Mating Systems

1
Mating Systems
2
Mating System

• Species typical pattern of mate-finding,
  reproduction and parenting of offspring

3
Kinds of mating systems
Number of females
Number of males
Monogamy
Polygyny
Polygamous
Polygynandry
Polyandry
4
Kinds of mating systems
Monogamous Mating Systems
-a mating system in which one male and one female
for and mate with only each other during a given
breeding season
To put it another way -neither sex is able to
monopolize more than one member of the opposite
sex
5
Kinds of mating systems
Monogamous Mating Systems
First question - why should a male be monogamous?
If the particular niche dictates that a male will
do better reproductively staying with one mate -
will do so.

• mates are scarce
• resources are scarce or non-defendable

6
Kinds of mating systems
Monogamous Mating Systems
1. Mate assistance hypothesis
-male stays with one female because it is to his
advantage to help raise offspring
Hippocampus whitei
-male carries offspring -brood pouch contains 1
clutch -no point to new matings
7
Kinds of mating systems
Monogamous Mating Systems
2. Mate guarding hypothesis
-male spends time with mate to ensure
fertilization

• Assumes
• Females are scarce (highly male-biased OSR)
• Females will mate multiply

Hymenocera elegans

• male stays with female for weeks
• female receptive every 3 weeks

8
Kinds of mating systems
Monogamous Mating Systems
3. Female-enforced monogamy
-female blocks polygamous moves by mate
Icteria virens (yellow-breasted chat) -
aggression by females
More aggressive
0
Less aggressive
Toward Toward
Toward males females
wrens
9
Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - males mate with several females
a. Female Defense Polygyny
-females live in permanent groups that males
defend
Male
10
Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
b. Resource Defence Polygyny
- males defend resource females need
Lamprologus -males gather and defend oviposition
sites - mollusc shells
11
Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
c. Lek Polygyny
- males compete for high rank
12
Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
c. Lek Polygyny
- males compete for high rank
Upper limit on lek effectiveness
Mating rate
10
0
Lek size
13
Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
d. Scramble competition
-females are available for a short period -males
mate with as many as possible
14
Kinds of mating systems
Polygamous Mating Systems

• Polygamous
• Polygyny

a. Female Defence Polygyny
Male controls access to resources
b. Resource Defence Polygyny
c. Lek Polygyny
Male cant control access to resources
d. Scramble Competition
15
Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Jacana
Male territories
Female territory
16
Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Kinds of Polyandry
1. Sperm replenishment
-females mate multiply to get extra sperm
e.g. Drosophila
1 mate
Multiple mates
of eggs
Time
17
Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Kinds of Polyandry
1. Sperm replenishment
2. Prostitution - females mate with males to get
access to resources
3. Resource Defense - females control access to
resources
4. Lek Polyandry - females compete for dominance
- some primate troops
18
Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Benefits of Polyandry

• Sperm replenishment
• - add to a depleted supply of sperm
• - avoid cost of storage

2. Material benefits
3. Genetic benefits -replace inferior sperm -
increase genetic variance in offspring
4. Convenience - avoid cost of fending off
copulatory attempts
19
Kinds of mating systems
Are mating systems fixed? - do all members of
a species conform to one mating system
How monogamous is monogamy?
Indigo bunting
Within pair
Extra-pair
0
12
Days before egglaying
20
Kinds of mating systems
Are mating systems fixed? - do all members of
a species conform to one mating system
How monogamous is monogamy?
Indigo bunting
Rate of extra pair copulation - 27 - 76
21
Kinds of mating systems
Are mating systems fixed? - do all members of
a species conform to one mating system
How monogamous is monogamy?
Humans
U.S.-10 - 18
Yanomama - 9
!Kung - 2 - 3
22
Summary
Mating Systems
Monogamous 1. Mate assistance hypothesis

• Polygamous
• Polygyny

2. Mate guarding hypothesis
a. Female Defence Polygyny
3. Female-enforced monogamy
b. Resource Defence Polygyny
c. Lek Polygyny
d. Scramble Competition
2. Polyandry
a. Sperm replenishment
b. Prostitution
c. Resource Defence
d. Lek