Sex and Behaviour Flashcards
Sperm production
high number, little energy store
Egg production
low number, large energy store
Where does r selection tend to occur?
in unstable environments where the species has not reached its reproductive capacity
Where does k selection tend to occur
in stable environments
Characteristics of r selected species
smaller
shorter generation time
reproduce earlier in their lifetime
often reproduce only once in their lifetime
mature more rapidly
limited parental care
Characteristics of k selected species
larger and live longer
mature more slowly
high level of parental care
produce relatively few, larger offspring
can reproduce many times in their lifetime
High female investment in
egg structure in non-mammals
in the uterus and during the gestation period in mammals
Internal fertilisation benefits?
fewer eggs needed, increased chance of successful fertilisation, offspring retained internally for protection/development;higher offspring survival rate
External fertilisation benefits?
very large number of offspring produced
Internal fertilisation cost?
a mate must be located which requires energy expenditure, requires direct transfer of gametes from one partner to another
External fertilisation cost?
many gametes predated or not fertilised, no or limited parental care, few offspring survive
Sexual dimorphism
Females are generally inconspicuous; males usually have more conspicuous markings, structures and behaviours
What are mating systems based on?
how many mates an individual has during one breeding season
Successful courtship behaviour in birds and fish can be a result of
species-specific sign stimuli and fixed action pattern responses
What happens in lekking species
males gather to display at a lek, where female choice occurs
What is monogamy?
the mating of a pair of animals to the exclusion of all others
What Is polygamy?
individuals of one sex have more than one mate
What is polygyny?
one male mates exclusively with a group of females
What is polyandry?
one female mates with a number of males in the same breeding season
What does female choice involve?
females assessing honest signals
Honest signals indicate favourable
alleles that increase the chances of survival of offspring (fitness)
Honest signals indicate a low
parasite burden suggesting a healthy individual
Some species exhibit lekking behaviour where
dominant males occupy the centre of the lek, whereas subordinates and juveniles gather at the fringes as ‘satellite’ males
What occurs during the lekking display
female choice
