2.4 Sex and behaviour Flashcards
(23 cards)
Sperm are produced oil much larger numbers than eggs but each egg has a larger …..
Energy source.
Females make large investment in what?
Egg structure in non-mammals and uterus and gestation in mammals.
Parental investment is costly but increases what?
Probability of production and survival of young.
Describe R-selcted species.
Shorted gestation time, mature more rapidly, reproduce earlier in life, produce larger number at one time, smaller offspring.
Give limited parental care so most offspring will not reach adulthood.
Explain K-selected species.
Larger, live longer, mature slower, reproduce man times in one lifetime, produce relatively few offspring.
High level of parental care so offspring have high probability of surviving to adulthood.
R-selcted offspring and K tends to occur where?
R - unstable environments where species has not reached reproductive capacity.
K - stable environments.
Explain internal fertilisation.
Fewer eggs needed, increases chance of fertilisation, Offspring retained internally for protection or development, high level of parental care so high survival rate.
Explain external fertilisation.
Very large numbers of offspring, many gametes predated or it fertilised, no or limited parental care so few offspring survive.
What is polygamy?
Individuals of one sex have more than 1 mate.
Disadvantages of internal fertilisation.
Energy used to locate male, requires difficult direct transfer of gametes from one partner to another.
What is monogamy?
Individuals only have one mate.
One male mates exclusively with a group of females.
Polygyny
One female mates with a number of males in the same breeding season.
Polyandry
Many animals have met-selction courtship rituals which include.
Species-specific sign stimulus and fixed action pattern.
What are sign stimuli?
Actions or appearances given by an individual that signal intent often for courtship or mating.
Sexual selection selects for characteristics that increase chance of mating but have little …
Survival benefit.
What is sexual dimorphism?
Females are inconspicuous and males are conspicuous, markings, structures, behaviours.
What is fixed action pattern?
Instinctive sequences of behaviour in some birds or fish in which pieces of behaviour act as stimuli for responses which in turn act as further stimuli.
When females are more conspicuous than males its called?
Reversed sexual dimorphism.
Female choice involves?
Assessing honest signals form males.
What do honest signals indicate?
Favourable alleles that increase chances of survival of offspring, low parasite burden suggesting healthy individual.
Explain lekking.
Males gather to display and female choice occurs, dominant males occupy centre of lek subordinates and juveniles at the fringes as satellite males.
Male-male rivalry increases what?
Access to females through conflict, males fight for dominance using, antlers, tusks and horns.
