5) The distribution of terrestrial biomes is based mainly on regional variations in climate.

1) Interactions between organisms and environment determine distribution and abundance: dispersal, habitat selection, biotic factors, abiotic factors (climate very important: temperature and water).

2) Temporal and spatial scales of studies are important.

3) Global climate mostly determined by solar energy and earth’s movement in space. Permanent tilt on Earth’s axis causes seasonal variation in light, temperature and wind patterns. Hence, seasonal variation in distribution and abundance of organisms.

4) Aquatic biomes occupy the largest part of the biosphere; oceans have a major effect on global and local climate; freshwater biomes are closely linked to terrestrial biomes.

Aquatic Biomes

Largest component. Vertical stratification: light, temperature, salinity, density.Oceans (3% salt): rainfall, climate, wind. Give O2 and take CO2.Freshwater (< 1% salt): linked to soil and biota of terrestrial biomes.

Fig. 50.17

pages 1106-1109

Ocean zonation

Distance to shore & water depth, light penetration, substrate.pages 1109-1112

Fig. 50.22

Terrestrial BiomesDetermined by climate: latitudinal and regional patterns.Vertical stratification based on vegetation. Characteristic life forms.Gradation in boundaries: ecotone. Dynamic, not stable.

pages 1112-1113

Fig. 50.24

1- Are we going to be tested on material that you have not covered in lecture?

SOME questions from February 8th

2- When will the review sheet be posted? Will we have a study/review session?

3- Will there be questions about the third article on the test?

6- What are the lowest points in the ocean? What could possibly live there?

4- Do any chemicals evaporate with water or does water always separate from anything it is mixed with?

5- What is the Ekman transport vector? Why is it important?

Organismalecologycoping

Populationecology

limiting factors

Community ecologyinterspecific interactions and diversity

Ecosystem ecologyenergy flow and chemical cycling

Landscape ecologyeffects on interactions at lower levels

Biosphere ecologyglobal effects

Chapter 52- Population Ecology

Population: Group of individuals of the same species occupying the same general area.

67,171- 2000 Census

71,080- 2004 Estimate

Density.Dispersion.

pages 1151-1152

Uniform

Clumped

Random

Fig. 52.2

page 1153

DispersionPatterns

Additions (+)Natality (births).Immigration.

Changes in Population Size

Demography: Studies vital statistics that affect population size.

pages 1153 (1154)

Life Histories

pages 1156-1158

Reproductive success. Number of surviving offspring produced by an individual and that reach reproductive age.

Natural selection. Differences in reproductive success due to heritable differences in individuals.

Life histories. Patterns of resource allocation to maintenance (survival), growth, and reproduction.

Subtractions (-)Mortality (deaths).Emigration.

Individuals expected to behave so as to promote their own RS.

Fig. 52.5

Island of Rhum, Scotland

TID

Three basic life history “decisions”(remember not conscious choice except us): -When to begin reproducing? -How often to breed? -How many offspring to produce during each reproductive episode?

Life HistoriesIteroparity.

Semelparity (“once” and “beget”) (“repeat” and “beget”)

page 1156

Population Growth

population is growing ( >1 )population is declining ( <1 )zero population growth ( 1 )

λ = number of individuals at time t + 1divided by

number of individuals at time t

Finite rate of increase

population is growing ( r+ )population is declining ( r- )zero population growth ( r = 0 )r = ln λ

Instantaneous rate of change

115 100

100 115

100 100

Nt Nt+1 λ r % change

1 0 0

1.15 0.14 15

0.87 -0.14 -13

pages 1158-1159

Exponential model

Population Growth

rmax = maximum growth rate for the species

Intrinsic rate of growth rate

dt

dN= rmaxN

Ideal conditions: population growth constrained only by life history.

exponential population growthor

geometric population growthpages 1159-1160

Logistic model There is a limit to number of individuals that can occupy a habitat. Carrying capacity (K). Maximum population size an environment can support at a time with no habitat degradation. Not a fixed value.

Population growth rapid when population size well below K, slow when close to K and zero when at K.

Population Growth

K

K - NK = 100; N = 1; (K-N)/K = 0.99

K = 100; N = 90; (K-N)/K = 0.1

K = 100; N = 100; (K-N)/K = 0

dt

dN= rmaxN

K

K - N

pages 1160-1161

0

5000

10000

15000

20000N

um

be

r of

ind

ivid

ua

ls

Time

r = 0.02

Population Growth

S-shaped curve. Population growth levels off as population size approaches carrying capacity.

r = 0.02

Exponential curve. Population grows indefinitely.

pages 1161-1162

ICES J. Mar. Sci. 2003

Halichoerus grypus

J. Wildl. Manage. 2003

Phoca vitulina

Sable Island, CAN

pages 1162-1163

Many factors cause changes in birth and death rates in relation to population density: increased predation, competition for food or space, stress, parasitism, etc; slowing population growth rate.

Population-Limiting Factors

Why do they represent an example of negative

feedback?Food-limited

pages 1164-1165

Fig. 52.14

CRESLI

Eubalaena glacialis

Mandarte Isl., BC

Dynamics of Populations

They result from the interaction between biotic and abiotic factors. Long-term studies indicate that such factors make natural populations unstable.

Fig. 52.17pages 1165-1167

Assignedpaper to read for Quiz IV.

Isla Royale, Michigan

-Hare fluctuations.

-Fluctuations of food species.-Predation by various species.

Some populations have regular boom-and-bust cycles.

Fig. 52.19

pages 1167-1168

-Geographic variations due to large-scale climate effects (apparent lack of lynx migration between regions).

PNAS 2004