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UW-Madison ENVIRST 260 - Exam 1 Study Guide

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ENVIR ST 360 1st EditionExam # 1 Study Guide Lectures: 1-5Lecture 1 (September 4)Levels of Study: Individuals, Populations, Communities, Ecosystems, Biosphere (Earth) *from narrowest to broadestPopulation: Definition: A group of individuals of the same species living in the same place at the same time Population ecology: Study of the distribution and abundance of a given species in a specified area at a given timeo Two big questions: SIZE: Why are the populations the size they are? GROWTH: How does a population grow? 2 Types of Growth:o Exponential: Population continuously multiplyingo Logistic: Population grows quickly, then levels out over timeLecture 2 (September 9) Population: Controls on Size and Growth:o Biotic Factors: Competition, Predation, Parasites, Mateso Abiotic Factors: Light, Topography, Nutrients, Water, Climate Competition-occurs only when something is limitedo Two Types: Intraspecific Competition: Same species compete over resources Interspecific Competition: Many species compete over resourceso Competition has the greatest impact on a population when there is a limited resource for a single species Density-how tightly packed together a population iso Two types of factors that affect the population Density Dependent: Density affects the impact of the factor (Disease) Density Independent: Density does not affect the impact of the factor (Drought) What we can learn from studying populations:o Changes in climateo Changes in resourceso Changes in traits over time… evolutionEvolution Definition: Change in genetic makeup of a population over time (generational) Relative Fitness: Value of 0-1 describing the likelihood of a trait to survive and be passed down through generations 2 Equations to determine frequency of traitso p+q=1  p= percentage of dominant alleles q= percentage of recessive alleleso p2+2pq+q2=1 (Hardy-Weinberg Equation) p2= percentage of homozygous dominant genotype 2pq= percentage of heterozygous geneotype q2= percentage of homozygous recessive genotypeLecture 3 (September 11)Null Model: No Selection No Mutation No Gene Flow Random Mating Large Population SizeNatural Selection Requirements: Variation in traits Differences in fitness of genotypes Heritability of traitsSelection acts upon the phenotype, the expressed trait.Lecture 4 (September 16)How to calculate the genotype frequencies of a population  Starting Point: Know what percent of the population is homozygous recessive (what percentage is expressing recessive trait) Take the square root of that decimal to find q Plug q into the p+q=1 equation and find p Plug the values of p and q into the Hardy-Weinberg equation P2= %AA, 2pq= %Aa, q2= %aa*Detailed example with flower population in Lecture Note 4Lecture 5 (September 18)Student Questions/Answers Non-evolving populations need a large population size because large populations are less likely to change genetically based on random events due to their greater genetic variability. Initial Allele frequency is the frequency of the dominant allele at generation 0. (PopG) Genetic drift is typically found in small populations when there’s really random population changes that differ greatly from the theoretical line (PopG); Gene flow is the immigration and emigration of individuals from populations. Mutation is a random event due to mismatching in genes of an individual; natural selection occurs when an individual is better adapted to its environmental conditions. Natural selection can act upon mutations. If there’s a population that has all 5 conditions of the null model, but a mutation occurs that gives individuals an advantage, the population then has potential to be evolving**Go over the practice essays and rat population activity discussed in discussion groups.**Do practice PopG activities to prepare for questions on


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UW-Madison ENVIRST 260 - Exam 1 Study Guide

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