Key Area 4 - Sex & Behaviour Flashcards
Parental Investment
What sex gives greater parental investment?
Greater investment by females.
Female investment in the egg structure in
non-mammals or in the uterus and during
gestation in mammals.
Explain parental investment
Parental investment is costly but increases
the probability of production and survival of young.
Give characteristics of K-selected species
Characteristics of K-selected species: larger
and live longer; mature more slowly; can
reproduce many times in their lifetime;
produce relatively few, larger offspring; high level of parental care; many offspring have a high probability of surviving to adulthood.
Name two classifications of organisms based on the level of parental investment in offspring and the number of offspring produced
r-selected (r-strategists) and
K-selected (K-strategists).
Give characteristics of r-selected species
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.
Where do r-selected and K-selected species tend to occur?
r-selection tends to occur in unstable
environments where the species has not
reached its reproductive capacity, whereas K-selection tends to occur in stable environments.
Give costs and benefits of external
fertilisation
benefits: very large numbers of offspring
can be produced.
costs: many gametes predated or not
fertilised; no or limited parental care; few
offspring survive.
Give costs and benefits of internal fertilisation
benefits: increased chance of successful
fertilisation; fewer eggs needed; offspring
can be retained internally for protection
and/or development; higher offspring
survival rate.
costs: a mate must be located, which
requires energy expenditure; requires
direct transfer of gametes from one
partner to another.
Reproductive Behaviours & Mating
Systems in Animals
What are mating systems based on?
Mating systems are based on how many
mates an individual has during one breeding season.
Name the four ranges of mating systems
Monogamy, Polygamy, Polygyny, Polyandry.
Explain monogamy
Monogamy: the mating of a pair of animals to the exclusion of all others.
Explain polygamy
Polygamy: individuals of one sex have more
than one mate.
Explain polygyny
Polygyny: one male mates exclusively with a group of females.
Explain polyandry
Polyandry: one female mates with a number of males in the same breeding season.
Many animals have ‘ ‘-selection courtship
rituals
Many animals have mate-selection courtship rituals.
What can successful courtship behaviour in birds and fish be a result of?
Successful courtship behaviour in birds and
fish can be a result of species-specific sign
stimuli and fixed action pattern responses.
Describe females and males in terms of markings, structures and behaviours
Females are generally inconspicuous; males usually have more conspicuous markings, structures and behaviours.
What is sexual selection?
Sexual selection selects for characteristics
that have little survival benefit for the
individual, but increase their chances of
mating.
What does female choice involve?
Female choice involves females assessing
honest signals of the fitness of males.
What can many species exhibit as a product of sexual selection?
Many species exhibit sexual dimorphism as a product of sexual selection.
Reversed sexual dimorphism occurs in some species.
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.
Explain how some bird species exhibit lekking behaviour
Some bird species exhibit lekking behaviour. Dominant males occupy the centre of the lek, with subordinates and juveniles at the fringes as ‘satellite’ males. During the display, female choice occurs.
Where does female choice occur?
In lekking species, males gather to display at a lek, where female choice occurs.
What does success in male-male rivalry through conflict (real or ritualised) increase?
Success in male-male rivalry through conflict (real or ritualised), increases access to females for mating.
Males will fight for dominance and access to females, often using elaborate ‘weapons’
such as antlers, tusks, horns.
