Mating systems Flashcards
what are the 4 types of mating systems?
monogamy
polygamy:
- polygyny
- polyandry
- promiscuity
define:
polygyny
polyandry
promiscuity
males mate with multiple females
females mate with multiple males
both sexes have multiple partners
what are the features of monogamy?
male + female form pair bond
each male + female has 1 mate during a breeding season
sometimes have bi-parental care
what are the different hypotheses for being monogamous?
mate-guarding hypothesis
mate-assistance hypothesis
what is the mate-guarding hypothesis?
if the female remains receptive after the 1st mating
the male might stick with her and prevent her from mating with others
as low likelihood of finding a 2nd female
what is the mate-assistance hypothesis?
protection
- males protect breeding territory
bi-parental care
- 2 parents provide better care than 1
why would males protect females in the mate-assistance hypothesis if it increases their risk?
increases their risk of dying
BUT decreases inseminated female’s risk
female is carrying the male’s offspring
-> so would increase reproductive success
describe an experiment which demonstrates monogamous parents compensating
put a weight on a bird
= additional effort when it collects food for young
if the female was weighted the male compensated and vice versa
NOT completely compensated so overall less results
how do we know socially monogamous animals are NOT genetically monogamous?
extra-pair fertilisations and copulations are common
EPFs detected by DNA fingerprinting
what are the benefits of being polyandrous?
EPFs can allow females to find males with better genes
genetic variety of offspring
reduce infanticide risk
- some chance the offspring are that male’s
reduce male harassment
- if female mates with a male, heel leave her alone
more resources
what are the costs of polyandry?
STIs
predation while searching for mares
mating when could be getting food for young
what are the features of polyandry?
male provides care for young
females are larger + more aggressive
can lead to infanticide by females
e.g. in shorebirds
give an example of polyandry in mammals
Callitrichids
females always have twins which are large (25% of her weight at birth)
female mates with multiple males
-> their help is needed to carry the young
what are the features of polygyny?
some males mate with many females
BUT other males remain unmated
females mate with single mate
females provide most or all care for young
male size»>female size
what are the types of polygyny?
female defence
resource defnce
lek
describe female defence polygyny
females aggregate in favourable breeding sites where males can monopolise several females
- male guards territory
describe resource defence polygyny
- males settle on breeding territoires (resource)
- females choose a mate (i.e. territory)
some males are chosen by several females
-> the secondary/tertiary female pays a cost as the male only helps the primary female raise young
BUT better to have the good territory
describe the features of leks
males display on very small territories that have no resources = lek
males provide no care for young
females visit many males but copulate with one
male mating success heavily skewed
how are leks beneficial?
males
- if females are widely distributed
- > leks attract females
females
- reduced the cost of searching for a mate
describe the mating system of Dunnocks
highly variable
monogamy, polygyny, polyandry + polygynandry can all occur in the same population
when is RS highest for males and females in Dunnocks?
..so what is the observed mating system?
males
= polygyny
females
= polyandry
a compromise between the interests of males and females
-> outcome determined by resource distribution
what is the female distribution theory of mating systems?
females are distributed according to resources
males distributed according to females
give an example of why males might be parental
Stickleback
- males build nests that attract females to lay clutches
- > male protects eggs
male can guard 10 clutches until hatch
-> females can only lay 7 w/out care
give an example of a brood parasite
why do they accept the eggs?
what is the risk to being a brood parasite?
Cuckoos lay eggs in reed warbler nests
if parent mistakenly removes own egg
-> maybe most costly than excepting cuckoo egg
host might not accept all/any eggs
