Lecture 12 Life history selection Flashcards
Life-cycle
the stages and forms that an organism goes through from fertilization to reproduction and death
semelparity:
reproducing once in a lifetime and then dying
Iteroparity
reproducing many times in a lifetime
Trade-off relationship: semelparity and iteroparity
all reproduction allocated to reproduction versus same resources to survive and reproduce in the future
Example of Semel parity and iteropartiy with seeds 10 percent of seeds are able to germinate so more seeds = more succuss. Say one flower produces 15 seeds per year and lives for 5 years and one flower produces 100 seeds and dies, which one has more off-spring?
Flower that produces 100 seeds and dies
Marine arrow worm example: year 1 produces 138 eggs year 2 produces 500 eggs. 1% survival rate to year one and 40 percent survival rate to year 2. How many worms are produced? Calculate it.
(year 1) 0.01 x 138 eggs = 1.38 animals produced
(Year 2) 0.01 x 0.40 = 0.004 x 500 = 2.00
why reproducing at an earlier age?
higher adult mortality rate selects for reproducing at an earlier age.
Evolutionary component example: Fish reduces lifespan at reproductive maturity. What effect will this have on age of first reproduction?
Intense harvesting resulted in directional selection for younger age of reproductive maturity and consequently smaller size.
Hedging your bets
seeds will selectively germinate depending on the conditions of the environment.
For example, for a plant it will have a
Animals producing many small offspring compared to one where you dedicate all your energy towards.
(Individual)
Benefit: Ensure the survivability of offspring
Cons: A lot of energy and time dedicated to raising offspring
(Multiple)
Benefit: Potential for many offspring to survive
Cons: High mortality rate for young offspring
