic spectrum have the highest relative fitness
• Stabilizing Selection: When individuals expressing intermediate phenotypes have the highest relative fitness
• Disruptive selection: when extreme phenotypes have higher relative fitness that intermediate phenotypes

NOTES:
• Phenotype variation is brought about by continually mutating genes. the synthetic theory of evolution states that evolution is a two step process, the first is mutation of genes and the second is natural selection acting (and selecting from) the genes available. In short, phenotypic variation is caused by mutations, and natural selection tends to lessen variation (as those with preferable traits survive.)

• Genetic variation is what allows natural selection and more importantly new alleles to enter your population.

By having different genetic combinations, individuals of a population exhibit different traits which may or may not be to their benefit in regards to social and environmental interactions. Because of genetic variation, certain qualities are preferred over others due to a given surrounding and therefore change the allelic frequency towards
Show More

Related Documents: Essay on Evolution and Natural Selection

Evolution: Evolution and Natural Selection Essay

Evolution Darwin's theory of evolution explains how species of living things have changed over geological time. The theory is supported by evidence from fossils, and by the rapid changes that can be seen to occur in microorganisms such as antibiotic-resistant bacteria. Many species have become extinct in the past, and the extinction of species continues to happen. Adaptations - cold climates Every organism has certain features or characteristics that allow it to live successfully in its habitat.…

Words 1505 - Pages 7

Evolution: Evolution and Natural Selection Essay

Once you’ve got life – how it evolves Modern systhesis – is called evolution. It means descent with modification. Homologous character or gene – acquired thru shared ancestory. Theory of natural selection – mechanismof adaptation and adaptive evlution. Evolution Descendants of ancestral forms Vertrebrates have common anscertor with something in the past It requires Variation in populations – can arise thru mutations in dna. Ie a point mutation – wher ea single base pair is changed which…

Words 691 - Pages 3

Essay about Evolution: Evolution and Natural Selection

Does evolution fashion perfect organisms? The answer to this question, in a word, is no. There are at least four reasons why natural selection cannot breed perfection. 1. Organisms are locked into historical constraints. As we saw in Chapter 20, each species has a legacy of descent with modification from a long line of ancestral forms. Evolution does not scrap ancestral anatomy and build each new complex structure from scratch, but co-opts existing structures and adapts them to new situations…

Words 773 - Pages 4

Evolution By Natural Selection Is Wrong Essay

Evolution By Natural Selection Is Wrong!! All living things face many questions throughout their life such as what am I and what is the purpose on earth? Over the past centuries, science have been investigating these questions. At the same time, many cultures around the world have answers to these questions as well. According to science, these answers are concerned as myths or made up stories. Cultures all over the world believe “GOD” or “An Intelligent Designer” made all the living things. Modern…

Words 1609 - Pages 7

The Four Forces Of Evolution And Natural Selection

forces of evolution are mutation, gene flow, genetic drift, and natural selection. Mutation is a random change in a gene or chromosome, resulting in deletions, additions, or substitutions in the DNA sequence. Without mutation, there would be no evolution because the only way a sex cell can be passed down is through mutation. Gene flow is the exchange of genetic material between two populations. Genetic drift is the random change in allele frequency from one generation to the next. Finally, natural selection…

Words 412 - Pages 2

Essay on Anth: Evolution and Natural Selection

theories about natural selection has brought confusion to several scientists’ minds, debating whether these theories are true or not. As for Jonathan Weiner, he completely agrees with Darwin. In his article, Evolution in Action, he states how the biological life is quickly changing right in front of our eyes and claims that though there are arguments about whether Darwin’s theories are true or not, there has been evidence of natural selection. Weiner includes several examples of natural selection in his…

Words 492 - Pages 2

Essay on Evolution: Natural Selection and Human Behavior

important contribution to human behavior. EP posits that behavior is produced by specialized cognitive modules that evolved through natural selection in response to specific adaptive problems faced by our hunter-gatherer ancestors. Many aspects of modern human behavior can be explained through an evolutionary perspective. For example, EP helps us understand sexual selection through its explanation of gender differences in attraction and mating relationships. Buss (1995) found that gender differences…

Words 670 - Pages 3

Evolution: Natural Selection and Beneficial Mutations Essay

The theory of evolution is one of the best-known scientific theories around. Evolution is fascinating because it attempts to answer one of the most basic human questions: Where did life, and human beings, come from? The theory of evolution proposes that life and humans arose through a natural process. The basic theory of evolution is surprisingly simple and has a few essential parts and stresses a purely naturalistic descent. That is, complex creatures evolve from more simplistic ancestors naturally…

Words 596 - Pages 3

Peter And Rosemary Grant's Theory Of Evolution By Natural Selection

Peter and Rosemary Grant were able to show evidence for the Theory of Evolution by Natural Selection using 40 years of data following two species of finches on Daphne Major. By banding and taking samples from as many birds as possible, the Grants found support for all four of Darwin’s postulates. The first of thing that is necessary for a population to undergo evolution is that there must be variation among individuals. Before the drought in 1977, the Grants recorded variation in the beak sizes…

Words 487 - Pages 2

Why Do You Think Darwin's Theory Of Evolution By Natural Selection

1) Explain in what way Darwin's theory of evolution by natural selection was influenced by Thomas Malthus's Essay on the Principle of Population. (Ch 6, Bowler and Morus) First of all, what is Darwin’s theory of evolution by natural selection ?! Darwin’s theory of evolution entails the following fundamental ideas : Species (populations of interbreeding organisms) change over time and space. All organisms share common ancestors with other organisms. Over time, populations may divide into different…

Words 1790 - Pages 8