lecture 15

Question 1

Disruptive selection of males and females

Answer 1

started with isogametes which evolved into large ova and small, mobile sperm; selection for the extremes

Question 2

allopatric speciation

Answer 2

2 groups of one species are isolated geographically and diverge into separate species; ex. formation of Grand Canyon split a population into 2 isolated groups that diverged into separate species since barrier separates interbreeding

Question 3

sympatric speciation by polyploidy

Answer 3

process through which new species evolve from a single ancestral species while inhabiting the same geographic region; during mating, pass on entire genome so offspring becomes diploid, then next generation tetraploid and so on

Question 4

how are alternative phenotypes maintained

Answer 4

alternative strategies, mixed strategies, conditional strategies

Question 5

Strategy

Answer 5

a genetically based program

Question 6

tactic

Answer 6

phenotype that results from a strategy

Question 7

frequency independent fitness

Answer 7

fitness does not depend on frequency of a phenotype

Question 8

Frequency dependent-positive relationship

Answer 8

the higher frequency of phenotype Y, higher the fitness; results in trait being selected for and becoming fixed

Question 9

Frequency dependent-negative

Answer 9

higher frequency of phenotype, lower fitness; selection against a particular phenotype, can lead to multiple traits maintained

Question 10

Alternative strategy: Genetic Polymorphism

Answer 10

occurrence of more than one phenotype in the population, each of which have a separate strategy; usually exist at some equilibrium point where the fitness of both strategies is maximized; ex. when one sex becomes rarer, selection pushes back to make more of the rare sex

Question 11

Sex ratio in howler monkeys

Answer 11

selection works on group size from two directions; females do better in larger groups when there are more individuals to protect environment and offspring, but males do better when there are fewer males in group to compete with; as sex ratio approached 50/50 male fitness decreased and female fitness increased

Question 12

Genetic Polymorphism- Sponge isopods

Answer 12

3 types of males: alpha, beta, gamma; alpha are large and can defend harems of females within the sponge; beta mimic female morphology/behavior in order to enter harem; gamma are tiny and can sneak into harem undetected

Question 13

Seychelle’s Warblers sex ratio

Answer 13

warblers base whether they are having males or females on environmental situation; when on higher quality territory, tend to have less males; in high quality territories, young will stay behind and help at the nest; on good territory, produce more females (which will help) and less males (which will disperse)

Question 14

Condition dependent sex allocation in red deer

Answer 14

female deer with higher social rank will tend to produce more males

Question 15

dominance dependent sex allocation in yellow baboons

Answer 15

dominant females (higher rank) produce more daughters than males, in order to pass on social rank

Question 16

Human sex ratio related to periods of war

Answer 16

when a country was at war, sex ratio was adjusted to produce more males

Question 17

Mixed strategy

Answer 17

you have one genetic strategy that gives rise to more than one tactic; ex. clownfish: change sex depending on age and number of females in the group

Question 18

Nest adoption in paper wasps

Answer 18

2 tactics: found a nest or sit and wait; sit and wait tactic is only successful if high amount of nest founders and lower frequency of others with sit and wait tactic

Question 19

Conditional strategy

Answer 19

individual status affects tactic employed to maximize fitness

Question 20

Conditional strategy: bees

Answer 20

larger males are able to defend their own territory, smaller males are satellite males, who try to catch matings by flying in between territories; able to switch tactic depending on circumstances; satellite males were able to become territory owners when the larger males were eliminated