Unit 2: Organisms and Evolution, Sex and Behaviour Flashcards
Which sex has the greater parental investment?
There is greater investment by females
Why do females have greater parental investment than males?
Because there is female investment in the egg structure in non-mammals or in the uterus and during gestation in mammals.
What is a disadvantage and advantage of parental investment?
Parental investment is costly but increases the probability of production and survival of young.
What are the characteristics of an 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 the characteristics of a K-selected species?
-Larger and live longer
-mature more slowly
-reproduce many times in their lifetime
-produce a smaller number of larger offspring, each of which receive a larger energy input
-high level of parental care
-many offspring have a high probability of reaching adulthood
In what environment is an r-selected species and a K-selected most likely to occur?
r-selected species: In an unstable environment
K-selected species: in a stable environment
What are the costs of external fertilisation?
-many gametes predated or not fertilised
-no or limited parental care
-few offspring survive
What are the benefits of external fertilisation?
very large numbers of offspring can be produced
What are the benefits of internal fertilisation?
-Increased chance of survival for offspring
-Offspring can be retained internally for protection or development
-Increased chance of successful fertilisation
-Fewer eggs required
What are the costs of internal fertilisation?
-A mate must be located which increases energy expenditure
-Requires direct transfer of gametes from one partner to another
What are the four different mating systems called?
Monogamy
Polygamy
Polygyny
Polyandry
What is monogamy?
A pair of animals mate exclusively with each other
What is polygamy?
Individuals of one sex have more than one mate.
What is polygyny (polygamy)?
One male mates exclusively with multiple females
What is polyandry (polygamy)?
One female mates exclusively with a number of males in one breeding season
What can successful courtship rituals 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
What is sexual dimorphism?
The physical difference between males and females of a species
What are males’ traditional physical traits as a result of sexual dimorphism?
Males are usually more conspicuous with their markings, behaviour and structure.
What are females’ traditional physical traits as a result of sexual dimorphism?
Females are generally inconspicuous
What is reversed sexual dimorphism?
When females are more conspicuous and males are less noticeable and prominent
What are honest signals?
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 happens at 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.
What do males do in male-male rivalry when competing for females?
Males will fight for dominance and access to females, often using elaborate ‘weapons’ such as antlers, tusks, horns.
What does sexual selection select for?
It selects for characteristics that have little survival benefit for the individual, but increase their chances of
mating.
