Alternative repro strats

Question 1

Define sperm competition

Answer 1

The competition between the sperm of >2 males inside the females reproductive tract

Question 2

Describe how Damselflies outcompete rival sperm

Answer 2

Elaborate penis that removes the sperm of other males already in females repro tract

Question 3

Briefly, describe the difference between polyandrous / monogamous insect sperm quality

Answer 3

Polyandrous males produce higher proportion of viable sperm than monogamous males

Question 4

Why does sperm competition still occur in monogamous systems?

Answer 4

Extra-pair copulations

Question 5

Why do males mate guard in monogamous systems?

Answer 5

Extra-pair copulations cause males to guard mates to protect their paternity and drive off rivals

Question 6

Describe study into Mate Guarding in Seychelles Warblers

Answer 6

• Males mate guard 4 days before female lays egg (while fertile)
• Q: How successful is mate guarding in protecting paternity?
• R: When mate guarding was removed (fake egg) EPCs increased dramatically

Question 7

Describe Dickinson’s study into Blue Milkweed Beetles

Answer 7

• Normally, males remain on females back after copulation (mate guarding)
• These were artifically removed
• R: 25% of separated males found a new mate within 30mins = guarding results in missed opportunites
• R: 50% females found a new mate after male removal. Guarding prevents females from mating again
• R: Overall, guarding is beneficial if last male fathers >40% of the females offspring

Question 8

Describe another example of males trying to protect paternity (Fulmars)

Answer 8

• As they cannot stay with females after mating, male fulmar birds copulate over 50x with their partners
• Frequent copulation ensures optimal timing of insemination relative to fertilisation

Question 9

Describe Cryptic female choice

Answer 9

Female manipulation of sperm inside her reproductive tract so that a preferred male fertilises her eggs

Question 10

Describe sperm ejection in chickens

Answer 10

• Females can eject sperm from their cloacas
• Females can eject the sperm of subordinate males and accept the sperm of dominant males

Question 11

Why does male sperm transfer rely on nuptial gift size in Hanging Flies?

Answer 11

• While the female eats the gift, the male mates and transfers sperm
• If the gift is smaller, the male will have less time and transfer less sperm

Question 12

What might a female gain from manipulating paternity?

Answer 12

• Higher quality offspring (by cryptically choosing high quality fathers)
• More offspring (by cryptic choice of genetically compatible males)

Question 13

Describe an alternative mating strategy employed by non-dominant males (e.g in elephant seals)

Answer 13

E.g in Elephant seals
- Subordinate males hang out inshore and sneak copulations from females
- Not as rewarding as being the beachmaster, but ‘better than nothing’

Question 14

Describe the (unequally fit) male mating tactics in Scorpian Flies

Answer 14

Question 15

Describe the alternative Male morphs in Isopod (paracerceis sculpta)

(Shuster & Wade, 1991)

Answer 15

• Are these 3 morphs changeable or are the males bound to follow them?
• R: morphs are distinct genotypes
• R: depended on how many males and females live together
• R: morphs occur at frequencies at which their fitness is equal
• R: = each morph has equal fitness

Question 16

Describe alternative male mating tactics in Bluegill sunfish

Answer 16

• Example of ‘Best of a bad job’ strategy
• Molecular evidence shows territorial males father most of the offspring