BIOC54 March 26, 2011
•Mating systems is who mates with whom, and under what conditions. The different
ways in which animal societies are structured with respect to what individuals mate
and pair bond with each other.
•It specifies the number of individuals a male or female will mate with, and under what
circumstances that will happen.
•You can classify mating systems based on what males are doing, what females are doing
or on a combination of the two.
•If we look at the number of individuals someone mates with: 1 = monogamy. > 1 =
polygyny ( 1 male, many females), polyandry ( 1 female, many males), promiscuity (
both males and females mate with multiple individuals in the opposite sex).
•Polygamy: where one sex is mating with multiple partners.
•You can define mating systems in a couple of different ways, and in the past, mating
systems were defined as social mating systems. It was hard for people to figure out what
was really going on. It is based on the observed interactions between individuals. Do
they pair bond? Engage in parental care together? Do they stay together for a long time?
oThis is interesting when it comes to looking at sharing and rearing of offspring,
but can be inaccurate when looking at life time reproductive success, which is the
ultimate currency for evolutionary change.
oSo we need to know not just who is socially pair bonded, but also what the
genetic mating system is. This is based on paternity or maternity. People may be
socially bonded, but the maybe the male is helping rear offspring that are not his
oDNA fingerprinting helps identify paternity and maternity.
oWhich of the system is the most common mating system? Polygyny . Because of
differences in parental investment.
•Why do we have systems that are not polygynous?
oMale genetic monogamy is a puzzle.
oAbout 3% of mammals and 90% of birds are monogamous. Social monogamny is
far more common in birds.