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Week 1
• Ecology Chapters 52-54
Dispatch—Make 3 observations on
the distribution of biomes
Goal and Name same side
• Line up for pic
Air Cells
Descending air absorbs moisture
Ascending air releases moisture
Group whiteboard
• Draw a mountain
• Predict what happens to air as it rises over
a mountain
How mountains affect rainfall.
RAINSHADOW
Show the O2 and CO2 cycle
• Be as detailed as possible
• One person will be picked to present
Nitrogen cycle
Dispatch
• If your group needs to presentfind a
group to listen and approve you
• If your group is approved listen to
group’s nitrogen presentation if they
have all components, tell me
Nitrogen Cycle Animation
• http://www.dpi.vic.gov.au/dpi/vro/vrosite.ns
f/pages/soilhealth_nitrogen-cycle
Population vs. Community
Population Ecology
QUESTIONS:
1) What is a population?
2) What affects the size a
population can get?
Population
• A population is a group of individuals of a
single species that simultaneously occupy
the same general area.
• Two characteristics that affect populations
are ________ and _______
Population characteristics
Density~ # of individuals per unit of
area
• •counts
•sample size estimate
•
•indirect indicators
• •mark-recapture
Dispersion~ pattern of spacing
•random~ unpredictable,
patternless
spacing (a)
•clumped~ patchy aggregation (b)
•uniform~ even spacing (c)
Density is the result of a
dynamic interplay
– Between processes that add individuals to a
population and those that remove individuals
from it
Births and immigration add individuals to a population.
Births
Immigration
PopuIation
size
Emigration
Deaths
Deaths and emigration remove individuals from a
population.
Activity:
• Make a graph for a bacterial population
and an elephant population
Dispatch—Get a textbook
1)
Draw an exponential growth curve? What
species exhibit this growth?
2) What about the environment would make an r
species exhibit exponential growth?
3) Describe what a population’s carry capacity is
and what it means to the population?
4) Compare and contrast density- dependent to
density-independent factors?
Take our calendar and tell your tablemates 3
upcoming deadlines
Pick up a growth half sheet and a paper that says
class set
Wilderness Park 9:30 TOMORROW
Population Growth Models
• Exponential model (blue)
• idealized population in an
unlimited environment (J-curve);
r-selected species (r=per capita
growth rate)
• Logistic model (red)
•carrying capacity (K): maximum
population size that a particular
environment can support (S-curve); Kselected species
Demography: factors that affect growth & decline of populations
•
•
•
•
Birthrate (natality, fecundity)~ # of offspring produced
Death rate (mortality)
Age structure~ relative number of individuals of each age
Survivorship curve~ plot of numbers still alive at each age
R vs. K survivorship curves
Population life history
“strategies”
• r-selected (opportunistic)
• K-selected (equilibrial)
•
•
•
•
•
Short maturation & lifespan
Many (small) offspring; usually 1
(early) reproduction; no parental
care
High death rate
• Ex:________
•
Long maturation & lifespan
Few (large) offspring; usually
several (late) reproductions;
extensive parental care
Low death rate
• Ex:____________
Population limiting factors
• Density-dependent
factors
•competition
•predation
•stress/crowding
•waste accumulation
Density-independent
factors •weather/climate
periodic disturbances
Community Ecology
QUESTIONS:
1) What is a
community?
2) Who are the
members of this
community?
3) What is a food
chain?
Differences in Community structure
Community~ an assemblage of
populations living close enough
together for potential interaction. Many
different ______.
• Communities differ dramatically in their
species richness (number of species) &
relative abundance of different species
How can we account for the species
found together as members of a
community?
2 Hypotheses:
•Individualistic~ all the species just
happened to live in the same area b/c
they all had similar abiotic
requirements. Example they all
needed same temperature, rainfall,
soil type which is why they live in
the same habitat.
•Interactive~ all the species are
locked into association by
mandatory biotic interactions.
Species are found together b/c they
have formed relationships +, - and o.
Between Species
TASK: Add a column to the right and give an example of each type of
interaction
Activity: Interaction Charades
• I will give your group an interaction and
you act it out