General Biology 2 L2.2 PDF

GENERAL BIOLOGY 2 Ms. Clarie Ann Manalo EVOLUTION AND ORIGIN OF BIODIVERSI Lesson 2.2 Mechanisms that Produce TY Change in Populations MOST ESSENTIAL 1 Explain the mechanisms that LEARNING produce change in populations. COMPETEN CIES LEARNING...

GENERAL BIOLOGY 2 Ms. Clarie Ann Manalo EVOLUTION AND ORIGIN OF BIODIVERSI Lesson 2.2 Mechanisms that Produce TY Change in Populations MOST ESSENTIAL 1 Explain the mechanisms that LEARNING produce change in populations. COMPETEN CIES LEARNING State the Hardy-Weinberg OBJECTIVES 1 principle. 2 Explain why genetic variation is a prerequisite for changes to occur 3 among generations. Calculate the Hardy- Weinberg equation. POPULAT ION is a cluster of organisms of the same species that live together in the same area at the same time GENETIC VARIATI ON is the presence of differences in sequences of genes between For an individual, the chance of inheriting a trait has many possible outcomes and the sum of these outcomes is equal to 1. For populations, the laws on probabilities also apply to determine the occurrence of traits in the next generation. ALLELE FREQUENCY is the number of times the allele occurred in a population. Changes in populations can be described by showing the differences in allele frequencies across many generations. Frequency of HARDY-WEINBERG homozygou EQUATION The probabilities of all possible genotype s dominant frequencies are given by: Frequency of homozygou After the FOIL method, the H-W equation is s recessive derived: Frequency of Let’s Try This! In a population of 1000 ducks, yellow duck is dominant over black. If there are 250 black ducks in a population of 1000 ducks, find the following: 1. Frequency of dominant allele 2. Frequency of recessive allele 3. Frequency of each Hardy-Weinberg Principle It states that the allele and genotype frequencies in a population is constant in all generations given: There is random mating No natural selection, genetic drift, gene flow, or mutation. Forces Disrupting the Hardy-Weinberg Equilibrium Non-random Mating Natural Selection Genetic Drift Gene Flow Genetic Mutation During mate selection, some organisms can be “choosy”, or some individuals breed with only nearby neighbors, if not inbreeding with relatives. Non-random mating changes only the Natural selection occurs when individuals in a population respond variably to natural events or changes, favoring the survival and reproduction of the fittest. Over generations, the allele and genotype frequencies in a population change. Random allele frequency changes or fluctuations can occur across generations, called genetic drift, especially in a smaller population or if it decreased in size at some point. The H-W model behaves as though the population is large. Some individuals or groups in the population are added during immigration or lost by emigration. Through migration, new alleles can possibly arise or disappear from the Mutations can occur when genes are replaced, deleted, or duplicated. Hence, it is accounted as a different type of allele and changes the probabilities of inheriting the original types of alleles in the pool. Let’s Try This! A population can show variation of traits, but huge changes and possibly new species only emerge after many generations of disrupting the H-W equilibrium. In theory, population is the smallest unit of evolution. “Success is not final; failure is not fatal: It is the courage to continue that counts.” ~ Winston S. Churchill