Topic 10 - Reproduction Flashcards
(28 cards)
What is the goal of an energy budget
to have energy remaining to allocate to reproduction
Natural selection has resulted in strategies
these are called life history traits, they are meant to maximize lifetime reproductive success (fitness)
What is life history theory
Every species has a pattern of growth and development, reproduction, and death that is shaped by natural selection - success in the past shapes life history traits of a species
How does environment affect life history traits?
Influences energy budgets through available light, food sources, shelter, wind etc
Why does maximizing reproductive success involve trade-offs
fixed energy budgets and selective pressures of the environment
if there are two traits competing for limited resources, impossible to maximize both together
What is indeterminate growth
growth continues throughout the lifespan
ex: ectotherms like reptiles, fish, plants
determinate growth
growth ceases when adult state is reached
ex: endotherms like birds, mammals
What are the two types of reproduction
asexual and sexual
Asexual reproduction
produces clones
prokaryotes replicate their genome and divide by binary fission
some eukaryotes replicate genomes and divide by mitosis
Sexual reproduction
produces recombinants
replicated genomes are halved into gametes, combined with other gametes to produce a zygote, only in euks
What are the life history traits
growth rate, parental investment, fecundity(number of offspring), parity (frequency of reproduction_, size/age at sexual maturity, size of offspring, longevity/life expectance (mortality rate)
Tradeoff between growth rate and reproduction
as reproductive activity increases, growth rate decreases
What are the two types of parental investment
passive care = pre birth energy investment (gestation)
active care = post birth energy investment (raising offspring)
What is the tradeoff between reproduction and survival of parent
as you increase clutch size, adult survival goes down - not enoug energy for both high fecundity and high survivorship
What is the tradeoff between reproduction and the survival of the parent
if no offspring, more energy to sustain self until old age
reproduction is costly in the young and old
What is parity
How often should an individual reproduce
Semelparity
only breed once in lifetime (breed and die)
Iteroparity
breed more than once in lifetime
How is fecundity related to body size
Fecundity increases with body size, thus it is advantagous to delay sexual maturity until larger
What is the tradeoff between mating and lifespan
in fruit flies, females that lay eggs have shorter lifespans
males that reproduce have shorter lifespans, larger males live longer
How does predation affect life history traits
less predators = larger size at reprodcution
More predators - smaller size
Explain how life history strategies form a continuum
r-selected to k-selected
R-selected
Small offspring/adult size
Early sexual maturity
Semelparous
High fecundity (lots of offspring)
Low parental investment
Low juvenile survivorship
Short lifespan
Evolved to reproduce quickly
K-selected
Large offspring/adult size
Late sexual maturity
Iteroparous
Low fecundity (few offspring)
High parental investment
High juvenile survivorship
Long lifespan
Evolved to compete
