lecture 9

Question 1

Operational Sex Ratio

Answer 1

ratio of sexually active males and females

Usually 50 males to 50 females (50:50), but the sex ratio is skewed towards males because not all females are ovulating or they may already be pregnant

Question 2

Monogamy

Answer 2

only one mate, one female one male

ex: doves, wolfs

Question 3

Polygyny

Answer 3

1 male mates with multiple females

ex: birds, fish

Question 4

Polyandry

Answer 4

1 female mates with multiple males

ex: sandpipers

Question 5

Promiscuity

Answer 5

male and females mate with whoever

ex: chimps

Question 6

Bateman’s principal

Answer 6

More variability in male reproductive success than
females – only physically able to have so many, where males have to compete but have the capacity to impregnate many females

Question 7

Sexual Selection

Answer 7

The adaptation of traits that are meant to be attractive and increase reproduction. The reason why some males look different from females (sexual dimorphism, more common in polygyny)

Question 8

Sexual Selection impact on Natural Selection

Answer 8

Can be very fit, but must reproduce to pass on important traits.

Sexual selection can also give animals deleterious traits, as the two can contradict each other

Question 9

Visual Courtship

Answer 9

Visual courtship could be colorful decoration, size, dances (birds, especially – like peacocks)

Question 10

Auditory Courtship

Answer 10

Auditory
could be calling or singing (like in frogs)

Question 11

Olfactory Courtship

Answer 11

Olfactory can be pheromones
(like in humans, rats, and other mammals)

Question 12

Bright Bird Hypothesis

Answer 12

Colorfulness and brightness might display a bird’s ability to fight off parasites. It shows that they are honestly of such good quality that they can divert energy to their appearance and carry the handicap

Question 13

Runaway Selection Hypothesis

Answer 13

A trait might have originally helped with survival, but is now deleterious. Choosy females will keep tails going longer as they give birth to sons until they reach an optimal point in tail length

Question 14

Handicap Hypothesis

Answer 14

Traits can be burdensome, or a handicap, to the animal, so having this trait shows they are superior enough to bear it

ex: birds flying with weights

Question 15

Role of Symmetry

Answer 15

Animals prefer mates that are symmetrical – this is more attractive because it indicates good genes

Question 16

Conditional Male Courtship

Answer 16

Highest quality will give a nuptial gift, okay male will court with saliva, and poor quality will jump the female

Question 17

Non-conditional Male Courtship

Answer 17

Territorial male vs Sneaker male (will find eggs that were not fertilized by the territorial male and fertilize them himself)

Territorial male will not be as protective over these eggs

Question 18

Nuptial Gifts

Answer 18

Proving fitness with gifts – bringing food, spermatophores – usually occur in insects like fireflies

Question 19

Dishonest Signals in Courtship

Answer 19

Predatory females might make flashing lights for mating, but then eat the males

Question 20

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