Sexual Selection III

Question 1

what does a sexual signal say? What info might receivers get from it?

Answer 1

• readiness to mate
• quality or health of mate
• can show if they are related

Question 2

examples of intersexual selection

Answer 2

1. red-collared widowbirds
2. gray tree frogs

Question 3

intersexual selection examples - red-collared widowbirds

Answer 3

• researchers experimentally changed tail length by cutting it off
• females like long tails

Question 4

intersexual selection examples: red-collared widowbirds - what was the result

Answer 4

• long-tails are not good for the male
• but it still has it bc females like long tails

Question 5

intersexual selection examples: red-collared widowbirds - what does the results mean?

Answer 5

females are making mating decisions based on signal even if the signal has a cost

Question 6

intersexual selection examples - gray tree frogs

Answer 6

• female frogs are choosy and prefer males giving longer calls
• longer-calling males are more likely to find mates

Question 7

what are the hypotheses for receiver preferences evolve

Answer 7

1. null model
2. sensory bias
3. resource acquisition hypothesis
4. honest signal/good genes

Question 8

hypotheses for receiver preferences evolution - null model

Answer 8

• assumes preferences are arbitrary
• outcome: runaway sexual selection
• ornamentation continues to bet more ‘bigger’ without stopping

Question 9

hypotheses for receiver preferences evolution : null hypothesis - what is runaway sexual selection

Answer 9

• assumes that both sexual preference in females and ornamentation in males are genetically variable and heritable
• all about genetics

Question 10

hypotheses for receiver preferences evolution : null hypothesis - bird example

Answer 10

• first need variation in preference and display
• then assortative matting where a connection begins to form in preference and display
• if selection favors one of them, it will move the other
• can graph this relationship

Question 11

null hypothesis: bird example - adding natural selection to graph

Answer 11

• optimal display for reproduction is graphed
• optimal display for survival is graphed
• average display is a compromise between the two lines (equilibrium line)

Question 12

null hypothesis: bird example - adding drift to graph

Answer 12

• drift wll push the population off of the equilibrium
• they will eventually move back

Question 13

null hypothesis: bird example - adding dfit to graph