climate effects on species. concept 52.4: interactions between organisms and the environment limit...
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Climate Effects on Species
Concept 52.4: Interactions between organisms and the environment limit the distribution of species
• Species distributions are the result of ecological and evolutionary interactions through time
• Ecological time is the minute-to-minute time frame of interactions between organisms and the environment
• Evolutionary time spans many generations and captures adaptation through natural selection
• Events in ecological time can lead to evolution• For example, Galápagos finches with larger
breaks were more likely to survive a drought as they could eat the available larger seeds
• As a result, the average beak size was larger in the next generation
• This resulted in an evolutionary change
• Both biotic and abiotic factors influence species distribution– For example, temperature, water availability, and
interspecific interactions, affect the distribution of the saguaro cacti
Figure 52.15
Sonoran desertSaguaro cacti observed
100 km
N
CALIFORNIA
BAJACALIFORNIA
ARIZONA
SONORA
BAJACALIFORNIA
SUR GULF
OF
CALIFORNIA
Figure 52.15a
• Ecologists ask questions about where species occur and why species occur where they do
Figure 52.16-1
Why is speciesX absent
from an area?
Does dispersallimit its
distribution?
Figure 52.16-2
Why is speciesX absent
from an area?
Does dispersallimit its
distribution? Does behaviorlimit its
distribution?
Yes
No
Area inaccessibleor insufficient time
Figure 52.16-3
Why is speciesX absent
from an area?
Does dispersallimit its
distribution? Does behaviorlimit its
distribution?Do biotic factors(other species)
limit itsdistribution?
Yes
No
Area inaccessibleor insufficient time
Habitat selectionYes
No
Figure 52.16-4
Why is speciesX absent
from an area?
Does dispersallimit its
distribution? Does behaviorlimit its
distribution?Do biotic factors(other species)
limit itsdistribution?
Do abiotic factorslimit its
distribution?
Yes
No
Area inaccessibleor insufficient time
Habitat selectionYes
No
YesNo
Predation,parasitism,competition,disease
Figure 52.16-5
Why is speciesX absent
from an area?
Does dispersallimit its
distribution? Does behaviorlimit its
distribution?Do biotic factors(other species)
limit itsdistribution?
Do abiotic factorslimit its
distribution?
Yes
No
Area inaccessibleor insufficient time
Habitat selection
Water, Oxygen, Salinity,pH, Soil nutrients, etc.
Chemicalfactors
Physicalfactors
Predation,parasitism,competition,disease
Temperature, Light,Soil structure, Fire,Moisture, etc.
Yes
No
YesNo
Dispersal and Distribution
• Dispersal is the movement of individuals or gametes away from centers of high population density or from their area of origin
• Dispersal contributes to the global distribution of organisms
Natural Range Expansions and Adaptive Radiation
• Natural range expansions show the influence of dispersal on distribution– For example, cattle egrets arrived in the Americas in
the late 1800s and have expanded their distribution• In rare cases, long-distance dispersal can lead to
adaptive radiation– For example, Hawaiian silverswords are a diverse
group descended from an ancestral North American tarweed
Figure 52.17
Current
1970
19661965 1960
1961
1958
1951
1943
1937
1956
1970
Figure 52.17a
Species Transplants
• Species transplants include organisms that are intentionally or accidentally relocated from their original distribution
• If a transplant is successful, it indicates that its potential range is larger than its actual range
• 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– Predation– Herbivory
• For example, sea urchins can limit the distribution of seaweeds
– Competition– Mutualism– Parasitism
Figure 52.18
Sea urchin Limpet
Both limpetsand urchinsremoved
Only urchinsremoved
Only limpets removed
Control (both urchinsand limpets present)
August1982
Se
awee
d c
ove
r (%
)
February1983
August1983
February1984
100
80
60
40
20
0
Figure 52.18a
Sea urchin
Figure 52.18b
Limpet
Abiotic Factors
• Abiotic factors affecting the distribution of organisms include– Temperature– Water– Oxygen– Salinity– Sunlight– Soil
• Most abiotic factors vary in space and time
Temperature
• Environmental temperature is an important factor in the distribution of organisms because of its effects on biological processes
• Cells may freeze and rupture below 0°C, while most proteins denature above 45°C
• Mammals and birds expend energy to regulate their internal temperature
Water and Oxygen
• Water availability in habitats is another important factor in species distribution
• Desert organisms exhibit adaptations for water conservation
• Water affects oxygen availability as oxygen diffuses slowly in water
• Oxygen concentrations can be low in deep oceans and deep lakes
Salinity
• Salt concentration affects the water balance of organisms through osmosis
• Most aquatic organisms are restricted to either freshwater or saltwater habitats
• Few terrestrial organisms are adapted to high-salinity habitats
• Salmon are able to migrate between freshwater and ocean
Sunlight
• Light intensity and quality (wavelength) affect photosynthesis
• Shading by leaves makes competition for light intense on the forest floor
• Water absorbs light; as a result, in aquatic environments most photosynthesis occurs near the surface
• In deserts, high light levels increase temperature and can stress plants and animals
Figure 52.19
Rocks and Soil
• Many characteristics of soil limit the distribution of plants and thus the animals that feed on them– Physical structure– pH– Mineral composition
Figure 52.UN03a
Data from the Field Experiment
Average Biomass (g/100 cm2)
Spartina patens Typha angustifolia
Withneighbors
Withoutneighbors
SaltMarshes
FreshwaterMarshes
SaltMarshes
FreshwaterMarshes
8
10
3
20
0
0
18
33
Figure 52.UN03b
Data from the Greenhouse Experiment
Salinity (parts perthousand
% maximum biomass(Spartina patens)
80 1020
0
0
17
% maximum biomass(Typha angustifolia)
20 40 60 80 100
4077 29 9 0
0 0
Figure 52.UN03c
Spartina patens
Figure 52.UN03d
Typha angustifolia
Figure 52.UN04
Does dispersal limit its distribution?
Does behavior limit its distribution?
Do biotic factors (other species)limit its distribution?
Do abiotic factors limit its distribution?
Area inaccessible orinsufficient time
Habitat selection
Predation, parasitism,competition, disease
Physical factors:Temperature, light,soil structure, fire,moisture, etc.
Chemical factors:Water, oxygen, salinity,pH, soil nutrients, etc.
Yes
Yes
Yes
No
No
No
Figure 52.UN05
Figure 52.UN06
Seed collection sites
Sierra NevadaGreat Basin
PlateauAlt
itu
de
(m)
Mea
n h
eig
ht
(cm
) 75
50
25
0
3,000
2,000
1,000
0
Figure 52.UN07
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