Unit 7 Mating systems ad parental care Flashcards
Divorce
Divorce is when a mate dies, someone from a seperate pair-bond will swoop in and pick up where they left of. (Sophie Gregouir-Trudeau’s Doctor boyfriend)
Ecological correlates of mating systems (???)
Extra-group paternity (EGP) can form an important part of the mating system in birds and mammals. However, our present understanding of its extent and ecology comes primarily from birds. Here, we use data from 26 species and phylogenetic comparative methods to explore interspecific variation in EGP in mammals and test prominent ecological hypotheses for this variation. We found extensive EGP (46% of species showed more than 20% EGP), indicating that EGP is likely to play an important role in the mating system and the dynamics of sexual selection in mammals. Variation in EGP was most closely correlated with the length of the mating season. As the length of the mating season increased, EGP declined, suggesting that it is increasingly difficult for males to monopolize their social mates when mating seasons are short and overlap among females in oestrus is likely to be high. EGP was secondarily correlated with the number of females in a breeding group, consistent with the idea that as female clustering increases, males are less able to monopolize individual females. Finally, EGP was not related to social mating system, suggesting that the opportunities for the extra-group fertilizations and the payoffs involved do not consistently vary with social mating system.
Extra-pair behaviour/copulation (Two types)
EPC
EPF
Hypotheses to explain the evolution of leks
Hotspot
Hotshot
Female pref
Monogamy
Socially, this is when one male is bonded to one female. It’s actually fairly
uncommon.
● Genetically, this would mean pairs are exclusive sex partners.
● Serial monogamy is a form of monogamy: moving from one
monogamous
relationship to another, but only being paired to one individual at a
time.
* Monogamy is the main system in birds, some primate species (humans are
fairly monogamous), and termites.
* Yes, termites. There is a king and queen termite that bond for life.
Male parental care
Gubernick, David J., and Taye Teferi. “Adaptive significance of male parental care in a
monogamous mammal.” Proceedings of the Royal Society of London B: Biological
Sciences 267.1439 (2000): 147-150.
- male hamster will pull the babies out like an OBGYN - having the father
around results in higher survival rate of their offspring
-
-Male care
in insects
* Care essential
for egg
survival
* Ancestor laid
on vegetation,
sometimes
male back
Parental care in St. Peter’s fish can come from either the male or female.
● Non-parental females are ready to spawn much more quickly, meaning
that
if the male relieves some of the cost of parental care, his mate can
reproduce again more quickly.
● There is a high cost to female parental care for the reproductive success
of
both males and females.
- sometimes
When you have bi-parental care, how beneficial is the male care?
- trade off between testosterone and parental care
- when you castrate a male, they do better at raising the kids - give them more
testosterone and they do a worse job
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Monogamy
one male paired with one female (2 seperate types exist (social monogamy and genetic monogamy))
-social means exclusive pair band
-genetically this means a pair exclusively reproduces with each other
Parental favouritism
???
Polyandry
FEMALES have multiple male partners, socially, or genetically
Polygamy
There are two forms of polygamy
Ployandry and Polygyby
Polygyny
males have multiple female partners, socially or genetically
Promiscuity
Lack of any kind of social mating system, no social pair bonds form
Pas de male investment (mainly female)
-aka socially “promiscuous”
Promiscuous systems have males get higher fitness lvl after they leave.
Sexual selection and mating systems
(Graph question)
Il y a lo repro. skew
Less dimorphism
Also mut. assessment
Adoption (and its evolution)
Adoption is a mystery in evolution (in animals) to ensure the allocation of resources to offspring that is genetatically unrelated.
- you are providing resources for offspring that are not your own
- adoption may make sense in some case
- ducks adopt a lot
- sometimes the babies are orphans
- sometimes a female will lay her eggs in a different females nest
- birds are not good at counting so they do not determine that there are
too many eggs in their nest - non-adaptive behavior
- why haven’t birds evolved to figure out which eggs are not theirs and
dump them? - brood parasite, etc.
- evolution is stepwise - if birds could discriminate perfectly, no problem
but at the beginning that isn’t true and they would end up killing their
own kids so adoption becomes less costly than rejection and they just
accept it (it is rare) - the adaptive explanation: in ducks, the females don’t have to do much, she
just brings them around she doesn’t have to feed them - ducklings are slow
and vulnerable to predation, so if the female is toting around offspring that is
not hers, she dilutes the risk to her offspring when predators come to pick
The polygyny threshold model (Graph)
Being the second female is bad…
* But being on a good territory is good…
* Some territories are so good that they
make up for the costs to females of
polygyny
* P1: Fitness of monogamous and
polygynous females is equal
* P2: Improving mated males’ territories
increases polygyny
* Both predictions generally supported
in birds
It’s variation in the resources (like territory quality) of different males that makes polygyny a viable option.
* Territory quality has implications for reproductive success.
A female can have higher fitness as a second female on a high-quality territory than as a single
female on a poorer-quality territory.
She should choose the mate that can
increase her fitness.
* The difference in fitness for a female when either monogamous or polygynous is known as the polygyny threshold model
- B is the polygny threshold - the territory has to be “B” better to be a
secondary female than a primary female
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Parental Care
(and reasons males/females offer it)
(cost and benefits)
P. Care boosts fitness ability and survival rate of offspring
: Sometimes offsprings cannot fend for own safety
But energy put into offspring (current) means reduced energy for offspring later.
*
Kinds of Mating systems (6)
-social vs genetetic
-nature is messy
-mixed systems
-rapid evo.
-promiscuity
-monogamy
-polygyny
-polyandry
social mating system
Is socially ________ but can/might mate with multiple partners if desired. (People)
