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
Less aggressive
Toward Toward Toward
males females wrens

9. Kinds of mating systems
Monogamous Mating Systems
3. Female-enforced monogamy
-female blocks polygamous moves by mate
Burying beetle – Nicophorus defodiens

10. 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

11. 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
Yellow-bellied marmot

12. 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

13. Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
c. Lek Polygyny
- males compete for high rank

14. 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
Lek size

15. Kinds of mating systems
Polygamous Mating Systems
1. Polygyny - male mate with several females
c. Lek Polygyny
Hypotheses for the formation of leks
1. Hotspot Hypothesis
2. Hotshot Hypothesis
3. Female Preference Hypothesis

16. 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

17. 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 can’t control access to resources
d. Scramble Competition

18. Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Jacana
Male
territories
Female
territory

19. 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

20. 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

21. Kinds of mating systems
Polygamous Mating Systems
2. Polyandry - one female mates with several males
Genetic Benefits of Polyandry
1. Egg fertilization insurance via acquisition of sufficient numbers of competent sperm.
2. Better sperm with genes acquired from preferred sexual partners.
3. Genetic variety gained via acquisition of genetically diverse sperm.
Material Benefits of Polyandry
1. Acquisition of resources controlled by mating partners.
2. Acquisition of parental care from mating partners.
3. Improved foraging success via distraction of a male foraging competitor.
4. Reduced risk of sexual harassment form non-partners.

22. Polyandry – do the data support the hypothesized benefits?
Egg fertilization insurance via acquisition of sufficient numbers of competent sperm.
Prairie dogs

23. Polyandry – do the data support the hypothesized benefits?
3. Genetic variety gained via acquisition of genetically diverse sperm.
Yellow-toothed cavy

24. 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 12
Days before egglaying

25. 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 %

26. Kinds of mating systems
What are females gaining in extra-pair copulations?
Agelaius phoeniceus
100 50
% of broods with EPC nestlings

27. 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 %
Yanomama - 9%
!Kung %

28. 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