V02 Evolutionary medicine

What is evolution?

Changes in traits over generations

• Variation among idividuals

• Variation influences survival and reproduction

• Variation is heritable (geenetic basis)

→ natural selection

What is adaptation?

• Is about the design

• an inhereted trait that makes an organism more firt in it’s environement and has arisen

What is important about the variation in traits?

• e.g. 80% is genetically determined (height of indiviuals)

• Sources of variation lies in the mutation(=Typos, others: gene duplication, deletion etc.) and recombination (picture in page 6 and examples of heritability on page 7)

Can you explain the three factors that make evolution ongoing?

Example Cholesterol levels in wome

• Variation: women show different cholesterol levels

• Heredity: daughters have similar cholesterol levels as their mothers

• Different reproxductive success: women with low cholesterol levels have more children

→ lower choleteral in women have more reproductive success than women with higher levels → Natural selection in contemporary human population

What have we done to ourselves in terms to our modern human environement?

• Insulated our bodies from climate (shelter and clothing, heating and cooling, sunshades etc.)

• Prosuces our food (basic foodstuff, fermentation, additives vitamins etc)

• Removes parasites (actually not normal for mammals), hygiene

• Repaired our bodies (prosthetics, cleaning)

• Increased our physical perfomance (tools, lifts, cars airplanes, binoculars, microsopes, weapons)

• etc.

Can you explain Hennebergs and Stephens theory of relaxed natural selection?

Medicine, Technology and living conditions reduce the pressure that once affected wether people survived and had children. For example, someone with a condition previosusly made reprodduction difficullt may now have children with helpn of IVF. Its sugessted that this could alow some inherited conditions to üresist but it doesn’t mean humans have stopped evolving: selcetion still happens and factors ssuch as migration also change population over time. → modern world is more practical than nature

What is a micro- and macroevolution?

Microevolution: How oorganisms become adapted to ther environments (changes within one species)

Macroevolution: Origins of species and divirsity of life

What is the evidence to convergent evolution (adaptation by natural selection)? And what is its difference with fittness?

Shark (fish), Icthyosaur (reptile), Penguin (bird) and Dolphin (mammall) all live in the water and have all created traits tomake it pausible even thogh they all have different orgins ecause of previous similar behaviour

→ Similar selection pressures prduce similar adaptions rhough not always by the same means

Fittness explains expected reproductive success of an individual with a specific trait relative to other members of the population → within the same species ¨otherwise not comperable

What does the fittnes depend on?

It depends on the ecosystem

• example (picture page 8 )

• Human skin color distribuition

• lactase persistance

• hight

• artic environment

• high fat diet

• CYP2D6 (page 15 and 16)

Why traits do not change fast all time?

In major changes of the environment that trait can change unless it’s stay, the adaptation is stable

• very common, since existing variants well adapted to their environment

• evolutionary change only if change in environment (picture page 17)

What is a balanced selction (example in sickle-cell anemia)

Construction of the disease genetically :

Heterozygous (Aa)

• changed hemoglobin stucture

• less prone to malaria

• no sicklecell -anemia

Homozygous (AA)

• sicklecell animaemia

• Few malaria restistance

• short life expactancy

→ the sickle cell gene makes a change in the structure in the bloodcell and the parasitte ccannot invade

Explain the concept of sexual-selection

• there is itrasexual competiotion (male to male fight and female to female fight for the repectve opposite/same sex)

• mating menaing that there is a mating season where usually the female picks e.g the most handsome peacock

The trade offs in the immune systeme:

• high levels to testoterone can lead wto prostata cancer even though the hormone would help the intrasexual competition and offspring creation (page 20)

→ selcetion will be on-going as long as people vary in how many kids they have (passing one geenes no matter what)

Diffrence in monogamous vs polygamous societies when it comes to passing down ones genes

monogamous:

• men and woman have a say about reproduction and the amout of pffspring (so both have the chance to give their genes on)

polygamous:

• men who mate have a higher chance to give their genes on than woman but there will be a lot of “lonely men“

Why is the evolutionary perspective of diseases important?

• to better understand the diseas/ trait (its cause, its context, its variability, its population distribuition and its treament)

There are diseases where it is confirrmed (like Malaria, G6PD defients and sickle cell anemia) and suspected (HIV-resistance) to have an root in evolution.

How long does it take for an adpatation?

Seconds, Hours, Days: ongoing physiology, adaptation (homeostasis)

Days, Months, Years, Generation: e.g Epigenetics (Developmental plasticity)

Years, Generation, Milenia: Selection

Why are not all evolutionary changes not due to selection or not all traits are adaptations?

Many mutations are neutral (genetic code is redundant, mutations may occur in non-coding regions), protein structure not influenced → No change in traits

Traits can change for non—adaptive reasonss → Genetic drift, bottlenecks, fouder effect, pleiotropy, etc.

Why is it hard to study evolution?

It often takes may gerations to see natural selection in real time (human generation times 22 -32 years). Even in persumably short generations it takes for anmilas like dogs thousands of years!

tools:

• genetics, comparative method, fossil frecors, labaratory studies etc.

  • E coli has generation a time less than an hour (too much data !!!)

    • 24h*1year(365d)= 8760 generations per year

  • Due to this the human dieseas network is too vast (page 29)

Can you give an example for environmental intercation ?

Hypertension can be cause polygenically or by exogenic interactions like salt, obesity, Exercise, stress, … that can define the occurence, intecety applied into those genes. (page 30)

• for that we can go into te adaptive thinking the so called tool in Evolutionary Medicine

  • drug resistance

  • symtomps or dieseases that can ovarlapped for manny causaioous diseases (like axiety being the symptome of depression, Add, OCD, …