Sex and Behaviour Flashcards
Who invests more energy during reproduction - males or females
Females due to: investment in egg structure (non-mammals) during gestation (mammals)
Pros and cons of parental investment
+ increases the probability of production and survival of young
- costly
Characteristics of r-selected species
smaller shorter gen time mature more rapidly reproduce earlier in life and often once produce larger no of offspring each of which receives smaller energy input Limited parental care Most offspring will not reach adulthood
Characteristics of k-selected species
larger live longer mature more slowly can reproduce many times produce relatively few high level of parental care many offspring have high chancer of survival to adulthood
In what environment would r-selection occur?
In unstable environments where the species has not reached its reproductive capacity
In what environment would K-selection occur
In stable environments
What are the costs and benefits of external fertilisation
Very large numbers of offspring
Many gametes are predated or not fertilised
No/limited parental care
Few offspring survive
What are the costs and benefits of internal fertilisation
Increased chance of successful fertilisation
Fewer eggs needed
Offspring can be retained internally for protection and development
Higher offspring survival rate
A mate must be located, which requires energy expenditure
Requires direct transfer of gametes
What is polygamy
individuals of one sex have more than one mate
What is polyandry
one female mates with a. number of males in the same breeding season
What is polygyny
one male mates exclusively with a group of females
What is monogamy
the mating of a pair of animals to the exclusion of all others
What is successful courtship behaviour in birds and fish a result of
Species specific sign stimuli and fixed action pattern responses
Explain sexual selection
When a species selects for the characteristics that have little survival benefit for the individual but increase their chances of mating
What is female choice
When females assess honest signals of the fitness of males
