Mate Choice

Question 1

What is anisogamy?

Answer 1

• root of the problem
• scarcity of females (due to time it takes to have and recover from having children) means they’re more valued to males leading to increased competition

Question 2

Definition of monogamy?

Answer 2

• each sex has one partner
• favoured when: there’s input from both parents needed to raise offspring, male has to guard mate, low chance of meeting many females

Question 3

Example of monogamy?

Answer 3

• house sparrows
• when given supplementary food the male spent more time with the female, 10% of chicks were from extra pediments
• when not given extra food, 35% of chicks were sired by other male birds that flew in while the male was out collecting food

Question 4

Definition of polygyny?

Answer 4

• males have more than 1 partner while females only have 1
• promotes conflict between males and choosiness by females
• favoured when one sex is operationally rare

Question 5

Why do males fight?

Answer 5

• to establish dominance and access females
• for control of resources that females require
• for direct control over groups of females

Question 6

Definition of polyandry?

Answer 6

• females have more than 1 partner while males have 1 partner
• favoured when: females can escape parental care duties, females require resources provided by more than 1 male, males have biased sex ratio

Question 7

Example of polyandry?

Answer 7

• spotted sandpipers
• females behave like males: larger, arrive at breeding grounds first, fight for territory, attract several males, skewed reproductive success

Question 8

Example of ecological factors favouring polyandry?

Answer 8

• sandpipers
• live in very cold climate
• females need to insulate and incubate eggs thoroughly, can lay many eggs but only 4 fit in nest
• so she has male lay on eggs and incubate them
• chicks are altricial so can fend for themselves so little cost to the male

Question 9

Definition of polygynandry?

Answer 9

• females have more than 1 partner and males also have more than 1 partner
• favoured when males can’t monopolise females and females gain from multiple matings

Question 10

Example of costs in energy of choosing?

Answer 10

• satin bowerbirds
• females move around large hilly, mountainous and jungly landscape that allows wide selection of males
• costly due to having to fly between them and remember where each one is

Question 11

Example of costs in time of choosing?

Answer 11

• sage grouse

- since they lek the female has to spend nearly 50 times the amount of energy just standing there and watching

Question 12

What are the benefits of choosing?

Answer 12

• direct benefits: territory, nuptial food, paternal food, paternal care, reduced harassment, sperm
• indirect benefits (females offspring gain benefits and lives longer/produces more offspring)

Question 13

What should choosy females do?

Answer 13

• pay attention to signals of available benefits
• prefer males with exaggerated signals
• prefer signals that can’t fake
• maximise their benefits

Question 14

What are signals for direct benefits?

Answer 14

• repertoire size is equal to parental care (e.g. warbler song is indicator of care it will provide later in life)
• may indicate an absence of predator

Question 15

What are signals for indirect benefits?

Answer 15

• area of fathers eyespots relate to chick survival in peacocks
• attractive fathers produce ‘sexy sons’