College Level Evolution

Page 187

is studying these and other diseases in terms of genetics is that the human genome is large and it is laborious to look at the entire genomes of many people in order to find the necessary trends. Still, there are some diseases that have been linked to certain genes in humans. An example of this is the presence of sickle cell gene and malaria resistance. People who have the Duffy blood group or Melanesian ovalocytosis also have protection against malaria. People with a prion protein gene variant are protected from Creutzfeldt-Jakob disease and those with a CCchemokine receptor 5 mutation do not get HIV-1 disease to a great degree. Being a blood group non-secretor protects against Norwalk viral infections. There is some evidence that there are genes affecting the innate immune system that confer a decreased risk to a number of infectious diseases, particularly if the person is heterozygous for the genes. Most of the diseases that have been studied are chronic diseases like malaria, tuberculosis, and leprosy. Related to this is the finding of certain genes that increase the risk of autoimmune diseases, particularly in European populations.

HOST AND PATHOGEN EVOLUTION A pathogen thrives if it can survive, reproduce, and spread to a different host. Parasites, host immunity, predators, and limitations in the environment all exert evolutionary pressures on the survivability of a particular pathogen. We have already talked about the evolutionary arms race, in which the pathogen and host continually adapt in order to outdo each other. The hosts that have resistance are selected for and the pathogen that can successfully beat those resistances are also selected for. There are physical barriers that first protect the host from disease. Pathogens have evolved to have toxins and enzymes that can break through these defenses. Host complement systems also protect the host but there are enzymes in the bacterial species that can get through these defenses as well. Other defense mechanisms include sequestering host resources, such as iron, which is sequestered in the liver, lymph cells in the immune system, and antibiotics made by the host that can fight off disease. The previous chapter on coevolution explained how it is coevolution that causes the changes in the host and pathogen over time so that both the host and pathogen can survive. Because it takes much longer for human and higher animal evolution to occur compared to that of bacterial and viral organisms, mankind has augmented the lack of evolution through the invention of

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Course Questions and Answers

1hr
pages 212-279

Summary

6min
pages 208-211

Key Takeaways

1min
page 203

Quiz

2min
pages 204-207

Future of the Planet with Global Warming

4min
pages 200-202

Human Extinction

2min
page 199

Ways Humans Might Evolve

2min
page 198

Quiz

2min
pages 192-194

Evolution of Senescence

4min
pages 188-190

Host and Pathogen Evolution

2min
page 187

Disease Susceptibility

2min
page 186

Quiz

3min
pages 180-183

Key Takeaways

1min
page 179

Mosaic Coevolution

1min
page 178

Antagonistic Coevolution

1min
page 177

Host-Parasite Coevolution

1min
page 176

Quiz

2min
pages 168-171

Key Takeaways

1min
page 167

Coevolution and Mutualism

1min
page 175

Cooperation in Populations

2min
page 163

Group Living

2min
page 164

Hardy-Weinberg Model

1min
page 162

Quiz

3min
pages 155-158

Key Takeaways

1min
page 154

Sex and Mate Selection

3min
pages 152-153

Mating Systems

1min
page 151

Quiz

3min
pages 141-144

Evolution of Sexual Reproduction

6min
pages 147-149

Key Takeaways

1min
page 140

Mass Extinction

6min
pages 136-139

Background Extinction

2min
page 135

Quiz

2min
pages 127-130

Key Takeaways

1min
page 126

Evolution before the Homo Genus

1min
page 121

Modern Human Evolution

1min
page 125

Evidence for Human Evolution

2min
page 120

Evolution of the Homo Genus

4min
pages 122-123

Human Migration

1min
page 119

Human Structural Changes

3min
pages 117-118

Human Evolution

1min
page 116

Quiz

3min
pages 110-113

Key Takeaways

1min
page 109

Speciation and Modes of Speciation

4min
pages 106-107

Genetics of Speciation

1min
page 108

Quiz

3min
pages 99-102

Key Takeaways

1min
page 98

Transition to Group Living

3min
pages 96-97

Evolution of Individuality

2min
page 95

Origin of Eukaryotes

2min
pages 91-92

Evolution of Multicellularity

4min
pages 93-94

Prokaryotic Cell and Eukaryotic Cell Evolution

6min
pages 82-85

Quiz

2min
pages 87-90

Viral Evolution

2min
page 81

Early Forms of Life

1min
page 80

Quiz

2min
pages 70-73

Key Takeaways

1min
page 69

Genetic Processes

6min
pages 61-64

Genetic Variability and Mutation

1min
page 67

History of Genetics

1min
pages 59-60

Mendelian Genetics

2min
pages 65-66

Mutations

2min
page 68

Quiz

3min
pages 54-57

Key Takeaways

1min
page 53

Phylogenetics and Molecular Phylogenetics

2min
pages 51-52

Adaptation, Fitness, and Reproductive Success

8min
pages 32-35

Phylogenic Trees

3min
pages 46-48

Key Takeaways

1min
page 38

Quiz

2min
pages 39-42

Cladistics

2min
pages 49-50

Quiz

3min
pages 23-26

Key Takeaways

1min
page 22

The Story of Darwin

3min
pages 20-21

Evolutionary Thought in Ancient Times

2min
page 15

Nineteenth Century Evolution

4min
pages 17-18

Christian Philosophies on Evolution

2min
page 16

Preface

6min
pages 8-11

Timeline of Evolutionary Theories

1min
page 14

After Darwin and Natural Selection

1min
page 19
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