Task 3

Question 1

What did Maltheus stated in his essay on the principle of population?

Answer 1

• first of all that the population increases exponentially and the food supply linear, therefore competition and natural selection

BUT important things:
1. Population could grow exponentially, in practice not
because incomplete survival /reproduction and competition
2. If the population would increase exponentially it would explode quickly
-> not the case because of war, mortality etc.

Question 2

What is the reproductive success?

Answer 2

the reproductive success is the number of living offspring produced

Question 3

What is the differential reproductive success?

Answer 3

when some animals have an advantage of reproduction over the other, when it is better adapted to the environment
e.g. yellow cars have a lower mortality rates living in sandy environment than black cats

Question 4

What does natural selection mean?

Answer 4

• natural selection eliminate species that are not well adapted to the current environmental situation
• natural selection is changing the frequencies of the underlying alleles

Question 5

What is the fitness of an allele ?

Answer 5

fitness of an allele is the number of copies in the next generation

Alleles that increase in frequency:

1. Advantageous dominant allele = quite fast
2. Advantageous recessive allele = slower

-> Natural selection increases the frequency of alleles with high fitness and decreases the frequencies of or eliminates alleles with low fitness

Question 6

What is a polygenic characteristic?

e.g. Height

Answer 6

• a polygenic characteristic is when the characteristic is not due to one gene, but due to a combination of many genes
• if height is advantageous in a particular environment, its gene will gradually increase in frequency
• evolutionary change gets faster with increasing selective advantage of whatever trait is being selected and also gets faster the more heritable the trait is

Question 7

What does reproductive restraint mean?

Answer 7

when food is scarce, animals produce less offspring (lay less eggs)

Wynne Edwards interpretation:

• when less food available, animals become stressed
• lead to population dies out

Question 8

Altruism vs. Selfishness in population

Answer 8

• selfish animals will always outcompete altruistic and survive
• altruism is not an evolutionary stable strategy (ESS)

Question 9

What is purifying selection?

Answer 9

the selective removal of alleles that are deleterious

• at loci with no phenotypic effect, there is nor purifying selection
• more or less lead to a stabile pattern

Question 10

What is the stabilizing selection?

Answer 10

• when the average is the optimum, therefore the graph gets narrower
• favors intermediate variants and acts against extreme phenotypes

Question 11

What is directional selection?

Answer 11

• favors individuals at one end of the phenotypic range

e. g. small fishes can hide behind stones, big and intermediate get eaten

Question 12

What is disruptive selection

Answer 12

favors individuals at both extremes of the phenotypic range
- lead to less average animals

e.g. small fish and big fish
intermediate fishes get eaten

Question 13

What is the mutation-selection balance?

Answer 13

• mutation constantly introduces new variants into a population
• selection reduces the variants
• the amount of genetic variation will be the result of the mutation selection balance

Question 14

What is the heterozygote advantage?

- one of the five mechanisms to sustain genetic variation

Answer 14

heterozygote individuals have an advantage over homozygote individuals

• e.g. homozygots (ss) have abnormalities in their red blood cells that cause health problems
• if you are heterozygote (Ss) , the dominant S will take over, therefore you will have some abnormalities, but not to the extent that cause health problems

Question 15

What is the negative frequency-dependent selection?

- one of the five mechanisms to sustain genetic variation

Answer 15

a phenotype that is associated with relatively high fitness when it is rare, but relatively low fitness when it is common

=> cheaters, fishes who build nests and cheaters who lay their eggs into those nests and the other fishes fead them

• cheaters will have a high reproductive success
• when cheaters is rare it will survive

Question 16

What is Force mutation?

- one of the five mechanisms to sustain genetic variation

Answer 16

more genetic variation when mutation is strengthen and selection of the mutation is not that strong

More mutation resist = more variation

Question 17

What is inconsistent selection?

- one of the five mechanisms to sustain genetic variation

Answer 17

can happen when the environment changes a lot

e.g. during drought year

Question 18

What is the sexually antagonistic selection?

- one of the five mechanisms to sustain genetic variation

Answer 18

• the optimal phenotype might not be the same for males and females

e. g. an allele that increases height might be optimal to increase fitness among men, but nor in women –> we will always have variation
- height selection in men is directional and in female stabilizing

Question 19

What is the adaptionist hypothesis?

Answer 19

if some feature or behaviour is commonly found in a type of organism, then it is probably an efficient design solution to some problem that an organism has faced

• if not feature would have been outcompeted

Question 20

What is the ultimate explanation?

Answer 20

• why question
• phenotype -> genotype
• e.g. why are the eyes of an aquatic creature 2.55 diameters? because it is the best design to see underwater

Question 21

what is the proximate explanation?

Answer 21

• how question / mechanism
• genotype -> phenotype
• e.g. the mechanism behind the phenotype like genes, proteins and growth process involved in making such an eye

-> natural selection favors whatever proximate mechanism produces the optimal phenotype with the highest reliability and the smaller cost

Question 22

Why are structures not always the optimal design?

1. Time lags

Answer 22

1. Time lags
   - if the environment changes, the optimal phenotype changes and it takes many generations for selection to respond
   - we arent adapted, our parents are, we are the productive success of our parents
   - we are adapted to the environment of our parents
   - evolution is always one step behind

Question 23

Why are structures not always the optimal design?

2. Selective regime

Answer 23

Selective regime

• the ability of changing own appearance depending on environment
• phenotypic plasticity = the ability to alter the appearance depending on the context
• a sub- optimality
• if the fluctuation in environment change that needs either darker or green leaves, the organism will evolve a mechanism that can deal with both via phenotypic plasticity (= the ability to alter phenotype depending on context)
  e. g. when grasshopper can change color when put in front of a different/darker background (= but this mechanism need time)

Question 24

Why are structures not always the optimal design?

3. Genetic correlations
   - hitch -hiking
   - trade-offs

Answer 24

3. genetic correlations
   - changes to most genes will have not just one, but many different phenotypic consequences
   - Pleiotropy
   e.g. two genes are linked to each other, one dominates the other (one positive, the other neutral)
   the positive increases and neutral too because they are combined with each other
   e.g. black skin color and black hair
   -> skin color is hitch-hiking on black hair

Trade -off

• > when two traits have opposite effects on fitness but are genetically correlated with each other
• peacock ornamentation is like a handicap, but lead to more selection by females
• selecting for attractive males = die fast
  -selecting fro long lifespan = more terns
  => selection cannot maximize both lifespan and attractiveness

Question 25

shape of the adaptive landscape

Answer 25

for selection to be able to reach an optimal design, there must be a continuous series of intermediate phenotypes (linear decrease until optimum) BUT not always the case, if there is a big valley /big environmental change between the current state and optimum, selection get stuck

Question 26

What is a sexual dimorphism?

Answer 26

sexual dimorphism is the difference between male and female forms of the same species e.g. males with ornaments, females quite ugly or makes are larger than females

Question 27

What is sexual selection?

Answer 27

sexual selection is like natural selection on the ability to gain mates - differentiation between intersexual selection intrasexual selection

Question 28

What is batements principle?

Answer 28

- males reproductive success increases with each additional partner - males can produce many sperm in little time, with low energy = can produce limitless number of offspring - females producing egg cells is high costly, can only produce a certain number, there is no reproductive success by mating with more partners than she can produce eggs => variance of reproductive success is greater for males than for females

Question 29

What is InTRAsexual selection?

Answer 29

- males fight against each other - the winner can mate yaaaay

Question 30

What is InTERsexual selection?

Answer 30

- males are looking good -> male with most impressive ornament is chosen -> signal for good health

Question 31

What is the sexy son hypothesis about?

Answer 31

females who choose peacocks with big ornaments will have sons with big ornaments too = attractive son

Question 32

What is the good gene hypothesis about?

Answer 32

to have ornaments cost a lot of energy, to have big ornaments show that one has much spare energy - impressive ornaments is an evidence for good genes - high quality of genes is heritable -> offsprings will survive better and have lower parasite loads

Question 33

What about sex- role reversal?

Answer 33

In case when: 1. females do all the post-fertilization care -> ornaments of males are exaggerated 2. females and males equally do the post-fertilization care -> not more ornaments (penguins) 3. Males do all the post-fertilization care -> females are usually more ornamented than males and bigger the sex roles are reversed -> the difference in costs of reproduction is reversed

Question 34

Why do females made with multiple males and do extra pair copulation?

Answer 34

extra pair mating = mating that takes place with a male other than the social partner reason: the best male already paired up, female settle for available male but she chooses to get fertilized by the high quality male

Question 35

Survival of the fittest

Answer 35

individuals with certain heritable adaptive characteristics survive and reproduce at a higher rate than other individuals

Question 36

Genetic drift

Answer 36

random, describes how allele frequencies fluctuate randomly from one generation to the next - the smaller the sample the greater chance of deviation - tend to reduce genetic variation - can cause harmful alleles to become fixed

Question 37

the bottleneck effect

Answer 37

- a sudden reduction in population size due to environmental changes (natural disaster) - the resulting gene pool may no longer reflect the original gene pool - if the population remain small, it may be further affected by genetic drift

Question 38

The founder effect

Answer 38

- occurs when a few individuals become isolated from a larger population - allele frequencies in small founder population can be different from those in the larger parent population

Question 39

What is relative fitness?

Answer 39

relative fitness is the contribution of an individual to the gene pool in comparison to other individuals

Question 40

50:50 Ratio - Article

Answer 40

natural selection usually favors a 50:50 sex ratio (half men and half women) Equillibrium point -> if a population deviates from it , natural selection will drive it back - firstly 50:50 seems inefficient bc males can fertilize more than women, better to have more males, but then unfair bc males reproductive fitness higher and being a male is beneficial - sex ratios can also be biased -> sons or daughters can also act as helpers, natural selection favors then parents who produce more helping offspring

Question 41

Adaptation (evaluating evidence of psychological adaptation) - Article

Answer 41

adaptation 1. Any attribute that helps a creature survive and reproduce (e.g. new diet) 2. The historical end product of the process of evolution (peacock tails) e.g. pregnancy sickness is adaptation or incest avoidance or men's short -term desire for sexual variety as a psychological adaptation

Question 42

Left handedness and homocide + negative frequency dependent selection

Answer 42

- left handed are in minority - can better do sports like fencing, tennis and baseball, fights and combats but are not good in interactive sports e.g. gymnastic - positive correlation between number of left-handed people and homocide /violence - > because being surprised, less left handed in population - > but they are more prone to accidents