Bio Ch 52

Front 1

Ecology

Back 1

-Ecology is the scientific study of the interactions between organisms and the environment
-These interactions determine the distribution of organisms and their abundance
-Modern ecology includes observation and experimentation

Front 2

Global Ecology

Back 2

-The biosphere is the global ecosystem, the sum of all the planet’s ecosystems
-Global ecology examines the influence of energy and materials on organisms across the biosphere

Front 3

Landscape Ecology

Back 3

-A landscape or seascape is a mosaic of connected ecosystems
-Landscape ecology focuses on the exchanges of energy, materials, and organisms across multiple ecosystems

Front 4

Ecosystem Ecology

Back 4

-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

Front 5

Community Ecology

Back 5

-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

Front 6

Population Ecology

Back 6

-A population is a group of individuals of the same species living in an area
-Population ecology focuses on factors affecting population size over time

Front 7

Organismal Ecology

Back 7

-Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges
-Organismal ecology includes physiological, evolutionary, and behavioral ecology

Front 8

Four major abiotic components of climate are

Back 8

temperature, precipitation, sunlight, and wind

Front 9

Macroclimate

Back 9

consists of patterns on the global, regional, and landscape level

Front 10

Microclimate

Back 10

consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

Front 11

Global Climate Patterns

Back 11

-Global climate patterns are determined largely by solar energy and the planet’s movement in space
-The warming effect of the sun causes temperature variations, which drive evaporation and the circulation of air and water
-This causes latitudinal variations in climate

Front 12

Latitudinal Variation in Sunlight Intensity

Back 12

-The angle at which sunlight hits Earth affects its intensity, the amount of heat and light per unit of surface area
-The intensity of sunlight is strongest in the tropics (between 23.5° north latitude and 23.5° south latitude)

Front 13

Global Air Circulation and Precipitation Patterns

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-Water evaporates in the tropics, and warm, wet air masses flow from the tropics toward the poles
-Rising air masses release water and cause high precipitation, especially in the tropics
-Dry, descending air masses create arid climates, especially near 30° north and south
-Air flowing close to Earth’s surface creates predictable global wind patterns
-Cooling trade winds blow from east to west in the tropics; prevailing westerlies blow from west to east in the temperate zones

Front 14

Seasonality

Back 14

-Seasonal variations of light and temperature increase steadily toward the poles
-Seasonality at high latitudes is caused by the tilt of Earth’s axis of rotation and its annual passage around the sun
-Belts of wet and dry air straddling the equator shift throughout the year with the changing angle of the sun
-Changing wind patterns affect ocean currents

Front 15

Bodies of Water

Back 15

-Oceans, their currents, and large lakes moderate the climate of nearby terrestrial environments
-The Gulf Stream carries warm water from the equator to the North Atlantic
-During the day, air rises over warm land and draws a cool breeze from the water across the land
-As the land cools at night, air rises over the warmer water and draws cooler air from land back over the water, which is replaced by warm air from offshore

Front 16

Mountains

Back 16

-Rising air releases moisture on the windward side of a peak and creates a “rain shadow” as it absorbs moisture on the leeward side
-Mountains affect the amount of sunlight reaching an area
-In the Northern Hemisphere, south-facing slopes receive more sunlight than north-facing slopes
-Every 1,000 m increase in elevation produces a temperature drop of approximately 6C

Front 17

Microclimate

Back 17

Microclimate is determined by fine-scale differences in the environment that affect light and wind patterns

Front 18

Every environment is characterized by differences in

Back 18

-Abiotic factors, including nonliving attributes such as temperature, light, water, and nutrients
-Biotic factors, including other organisms that are part of an individual’s environment

Front 19

Global Climate Change

Back 19

-Changes in Earth’s climate can profoundly affect the biosphere
-One way to predict the effects of future global climate change is to study previous changes
As glaciers retreated 16,000 years ago, tree distribution patterns changed
-As climate changes, species that have difficulty dispersing may have smaller ranges or could become extinct

Front 20

Biomes

Back 20

-Biomes are major life zones characterized by vegetation type (terrestrial biomes) or physical environment (aquatic biomes)
-Climate is very important in determining why terrestrial biomes are found in certain areas

Front 21

Climate and Terrestrial Biomes

Back 21

-Climate affects the latitudinal patterns of terrestrial biomes
-A climograph plots the temperature and precipitation in a region
-Biomes are affected not just by average temperature and precipitation, but also by the pattern of temperature and precipitation through the year

Front 22

General Features of Terrestrial Biomes

Back 22

-Terrestrial biomes are often named for major physical or climatic factors and for vegetation
-Terrestrial biomes usually grade into each other, without sharp boundaries
-The area of intergradation, called an ecotone, may be wide or narrow
-Vertical layering is an important feature of terrestrial biomes, and in a forest it might consist of an upper canopy, low-tree layer, shrub understory, ground layer of herbaceous plants, forest floor, and root layer
-Layering of vegetation in all biomes provides diverse habitats for animals
-Biomes are dynamic and usually exhibit extensive patchiness
-Similar characteristics can arise in distant biomes through convergent evolution

Front 23

Disturbance and Terrestrial Biomes

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-Disturbance is an event such as a storm, fire, or human activity that changes a community
-For example, frequent fires can kill woody plants and maintain the characteristic vegetation of a savanna
-For example, fires and outbreaks of pests create gaps in forests that allow different species to grow

Front 24

Terrestrial Biomes

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Terrestrial biomes can be characterized by distribution, precipitation, temperature, plants, and animals

Front 25

Tropical Forest

Back 25

-Distribution is in equatorial and subequatorial regions
-In tropical rain forests, rainfall is relatively constant, while in tropical dry forests precipitation is highly seasonal
-Temperature is high year-round (25–29C) with little seasonal variation
-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
-Rapid human population growth is now destroying many tropical forests

Front 26

Desert

Back 26

-Deserts occur in bands near 30 north and south of the equator and in the interior of continents
-Percipitation 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
-Urbanization and conversion to irrigated agriculture have reduced the natural biodiversity of some deserts

Front 27

Savanna

Back 27

-Equatorial and subequatorial regions
-Savanna precipitation is seasonal
-Temperature averages 24–29C but is more seasonally variable than in the tropics
-Grasses and forbs make up most of the ground cover
The dominant plant species are fire-adapted and tolerant of seasonal drought
-Common inhabitants include insects and mammals such as wildebeests, zebras, lions, and hyenas
-Fires set by humans may help maintain this biome

Front 28

Chaparral

Back 28

-Chaparral occurs in midlatitude coastal regions on several continents
-Precipitation is highly seasonal with rainy winters and dry summers
-Summer is hot (30C+); fall, winter, and spring are cool (10–12C)
-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
-Humans have reduced chaparral areas through agriculture and urbanization

Front 29

Temperate Grassland

Back 29

-Temperate grasslands are found on many continents
-Precipitation is highly seasonal
-Winters are cold (often below –10C) and dry; summers are hot (often near 30C) and wet
-The dominant plants, grasses and forbs, are adapted to droughts and fire
-Native mammals include large grazers such as bison and wild horses and small burrowers such as prairie dogs
-Most grasslands have been converted to farmland

Front 30

Northern Coniferous Forest

Back 30

-The northern coniferous forest, or taiga, spans northern North America and Eurasia and is the largest terrestrial biome on Earth
-Precipitation varies; some have periodic droughts and others, especially near coasts, are wet
-Winters are cold; summers may be hot (e.g., Siberia ranges from –50C to 20C)
-Conifers such as pine, spruce, fir, and hemlock dominate
-The conical shape of conifers prevents too much snow from accumulating and breaking their branches
-Animals include migratory and resident birds and large mammals such as moose, brown bears, and Siberian tigers
-Some forests are being logged at an alarming rate

Front 31

Temperate Broadleaf Forest

Back 31

-Temperate broadleaf forest is found at midlatitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand
-Significant amounts of precipitation fall during all seasons as rain or snow
-Winters average 0C; summers are hot and humid (near 35C)
-Vertical layers are 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
-These forests have been heavily settled on all continents but are recovering in places

Front 32

Tundra

Back 32

-Tundra covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes
-Precipitation is low in arctic tundra and higher in alpine tundra
-Winters are cold (below –30C); summers are relatively cool (less than 10C)
-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
-Mammals include musk oxen, caribou, reindeer, bears, wolves, and foxes; many migratory bird species nest in the summer
-Settlement is sparse, but tundra has become the focus of oil and mineral extraction

Front 33

Aquatic biomes

Back 33

-Aquatic biomes account for the largest part of the biosphere in terms of area
-They show less latitudinal variation than terrestrial biomes
-Marine biomes have salt concentrations of about 3%
-The largest marine biome is made of oceans, which cover about 75% of Earth’s surface and have an enormous impact on the biosphere
-Freshwater biomes have salt concentrations of less than 0.1%
-Freshwater biomes are closely linked to soils and the biotic components of the surrounding terrestrial biome
-Major aquatic biomes can be characterized by their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs

Front 34

Zonation in Aquatic Biomes

Back 34

-Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth
-The upper photic zone has sufficient light for photosynthesis, while the lower aphotic zone receives little light
-The photic and aphotic zones make up the pelagic zone
-Deep in the aphotic zone lies the abyssal zone with a depth of 2,000 to 6,000 m
-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
-In oceans and most lakes, a temperature boundary called the thermocline separates the warm upper layer from the cold deeper water
-Many lakes undergo a semiannual mixing of their waters called turnover
-Turnover mixes oxygenated water from the surface with nutrient-rich water from the bottom

Front 35

Lakes

Back 35

-Size varies from small ponds to very large lakes
-Temperate lakes may have a seasonal thermocline; tropical lowland lakes have a year-round thermocline
-Oligotrophic lakes are nutrient-poor and generally oxygen-rich
-Eutrophic lakes are nutrient-rich and often depleted of oxygen if ice covered in winter
-Eutrophic lakes have more surface area relative to depth than oligotrophic lakes
-Rooted and floating aquatic plants live in the shallow and well-lighted littoral zone close to shore
-Water is too deep in the limnetic zone to support rooted aquatic plants; small drifting animals called zooplankton graze on the phytoplankton
-Zooplankton are drifting heterotrophs that graze on the phytoplankton
-Invertebrates live in the benthic zone
-Fishes live in all zones with sufficient oxygen
Human-induced nutrient enrichment can lead to algal blooms, oxygen depletion, and fish kills

Front 36

Wetlands

Back 36

-A wetland is a habitat that is inundated by water at least some of the time and that supports plants adapted to water-saturated soil
-Wetlands have high organic production and decomposition and have low dissolved oxygen
-Wetlands can develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas
Wetlands are among the most productive biomes on Earth
Plants include lilies, cattails, sedges, tamarack, and black spruce
-Wetlands are home to diverse invertebrates and birds, as well as otters, frogs, and alligators
-Humans have destroyed up to 90% of wetlands; wetlands purify water and reduce flooding

Front 37

Streams and Rivers

Back 37

-The most prominent physical characteristic of streams and rivers is current
-Headwaters are generally cold, clear, turbulent, swift, and oxygen-rich; they are often narrow and rocky
-Downstream waters form rivers and are generally warmer, more turbid, and more oxygenated; they are often wide and meandering and have silty bottoms
-They may contain phytoplankton or rooted aquatic plants
-A diversity of fishes and invertebrates inhabit unpolluted rivers and streams
-Pollution degrades water quality and kills aquatic organisms
-Damming and flood control impair natural functioning of stream and river ecosystems

Front 38

Estuaries

Back 38

-An estuary is a transition area between river and sea
Salinity varies with the rise and fall of the tides
-Estuaries are nutrient-rich and highly productive
-Estuaries include a complex network of tidal channels, islands, natural levees, and mudflats
-Saltmarsh grasses and algae are the major producers
-An abundant supply of food attracts marine invertebrates, fish, waterfowl, and marine mammals
-Humans consume oysters, crabs, and fish
-Human interference upstream has disrupted estuaries worldwide

Front 39

Intertidal Zones

Back 39

-An intertidal zone is periodically submerged and exposed by the tides
-Intertidal organisms are challenged by variations in temperature and salinity and by the mechanical forces of wave action
-Oxygen and nutrient levels are high
-Substrate varies from rocky to sandy
-Sandy zones support sea grass and algae; rocky zones support attached marine algae
-In rocky zones, many animals have structural adaptations for attaching to the hard substrate
-In sandy zones, worms, clams, and crustaceans bury themselves in sand
-Other animals include sponges, sea anemones, echinoderms, and small fishes
-Oil pollution has disrupted many intertidal areas

Front 40

Oceanic Pelagic Zone

Back 40

-The oceanic pelagic zone is constantly mixed by wind-driven oceanic currents
-Oxygen levels are high
-Turnover in temperate oceans renews nutrients in the photic zones; year-round stratification in tropical oceans leads to lower nutrient concentrations
-This biome covers approximately 70% of Earth’s surface
-Phytoplankton and zooplankton are the dominant organisms in this biome; also found are free-swimming animals
-Zooplankton includes protists, worms, copepods, krill, jellies, and invertebrate larvae
-Other animals include squids, fishes, sea turtles, and marine mammals
-Overfishing has depleted fish stocks
-Humans have polluted oceans with dumping of waste

Front 41

Coral Reefs

Back 41

-Coral reefs are formed from the calcium carbonate skeletons of corals (cnidarians)
-Shallow reef-building corals live in the photic zone in warm (about 20–30C), clear water; deep-sea corals live at depths of 200–1,500 m
-Corals require high oxygen concentrations and a solid substrate for attachment
-A coral reef progresses from a fringing reef to a barrier reef to a coral atoll
-Unicellular algae live within the tissues of the corals and form a mutualistic relationship that provides the corals with organic molecules
-Fish and invertebrate diversity is exceptionally high
-Global warming and pollution may be contributing to large-scale coral death
-Collecting of coral skeletons and overfishing have reduced populations of corals and reef fishes

Front 42

Marine Benthic Zone

Back 42

-The marine benthic zone consists of the seafloor below the surface waters of the coastal, or neritic, zone and the offshore pelagic zone
-Organisms in the very deep benthic (abyssal) zone are adapted to continuous cold and extremely high water pressure
-Substrate is mainly soft sediments; some areas are rocky
-Shallow areas contain seaweeds and filamentous algae
-Deep-sea hydrothermal vents of volcanic origin on mid-oceanic ridges are surrounded by unique chemoautotrophic prokaryotes, as well as echinoderms and arthropods
-Neritic benthic communities include invertebrates and fishes
-Overfishing and dumping of waste have depleted fish populations

Front 43

ecological and evolutionary interactions through time

Back 43

-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
-Both biotic and abiotic factors influence species distribution
-For example, climate, interspecific interactions, and other factors affect the distribution of the red kangaroo

Front 44

Dispersal and Distribution

Back 44

-Dispersal is the movement of individuals away from centers of high population density or from their area of origin
-Dispersal contributes to the global distribution of organisms

Front 45

Natural Range Expansions and Adaptive Radiation

Back 45

-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

Front 46

Species Transplants

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-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

Front 47

Behavior and Habitat Selection

Back 47

-Some organisms do not occupy all of their potential range
-Species distribution may be limited by habitat selection behavior

Front 48

Biotic Factors

Back 48

-Biotic factors that affect the distribution of organisms may include
--Predation
--Herbivory
---example, sea urchins can limit the distribution of seaweeds
--Competition

Front 49

Abiotic Factors

Back 49

-Abiotic factors affecting the distribution of organisms include
+Temperature
+Water
+Sunlight
+Wind
+Rocks and soil
-Most abiotic factors vary in space and time

Front 50

Temperature

Back 50

-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

Front 51

Water and Oxygen

Back 51

-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

Front 52

Salinity

Back 52

-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