Lecture 10 - mating systems

Question 1

what does mating system classification encompass?

Answer 1

Copulation behaviour
Social organisation
Parental care system
Competition for mates

Question 2

what is monogamy and what animals is it seen in?

Answer 2

1 male and 1 female

- most birds a few mammals and fish

Question 3

how many socially monogamous birds and also genetically monogamous?

Answer 3

<25%

- splendid fairy wren has about 70% of chick in its nest fathered by males not caring for them

Question 4

what is polygyny and what animals is it seen in?

Answer 4

1 male and >1 female

- few birds, most mammals

Question 5

what is simultaneous polygyny?

Answer 5

e.g. red winged blackbird- has a large territory with lots of females and breeds with them all at the same time

Question 6

what is successive/sequential polygyny?

Answer 6

e.g orangutan - meets breifly with a female and then moves on - this is the most pro-dominant mating system in mammals

Question 7

what is polyandry and what animals is it seen in?

Answer 7

1 female and >1 male

few birds, fish and mammals

Question 8

examples of successive and simultaneous polyandry?

Answer 8

successive - spotted sandpiper - flies to many males nests lays eggs and moves on
simultaneous - painted snipe - sex role reversal - females have impressive secondary sexual characteristics

Question 9

what is polygynandry and what animals is it seen in?

Answer 9

> 1 female and >1 male Few birds, few mammals, many fish, reptiles and amphibians

Question 10

can species how more than one mating system?

Answer 10

yes e.g. dunnocks show monogamous, polyandrous and polygynandrous systems

Question 11

describe the reproductive potential of males and females

Answer 11

male reproductive potential > females reproductive potential

• males are limited by access to females
• females are limited by access to resources

Question 12

what is the general model for the evolution of mating systems?

Answer 12

ecology e.g. resource distribution -> female dispersion -> male dispersion

resource defence effects male dispersion

the interaction between female and male dispersion affects the mating system

Question 13

what is resource defence polygyny and an example

Answer 13

• males defend key resources wanted by females

- tent making bats - Males construct and defend roosting tents which house harems of females

Question 14

what does female monopolisation by males and hence mating systems depend on?

Answer 14

• female group size

- female range size

Question 15

what mating systems occur if females live solitarily but have a defendable range size?

Answer 15

• if there range is small polygyny often occurs where one male had a large range with more than one female in it
• if the females range is larger monogamy often occurs where the male defends a range the same size as one female

Question 16

what mating system occurs females live solitarily but their range is not defendable?

Answer 16

scramble competition polygyny occurs e.g. like the orangutan - males only come into contact with females for a short period of time

Question 17

what mating systems occur if females live socially and have a defendable range size?

Answer 17

• in small groups you get uni-male polygyny - one male dominates many females
• in large groups you get multi-male polygyny - many males and many females

Question 18

what mating systems occur if females live socially but have a large range size not defendable?

Answer 18

Males may aggregate in leks when competition for females is intense - males produce no resources -> extreme sexual selection occurs

Question 19

what does the lek formation show under the general model?

Answer 19

male dispersion relies heavily on female dispersion

Question 20

describe the mating system experiment on blue headed wrasse to provide evidence that resources determine female dispersion which in turn determines male dispersion

Answer 20

Females- Forage over large overlapping ranges
Spawn daily at predictable, favoured sites
Males- Can’t defend females
Compete for and defend spawning sites
experiment - Removed males, replaced with new males
=22/24 sites still used, no new sites
- Removed females, replaced with new females
= 11 sites lost, 10 new ones
results showed that if females stayed in the same place males continue to defend them but if the females move so do the males
spawning sites -> female dispersion -> male dispersion

Question 21

describe the grey sided vole experiment

Answer 21

1) - added food and females range changed - showed that females range/ dispersion was affected by food distribution - males also converged on food
2) captive females and radio tracked males - showed that female dispersion determines male dispersion
3) captive males and radio- tracked females - proved the only thing affecting male dispersion was the female dispersion

Question 22

how does the reproductive potential of male and females vary?

Answer 22

• males have a lot more variance in reproductive success than females e.g. elephant seal - one beach master but other males done get many copulations

Question 23

what can effect the general model of mating systems?

Answer 23

if males provide alot of parental care less can be invested into mating - for females these males are a very important resource - affects the female behaviour as they try and monopolise the care the males can offer

Question 24

explain sexual conflict over mating systems

Answer 24

• Males ‘prefer’ polygyny
• Females may ‘prefer’ polyandry if they get more/better resources (e.g. paternal care)
• In many species, monogamy occurs as a compromise between conflicting interests of the sexes

Question 25

what did the yellow bellied marmot experiment show about sexual conflict over mating systems?

Answer 25

Females raise more offspring in small groups
Males raise more offspring in large groups
- in large groups the females have to share the males resources

Question 26

describe female enforced monogamy in burying beetles

Answer 26

• Female and male make a nest containing a corpse, and then care for offspring.
• Males attempt to attract additional females, females try to prevent them doing so