mating systems Flashcards
what is a mating system
any pattern of male-female pairings
describes how male and female interactions are built around choosing mates
females invest heavily in each of a:
where as males invest little in each of a:
small number of gametes
large number of gametes
males produce
large number of small motile sperm
females produce
small number of eggs w large investment in each; leads to mate choice
natural selection favoured small and fast motile gametes; to balance this:
large nutrient rich gametes gives rise to large, well developed offspring
protandrous
males early in development, females later, like clownfish
protogynous (gyn first)
females when smaller, then males when larger
sex carries a high evolutionary cost:
cost of meiosis (splitting the genome up)
sexual reproduction ____ genes are passed on, asexual reproduction ____ genes passed on
half, all
intersexual selection (between different sexes)
effects that mating preferences of one sex have on the characteristics of the other ex mate attraction and mate choice
intrasexual selection (within same sex)
effects of competition within one sex for mates, ex combats, displays
any trait preferred by females will be
strongly favoured
females should make their choices among males based on the likelihood that mating w the chosen male will
enhance the survival of the female’s offspring; good genes passed on
bad boy phenomenon
male attractiveness rather than gene quality is the currency –> explanation: sexy sons more likely to get matings BUT bad boys don’t make good dads
what factors go into mate choice (10)
- species identification
- good genes
- inbreeding avoidance
- optimal outbreeding
- resources
- symmetry
- immuno- competence
- immuno- complementarity
- quality as a parent
- sexy son
runway inter-sexual selection
can result in features being overly emphasized to the point they impede on survival
costly signals provide
info on the mate; honest info on males quality, male cannot pretend ex deep voice or big horns
index hypothesis
dishonest signals cannot be faked
handicap principle
dishonest signals too costly to fake
dishonest signals
false representation of an animal’s genotype or of its resources, includes misrepresentation of mate quality in mate choice or females two timing males
courtship is
an exchange of info between male and female
courtship should
- include signals that allow makes and females to ensure they are mating w animal of same species
- include info that would prevent inbreeding
- give animal opportunity to present info about their quality as a potential mate
monogamy
one male mates exclusively w one female
polygamy
individuals mate w more than one parter
2 types of polygamy
- polygyny; males mate w more than one female
- polyandry; females mate w more than one male
promiscuity
males mate w more than 1 female and vice versa
cat mating system
- toms not involved in parental care
- compete of oestrous female
- copulation favours ovulation
- females receptive shortly after copulation
- infanticide can occur
dog mating system
- pair bonded male and female head the pack
- males contribute to parental care
- oestrous females attract males and may mate w more than one
- possible mate guarding; stuck together during mating
what hormones in females are linked to receptivity; postural behaviours and displaying etc
LH and FSH
what is the hormone of pregnancy and sexual receptivity and will inhibit sexual behaviour if pregnant
progesterone
what hormone in males increase during maturity and remain constant
testosterone
what 2 hormones prime some animals to pair bond
oxytocin and vasopressin
testosterone causes
territoriality, fighting, roaming, muscle development, dominance
____ and ____ combine to make social system
social organization and mating system
