Lecture 11: Reproductive Behaviour

Question 1

African buffalo defence against lions

Answer 1

• sometimes simply charging is enough to scare

- can also tho fight away with long horns

Question 2

function of buffalo horns:

Answer 2

• fight against predators = increasing chances of survival

- male vs male fighting (intrasexual selection)

Question 3

females vs male difference in horns

Answer 3

female= slim horns
male= much wider and long, has a large boss and base.
WHY? male vs male competition

Question 4

Darwins beetle jaw:

Answer 4

• Jaw enlarged like massive plyers. WHY?

- males climb up trees (max 20m), fight other males up high, chuck the smaller plyered male off tree

Question 5

ultimate goal of fitneess

Answer 5

pass genes on to next generation (death doesnt rlly matter)

Question 6

intrasexual selection

Answer 6

within sex selection

-male vs male for females

Question 7

what did Darwin acknowledge about intrasexual selection

Answer 7

cannot explain all diversity from sexual selection, intERsexual selection as well

Question 8

Male stalk eyed fly

Answer 8

• soon after pupating he injects air into tip to make long eye stalks
• stalks impede ability to fly away from predators
• Why do they have them? not used for fighting, males aggregate together at roosting site, females prefer to mate with males with longest eye stalks. SEXUAL SELECTION

Question 9

Intersexual selection

Answer 9

• between sex

- mate choice component

Question 10

cost & benefits male cape sugar bird

Answer 10

• plumage impresses females increases chances of mating

- struggle to fly with large plumage

Question 11

costs to male buffalo and darwin beetles

Answer 11

risk their lives fighting each other for fertile females

Question 12

stalk eyed flies costs

Answer 12

-use great amount of energy and make themselves more susceptible to predation

Question 13

hypothetical species males and display to attract females (b)

Answer 13

male a = doesnt display -survives 10 yrs, 2 offspring per year
male b = does display, survives 5 yrs, 5 offspring per year.
a= 20 offspring reproductive success
b= 25 offspring
B greater reproductive success! - better fitness.

Question 14

Anisogamy=

Answer 14

• sexual reproduction by the fusion of dissimilar gametes.

- eggs more costly to produce than sperm

Question 15

Robert Trivers concept of parental investment:

Answer 15

• provides theoretical basis for understanding sex differences in behaviour
• females tend to make greater initial investment in offspring: constrained to provide greater amount of parental care in species with internal fertilisation & internal development like mammals & anisogamy.
• The operational sex-ratio is male-biased.(males competing to mate with females)

Question 16

In animals with internal fertilisation (e.g. birds), males can

Answer 16

males can mate again sooner

Question 17

Dance fly species: males provide greater initial investment

Answer 17

• Role reversal

- females compete for mating with males

Question 18

when females mate with multiple males sexual selection continues after

Answer 18

mating on sperm, drives evolution of adaption like large testes.

Question 19

Parental investment=

Answer 19

the amount of resources devoted to a particular offspring

Question 20

why is parental investment a trADE OFF?

Answer 20

investment in on offspring reduces that availble for other offspring

Question 21

PI: in Peafowl

Answer 21

showy males + choosy females

= female biased

Question 22

PI: in mute swan

Answer 22

similar appearance + behaviour

=equal

Question 23

PI: in Jacana

Answer 23

• females larger + compete for males

- male biased

Question 24

precopulatory types of sexual selection:

Answer 24

= on behaviour / morphology

-intrasexual (MvsM) & intersexual (MvsF)

Question 25

postcopulatory types of sexual selection:

Answer 25

= on sperm

• Sperm competition
• Cryptic female choice

Question 26

chimpanzee testes:

Answer 26

greater than what they should be for body size

Question 27

Suicidal sex in marsupial insectivores

Answer 27

• In 20% of insectivorous marsupial species, males die off completely after mating, due to synchronised immune collapse.
• They mate synchronously.
• Stop producing sperm before breeding season – they rely on stored sperm.
• Males range widely and females are promiscuous.
• Males are not aggressive towards each other.
• This reproductive strategy has evolved multiple times but only in this group.
• They live in temperate forests with a predictable, synchronous food peak.
• Females only produce one litter per year.

Question 28

Semelparity

Answer 28

used to describe an organism that reproduces just once during its lifetime, after which its death is inevitable. Examples include most annual and biennial plants.

Question 29

Key concepts in behavioural ecology (adaptation of behaviour):

Answer 29

• Sexual selection
• Kin selection / inclusive fitness
• Parental investment