Natural Selection SC.912.L.15.13 Describe the conditions required for natural selection, including: overproduction of offspring, inherited variation, and the struggle to survive, which result in differential reproductive success. To the Teacher:

What do I need to know? the conditions required for natural selection to occur. These include: overproduction of offspring, inherited variation, and the struggle to survive, which result in differential reproductive success.  understand genetic drift and gene flow. how mutation and genetic recombination increase genetic variation.  To the Teacher:

Conditions required for natural selection In any population there is variation. More offspring are produced than can survive. The over production of offspring causes competition. Individuals with the most advantageous traits (adaptation) out compete others, survive and reproduce. This differential reproductive success causes a change in the observed phenotypes of a population. To the Teacher: Source: http://evolution.berkeley.edu/evolibrary/article/evo_14

Conditions required for natural selection Guiding Questions 1) How does selection occur through differential reproductive success? 2) What are the two ways to create variation in a population? 3) How do adaptations lead to the evolution of a population. To the Teacher:

Genetic Drift Genetic Drift: Random change in the number of times a particular allele occurs in a population. Often occurs in small populations such as ones that have gone through genetic bottlenecks (drastic reduction in population size) or ones that have colonized a new area (founder effect). To the Teacher: Source:https://www.lcmrschooldistrict.com/roth/Biology_animate/Ch16/ActiveArt/genetic_drift.jpg

Genetic Drift Guiding Questions: What are potential causes of genetic drift? How might genetic drift impact the survival of a population? To the Teacher:

Gene Flow Gene flow: Movement of genes through a large population or between members of different populations To the Teacher: Source:http://www.mrzimmerman.org/New%20Folder/NEWSTUFF/EvolutionTutorial/Geneflow_diagram.gif

Gene Flow Guiding Questions: 1) What is gene flow? 2) What is the evolutionary importance of gene flow? To the Teacher:

Causes of Genetic Variation Sexual Reproduction: Combination of genetics from two different parents. Leads to offspring with a combination of traits from both parents. Genetic Mutation: Changes in DNA can lead to the formation of new variants of a trait. Crossing Over: Process in which homologous pairs of chromosomes exchanges pieces of with each other during meiosis. To the Teacher: Source: http://www.darwinwasright.org/genetics.html

Causes of Genetic Variation Guiding Questions: 1) What is genetic variation? 2) What are the 3 sources of genetic variation? 3) What is the evolutionary significance of genetic variation? To the Teacher:

Show What You Know A species that lacks the variation necessary to adapt to a changing environment is more likely to   A. develop many mutated cells   B. become extinct over time   C. begin to reproduce sexually   D. develop resistance to diseases To the Teacher:

Show What You Know Which statement is best supported by the theory of evolution?   A. Genetic alterations occur every time cell reproduction occurs.   B. The fossil record provides samples of every organism that ever lived.   C. Populations that have advantageous characteristics will increase in number.   D. Few organisms survive when the environment remains the same. To the Teacher:

Show What You Know Science explains that different forms of life on Earth developed over a long period of time from a common ancestor. The process by which unrelated organisms come to resemble one another (e.g., birds, bats, and butterflies all having wings) is known as which term? A. adaptive radiation B. convergent evolution C. genetic drift D. punctuated equilibrium To the Teacher:

Show What You Know A particular species of shark normally reproduces sexually. In captivity, it was found that a female could also reproduce asexually. One negative result from asexual reproduction is   A. increased gene recombination.   B. increased number of males produced   C. decreased number of eggs used   D. decreased biodiversity within the species To the Teacher:

Show What You Know Which concept is best illustrated in the flowchart below? A. natural selection B. genetic manipulation   C. dynamic equilibrium   D. material cycles To the Teacher: