Sex and Behaviour Flashcards
What are the pros and cons of parental investment?
costly but increases the probability of production and survival of young
What are the 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 the 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.
When does r-selection and k-selection 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
What are the 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
What are the 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
What are mating systems based upon?
Mating systems are based on how many mates an individual has during one breeding season
These range from polygamy (polygyny & polyandry) to monogamy, what are these?
the mating of a pair of animals to the exclusion of all others. Polygamy individuals of one sex have more than one mate. Polygyny_ one male mates exclusively with a group of females. Polyandry_ one female mates with a number of males in the same breeding season_
What does sexual selection do?
selects for characteristics that have little survival benefit for the individual, but increase their chances of mating
What often happens as a result of sexual selection?
Sexual dimorphism - Females are generally inconspicuous; males usually have more conspicuous markings, structures and behaviours. Reversed sexual dimorphism can also occur.
What does female choice involve?
females assessing honest signals of the fitness of males
What are honest signals?
They can indicate favourable alleles that increase the chances of survival of offspring (fitness) or a low parasite burden suggesting a healthy individual.
What is lekking?
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.
What is male-male rivalry?
Males will fight for dominance and access to females, often using elaborate ‘weapons’ such as antlers, tusks, horns. Success in male-male rivalry through conflict (real or ritualised), increases access to females for mating
