Evolution Basics

Question 1

microevolution

Answer 1

genetic changes in a species/population of living things over generations
- requires optimal fitness which means adaptation to its environment

Question 2

macroevolution

Answer 2

speciation and extinction

Question 3

evolutionary Medicine

Answer 3

evolutionary methods used to understand disease and medicine

Question 4

4 Key forces of Evolution

Answer 4

variation
selection
population genetics
culture

Question 5

variation

Answer 5

mechanism for evolutionary change and has selective advantages
- example: skin pigmentation

Question 6

mutation

Answer 6

• # 1 mechanism for variation
• most are neutral recessive or silent b/c variation must be compatible with life
• leads to new traits/diseases

Question 7

certain genes are highly conserved across species b/c………..

Answer 7

they play a major role in body functions so not usually mutations here since it could cause death
- ex: HOX gene
- mutations happen in less crucial genes so its more compatible with life

Question 8

fixed alleles

Answer 8

all other versions of the gene die out except for one, so a whole population could share that one gene

Question 9

sexual reproduction
- 3 ways to get genetic diversity

Answer 9

sexual reproduction ensures genetic diversity and integrity through meiosis
1. independent assortment (chromosomes)
2. random fertilization: high # of chromosomes in egg/sperm
3. recombination: during meiosis swap genetic material to create variation

Question 10

Skin Pigmentation

Answer 10

• folate and Vit D hypothesis explains the evolution of skin pigmentation
• UV light catalyzes synthesis of Vit D precursor in the skin from dehydrocholesterol
  
  • used for bone development and calcium metabolism
• excessive UV exposure causes photolysis of folate and it’s deficiency
• less sun = need to absorb more UV light = less pigment = lighter skin tone
• more melanin = darker skin = more protection from UV rays so protects from folate depletion

Question 11

3 Types of Selection

Answer 11

artificial: minimal genetic engineering or selection for certain traits by humans on other animals like dogs
natural: competition between and within a species and the environment restricts population growth
sexual: different sexual success within one species

Question 12

4 effects of natural selection

Answer 12

1. positive (bigger) or negative (smaller): like giraffe neck length increasing is +
2. stabilizing (birth weight: which is associated with diabetes )
3. balancing (ex: sickle cell anemia homo=bad, hetero=good)
   4 disruptive which is selective against the mean (Darwin’s finches beaks became large or small depending on food source)

Question 13

sexual selection

Answer 13

• Intrasexual competition
• leads to sexual dimorphism
  one constraint is natural selection, like in peacocks if the tail is to large you cant run from predators
• ex: male mortality

Question 14

example of sexual selection

Answer 14

male mortality:
- males evolved to compete with other males to demonstrate they are the optimal mate but humans also live in a stable social group
- women live longer than men due to extrinsic causes like violence/aggression, smoking/alcohol, risk taking behavior

Question 15

population genetics mechanisms

Answer 15

migration: certain ethnicities are prone to certain diseases /mutations b/c o genetics
gene flow: ppl carry alleles in their genome as the move from place to place
genetic drift: allele changes occur due to a random event
- founder effect: a population moves to a new area but the gene pool becomes limited
- bottle neck: large gene pool but an event happens where only a few survive and procreate to make a new population

Question 16

culture

Answer 16

• socially learned behaviors that differ between cultures
• creates selective pressures (gene culture evolution) like lactase persistence
• its rapid and influences our biological evolution

Question 17

lactose tolerance

Answer 17

• Due to pastoralism diary is introduced to the diet post weening of children so the mutation that allows us to consume dairy is advantageous
• If lactose intolerant the bacteria will ferment the lactose and increased osmolarity draws water into the intestine causing bloating, diarrhea, cramps
• Evolutionary Convergence

Question 18

Evolutionary Convergence

Answer 18

similar traits are naturally selected for in different populations/areas in different ways that are independent of each other

Question 19

6 fundamental principles of evolution

Answer 19

• environmental influence
• evolution has no specific goal
• adaptation
• sexually selected traits
• fixed mutations: neutral mutation of genetic drift
• exaptation: a specific trait is selected for a specific purpose but now that trait is used for a new purpose(not OG one). Like feathers are originally for heat but used for flying later

Question 20

what is adaptation?
what are 3 types of adaptation?

Answer 20

a trait that promotes fitness and has a specific function which is driven by natural selection
3 types
1. Anatomical: physical change (bipedalism)
2. Physiological: body actions changed (shivering to keep warm)
3. Behavioral (child more dependent on mother so monogamy and parental care)

Question 21

macroevolution and adaptation

Answer 21

adaptation occurs over many lifetimes where organisms adapt to their environment

Question 22

adaptability

Answer 22

an individuals ability to make physical changes within their lifetime and is influenced by their evolutionary history

Question 23

environments are constantly changing

Answer 23

• Adaptability is important because new stressors appear so traits best suited for that environment survive
• Environments aren’t constant like currently
• Population growth affects change in social and cultural environments

Question 24

5 Evolutionary Constraints

Answer 24

1. limits on physical processes: increased body size is constrained by amount of nutrients available, gravity, perfusion, movement (ppl from islands are smaller b/c less nutrients)
2. evolution incrementally works over a very long time scale (ex: bipedalism causes risk for herniated disks and plantar fasciitis since body hasn’t fully adjusted to being upright)
3. Mismatch between environment and rate of adaptation/selection processes (ex: we are adapted for famines but now have food surplus so obesity epidemic)
4. selection operates on phenotype: many genes affect the phenotype
5. exaptation &/or chance results can occur

Question 25

co-evolution

Answer 25

• No species lives in isolation from others
• Definition: 2 species have a reciprocal relationship because of selective pressures that affect both
• This can lead to an arms race where both species continually evolve to stay fit
• Ex: human immune system and bacteria

Question 26

evolution has no specific direction

Answer 26

• Species evolve to be successful in their specific environment
• It’s not survival of the fittest but there are drivers like natural selection and environmental changes

Question 27

taxonomy

Answer 27

study of how organisms are classified and Classify species based on their characteristics, Carl Linnaeus

Question 28

homologous

Answer 28

similar structures with same evolutionary history but doesn’t necessarily have same function

Question 29

analogous

Answer 29

different structures with similar adaptation/function with NO common evolutionary history
- ex: convergent evolution and lactose tolerance

Question 30

biological species concept

Answer 30

interbreeding individuals that are reproductively isolated from other such groups

Question 31

biological species concept example

Answer 31

ligers can be artificially bred in captivity but don’t produce fertile offspring and are isolated from each other in their natural habitats, so they are 2 diff species because they are reproductively isolated