Class Notes (922,589)
CA (542,889)
UTSC (32,931)
BIOC54H3 (13)
Lecture

Lecture Notes

9 Pages
80 Views

Department
Biological Sciences
Course Code
BIOC54H3
Professor
Maydianne Andrade

This preview shows pages 1-3. Sign up to view the full 9 pages of the document.
BIOC54 March 26, 2011
Lecture 6
Mating Systems
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.
www.notesolution.com
BIOC54 March 26, 2011
Lecture 6
oHowever, when you look at genetic monogamy, 90% of 180 social monogamous
species are polygamous.
oGenetic monogamy is rare.
oExample: Clown Shrimp: marine invertebrates they show social and genetic
monogamy in a 3 week breeding period. Females have a short period receptivity,
and produce eggs. And males will only fertilize one females eggs.
oSea Horses : similar to pipe fish. Males have brood pouches. The females give
eggs to only one male, and male accepts eggs from only one female. Social and
genetic monogamy
oPrairie voles : socially and genetically monogamy and they produce life long pair
bonds.
oFiordland crested penguins : socially and genetically monogamous. They live in
newzealand and pair bond for life and rear offspring together for life
oMarmosets : socially and genetically monogamous : Its very hard to produce the
offspring. Females lose 20% of their weight while lactating, and must feed
continuously to feed the baby. The males must always carry the offspring until
they are independent.
Hypotheses for male monogamy :
oFemale enforced monogamy: females attack males and constrict them from
mating with many people. Conflict between males and females.
oMate assistance hypothesis: Males get a net benefit from providing parental care.
Cost-benefit based on the males own reproductive success
oMate guarding: Payoffs for guarding is high and a few mating opportunities exist.
Conflict between males and females.
Female enforced monogamy:
o Razorbill: a sea bird in the North Atlantic. Males help to rear offspring.
Females physically attack males if they try mating with other females. It is
expensive for males to form extra pair bonding if females are vigilant.
oBurying Beetles: in beetles when something dies, they take the body, strip off
all the fur, dig a hole and put the dead animal in it. Once the dead organism rots,
they lay their eggs on it. The babies hatch, and parents chew up the rotting
www.notesolution.com
BIOC54 March 26, 2011
Lecture 6
carcass and give it to the baby. Males find the dead body, and release
pheromones to attract females. If the carcass is big, the male tries to attract even
more females, and at that point the females attack them.
Male assistance hypothesis:
oCalifornia Mice: breed in California during the coldest part of the year. They
dig /inhabit burrows. They care for pubs until the pubs are independent (old
enough). Temperature in the burrow is critical. Having the males in the burrow
increases the temperature of the burrow. Having male in the burrow doesnt
affect the birth, but it affects how many survive and emerge. It is too costly for
the males to abandon the females.
oThis hypothesis explains why monogamy is more common in birds
In birds, male can contribute more to the offspring survival than in
mammals. Example : in barn swallow : the male and females both have
brood patches
In mammals: only females can lactate and gestate the young, and the
males cannot assist as much.
Mate guarding :
oPayoff for guarding is high : Blue milkweed beetle : last male sperm precedence
oOther mating opportunities is limited
oDeep-sea anglerfish : females are so widely distributed and hard to find and
the males just attach to the females for the rest of their life
oClown Shrimp: their other mating opportunities are limited.
Why do female engage in EPC? In any mating systems (Polyandry)
oHistorical studies on mating system were done only by observations (social
groupings), so polyandry came as a surprise and a puzzle.
oBiological reasons why this is unusual is because females can fertilize all their
eggs from the sperm that the mate gives her. And female reproductive output
does not increase with the number of mated.
EPC is expensive for females when they form EPC and the parental care decreases by
their mates. There are also STD.
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
BIOC54 March 26, 2011 Lecture 6 Mating Systems 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? o This 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. o So 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 o DNA fingerprinting helps identify paternity and maternity. o Which 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? o Male genetic monogamy is a puzzle. o About 3% of mammals and 90% of birds are monogamous. Social monogamny is far more common in birds. www.notesolution.com
More Less
Unlock Document


Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit