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CHAPTER 13. EVOLUTION. NOTE: IT IS MANDATORY TO SOLVE THE FOLLOWING PROBLEMS FROM THE LAB MANUAL: 1. GENETICS PROBLEMS ( pp.132, 133, AND 134: ALL THE PROBLEMS) 2. SUPPLEMENTAL GENETIC PROBLEMS (pp. 135 to 138) problems numbers : 1,2,3,4,5,6,7,8,9,10,11,16,18,19,21,22,25,26,27,31 AND 34.
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CHAPTER 13 EVOLUTION
NOTE: IT IS MANDATORY TO SOLVE THE FOLLOWING PROBLEMS FROM THE LAB MANUAL: 1. GENETICS PROBLEMS ( pp.132, 133, AND 134: ALL THE PROBLEMS) 2. SUPPLEMENTAL GENETIC PROBLEMS (pp. 135 to 138)problems numbers: 1,2,3,4,5,6,7,8,9,10,11,16,18,19,21,22,25,26,27,31 AND 34
Finches “Descent with Modification” / Natural Selection
MEGATERIUM: A Gigantic sloth 20 feet= 6m Modern tree sloth
Finches “Descent with Modification” / Natural Selection
1. Evolution: Change over time in the genetic composition of a population which eventually may constitute a new species.ieSpecies of organisms living on Earth nowadays, are the descendants of ancestral species (that were different from modern species.)
Cont. Evolution: On a grand scale, evolution is the gradual appearance of biological diversity from microbes to all organisms living today.
2. Mechanisms that drive evolution: • Natural selection: If a population goes through an environmental pressure (ie climate change, predators, pathogenic microbes) those individuals whose characteristics (alleles) allow them to adapt best to their environment are more likely to survive and reproduce, and leave more offspring. Therefore, favored traits will be represented more and more in coming generations.
Natural Selection Animation This is a population of insects. Each color means a different allele for the gene “color of insects”. The background is the environment in which these insects live.
NATURAL SELECTION THE PROCESS
OLD POPULATION NEW POPULATION
OLD POPULATION NEW POPULATION
2. Cont. Mechanisms that drive evolution: b. Genetic drift: Change in allele frequencies that occur from chance. The smaller the population, the higher the probabilities its allele frequencies will vary from generation to generation, and even an allele may be lost.
Founder Effect: Colonization through the Bering Strait to the Americas (20,000 – 14,000 years ago)
GENETIC DRIFT THE PROCESS
NEW POPULATION OLD POPULATION
NEW POPULATION OLD POPULATION
NEW POPULATION OLD POPULATION
2. Cont. Mechanisms that drive evolution: POPULATION 2 POPULATION 1
2. Cont. Mechanisms that drive evolution: POPULATION 2 POPULATION 1
MECHANISMS THAT DRIVE EVOLUTION • MUTATION • GENE FLOW • GENETIC DRIFT • 4. NATURAL SELECTION
The muscles connected to the ears of a human do not develop enough to have the same mobility allowed to monkeys. Several animals such as pigs, dogs, deer and cattle have reduced non functional digits
Humans: 46 chromosomes Chimpanzees: 48 chromosomes