Sexual conflict and sexual selection

Question 1

sexual selection

Answer 1

involves gamete formation
in virtually all multicellular animals = fundamental difference between male and female gametes
sperm = unlimited small and cheap to produce
egg= large, relatively scarce and cost a lot to produce

Question 2

anisogamous sexual reproduction

Answer 2

fusion of 2 gametes which differ in size or form

Question 3

Inequality in PE and PI = sexual conflict

different ideal strategies?

Answer 3

differential PE leads to different ideal strategies to maximise reproductive success
-Male PE is lower
= males should maximise reproductive success by ruthless promiscuity
= females should be choosy and coy (to offset high cost of reproduction)
(so females do choosing and males compete for access)

Question 4

Who will mainly invest in parental effort?

who invests mainly in mating effort?

Answer 4

female
male
–> degree to which this is true is dependent on inequality of PE (and degree of inequality is dependent on mating systems)

Question 5

Define
monogamy
polygyny
polyandry
polygamy

Answer 5

-m and f form exclusive pair bond
- m mates with several fs
-f mates with several ms
polygyny + polyandry = polygamy

Question 6

If PE is equal (monogamous) more or less equal mating effort?

Answer 6

PE is equal = more equal mating effort

PE not equal (polygamous) = less equal ME

Question 7

Sexual selection

if females choose and males compete = lead to

Answer 7

selection of traits which are solely concerned with increasing mating success
1 aspect of natural selection was the descent of man and selection in relation to sex

Question 8

2 types of sexual selection?

Answer 8

1) intrasexual selection = males compete for access to females - those best equipped win and will pass on their genes
leads to : sexual dysmorphism = males a lot bigger than females (m’s become fighting machines)
competition doesn’t necessarily stop after copulation
Black winged damsel flies have adapted to have lateral horns on penis to scrape out sperm and then they will replace it with own
2) Intersexual selection = reluctant females will prefer males who can show evidence of material resources or better genes
eg. hanging flies - females will only mate with males if he provides food - size of insect relates to duration

Question 9

intersexual selection continued:
evidence of genetic benefits may underlie development of elaborate adornments
2 hypotheses?

Answer 9

development of elaborate adornments
eg. widow bird- longer tails = more active nests in territory
however, long tails are not optimal for flight, so how have these evolved as a result of selection by females for genetic benefit?
1) Fishers 1930 hypothesis - starts as a simple preference, it gets positive feedback between F preference and longer tails = runaway process
2) handicap hypothesis - Zahani 1975
elaborate adornment = handicap in day to day life, so survival demonstrates ability to survive even with handicap (only healthy animals show fully developed secondary sexual characteristics)

Question 10

Intersexual selection can also lead to…

Answer 10

courtship displays and rituals

- may arise from similar patterns to those which underlie adornments

Question 11

Asymmetry?
Parental investment?
Parental effort?

Answer 11

females may also gestate and feed their offspring
therefore, there is an asymmetry/ inequality of:
1)parental investment - effort put into rearing individual offspring
2) parental effort -effort pit into rearing all offspring produced over lifetime