Ecology Chapter 51: Species Distribution

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Questions and Answers

What is the focus of organismal ecology?

Interspecific interactions

Population size analysis

Physiology, structure, and behavior of organisms (correct)

Energy flow and chemical cycling

Climate is the most significant influence on the distribution of organisms on land.

True

What is the term used to refer to very fine, localized patterns in climate?

Microclimate

_____ trees moderate the microclimate below them.

Forest Signup and view all the answers

Match the following ecological levels with their descriptions:

Population Ecology = Analyzes factors affecting population size Community Ecology = Examines interspecific interactions Ecosystem Ecology = Emphasizes energy flow and chemical cycling Global Ecology = Studies global patterns of energy and material exchange Signup and view all the answers

What is a climograph used for?

Plotting the annual mean temperature and precipitation in a region Signup and view all the answers

Which biome is dominated by broadleaf evergreen trees?

Tropical Forest Signup and view all the answers

Deserts receive more than 100 cm of precipitation annually.

False Signup and view all the answers

_______ is an event such as a storm, fire, or human activity that changes a community.

Disturbance Signup and view all the answers

Match the following terrestrial biomes with their characteristics:

Temperate Grassland = Highly seasonal precipitation with dry winters and wet summers Chaparral = Highly seasonal precipitation with rainy winters and dry summers Northern Coniferous Forest = 30-70 cm annual precipitation with evergreen conifers Tundra = Winters below -30ºC and mostly herbaceous vegetation Signup and view all the answers

What are some examples of abiotic factors affecting the distribution of organisms? (Select all that apply)

Salinity Signup and view all the answers

Desert organisms exhibit adaptations for water conservation.

True Signup and view all the answers

Most aquatic organisms are restricted to either freshwater or __ habitats by limited ability to osmoregulate.

saltwater Signup and view all the answers

What are the zones defined by in aquatic biomes?

All of the above Signup and view all the answers

Match the abiotic factor with its impact on organisms:

Temperature = Environmental factor impacting biological processes Salinity = Affects water balance through osmosis Sunlight = Limits distribution of photosynthetic species Signup and view all the answers

The abyssal zone is located in the photic zone.

False Signup and view all the answers

What is the term for the organic and inorganic sediment at the bottom of all aquatic zones?

benthic zone Signup and view all the answers

The communities of organisms in the benthic zone are collectively called the _______.

benthos Signup and view all the answers

Match the following with their descriptions:

Oligotrophic lakes = Nutrient-poor and O2-rich with low organic content in sediments Eutrophic lakes = Nutrient-rich and high in organic content in sediments; O2 is periodically depleted in deeper layers due to high rates of decomposition Phytoplankton = Inhabit the limnetic zone where the water is too deep to support rooted plants Signup and view all the answers

Study Notes

Overview of Ecology

Ecology is the scientific study of the interactions between organisms and their living and nonliving environment.
Ecologists ask research questions at different levels in the biological hierarchy: organismal, population, community, ecosystem, landscape, and global.

Determining Distribution of Organisms

Climate, including temperature and precipitation, has the strongest effect on where terrestrial organisms live.
Light and nutrient availability are two factors that have a strong effect on where aquatic organisms live.

Global Climate Patterns

Global climate patterns are determined largely by solar energy and Earth's movement in space.
The warming effect of the sun establishes temperature variations, circulation of air and water, and evaporation of water.
Latitudinal variations in climate:
- Sunlight is most direct and therefore most intense in the tropics (23.5°N to 23.5°S latitude).
- At higher latitudes, sunlight hits at an oblique angle, making the light energy more diffuse and less intense.

Air Circulation and Precipitation Patterns

Intense sunlight causes water to evaporate in the tropics, and warm, wet air masses rise and 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°N and 30°S.

Regional and Local Effects on Climate

Climate varies seasonally and is modified by other factors, including large bodies of water and mountain ranges.
Seasonality in middle to high latitudes is caused by the tilt of Earth's axis of rotation and its annual passage around the sun.
Regional climate patterns:
- Wet and dry air belts shift as the angle of the sun changes.
- This causes wet and dry seasons at 20°N and 20°S latitudes, where tropical deciduous forests grow.

Effects of Vegetation on Climate

Terrestrial organisms, particularly forests, can alter climate at local and regional scales.
The darker color of forests causes them to absorb more solar energy than deserts or grasslands.
Transpiration causes evaporative cooling, which reduces surface temperatures and increases precipitation rates.

Global Climate Change

The burning of fossil fuels and deforestation have increased the concentration of greenhouse gases in the atmosphere.
This has caused climate change, a directional change to the global climate lasting three decades or more.
Earth has warmed an average of 0.9°C (1.6°F) since 1900 and is projected to warm 1-6°C (2-11°F) more by the year 2100.

Distribution of Terrestrial Biomes

Climate is a major factor determining the locations of terrestrial biomes because it strongly influences the distribution of plants.
Biomes are named for major physical or climatic features and predominant vegetation.
Terrestrial biomes usually grade into each other, without sharp boundaries.

Terrestrial Biomes

Tropical Forest:
- Occurs in equatorial and subequatorial regions.
- In tropical rain forests, rainfall is relatively constant, about 200-400 cm annually.
- Temperature is high year-round (25-29°C) with little seasonal variation.
Desert:
- Occurs in bands near 30°N and 30°S of the equator and in the interior of continents.
- Precipitation is low and highly variable, generally less than 30 cm per year.
- Desert temperature varies seasonally and daily.
Savanna:
- Occurs in equatorial and subequatorial regions.
- Precipitation is seasonal (average 30-50 cm per year) with dry seasons lasting eight to nine months.
- Savanna is warm year-round, with annual temperature averages 24-29°C, but is more seasonally variable than in the tropical forests.
Chaparral:
- Occurs in midlatitude coastal regions on several continents.
- Precipitation is highly seasonal with rainy winters and dry summers, annual average about 30-50 cm.
- Summer is hot (30-40°C); fall, winter, and spring are cool (10-12°C).
Temperate Grassland:
- Found on many continents.
- Precipitation is highly seasonal with dry winters and wet summers.
- Annual precipitation averages 30-100 cm; periodic drought is common.
Northern Coniferous Forest:
- The northern coniferous forest, or taiga, spans northern North America and Eurasia and is the largest terrestrial biome on Earth.
- Annual precipitation is 30-70 cm, and periodic drought is common.
- Winters are usually cold, while summers may be hot.### Temperate Broadleaf Forest
Found primarily at mid-latitudes in the Northern Hemisphere, with smaller areas in Chile, South Africa, Australia, and New Zealand
Receives significant precipitation throughout the year, with annual totals ranging from 70 to over 200 cm
Winter temperatures average 0°C, while summers are hot and humid with temperatures up to 35°C
Vertical layers include a closed canopy, understory trees, a shrub layer, and an herb layer
Dominant plants are deciduous trees in the Northern Hemisphere and evergreen eucalyptus in Australia
Mammals, birds, and insects utilize all vertical layers
Many mammals hibernate, and many birds migrate in winter

Tundra

Covers expansive areas of the Arctic, with alpine tundra existing on high mountaintops at all latitudes
Annual precipitation is lower in arctic tundra (20-60 cm) than alpine tundra (>100 cm)
Winters are cold, with averages below -30°C, while summers are generally less than 10°C
Vegetation is mostly herbaceous, including mosses, grasses, forbs, dwarf shrubs, and trees, and lichens
Permafrost, a permanently frozen layer of soil, restricts plant root growth
Mammals include musk oxen, caribou, reindeer, bears, wolves, and foxes, and many migratory birds have summer nesting grounds in the tundra

Aquatic Biomes

Cover most of Earth's surface and have less latitudinal variation than terrestrial biomes
Characterized by physical and chemical environment, with average salt concentration in marine biomes (3%) and freshwater biomes (<0.1%)
Oceans have a major impact on the biosphere, covering about 75% of Earth's surface
Photosynthetic marine organisms provide most of the planet's O2 and consume large amounts of CO2
Ocean temperatures affect global climate and wind patterns, and moderate the climate of nearby land

Zonation in Aquatic Biomes

Many aquatic biomes are stratified into zones 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 abyssal zone is located in the aphotic zone with depths of 2,000-6,000 m
The benthic zone includes the organic and inorganic sediment at the bottom of all aquatic zones

Lakes

Size varies from small ponds to very large lakes of thousands of square kilometers
Temperate lakes may have a seasonal thermocline, while tropical lowland lakes have a year-round thermocline
Salinity, O2 concentration, and nutrient content vary among lakes and between seasons
Oligotrophic lakes are nutrient-poor and O2-rich with low organic content, while eutrophic lakes are nutrient-rich and high in organic content
Rooted and floating aquatic plants live in the shallow, well-lit littoral zone, while phytoplankton inhabit the limnetic zone
Zooplankton graze on phytoplankton, and fish live in all zones with sufficient oxygen

Wetlands

Are inundated by water at least some of the time and support plants adapted to water-saturated soil
Rapid organic production and decomposition periodically deplete dissolved oxygen
Wetlands develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas
Plants include lilies, cattails, sedges, bald cypress, and black spruce
Invertebrates and birds, as well as otters, frogs, and alligators, inhabit wetlands

Streams and Rivers

Headwater streams are usually cold, clear, swift, and turbulent, while downstream rivers are warm and turbid
Salt and nutrient content increase from headwaters to the mouth
Streams and rivers are generally O2-rich, but organic enrichment can deplete O2 downstream
Headwater streams may be rich in phytoplankton or rooted aquatic plants
Fish, invertebrates, and aquatic mammals inhabit unpolluted rivers and streams

Estuaries

Are nutrient-rich and productive transition zones between a river and the sea
Salinity varies spatially and with the changing tides
Include a complex network of tidal channels, islands, natural levees, and mudflats
Saltmarsh grasses and algae are the major producers
Invertebrates, fish, waterfowl, and marine mammals are abundant

Intertidal Zones

Are periodically submerged and exposed by the tides
Upper intertidal zones experience longer exposure to air and greater variation in temperature and salinity
Physical differences between intertidal zones limit the organisms to particular strata
Oxygen and nutrient levels are generally high
Substrates are generally either rocky or sandy
Sandy intertidal zones tend not to have attached plants or algae, while rocky intertidal zones support attached algae

Oceanic Pelagic Zone

Is an expanse of open water covering approximately 70% of Earth's surface
Is constantly mixed by wind-driven oceanic currents
Oxygen levels are generally high, but nutrient concentrations are lower than coastal waters
Phytoplankton and zooplankton are the dominant organisms
Fish, squid, turtles, and marine mammals are common
Overfishing, pollution, ocean acidification, and global warming harm this biome

Coral Reefs

Are formed from the calcium carbonate skeletons of corals
Shallow reef-building corals live in the photic zone in warm, clear water
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
Corals form a mutualistic relationship with unicellular algae, which provide them with organic molecules
In addition to corals, other invertebrates and fish are also exceptionally diverse

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 very high water pressure
Oxygen is typically abundant enough to support diverse animal life
Soft sediments or rocks can form the substrate
Photosynthetic organisms, seaweeds, and filamentous algae are restricted to shallow areas
Deep-sea hydrothermal vents are found on mid-oceanic ridges### Environmental Factors Affecting Ecological Distribution
Rocks and soil limit the distribution of plants and animals due to factors such as pH, mineral composition, and physical structure.
Soil pH can directly affect distribution due to extreme acid or basic conditions, or indirectly by affecting the solubility of toxins and nutrients.

Substrate and Water Chemistry

The substrate of rivers affects water chemistry and determines which organisms can burrow into or attach to it in freshwater and marine environments.

Ecological Change and Evolution

Ecological interactions can cause evolutionary change, and vice versa, in a reciprocal relationship.
The diversification of plants on land provided new habitats and food sources for animals, leading to bursts of speciation and further ecological change.
Conversely, ecological change can stimulate evolutionary change in animals, leading to further ecological change.

Rapid Feedback Effects

Ecological change and evolution can exert rapid feedback effects on each other, leading to rapid changes in ecological interactions.
For example, color patterns, jaw morphology, and feeding preference evolved rapidly in Trinidadian guppies when predators were removed.
These evolved traits then had contrasting effects on algal abundance, demonstrating the reciprocal relationship between ecological change and evolution.

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This quiz covers the factors that determine the geographical distribution of a species, including climate, temperature, and precipitation. Learn how scientists study the environmental factors that limit where a species can be found.