environmental science unit 3.3

natality

birth rate

fecundity

ability to reproduce

fertility

number of offspring produced

mortality 

death rate 

life expectancy

predicted length of survival

survivor-ship curve

shows the probability of survival for a given group/species

survivor ship curve is based on these rates

natality and mortality rate of indivduals

type 1

• low fertility 

• high parental care 

• ex. humans, large mammals 

type 2

• constant mortality throughout life 

• ex. birds 

type 3

• high fertility 

• low parental care

• high mortality

K strategists

• live in stable environments 

• reproduce slowly - fewer offspring 

• long-life expectancy 

• strong + large 

• type 1 or 2 survivorship curve 

• high energy + high levels of parental care 

• ex. humans, whales

R strategists 

• live in unstable environments 

• reproduce quickly - ensures some offspring survive

• short-life expectancy - weak/subject to predation

• type 3 survivorship curve 

• low energy + low levels of parental care 

• ex. bacteria, insects 

what type are K strategists?

type 1 or type 2 survivorship curve

what type are R strategists?

type 3 survivorship curve

population pyramid

shows a snapshot of the current population, including age + gender

• shows an expanding population b/c many young individuals