sex role reversal:

Question 1

Parental investment inequality:

Answer 1

• females investment per offspring more than males
• The potential reproductive success of males is greater than females
• The variance in reproductive success is higher for males than for females
• The operational sex ratio is usually male biased even if the actual sex ratio is not

Question 2

Sexual Conflict:

Answer 2

• Males compete with each other for mating opportunities with females (intrasexual conflict)
• Females can afford to be choosey and select the best possible mates
• Females and males are selected for different traits (intersexual conflict)

Question 3

Sexual selection:

Answer 3

• Males and females are selected for different behavioural / morphological traits
• The sex with the lowest parental investment has the highest variance in reproductive success
• The sex with the highest variance in reproductive success is under the strongest sexual selection
• Sexual selection often leads to exaggerated sexual dimorphism

Question 4

sex role reversed species example…

Answer 4

e. g. Mormon cricket
- males produce a nuptial gift (e.g. Mormon cricket spermatophylax which is a large investment) = influences offspring fitness
- males can only mate once
- females can produce multiple clutches of eggs

= females compete for males

e. g. gulf pipe fish and seahorses
- males carry fertilized eggs = male pregnancy
- females have more mates, males only have one
- males choose large females

Question 5

environment influences sex role reversal… example -

Answer 5

e. g. Mormon cricket males that had low protein diets and couldn’t produce spermatophylax as often =
1) lower numbers of sexually active males
2) larger females mated successfully
3) males were choosey and rejected small females

Question 6

in sex role reversed species…

Answer 6

• Males care for brood in all these species
• Females are often larger and more brightly coloured than males
• Females are the subject of sexual selection