Organisms in Their Environment

1
Organisms in Their Environment
42
2
Chapter 42 Organisms in Their Environment

• Key Concepts
• 42.1 Ecological Systems Vary in Space and over
  Time
• 42.2 Climate and Topography Shape Earths
  Physical Environments
• 42.3 Physical Geography Provides the Template for
  Biogeography
• 42.4 Geological History Has Shaped the
  Distributions of Organisms

3
Chapter 42 Organisms in Their Environment

• Key Concepts
• 42.5 Human Activities Affect Ecological Systems
  on a Global Scale
• 42.6 Ecological Investigation Depends on Natural
  History Knowledge and Modeling

4
Chapter 42 Opening Question

• Why did the rangeland restoration method that
  worked in Europe fail to work in the Borderlands?

5
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Physical geographystudy of the distribution of
  Earths climates and surface features
• Biogeographystudy of the distributions of
  organisms

6
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Abiotic components of the environment nonliving
• Biotic componentliving organisms
• An ecological systemone or more organisms plus
  the external environment with which they interact

7
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Ecologyterm coined by Ernst Haeckel in 1866
  made it a legitimate scientific subject and
  emphasized its relevance to evolution because
  ecological interactions drive natural selection.
• Systema whole, comprising a set of interacting
  parts neither the parts nor the whole can be
  understood without taking account of the
  interactions.

8
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Ecological systems can include any part of the
  biological hierarchy from the individual to the
  biosphere.
• Each level brings in new interacting parts at
  progressively larger spatial scales.

9
Figure 42.1 The Hierarchy of Ecological Systems
10
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Populationgroup of individuals of the same
  species that live, interact, and interbreed in a
  particular area at the same time.
• Communityassemblage of interacting populations
  of different species in a particular area.
• Ecosystemcommunity plus its abiotic environment
• Biosphereall the organisms and environments of
  the planet

11
Concept 42.1 Ecological Systems Vary in Space and
over Time

• Generally, large ecological systems tend to be
  more complex and have more interacting parts.
• But small systems can also be complex
• The human large intestine is densely populated
  with hundreds of microbial species.
• The gut environment provides stable conditions
  and ample nutrients.
• The microbial species interact with each other
  and with their environment in many complex ways.

12
Concept 42.1 Ecological Systems Vary in Space and
over Time

• At any given time, an ecological system is
  potentially unique.
• In the human gut, the microbial species vary from
  person to person and with diet.
• The hosts genotype and diet affect the gut
  environment from the bacterial point of view and
  the bacteria influence their environment, which
  includes the host.
• Some health disorders may be treatable by
  manipulating the gut bacterial community.

13
Figure 42.2 The Microbial Community of the Human
Gut Depends on the Hosts Diet (Part 1)
14
Figure 42.2 The Microbial Community of the Human
Gut Depends on the Hosts Diet (Part 2)
15
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Variation in physical environments results from
  atmosphere and ocean circulation patterns and
  geological processes.

16
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Weatherthe state of atmospheric conditions in a
  particular place at a particular time
• Climateaverage conditions and patterns of
  variation over longer periods
• Adaptations to climate prepare organisms for
  expected weather patterns.

17
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Earth receives uneven inputs of solar radiation
  due to its spherical shape and tilt of its axis
  as it orbits the sun.
• Subsequent results in temperature variation
• Air temperatures decrease from low to high
  latitudes.
• High latitudes experience more seasonality
  greater fluctuation over the course of a year.

18
Figure 42.3 Solar Energy Input Varies with
Latitude
19
Figure 42.4 The Tilt of Earths Axis of Rotation
Causes the Seasons
20
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Solar energy inputs are always greatest in the
  equatorial region, which drives global patterns
  of air circulation.
• Hadley cells
• The tropical air is warmed, rises, and then cools
  adiabatically (an expanding gas cools).
• The rising warm air is replaced by surface air
  flowing in from the north and south.
• The cooling air sinks at 30N and 30S.

21
Figure 42.5 Global Atmospheric Circulation
22
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Other circulation cells form at the mid-latitudes
  and at the poles.
• The circulation patterns influence prevailing
  winds and precipitation patterns.
• Rising warm tropical air releases lots of
  moisture as rainfall. The sinking air at 30N and
  30S is drymost of the great deserts are at
  these latitudes.
• Prevailing winds are deflected by the rotation
  of the Earththe Coriolis effect.

23
Figure 42.6 Direction of Prevailing Surface Winds
24
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Prevailing winds drive the major ocean surface
  currents.
• Example northeast trade winds drive water to the
  west when it reaches a continent it is deflected
  northward until the westerlies drive the water
  back to the east.

25
Figure 42.7 Ocean Currents
26
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Deep ocean currents are driven by water density
  differences.
• Colder, saltier water is more dense and sinks to
  form deep currents.
• Deep currents regain the surface in areas of
  upwelling, completing a vertical ocean
  circulation.

27
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Oceans and large lakes moderate climate because
  water has a high heat capacity.
• Water temperature changes slowly as it exchanges
  heat with the air.
• Poleward-flowing ocean currents carry heat from
  the tropics toward the poles, moderating climate
  at higher latitudes.
• Example the Gulf Stream warms northern Europe.

28
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Climate diagramsuperimposed graphs of average
  monthly temperature and precipitation throughout
  a year.
• The axes are scaled so that precipitation is
  adequate for plant growth when the precipitation
  line is above the temperature line.
• The growing season occurs when temperatures are
  above freezing and there is enough precipitation.

29
Figure 42.8 Walter Climate Diagrams Summarize
Climate in an Ecologically Relevant Way
30
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Earths topography also influences climate.
• As you go up a mountain, air temperature drops by
  about 1C for each 220 m of elevation.
• When prevailing winds bump into mountain ranges,
  the air rises up, cools, and releases moisture.
  The now-dry air descends on the leeward side.
• This results in a dry area on the leeward side,
  called a rain shadow.

31
Figure 42.9 A Rain Shadow
32
Concept 42.2 Climate and Topography ShapeEarths
Physical Environments

• Topography also influences aquatic environments
• Flow velocity depends on slope.
• Water depth determines gradients of many abiotic
  factors, including temperature, pressure, light
  penetration, and water movement.

33
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Organisms must be adapted to their physical
  environments.
• For example, a plant that has no means of
  conserving water cannot thrive in a desert.
• Species are found only in environments they can
  tolerate.

34
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Early naturalistexplorers began to understand
  how the distribution of Earths physical
  environments shapes the distribution of
  organisms.
• Their observations revealed a convergence in
  characteristics of vegetation found in similar
  climates around the world.

35
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Biomea distinct physical environment inhabited
  by ecologically similar organisms with similar
  adaptations.
• Species in the same biome in geographically
  separate regions display convergent evolution of
  morphological, physiological, or behavioral
  traits.

36
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Terrestrial biomes are distinguished by their
  characteristic vegetation.
• Distribution of terrestrial biomes is broadly
  determined by annual patterns of temperature and
  precipitation.
• These factors vary along both latitudinal and
  elevational gradients.

37
Figure 42.10 Temperature and Precipitation
Gradients Determine Terrestrial Biomes
38
Figure 42.11 Global Terrestrial Biomes
39
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Other factors, especially soil characteristics,
  interact with climate to influence vegetation.
• Example Southwestern Australia has Mediterranean
  climate with hot, dry summers and cool, moist
  winters. The vegetation is woodland/shrubland,
  but no succulent plants are here.
• The soils are nutrient-poor, and there are
  frequent fires. Succulents are easily killed by
  fires.

40
Figure 42.12 Same Biome, Different Continents
(Part 1)
41
Figure 42.12 Same Biome, Different Continents
(Part 2)
42
Figure 42.12 Same Biome, Different Continents
(Part 3)
43
Figure 42.12 Same Biome, Different Continents
(Part 4)
44
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• The biome concept is also applied to aquatic
  environments.
• Aquatic biomes are determined by physical factors
  such as water depth and current, temperature,
  pressure, salinity, and substrate characteristics.

45
Table 42.1 Major Aquatic Biomes
46
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• The primary distinction for aquatic biomes is
  salinity freshwater, saltwater, and estuarine
  biomes.
• Salinity determines what species can live in the
  biome, depending on their ability to
  osmoregulate.

47
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• In streams, current velocity is important.
  Organisms must have adaptations to withstand
  flow.
• Current also impacts the substratewhether rocky,
  sandy, silty, etc. Substrate also determines what
  species are present.

48
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Still-water biomes (lakes and oceans) have zones
  related to water depth.
• Nearshore regions (littoral or intertidal) are
  shallow, impacted by waves and fluctuating water
  levels. Distinct zonation of species is common.
• Photic zonedepth to which light penetrates
  photosynthetic organisms are restricted to this
  zone.

49
Figure 42.13 Water-Depth Zones (Part 1)
50
Figure 42.13 Water-Depth Zones (Part 2)
51
Concept 42.3 Physical Geography Provides the
Template for Biogeography

• Aphotic zone is too deep for light penetration.
• Benthic zonelake or ocean bottom
• Water pressure increases with depth. Organisms in
  the deepest oceans (abyssal zone) must have
  adaptations to deal with high pressure, low
  oxygen, and cold temperatures.

52
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Alfred Russel Wallace studied species
  distributions in the Malay Archipelago and
  observed dramatically different bird faunas on
  two neighboring islands, Bali and Lombok.
• The differences could not be explained by soil or
  climate.

53
Figure 42.14 Wallaces Line
54
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• He suggested that the deep channel between the
  islands would have remained full of water (and a
  barrier to movement of terrestrial animals)
  during the Pleistocene glaciations when sea level
  dropped.
• Thus, the faunas on either side of the channel
  evolved mostly in isolation over a long period of
  time.

55
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Wallaces observations led him to divide the
  world into six biogeographic regions.
• They contain distinct assemblages of species,
  many of which are phylogenetically related.
• Many of the boundaries correspond to geographic
  barriers to movement bodies of water, extreme
  climates, mountain ranges.

56
Figure 42.15 Movement of the Continents Shaped
Earths Biogeographic Regions
57
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Boundaries of some biogeographic regions are
  related to continental drift.
• Example southern beeches (Nothofagus) are found
  in South America, New Zealand, Australia, and
  some south Pacific islands.
• The genus originated on the southern
  supercontinent Gondwana during the Cretaceous and
  was carried along when Gondwana broke apart.

58
Figure 42.16 Distribution of Nothofagus (Part 1)
59
Figure 42.16 Distribution of Nothofagus (Part 2)
60
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Biotas of the seven biogeographic regions
  developed in isolation throughout the Tertiary
  (65 to 1.8 mya), when extensive radiations of
  flowering plants and vertebrates took place.

61
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Continental movement has recently eliminated some
  barriers, allowing biotic interchange.
• Examples when India collided with Asia about 45
  mya, and when a land bridge formed between North
  and South America about 6 mya.

62
Concept 42.4 Geological History Has Shapedthe
Distributions of Organisms

• Biogeographers use phylogenetic information,
  along with the fossil record and geological
  history, to study modern distributions of
  species.
• Geographic areas are superimposed on phylogenetic
  trees. The sequence and timing of splits in the
  phylogenetic tree are compared with sequence and
  timing of geographic separations or connections.

63
Apply the Concept, Ch. 42, p. 837
64
Concept 42.5 Human Activities Affect Ecological
Systemson a Global Scale

• Human activities are altering ecological systems
  on a global scale.
• Some have suggested we are entering a new
  geological period, the Anthropocene.
• We are changing the distributions of organisms,
  vegetation, and topography, as well as Earths
  climate.

65
Concept 42.5 Human Activities Affect Ecological
Systemson a Global Scale

• Human-dominated ecosystems, such as croplands,
  pasturelands, and urban settlements now cover
  about half of Earths land area.
• These ecosystems have fewer interacting species
  and are less complex.

66
Concept 42.5 Human Activities Affect Ecological
Systemson a Global Scale

• In agricultural lands, monocultures replace
  species-rich natural communities.
• Diversity of crops planted is also very low 19
  crops comprise 95 of total global food
  production.
• Agricultural systems are more spatially and
  physically uniform than natural ecological
  systems.

67
Figure 42.17 Human Agricultural Practices
Produce a Uniform Landscape
68
Concept 42.5 Human Activities Affect Ecological
Systemson a Global Scale

• Human activities also reduce complexity in
  natural ecosystems
• Damming and channelization of rivers
• Pollution and habitat fragmentation
• Overexploitation of wild species
• Introductions of new species

69
Concept 42.5 Human Activities Affect Ecological
Systemson a Global Scale

• Humans move species throughout the globe,
  sometimes deliberately, sometimes inadvertently.
• Human-assisted biotic interchange is homogenizing
  the biota of the planet, blurring the spatial
  heterogeneity in species composition that evolved
  during long periods of continental isolation.

70
Concept 42.6 Ecological Investigation Depends
onNatural History Knowledge and Modeling

• Natural historyobservation of nature outside of
  a formal, hypothesis-testing investigationprovide
  s important knowledge about ecosystems.
• These observations are often the source of new
  questions and hypotheses and aid in design of
  ecological experiments.

71
Concept 42.6 Ecological Investigation Depends
onNatural History Knowledge and Modeling

• Computer models are important tools in the study
  of ecosystems.
• Natural history knowledge is used to build these
  models.
• Example rangeland grasses are affected by other
  plants and herbivores, soil fertility, climate,
  and fire. To predict the effect of removing
  cattle to bring back grasses, all these
  interactions must be known.

72
Answer to Opening Question

• Grasslands in different parts of the world differ
  in significant ways.
• Grasslands occupy a range of climatic conditions
  from moist to very arid.
• In Europe and eastern North America, pastures
  were once forests resting the range and
  managing herd size can restore much of the
  ecosystem.

73
Figure 42.18 Harmonious Grazers
74
Answer to Opening Question

• Temperate grasslands of midwestern North America,
  Eurasia, South America, and African savannas have
  long histories of evolution with grazing mammals.
  
• It is not clear why removal of cattle has not
  restored grasslands in the U.S.Mexico
  Borderlands it is an area of active research.