evolution and human health – chapter 14 - flu virus evolution - antibiotic resistance - cancer as...
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Evolution and Human Health – Chapter 14
- Flu virus evolution
- Antibiotic resistance
- Cancer as set of evolving population
- Adaptative reasoning and humans
- Pathogens and dietary/lifestyle choices cause disease
- Immune systems of hosts select for resistant pathogens
- Humans further select for resistant pathogens via drug development and use
- Physiological traits and behaviors can be understood by considering evolutionary concepts and evolutionary history
Key Concepts
Antigenic sites:
Sites that the hostimmune systemrecognizes toform a memory and design antibodies.
Viruses from the freezer: Hemagglutinin evolution
Flu strains with novel antigenic sites enjoy a selective advantage
Evolutionary history of influenza A is surprisingly linear!
Phylogeny of Influenza viruses based on nucleoprotein DNA sequences
Nucleoprotein enables a virus to infecta particular host and therefore is mostlikely to ‘capture’ the history of particularstrains.
However, some strains within clades havealleles at other loci (hemagglutinin or neuraminidase) that were obtainedfrom unrelated strains.
Flu strains trade genes
Prior to 1968 Flu EpidemicThere was no human strainWith H3…..where did it come from?
Cross-Species Transmissions (tree based on nucleoprotein)
Bird to Pig
The source of the 1918 pandemic flu remains unknown.
Reid et al., 2004
Humans further select for resistant pathogens via drug development
BacterialResistance
ToAntibiotics
Time
Societal change in antibiotic use
Based on Austin et al., 1999
The cost ofresistance can be
overcome byselection.
Schrag et al., 1997
Evolutionary History of Cancer
Shibata et al., 1996
Colorectal adenocarcinoma
from 43 yr patient
Adenoma samples are older and show higher levels of genetic diversity
What is the Evolutionary Significance of Fever?
Fever represents a condition that is induced by a pathogen for the benefit of the pathogen.
Higher temperature of host would increase reproduction/growth of the pathogen.
Fever represents a condition that is induced by a pathogen for the benefit of the host.
Higher temperature of host would allow the immune response to be more effective.
Behavioral feverIncreases survivalof iguanids afterInjection ofAeromonas
What happens if you prescribe aspirin?
Should Patient’s Allow Fevers to Run their Course?
- Fever may be adaptive against some but not all pathogens.
- Fever may carry significant costs in some cases, but lowcosts in other cases
Evolution and Parenthood: Parents Invest in Ways to Increase Their Fitness
Flinn and England, 1997
Stress, cortisol levels, illness, and reproductive success
Stepchildren vs Genetic Offspring
Stepparents kill stepchildren at a higher rate than biological parents kill biological children
Daly and Wilson, 1988a,b
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