Post on 25-Dec-2015
THE ECOLOGICAL STUFF….
AP Bio Summer assignment Ch 52 and 53
Overview: The Scope of Ecology
Ecology is the scientific study of the interactions between organisms and the environment
These interactions determine distribution of organisms and their abundance
Ecology reveals the richness of the biosphere
Fig. 52-2Organismalecology
Populationecology
Communityecology
Ecosystemecology
Landscapeecology
Globalecology
A population is a group of individuals of the same species living in an area
Population ecology focuses on factors affecting how many individuals of a species live in an area
A community is a group of populations of different species in an area
Community ecology deals with the whole array of interacting species in a community
An ecosystem is the community of organisms in an area and the physical factors with which they interact
Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components
Fig. 52-2f
Ecology and Environmental Issues
Ecology provides the scientific understanding that underlies environmental issues
Ecologists make a distinction between science and advocacy
Rachel Carson is credited with starting the modern environmental movement with the publication of Silent Spring in 1962
Fig. 52-4
Concept 52.2: Interactions between organisms and the environment limit the distribution of species
Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere
Biogeography is a good starting point for understanding what limits geographic distribution of species
Ecologists recognize two kinds of factors that determine distribution: biotic, or living factors, and abiotic, or nonliving factors
Fig. 52-5
Kangaroos/km2
0–0.10.1–11–55–1010–20> 20Limits ofdistribution
Dispersal and Distribution
Dispersal is movement of individuals away from centers of high population density or from their area of origin
Dispersal contributes to global distribution of organisms
Natural range expansions show the influence of dispersal on distribution
Fig. 52-7
Current
1966
1970
1965 1960
19611958
1951
1943
1937
1956
1970
Species Transplants
Species transplants include organisms that are intentionally or accidentally relocated from their original distribution
Species transplants can disrupt the communities or ecosystems to which they have been introduced
Behavior and Habitat Selection
Some organisms do not occupy all of their potential range
Species distribution may be limited by habitat selection behavior
Biotic Factors
Biotic factors that affect the distribution of organisms may include:Interactions with other speciesPredationCompetition
Fig. 52-8
RESULTS
Sea urchin
100
80
60
40
20
0
Limpet
Seaw
eed c
ove
r (%
)Both limpets and urchinsremoved
Only urchinsremoved
Only limpets removedControl (both urchinsand limpets present)
August1982
August1983
February1983
February1984
Abiotic Factors
Abiotic factors affecting distribution of organisms include:TemperatureWaterSunlightWindRocks and soil
Most abiotic factors vary in space and time
Climate
Four major abiotic components of climate are temperature, water, sunlight, and wind
The long-term prevailing weather conditions in an area constitute its climate
Macroclimate consists of patterns on the global, regional, and local level
Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log
Fig. 52-10aLatitudinal Variation in Sunlight Intensity
Low angle of incoming sunlight
Sun directly overhead at equinoxes
Low angle of incoming sunlight
Atmosphere90ºS (South Pole)60ºS
30ºS
23.5ºS (Tropic ofCapricorn)
0º (equator)
30ºN23.5ºN (Tropic ofCancer)
60ºN90ºN (North Pole)
Seasonal Variation in Sunlight Intensity
60ºN30ºN
30ºS
0º (equator)
March equinox
June solstice
Constant tiltof 23.5º
September equinox
December solstice
Fig. 52-10e
Descendingdry airabsorbsmoisture
Descendingdry airabsorbsmoisture
Ascendingmoist airreleasesmoisture
Aridzone
Aridzone
Tropics
30º 23.5º 0º 23.5º30º
60ºN
30ºN
0º(equator)
30ºS
60ºS
Fig. 52-10f
0º(equator)
30ºS
60ºS66.5ºS(Antarctic Circle)
30ºN
66.5ºN(Arctic Circle)
60ºNWesterlies
Northeast trades
Doldrums
Southeast trades
Westerlies
Bodies of WaterThe Gulf Stream carries warm water
from the equator to the North AtlanticOceans and their currents and large
lakes moderate the climate of nearby terrestrial environments
Fig. 52-11
Labradorcurrent
Gulfstream
Equator
Cold water
Warmwater
Fig. 52-12
Warm airover land rises.
1
23
4
Air cools athigh elevation.
Cool air over watermoves inland, replacingrising warm air over land.
Coolerair sinksover water.
MountainsMountains have a significant effect on
The amount of sunlight reaching an areaLocal temperatureRainfall
Rising air releases moisture on the windward side of a peak and creates a “rain shadow” as it absorbs moisture on the leeward side
Fig. 52-13
Winddirection
Mountainrange
Leeward sideof mountain
Ocean
Aquatic biomes account for the largest part of the biosphere in terms of area
They can contain fresh water or salt water (marine)
Oceans cover about 75% of Earth’s surface and have an enormous impact on the biosphere
Fig. 52-15
LakesCoral reefsRiversOceanicpelagic andbenthic zonesEstuariesIntertidal zones
Tropic ofCancerEquator
Tropic ofCapricorn
30ºN
30ºS
Fig. 52-16b
(b) Marine zonation
2,000–6,000 mAbyssal zone
Benthiczone
Aphoticzone
Pelagiczone
Continentalshelf
200 mPhotic zone
0
Oceanic zoneNeritic zone
Intertidal zone
The upper photic zone has sufficient light for photosynthesis while the lower aphotic zone receives little light
The organic and inorganic sediment at the bottom of all aquatic zones is called the benthic zone
The communities of organisms in the benthic zone are collectively called the benthos
Detritus, dead organic matter, falls from the productive surface water and is an important source of food
The most extensive part of the ocean is the abyssal zone with a depth of 2,000 to 6,000 m
Fig. 52-16a
Littoralzone Limnetic
zone
Photiczone
PelagiczoneBenthic
zoneAphoticzone
(a) Zonation in a lake
Fig. 52-17-5
Winter
4º4º
4º
4ºC
4º4º
Spring Summer Autumn
Thermocline
4º4º
4º
4ºC
4º4º
4º4º
4º
4ºC
2º0º
4ºC5º6º
8º18º
20º22º
Terrestrial BiomesTerrestrial biomes can be characterized
by distribution, precipitation, temperature, plants, and animals
Tropical ForestIn tropical rain forests, rainfall is
relatively constant, while in tropical dry forests precipitation is highly seasonal
Tropical forests are vertically layered and competition for light is intense
Tropical forests are home to millions of animal species, including an estimated 5–30 million still undescribed species of insects, spiders, and other arthropods
Fig. 52-21a
A tropical rain forest in Borneo
DesertPrecipitation is low and highly variable,
generally less than 30 cm per year; deserts may be hot or cold
Desert plants are adapted for heat and desiccation tolerance, water storage, and reduced leaf surface area
Common desert animals include many kinds of snakes and lizards, scorpions, ants, beetles, migratory and resident birds, and seed-eating rodents; many are nocturnal
Fig. 52-21b
A desert in the southwesternUnited States
SavannaSavanna precipitation and temperature
are seasonalGrasses and forbs make up most of the
ground coverCommon inhabitants include insects and
mammals such as wildebeests, zebras, lions, and hyenas
Fig. 52-21c
A savanna in Kenya
ChaparralChaparral climate is highly seasonal,
with cool and rainy winters and hot dry summers
The chaparral is dominated by shrubs, small trees, grasses, and herbs; many plants are adapted to fire and drought
Animals include amphibians, birds and other reptiles, insects, small mammals and browsing mammals
Fig. 52-21d
An area of chaparralin California
Temperate GrasslandTemperate grasslands are found on
many continentsWinters are cold and dry, while summers
are wet and hotThe dominant plants, grasses and forbs,
are adapted to droughts and fireNative mammals include large grazers
and small burrowers
Fig. 52-21e
Sheyenne National Grasslandin North Dakota
Northern Coniferous ForestThe northern coniferous forest, or
taiga, extends across northern North America and Eurasia and is the largest terrestrial biome on Earth
Winters are cold and long while summers may be hot
The conical shape of conifers prevents too much snow from accumulating and breaking their branches
Animals include migratory and resident birds, and large mammals
Fig. 52-21f
Rocky Mountain National Parkin Colorado
Temperate Broadleaf ForestWinters are cool, while summers are hot
and humid; significant precipitation falls year round as rain and snow
A mature temperate broadleaf forest has vertical layers dominated by deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia
Mammals, birds, and insects make use of all vertical layers in the forest
In the Northern Hemisphere, many mammals hibernate in the winter
Fig. 52-21g
Great Smoky MountainsNational Park in North Carolina
TundraTundra covers expansive areas of the
Arctic; alpine tundra exists on high mountaintops at all latitudes
Winters are long and cold while summers are relatively cool; precipitation varies
Permafrost, a permanently frozen layer of soil, prevents water infiltration
Vegetation is herbaceous (mosses, grasses, forbs, dwarf shrubs and trees, and lichen) and supports birds, grazers, and their predators
Fig. 52-21h
Denali National Park, Alaska,in autumn
Population ecology is the study of populations in relation to environment, including environmental influences on density and distribution, age structure, and population size
A population is a group of individuals of a single species living in the same general area
Density is the result of an interplay between processes that add individuals to a population and those that remove individuals
Immigration is the influx of new individuals from other areas
Emigration is the movement of individuals out of a population
Fig. 53-3
Births
Births and immigrationadd individuals toa population.
Immigration
Deaths and emigrationremove individualsfrom a population.
Deaths
Emigration
Patterns of Dispersion
Environmental and social factors influence spacing of individuals in a population
In a clumped dispersion, individuals aggregate in patches
A clumped dispersion may be influenced by resource availability and behavior
Fig. 53-4
(a) Clumped
(b) Uniform
(c) Random
Demographics
Demography is the study of the vital statistics of a population and how they change over time
Death rates and birth rates are of particular interest to demographers
Life Tables
A life table is an age-specific summary of the survival pattern of a population
It is best made by following the fate of a cohort, a group of individuals of the same age
The life table of Belding’s ground squirrels reveals many things about this population
Table 53-1
Survivorship Curves
A survivorship curve is a graphic way of representing the data in a life table
The survivorship curve for Belding’s ground squirrels shows a relatively constant death rate
Fig. 53-5
Age (years)20 4 86
10
101
1,000
100
Nu
mb
er
of
surv
ivors
(lo
g s
cale
)
Males
Females
Survivorship curves can be classified into three general types:Type I: low death rates during early and middle
life, then an increase among older age groupsType II: the death rate is constant over the
organism’s life spanType III: high death rates for the young, then a
slower death rate for survivors
Fig. 53-6
1,000
100
10
10 50 100
II
III
Percentage of maximum life span
Nu
mb
er
of
surv
ivors
(lo
g s
cale
)
I
Reproductive Rates
For species with sexual reproduction, demographers often concentrate on females in a population
A reproductive table, or fertility schedule, is an age-specific summary of the reproductive rates in a population
It describes reproductive patterns of a population
Table 53-2
Fig. 53-9
(a) Dandelion
(b) Coconut palm
Exponential Growth
Exponential population growth is population increase under idealized conditions
Under these conditions, the rate of reproduction is at its maximum, called the intrinsic rate of increase
Fig. 53-11
8,000
6,000
4,000
2,000
01920 1940 1960 1980
Year
Ele
ph
an
t p
op
ula
tion
1900
Concept 53.4: The logistic model describes how a population grows more slowly as it nears its carrying capacity
Exponential growth cannot be sustained for long in any population
A more realistic population model limits growth by incorporating carrying capacity
Carrying capacity (K) is the maximum population size the environment can support
Fig. 53-12
2,000
1,500
1,000
500
00 5 10 15
Number of generations
Pop
ula
tion
siz
e (N
)
Exponentialgrowth
1.0N=dNdt
1.0N=dNdt
K = 1,500
Logistic growth1,500 – N
1,500
Some populations overshoot K before settling down to a relatively stable density
Fig. 53-13b
Nu
mb
er
of Daphnia
/50
mL
0
30
60
90
180
150
120
0 20 40 60 80 100 120 140 160Time (days)
(b) A Daphnia population in the lab
The Logistic Model and Life Histories
Life history traits favored by natural selection may vary with population density and environmental conditions
K-selection, or density-dependent selection, selects for life history traits that are sensitive to population density
r-selection, or density-independent selection, selects for life history traits that maximize reproduction
Population Change and Population Density
In density-independent populations, birth rate and death rate do not change with population density
In density-dependent populations, birth rates fall and death rates rise with population density
Fig. 53-15
(a) Both birth rate and death rate vary.
Population density
Density-dependentbirth rate
Equilibriumdensity
Density-dependentdeath rate
Bir
th o
r d
eath
rate
per
cap
ita
(b) Birth rate varies; death rate is constant.
Population density
Density-dependentbirth rate
Equilibriumdensity
Density-independentdeath rate
(c) Death rate varies; birth rate is constant.
Population density
Density-dependentdeath rate
Equilibriumdensity
Density-independentbirth rate
Bir
th o
r d
eath
rate
per
cap
ita
Disease
Population density can influence the health and survival of organisms
In dense populations, pathogens can spread more rapidly
Predation
As a prey population builds up, predators may feed preferentially on that species
Toxic Wastes
Accumulation of toxic wastes can contribute to density-dependent regulation of population size
Intrinsic Factors
For some populations, intrinsic (physiological) factors appear to regulate population size
Population Dynamics
The study of population dynamics focuses on the complex interactions between biotic and abiotic factors that cause variation in population size
Stability and Fluctuation
Long-term population studies have challenged the hypothesis that populations of large mammals are relatively stable over time
Weather can affect population size over time
Fig. 53-18
2,100
1,900
1,700
1,500
1,300
1,100
900
700
500
01955 1965 1975 1985 1995 2005
Year
Nu
mb
er
of
sheep
Fig. 53-19
Wolves Moose
2,500
2,000
1,500
1,000
500
Nu
mb
er
of
moose
0
Nu
mb
er
of
wolv
es
50
40
30
20
10
01955 1965 1975 1985 1995 2005
Year
Fig. 53-20
Snowshoe hare
Lynx
Nu
mber
of
lyn
x(t
hou
san
ds)
Nu
mber
of
hare
s(t
hou
san
ds)
160
120
80
40
01850 1875 1900 1925
Year
9
6
3
0
Concept 53.6: The human population is no longer growing exponentially but is still increasing rapidly
No population can grow indefinitely, and humans are no exception
Fig. 53-22
8000B.C.E.
4000B.C.E.
3000B.C.E.
2000B.C.E.
1000B.C.E.
0 1000C.E.
2000C.E.
0
1
2
3
4
5
6
The Plague
Hu
man
pop
ula
tion
(b
illi
on
s)
7
Regional Patterns of Population Change
To maintain population stability, a regional human population can exist in one of two configurations:Zero population growth =
High birth rate – High death rateZero population growth =
Low birth rate – Low death rateThe demographic transition is the
move from the first state toward the second state
The demographic transition is associated with an increase in the quality of health care and improved access to education, especially for women
Most of the current global population growth is concentrated in developing countries
Age Structure
One important demographic factor in present and future growth trends is a country’s age structure
Age structure is the relative number of individuals at each age
Age structure diagrams can predict a population’s growth trends
They can illuminate social conditions and help us plan for the future
Fig. 53-25
Rapid growthAfghanistan
Male Female Age AgeMale Female
Slow growthUnited States
Male Female
No growthItaly
85+80–8475–7970–74
60–6465–69
55–5950–5445–4940–4435–3930–3425–2920–2415–19
0–45–9
10–14
85+80–8475–7970–74
60–6465–69
55–5950–5445–4940–4435–3930–3425–2920–2415–19
0–45–9
10–14
10 10 8 866 4 422 0Percent of population Percent of population Percent of population
66 4 422 08 8 66 4 422 08 8
Limits on Human Population Size
The ecological footprint concept summarizes the aggregate land and water area needed to sustain the people of a nation
It is one measure of how close we are to the carrying capacity of Earth
Countries vary greatly in footprint size and available ecological capacity
Fig. 53-27
Log (g carbon/year)13.49.85.8
Not analyzed