Unit 2 - Sex and Behaviour Flashcards
Who has greater parental investment?
Greater investment by females
What is female investment?
Female investment in the egg structure in
non-mammals or in the uterus and during
gestation in mammals
What is parental investment?
Parental investment is costly but increases
the probability of production and survival of
young
What are characteristics of r-selected species?
- smaller,
- have a shorter generation time
- mature more rapidly,
- reproduce earlier in their lifetime, often only once,
- produce a larger number of smaller offspring, each of which receives only a smaller energy input,
- limited parental care,
- most offspring will not reach adulthood
What are characteristics of k-selected species?
- larger
- live longer
- mature more slowly,
- can reproduce many times in their lifetime,
- produce relatively few,
- high level of parental care,
- many offspring have a high probability of surviving to adulthood.
Where do r-selection take place?
r-selection tends to occur in unstable
environments where the species has not
reached its reproductive capacity
Where do k-selection take place?
whereas K-selection tends to occur in stable environments
What are the benefits of external fertilisation?
-benefits: very large numbers of offspring
can be produced
What are the costs of external fertilisation?
- many gametes predated not fertilised
- no or limited parental care
- few offspring survive
What are the benefits of internal fertilisation?
- increased chance of successful fertilisation
- fewer eggs needed
- offspring can be retained internally for protection
and/or development - higher offspring survival rate
What are the cost of internal fertilisation?
- a mate must be located, which
requires energy expenditure - requires direct transfer of gametes from one
partner to another
What are mating systems based on?
Mating systems are based on how many
mates an individual has during one breeding
season
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 is a fixed action pattern (FAP)?
An instinctive behaviour response triggered by a specific stimulus. Once triggered, the FAP behaviour can’t be stopped midstream but must play out to completion.
What is a sign stimulus?
A trigger that provokes a behavioural response.
What characteristics do sexual selection select?
characteristics that have little survival benefit for the individual, but increase their chances of mating
What are female species typically?
Females are generally inconspicuous
What are male species typically?
usually have more conspicuous markings,
structures and behaviours.
Why are females typically more inconspicuous?
To remain concealed, reducing predation and increasing survival chance of her offspring.
What does successful courtship behaviour can be as a result of?
species-specific sign
stimuli and fixed action pattern responses
What is reversed sexual dimorphism?
When the normally inconspicuous female is larger or more ornate than the male.
What can honest signals indicate?
Honest signals can indicate favourable
alleles that increase the chances of survival
of offspring (fitness) or a low parasite burden
suggesting a healthy individual.
What does female choice involve?
Female choice involves females assessing
honest signals of the fitness of males
What is lekking and what are some animals that do this?
- males gather to display at a lek, where female choice occurs.
- Some bird species exhibit lekking behaviour.
What does success in male-male rivalry increase?
Success in male-male rivalry through conflict
(real or ritualised), increases access to
females for mating
What is male-male rivalry?
Males will fight for dominance and access to
females, often using elaborate ‘weapons’
such as antlers, tusks, horns.
What happens during a lek?
Dominant males occupy the centre of the lek,
with subordinates and juveniles at the fringes
as ‘satellite’ males. During the display,
female choice occurs.
