Sex and Behaviour (a) Parental Investment Flashcards
Comparison of sperm and egg production in relation to number and energy store.
Invetsment during different stages
- Greater investment by females
- High female investment in the egg structure in non-mammals
-High female investment in the uterus and during gestation in mammals.
Parental investment is costly but increases the…
Probabillity of production and survival of young.
Characteristics of r-selected species include:
-Smaller
-Shorter generation time
-Mature more rapidly
-Limited parental care
-Most offspring will not reach adulthood
-Reproduce earlier in their lifetime
-Often only reproduce once
-Produce a larger number of smaller offspring
-Each offspring recieves only a smaller enegy input
Characteristics of a k-selected species include:
-Larger and live longer
-Produce relatively few, larger offspring
-High level of parental care
-Many offspring have a high probability of surviving to adulthood
-Mature more slowly
-Can reproduce many times in their life
Classification of r-selected and k-selected organisms based on level of parental investment in offspring and number of offspring produced.
r-selection tends to occur in…
Unstable environments where the species has not reached its reproductive capacity
k-selection occurs in…
In stable environments
Costs and Benefits of External Fertilisation:
Benefits:
-Very large number of offspring produced
Costs:
-Many gametes predated ir not fertilised
-No or limited parental care
-Few offspring survive
Costs and Benefits of Internal Fertilisation:
Benefits:
-Increased chances of successful fertilisation
-Fewer eggs needed
-Offspring retained internally for protection
-Offspring retained internally for development
-Higher offspring survival rate
Costs:
-A mate must be located, which requires energy expenditure (1)
-Requres direct transfer of gametes from one partner to another
