Lecture 8: Natural & Sexual Selection

Question 1

natural selection

Answer 1

-the only adaptive evolutionary force

Question 2

adaptation

Answer 2

-a natural change that allows an orgnism to either survive better, or reproduce more

Question 3

adaptive

Answer 3

-adaptiveness isnt the cause of natural selection events

Question 4

selective forces defintion

Answer 4

-environmental factors which may reduce reproductive success in a population and thus contribute to evolutionary change or extinction through the process of natural selection

Question 5

selective forces examples

Answer 5

• predation
• parasitism
• climate factors
• mate attraction
• resource acquisition

Question 6

fitness

Answer 6

• quantified

- the # of offspring that survive into the next generation

Question 7

absolute fitness

Answer 7

-the total # of surviving offspring that an individual produces during its lifetime

Question 8

relative fitness

Answer 8

-the # of offspring in ratio to the highest possible # of offspring

Question 9

stabalizing selection

Answer 9

• stabilizes the populations variation around the best version of the trait(ends up being the mean)
• ex: birth weight

Question 10

directional selection

Answer 10

• when the environment changes

- mean always changes

Question 11

disruptive seleciton

Answer 11

• selection for both ends of the trait range and against the avg trait value
• most important for speciation

Question 12

balancing selection

Answer 12

• selection actively works to maintain multiple alleles or phenotypes in the population
• ways it works is through heterozygote advantage and negative frequency dependent selection

Question 13

heterozygote advantage

Answer 13

-heterozygote has a higher fitness than either of the 2 homozygotes

Question 14

negative frequency dependent selection

Answer 14

-the fitness of a genotype dec. when its frequency in the population becomes higher

Question 15

reproductive strategy examples

Answer 15

• mate choice
• mating frequency
• mate guarding
• parental care
• long-term mating behavior(monogamy vs. polygyny)
• offspring spacing

Question 16

parental investment

Answer 16

• men invest less to mate

- for women, the after effects of mating can be very costly so they’re cautious

Question 17

what happens when a male and female parental investment is equal or males invest more?

Answer 17

-partner choice are done cautiously by both men and female

Question 18

female choice

Answer 18

-they choose whoever wins male/male/competition

Question 19

male/male competition

Answer 19

-can be physical or more of a portrayal of appearance of dominance

Question 20

sexual dimorphism

Answer 20

-distincting btwn male and female animals

Question 21

parental care

Answer 21

-looking for good fathers, resource protection, good genes (oldest, largest, healthiest)

Question 22

territory defense and resource acquisition

Answer 22

-good for when she raises her kids

Question 23

good genes hypothesis

Answer 23

• females look for good genes
• old males: successful in surviving, getting food, resisting parasites
• health: denoted as good size, diet, thus less likely to have a disease

Question 24

handicap principle hypothesis

Answer 24

• applies to organisms that have display characteristics that’re hard to maintain
• males show off characters that are a handicap to their survival/success

Question 25

runaway selection

Answer 25

• women choose something about the other animal that probably once showed good health but is now a handicap but they still choose them
• “ghost of selection past”
• i.e. long tailed widowbird

Question 26

what is an example of directional selection?

Answer 26

• salmon

- selective pressure (humans) lower the mean weight by keeping higher weighted salmon

Question 27

what is an example of disruptive selection?

Answer 27

• colonial bentgrass
• grows in soil heavily contaminated with metals and is resistant to metals
• grass farthest away is also thriving

Question 28

what is an example of sexual dimorphism?

Answer 28

• males are a lot larger

- males have specialized structures for fighting

Question 29

what is an example of a reproductive strategy?

Answer 29

• austrailian riflebirds

- the males had a dance to show off to females in hope to mate