Mating Systems Flashcards
What is monogamy?
- A bond between a single male & single female
- Can last for part or whole of breeding season or for a lifetime
What is polygamy?
- Individual has more than 1 mate in a breeding season or lifetime
What is polygyny?
1 male, many females
What is polyandry?
1 female, many males
What is promiscuity?
Both males & females may mate with different individuals- have no outside relationship
When is monogamy favoured?
- When males have little opportunity to monopolise multiple females as they are widely dispersed
- When sex ratios are biased in favour of 1 sex (females hard to locate or receptive for brief periods, promotes mate guarding)
What is the disadvantage with mate guarding?
A female left by one male would potentially rapidly acquire another partner whose sperm would them fertilise her eggs
Therefore Venetian for a male to remain with his partner if receptive females are scarce
How is fitness in monogamy maximised?
Shared parental care
Of either parents deserts, increased risk of mortality (wouldn’t pass genes to next generation)= “mate assistance hypothesis”
What does monogamy assume?
Assumes mating only between the pair and that offspring are the progeny if the pair exclusively
In reality, they’re not always as monogamous as we think
Monogamous Examples
Red backed salamander- females are aggressive towards partners who stray and have pheromones from other females on them
Shingleback (lizard). Mostly monogamous and keep same partner up to 10yrs. Pairs ones mate earlier then unpaired= advantage.
What are the different types of polygyny?
- Female/harem defence polygyny
- Resource defence polygyny
- Scramble competition polygyny
- Lek polygyny
What is female/harem defence?
Males control access to females directly (due to female gregariousness)
What is resource defence polygyny?
Males control access to females indirectly by monopolising critical resources
(E.g- females in breeding condition they need access to resource must mate with them to gain access)
Male elephant seals, ‘beach master’
What affects the ability of males to monopolise resources?
The spatial distribution
What is the polygyny threshold model?
Predicts the female should accept the role of the 2nd mate when there are superior resources as opposed to being monogamous on a poor quality area.
Example of polygyny threshold model!
Female red winged blackbirds
- polygynous mating decreases reproductive success
- nesting over water increases reproductive success
What is the advantages/disadvantages of polygynous relationship in birds?
The females have a lower fledging success rate when shared with another female.
However males will have the success of both the ‘mistress’ and main partner combined
What is Scramble polygyny?
When receptive females are widely dispersed, males better off not being territorial but to just try their hardest to find a female.
Males success entirely dependant on ability to move around and compete for female
Example of scramble polygyny?
Female 13-lined ground squirrels live in fairly spaced out groups: males male rounds visiting burrow sites.
Involves direct male-male/sperm competition
Makes can smell via urine or hormones if female is coming into season (may visit this individual more often)
What is explosive breeding assemblage?
Females become receptive for only a brief time and congregate at a breeding site
Males gather there too and compete for females (frogs)
What is lek polygyny?
Males congregate at predictable location in lekking species
Males display for females and they choose males on appearance and displays (sexual selection)
Males provide no resources including parental care
Example of lek species?
Lechwe
Kob
Topi (antelope(
Leks form because males can’t monopolise females
What are the hypotheses for evolution of lekking?
- Hot Spots
- Hot Shots
- Female Preference
What is the hot spots hypothesis?
Males gather at sites where they are likely to encounter females
