Life History Strategies Flashcards
LG21
population ecology
study of how & why number of individuals in a population changes over time & space
population density
number of individuals of a population per unit area
metapopulation
population made up of many small, physically isolated populations connected by migration
- forced to move
(ie) Native American migration throughout history
(ie) animal habitats in the city - houses to forest ratio
immigration
migration INTO a particular population from other population
- increase population
IMI
emigration
migration AWAY from one population to another
- decreases population
EMA
demography
study of factors that determine size & structure of populations through time
age structure
proportion of individuals in a population that are of each possible age
generation
avg. time btwn mother’s 1st offspring & her daughter’s 1st offspring
life table
(data set) summarize probability when an individual in a certain population will survive & reproduce in any given year over the cause of its lifetime
age class
all individuals of a specific age in a population
cohort
group of individuals that are the same age & can be followed through time
survivorship
avg. proportion of offspring that survive to a particular age
- can be calculated
survivorship curve
graph depicting percentage of a population that survives to diff. ages
fecundity
avg # of female offspring produced by each female over course of her lifetime
age-specific fecundity
avg # of female offspring produced by a female in a certain age class
net reproductive rate (Ro)
growth rate of a population/generation
- equivalent to avg # female offspring each female produces over her lifetime
fitness trade-off
(evolutionary biology) inescapable compromise btwn 2 traits that cannot be optimized simultaneously
(ie) either spend energy reproducing or else surviving
life history
sequence of events in an individual’s life from birth to reproduction to death
- how individual allocates resources to growth, reproduction & activities or structures related to survival
- shaped by NS
arrangement patterns (AP)
(1) random
(2) clumped
(3) uniform
random (AP)
position is independent of others
(ie) seed dispersion
clumped (AP)
habitat quality = patchy or cliques
(ie) fish school
uniform (AP)
negative interactions occur among individuals
(ie) competition for space, H2O, resources
central processes of demography
(1) birth
(2) death
(3) emigration
(4) immigration
why are females the main focus of studying generations?
number of males rarely affect population growth
which age class is most important to save in conservation ecology?
The age-class producing the most babies
types of survivorship
(1) Type I
(2) Type II
(3) Type III
Type I survivorship
high survivorship throughout life
- most approach species max. life span
(ie) humans
Type II survivorship
same probability of dying each year of life
(ie) blackbirds & songbirds
Type III survivorship
extremely high death rates, but high survival rates later in life
(ie) plant seedlings
reason fitness trade-off occurs
individual has restricted amount of time energy @ dispersal
- limited resources
(ie) balance reproducing w/ staying healthy & alive
aspects of life history
(1) survivorship
(2) age-specific fecundity
(3) age @ first reproduction
(4) growth rate
