Sexual Selection and Co-evolution

Question 1

Fitness

Answer 1

An organism’s ability to pass its genetic material to its offspring

depends on both survival and reproductive success

Question 2

Maladapted Traits

Answer 2

Traits that aren’t beneficial for the survival aspect of fitness but directly impact the reproduction of individuals

as long as a trait increases reproduction more than it decreases survival, it will persist

extreme sexual dimorphism is a trade-off with survival

Question 3

Primary sexual characteristics

Answer 3

differences in the biological sexes directly related to reproduction (genitalia)

Question 4

Secondary sexual characteristics

Answer 4

traits which are used in sexual selection, but are not required for sexual reproduction

(horns, pretty feathers)

Question 5

Intrasexual Selection

Answer 5

direct competition between two members of the same sex

most often seen as male to male competition for a female, females can’t chose
bigger males, antlers, similar coloration (why)

Question 6

Epigamic/Intersexual Selection

Answer 6

Selective pressure from member of one sex having complete choice over a mate of the opposite sex

typically female choice

display or other courtship to attract members of the opposite sex

Question 7

Sexual dimorphism patterns

Answer 7

where males do not stay to help raise the offspring: males are often much more colorful than females (extreme sexual ornamentation)

sexes are often the same color when males help offspring

Question 8

Why do females care more about choosing a mate?

Answer 8

Males can have many mates, meaning the male can afford to select a suboptimal mate

pregnancy is energy intensive and have fixed number of eggs

reproductive success come from breeding with the best male, helps ensure offspring are as fit as possible

Question 9

Bateman’s Principle

Answer 9

the sex which invests the most in producing offspring will become a limiting resource over which the other sex competes

can be male investing more (staying with the kids), thus the females are big and bright

Question 10

Fischerian Runaway Selection Hypothesis

Answer 10

females prefer a sexual characteristic in males
female selects mate, passes that sexual characteristic to her male offspring
if has daughter, passes on trait to prefer that sexual characteristic

creates a positive feedback

Question 11

Sexy Son hypothesis + Handicap

Answer 11

females choose attractive mates because it means that their own male offspring will be better able to attract mates

having extreme SSC showing the opposite sex that the individual can afford to waste resources

Question 12

Co-evolution (reciprocal evolution)

Answer 12

When two or more species impact each other’s evolution

Question 13

NS vs Coevolution

Answer 13

Broad changes due to abiotic or biotic

small number of traits in one species are directly impacting the evolution of a second suite of traits in another species

Question 14

Specific/Pairwise Coevolution

Answer 14

Two species reciprocally impacting the other’s traits or genes

Question 15

Evolutionary Arms Race (symmetrical/asymmetrical arms race)

Answer 15

selection pressures are identical on two species, co-evolve the same trait (sunlight for trees)

contrasting selection pressures
both species are co-evolving however selection pressure is different (cheetah - sprinter, gazelle - endurance, evader)

Question 16

Coevolution through symbioses

Answer 16

close and prolonged interaction between organisms of different species can be beneficial, neutral, harmful
(mutualism, parasitism)

Question 17

Mutalism

Answer 17

interactions between two different species mutually benefit each other

obligate - must co-operate in order for both to survive
facultative - benefit but would survive if not

Question 18

Parasitism

Answer 18

one benefits at the expense of the other

however, parasitism relationships are very finely tuned to preserve the life of the host, the parasite needs the host to survive!

if either species were to succeed completely, the other would become extinct
can use mimicry