8. Mating Systems Flashcards
What is monogamy?
One male and one female in a mating pair
What is polygyny?
One male mating with multiple females
What is polyandry?
One female mating with multiple males
What is promiscuity?
Both males and females having multiple partners
What is polygamy?
Polyandry, Polygyny, and Promiscuity
What are the three types of mating systems?
No male care
Lekking and variations
With male care
In systems with no male care, what determines the males reproductive tactics?
Female distribution in space and time.
Even = low potential for polygamy
Patchy = high potential for polygamy
What is OSR?
Operational Sex Ratio
Ratio of receptive females to sexually active males
What are the two types on breeders found with temporal dispersion of females?
Prolonged breeders (Bullfrogs - 0-6 mates/male) Explosive breeders (Common toad - 1-2 matings/male)
What are the characteristics of a mammalian mating system when the females are solitary with defensible range?
If female range is small - Polygamy
If range is large - Monogamy
Males may help with offspring care or predator defense
Parental care - larger litter size
What are the characteristics of a mammalian mating system when the females are solitary with a non-defensible range?
Females and males only associate during oestrus
E.g. Orang-utan - Females move with resources (fruit)
When would scramble competition polygyny occur?
Females are solitary and the range is not defensible
e.g. ground squirrels, males constantly monitor females to find one in oestrus
What happens when females are social and the range is defensible?
Harems for many primates
Large range - several males defend territory
Males compete over females (sometimes leads to infanticide)
What happens when females are social and the range is not defensible?
Female dispersal in space and time.
If daily movements are predictable - defense of mating territories
If daily movements are not defensible - sometimes harem defence (seasonal or permanent)
What is lekking?
When males group together and advertise qualities.
Females only visit leks to mate
Mating success is normally very skewed within the lek
When does lekking normally occur?
When neither females nor resources are defensible
What are the 5 reasons as to why lekking may occur?
Hotspots hypothesis Hotshot males To increase female attraction To facilitate mate choice Reduce predation
What is the hotspot hypothesis?
Males cluster in areas that females frequent
What is the hotshot hypothesis?
Males cluster around high quality males
Why lek to attract females?
Stimulus pooling - Several males create a more powerful signal than one
Why lek to facilitate female choice?
Females prefer aggregations - provides a ‘testing ground’
Why lek to reduce predation?
Calling males are safer - dilution effect etc
When do males become a resource to females?
When they start providing parental care
What is obligate monogamy?
Both parents necessary to raise offspring
Increase in fitness if stay with same mating partner and share raising brood
Seeking a new mate can be costly - time taken to synchronise (White’s seahorse)
What are some of the benefits of polyandry? (similar to mate choice benefits in general)
Direct - resources, offspring care, reduction in infanticide
Indirect - good genes, inbreeding avoidance, diversity among offspring, disease resistance
How is monogamy often enforced?
By partner’s behaviour - anti-aphrodisiacs, damage to female, mate guarding, mating plugs
Costs of polygyny - time, energy, search costs, STI
Lack of available mates OSR
When do many polygamy conflicts occur?
When the males and females have different optimum mating behaviours
Which species have a sex role reversal
Pipefish
Red-necked phalarope
Spotted sandhopper
What is Batemann’s logic behind sex role reversal?
Male RS limited by time
Female RS limited by matings
Are males stuck to one mating tactic?
No they are able to switch between, once the male becomes large enough he will switch to aggressive tactic
When will only the largest males be successful?
When male-male competition is intense
What is a protogynous sex change?
Starting life as a female and switching to male when largest
What is a protoandrous sex change?
Starting life as a male and changing sex when largest
