Unit 2.4a Flashcards
What is parental investment?
It is resource usage by a parent to benefit future or existing offspring
How many sperm can a male release in a single ejaculation?
300 to 500 million sperm
How many eggs will a female release in her lifetime?
Around 450
How big is an egg in comparison to a sperm?
Egg = 100 um
Sperm = 50 um long 3 um wide
How do eggs support developing zygotes?
They have a large food store that provides energy until it can feed from the placenta
Larger or smaller eggs favoured?
Selection pressure favours larger eggs as it contains a lot of food store for the developing zygote
Is larger or smaller sperm favoured?
Selection pressures favour sperm with no excess mass to ensure they are fast moving to reach the egg
Do you male or females make a greater investment and making gametes?
Females make the greater investment as the egg is large, nutrients filled, expensive to produce, limited in number, infrequent and fertilisation has a high cost to the female.
Do females have a good chance of passing on genes?
No, as females produce far less gametes than males
Does the number of offspring and environment impact the parental care given?
Yes, the lower the number of offspring and the more stable environment is the more parental care will be given
What are ‘expensive’ young?
These are young, usually born in a stable environment, whose parents spend a lot of energy investing into the care of them
What are ‘cheap’ young?
These are young born in unstable environments in large numbers, whose parents put very low energy investments into their parental care
What are K-selected species?
Organisms that put a lot of parental investment, time and care into their offspring
What are r-selected species?
Organisms that produce lots of offspring and put very little time, care or parental investment into them
How can you remember what r-selected species are?
R = rapid rate of reproduction
