MSU ISB 202 Exam 3 Dyer

Darwinian medicine

application of modern evolutionary theory to understanding health and disease

Phylogenetic analysis

The process of grouping organisms based on multiple shared characteristics or traits

Levels of explanation

Physiological mechanism, Ontogeny, Phylogeny, Adaptive Function

Physiological mechanism

physiological causation

Ontongeny

changes over lifespan=

Phylogeny

Changes over evolution

Adaptive Function

Survival value (Selection Pressures)

How study of skin pigmentation is explained by the multiple levels of explanation

Physiological - cause of skin pigmentation differences

Ontogeny -changes in skin pignmentation within life of organism

Phylogenetic - history of dark skin in great apes and other mammals

Adaptive function - of dark (and light) skin pigmentation Adaptive tradeoff - advantage of dark skin; advantage of light skin

How can researchers detect parts of genome that may have been under intense positive selection?

Crossing over during meiosis

Alleles under positive selection will increase in frequency in population

Sickle cell

Malaria immune

Cystic fibrosis

Inherited, recessive allele in gene for chloride channel - affects ion balance in mucus producing cells

Lactose intolerance (vs lactase persistence)

Humans the only mammal to have predominantly Lactose tolerant population

Why hasn't natural selection removed Cystic Fibrosis?

Heterozygote advantage hypothesis: mutation reduces fluid loss in diarrhea

Diabetes

A condition in which the body is unable to produce enough insulin, the hormone required for the metabolism of sugar

What are the two types of diabetes?

Type 1 and Type 2

Type 1 Diabetes

Insulin not produced

Type 2 Diabetes

Insensitive to insulin

Causes of Diabetes

Viral infection (type 1)

Diet

Obesity

Inherited Genes (type 2)

Hypotheses for adaptive value of diabetes?

Thrift genotype

Carnivore Connection

Cold tolerance

ADHD

attention deficit hyperactivity disorder

Evidence that ADHD may enhance fitness in some environments

Ariall People - Kenya

Farmers not good

Nomads good

Evolution of virulence

Evolved resistance to antibiotics or vaccines

Implications of treating symptoms that are adaptive to host

Immunity

Virulence

probability of bad effect (especially death) on host

Variation in virulence

Pathogen and Host exert selection pressures on each other

Antagonistic coevolution

"Arms Race" or offensive and defensive traits

Mutualistic coevolution

Increasingly close for adapted traits

Fever and why it may be advantageous to host

Raises the temperature of the body, good in colder climates. Evidence: animals that live in colder environments "give themselves" the fever so they can survive the frigid weather

Diarrhea and why it may be advantageous to host

Flushes out the system, getting rid of any foreign bacteria out with it.

innate immunity

Properties: fast, non-specific, forgets

immune response

The body's defensive reaction to invasion by bacteria, viral agents, or other foreign substances.

Antigen Presenting Cell

Consumes foreign matter

Digests

Presents antigen on cell surface

Role of MHC proteins in APC

Activates T cells

Activation of T cells

divide rapidly and secrete cytokines that regulate or assist the immune response.

Activation of B cells

results in the production of antibodies.

Memory T-cells

Remember antigen and quickly stimulate immune response on re-exposure

Antibodies

Immunoglobulin protein with highly variable portion that recognizes different antigens

Clonal selection

Immune system produces wide variety of antibodies (somatic recombination)

Those that find antigens trigger cells to make more

Those that don't are degraded and destroyed

Why HIV is so dangerous

evolutionary arms race between HIV evolution and clonal selection

Auto-immune failures

Crohn's disease, Vitiligo. Lupus, etc

What goes wrong in immune system

viral infection that destroys important white blood cells and weakens the immune system

Hygiene hypothesis for increase in autoimmune disorders

A hypothesis that suggests the environments of Western children are unnaturally clean, dramatically decreasing their exposure to routine microorganisms.

Senescence

the natural physical decline brought about by aging

why is senescence a Darwinian puzzle

we just wear out

make room for the next generation

natural selection weakens with age

Darwinian explanation of senescence

change in strength of selection with age

Menopause: what it is?

reproductive senescence prior to general senescence

Why menopause is a Darwinian puzzle

purpose of life is to make off-spring

Rare in animals (which species have it?)

Humans (female), killer whales, short-finned pilot whales, belugas, and narwhals

Grandmother hypothesis

menopause evolved to switch women from investing in offspring production to investing in raising their off-spring to reproductive age

intergenerational competition hypothesis

reduces competition between her and her gravid and nursing daughters.

What is evolution?

the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

What is ecology?

The study of the process influencing the distribution and abundance of organisms

Evidence for human impact on the environment

species loss; habitat destruction; global warming

What influences ecological success?

If reproduction is high relative to mortality, then population grows

Population growth model:

ΔN = rNt (1-Nt /K)

Population growth model: K

Carrying Capacity

Population growth model: r

per capita rate

Population growth model: N

population size

Direct effects of one population on another

predation, mutualism and competition

Indirect effects of one population on another

food webs/food chains

Virulence Trade Off Model Equation

Food chains

Energy links between different organisms in an ecosystem based on feeding habits.

Food webs

A complex diagram representing the many energy pathways in an ecosystem

History of domestication

multiple species, multiple regions

Effects on humans (agriculture)

Cultural - more greens

biological - bigger greens, GMO

Effects on species that were domesticated

Parallel evolution of domestication syndromes

Dealing with pests

chemical warfare

Evolution as a tool in technology design

Artificial intelligence

Structural engineering

Biotechnology

Why these areas (Biotechnology)

Design is about searching through a space of possibilities to find ones that work best; Darwinian selection is a very powerful search algorithm

AI: can a program be evolved to solve logic problems?

Boolean logic (And, Not, XOR, etc)

Avida: platform for studying evolution experimentally in computer system

Biotechnology

A form of technology that uses living organisms, usually genes, to modify products, to make or modify plants and animals, or to develop other microorganisms for specific purposes.

protein design; antibody design; insect control

Gene Drive Mechanisms

genetic alleles that bias inheritance to increase probability of being passed on to offspring

Artificial selection (Biotechnology)

Long-standing tool for applying Darwinian selection to shaping biological systems

Why penicillin evolved

To survive / natural selection

How penicillin was discovered

Alexander Fleming accidentally discovered the antibiotic in 1928, when he came back from a vacation and found that a green mold called Pennicilium notatum had contaminated Petri dishes in his lab and were killing some of the bacteria he'd been growing.

Public health benefits of penicillin

fights off bacteria in your body

How penicillin resistance works

Bacteria evolves to survive its attacks

MRSA

Methicillin-resistant staphylococcus aureus : SuperBug

resistant to some commonly used antibiotics