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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