3rd set of slides 3/23 Flashcards
increase reproduction may decrease
survival
life history traits
-age at first reproduction
-# offspring produced each time
- number of reproductive cycles per lifetime
life history traits are
all the traits that are going to affect an organism schedule of reproduction and survival
why are life history traits important to understand for evolution
this is an important evolutionary concept because these evolutionary outcomes reflected on development,physiology and behaviors of an organism
how does limited resources relate to trade offs
limited resources are going to lead to tradeoffs between reproduction and survivalor between the number and size of offsprings vs. the survival of the offspring or of the parents
tradoffs
Number and size of offspring vs. survival of offspring or parent
parental survvial ex
the cost of larger set of baby birds to both male and female parents
K-selected (density-dependent) reproductive strategies life history traits
late reproduction
few offspring
invest a lot in raising offspring
primates
k selected means
K-selected species are controlled more by carrying capacity
r-selected (density-independent) life history traits
early reproduction
many offspring
little parental care
r-selected means
R-selected species are influenced heavily by the maximum population growth rate, and exhibit large increases followed by large decreases in population numbers.
limiting factors can be
density dependent or independent
density dependent limiting facotrs are
-competition: food, mates, nesting sites
-predators, parasites, pathogens
density independent limiting factors are
abiotic factors
sunlight (energy)
temperature
rainfall
density dependent limiting factors
influnce pop. size
density independent limiting facotors
does not effect pop.size birth rate and death rate do not change with pop. density
most limiting factors are
density dependent birth rates fall and death rates rise
density dependent populations are a
negative feedback
and its where pop. growth is going to be regulated with pop.density
intrinsic factors
will regulate pop.size and is a physiological factor
ex. mouse can only feed 4 babies which will control the number of offsprings she will have
population dynamics
are interactions with biotic and abiotic and how it affcts pop. size
Abiotic factors
pop. dynamics
sunlight & temperature
precipitation / water
soil / nutrients
Biotic factors
pop. dynamics
other living organisms
prey (food)
competitors
predators, parasites,
disease
Intrinsic factors
pop. dynamics
adaptations
Stability
Populations of large mammals relatively stable over time??? (usually)
Fluctuation
weather and predator population can affect population size over time
boom and bust cycle
With fewer predators, the prey population can increase again
To maintain population stability, two configurations:
Zero population growth = High birth rate – High death rate
Zero population growth =Low birth rate – Low death rate
Demographic transition =
the move from the first state to the second state
or
moving from high birth rate to low death rate or to low birth rate to high death rate
Age structure
is a diagram to predict growth trends and to see where an organism will be in the future
LOkk and understand how to read them
Infant Mortality and Life Expectancy
Both vary greatly among developed and developing countries
Do not capture the wide range of the human condition
only birth and death rate
Global Carrying Capacity
How many humans can the biosphere support?
Estimates of Carrying Capacity
humans
Earth for humans is uncertain
Average estimate is 10–15 billion
Limits on Human Population Size
is
One measure of how close we are to the carrying capacity of Earth
Countries vary greatly
We can regulate our growth, unlike others
Ecological footprint concept
Ecological footprint concept
aggregate land and water area needed to sustain the people of a nation
