2.4 sex and behaviour Flashcards
Parental investment definition
Any time or energy invested to benefit their offspring.
Parental investment detriment to parents
Looking after existing offspring
Continuing to reproduce
Lose out on their own well-being and survival
When does parental investment occur
Where the benefits to the species outweigh the cost.
Sperm and egg parental investment
Male members of a species invest in producing as many sperm as possible to fertilise the egg, however female members produce far fewer egg cells and invest in providing nutrients for developing offspring.
Factors determining parental investment
Number of offspring produced
Environmental stability
Advantages of parental investment
Lower risk of young being predated
Increased size of offspring due to more successful parental hunting.
Low mortality rate in parental investment
Where a species produces very small numbers of eggs and undergoes intensive parental investment
K selected species
Larger and live longer
Mature slowly
Can reproduce many times in lifetime
Produce few larger offspring
High level of parental care
High survival rate of offspring
Selection tends to occur in stable environments.
Internal fertilisation
Where the sperm and egg nuclei fuse inside the female
High mortality rate
Where many eggs are produced but there is a low amount of parental investment and therefore many offspring die.
External fertilisation
Where the egg and sperm fuse outside the female typically in water
R selected species
Smaller and shorter lifespan
Faster generation time
Mature rapidly
Reproduce earlier and usually only once
Produce large quantities of offspring
Limited parental care
Most offspring don’t reach adulthood
Unstable environments selected for.
Courtship behaviour in external fertilisation
Individuals will signal to individuals of the opposite gender when their eggs are ready to be fertilised.
Water necessity in external fertilisation
External water prevents gametes drying out and allows sperm to swim through medium
Internal fertilisation requirements
Highly advanced reproductive systems
Cooperative behaviour
Copulation
External fertilisation requirement
Water
External stimuli and courtship behaviours