Lecture 7: Animal Reproduction

Question 1

Intra-specific Interactions

Answer 1

Within species
Group living
Competition, i.e. food and mates
Reproduction
Sexual Conflict

Question 2

Inter-species Interactions

Answer 2

Among species
Predation and herbivory
Competition, i.e. food and spaces
Mutualism
Parasitism and disease
Pollination

Question 3

What are some challenges animals face when reproducing?

Answer 3

Choosing and finding a mate
Ensuring fertilization success
Ensuring offspring survive to reproduce

Question 4

Types of mate choice

Answer 4

Monogamy
-> most birds and humans
Polygyny - males mate with lots of females
-> most insects and mammals
Polyandry - females mate with lots of males
-> few birds and fish
Promiscuity - all males and females mate together
-> chimps and bonobos

Question 5

Intersexual selection

Answer 5

Selection for traits and increased attractiveness to females
-> colours in peacocks, bowerbirds build bowers

Question 6

Intrasexual selection

Answer 6

Selection of traits increase success at fighting

• > antlers
• > insects use ornaments to indicate strength w/o combat

Question 7

Hypothesis’ on how mate choice evolves

Answer 7

1. Good genes hypothesis - choosing mate with ‘good genes’ maximize females fitness
2. Sexy sons hypothesis - traits used in fights/display passed on to females sons, increasing likelihood of mating in future

Question 8

What are intromittent organs?

Answer 8

Specialist organ for delivery of sperm

Ex- penis

Question 9

Give examples of different kinds of intromittent organs

Answer 9

1. Hectocotylus - in octopus one arm has slightly different tissue and allows it to become erect
2. Aedeagus - insects
3. Hemipenes - squamates (snakes, lizards) stored inside until ready for copulation
4. Penis - often with baculum in mammals - tiny bones - apes

Question 10

How do males ensure sperm fertilizes females?

Answer 10

Male guarding to prevent other males near female

Ex- damselflies wheel position and use copulatory organ to remove sperm of other male

Question 11

Intersexual conflict

Answer 11

Fruit flies use chemicals to kill sperm of others - chemicals damage females
Bed bug male have needle like structure for traumatic insemination of females

Question 12

Cloacal ‘Kiss’

Answer 12

Some birds do not have special organs for reproduction - use same opening for excretion as for reproduction