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 CellsDescending 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 presentfind 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.nsf/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

PopuIationsize

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 deadlinesPick up a growth half sheet and a paper that says

class setWilderness 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); K-selected 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)

• Short maturation & lifespan• Many (small) offspring; usually 1

(early) reproduction; no parental care

• High death rate

• Ex:________

• K-selected (equilibrial)

• 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.

TASK: Add a column to the right and give an example of each type of interaction

Between Species

Activity: Interaction Charades

• I will give your group an interaction and you act it out