Lecture 1: Ecology & the Biosphere

What is ecology?

The scientific study of the interactions between organisms and their environment.

The environment includes other organisms (biotic) and physical aspects of an organism’s surroundings.

What is the difference between biotic and abiotic factors?

Biotic: environment including other organisms.

Abiotic: physical aspect of an organism’s surroundings.

What is a population?

A group of individuals of the same species living in the same area.

What is a community?

A group of populations of different species in an area. 

What is an ecosystem?

The community of organisms in an area and the physical factors with which those organisms interact.

What is a landscape?

A mosaic of connected ecosystems.

What is the biosphere?

The global ecosystem – the sum of all the plant’s ecosystems and landscapes.

What determines where terrestrial species live?

Temperature and precipitation (the climate).

What determines where aquatic species live?

Light, nutrient availability, and salinity.

Explain how polar bears are adapted to survive in the Arctic.

2 layers of fur that prevent almost all heat loss.

Up to 4.5 inches of fat.

Large paws with bumps that aid in traction on the ice.

Small ears and tails to prevent heat loss. 

Large size (330-1300 lb/150-600 kg)

Explain how fennec foxes are adapted to survive in the Sahara Desert.

Enormous ears to cool body down.

Fur on paws prevents them from burning on hot sand.

Kidneys adapted to minimize water loss.

Nocturnal.

Live in burrows.

What 3 things impact major weather patterns?

Earth’s shape, its tilt on its axis, and its rotation around the sun.

Why do temperature and precipitation vary globally?

1. Beam spreading causes temperature to decrease at higher latitudes.

   1. High latitudes: sunlight strikes earth at oblique angle = solar radiation less intense.

   2. Low latitudes: sunlight strikes at right angle = solar radiation more intense.

2. Absorption/scattering causes temperature to decrease at higher latitudes.

   1. Absorption/scattering is greater at high elevation because solar radiation travels further through atmosphere.

3. The tilt of the earth creates seasons.

   1. Tilt = 23.5º

What are the impacts of heat on air?

Sunlight warms air, warm air can absorb more water.

Warm air expands causing it to absorb more water, lose pressure, and get lighter.

Warm air rises to high altitudes where there is less atmospheric pressure, causing it to expand and adiabatically cool.

Cool air can hold less water, so air releases water as rain.

What is adiabatic cooling?

A decrease in temperature without the actual loss of heat energy.

Why does rain fall on the windward side of a mountain range?

Adiabatic cooling. Air must go over mountain, expanding and losing moisture via heavy rainfall.

What is a biome?

A distinct geographical region with specific climate, vegetation, and animal life.

Why do biomes sort by temperature and precipitation?

Because these factors affect primary production rates (how much plant material) and primary producer composition (what types of plants).

Everything else builds off of that.

What does it mean in a climate diagram if the precipitation line is above the temperature line?

Plant growth is limited by temperature. 

What does it mean in a climate diagram if the precipitation line is below the temperature line?

Plant growth is limited by precipitation.

Describe a tropical seasonal forest/savanna.

Fire-adapted, small-leaved trees scatter the landscape.

Rapidly growing grasses and forbs cover the ground.

Describe a subtropical desert.

Low density, scattered vegetation.

Desert plant adaptations include reduced leaf surface area, physical defenses, and tolerance to desiccation. 

Describe a temperate seasonal forest.

Distinct vertical layers, such as closed canopy, understory trees, shrubs, and herbs.

Deciduous trees dominant.

Describe a tropical rainforest.

Vertically layered, competition for light is intense.

Diversity is highest here than any other terrestrial biomes.

Describe a tundra.

Treeless, cold temperature, permafrost.

Low precipitation, low-growing vegetation like mosses, lichens, and dwarf shrubs. 

Describe a temperate rainforest.

High annual precipitation and mild temperatures.

Tall evergreen trees, dense undergrowth, and abundant mosses, ferns, and lichens.

What is salinity?

The amount of dissolved salts in water.

Why is the ocean salty?

Runoff from land: acidic rainwater erodes rocks, causing dissolved salts to runoff into streams/rivers, eventually ending up in oceans.

Seafloor openings: ocean water seeps into cracks on the ocean floor, gets heated by magma, and picks up metals from surrounding rocks.

What is primary production?

The amount of light energy converted to chemical energy by autotrophs (e.g. plants, phytoplankton, macroalgae) in an ecosystem over a certain period of time. 

What is primary production limited by?

Nutrients and light.

Why are aquatic habitats characterized by nutrient and light availability?

Because of primary production.

Why do coasts and poles have more nutrients?

Runoff from terrestrial inputs causes high nutrients near the coasts.

Nutrient upwelling: when winds push the warmer surface water away from the coast, it creates a type of vacuum which “pulls” colder nutrient-rich water from the ocean-bottom up to the shallow waters along the coast.

Why do some aquatic areas have more nutrients?

Water is generally shallow near poles/coasts = phytoplankton in these shallow waters benefit from lots of sunlight and nutrient upwelling (especially in warmer months) = high growth in phytoplankton populations.

What characterizes streams and rivers?

Flowing, fresh water.

What characterizes ponds and lakes?

Nonflowing fresh water with areas too deep for emergent vegetation.

What is the litoral zone?

Shallow water usually containing vegetation.

What is the limnetic zone?

Open water where light penetrates.

What is the profundal zone?

Bottom sediments that lie permanently below deeper water (aphotic/lacking light).

What are marine habitats divided by?

Light penetration and distance from shore.

What is the neritic zone?

Shallow water above continental shelves.

What is the oceanic zone?

Deep water beyond neritic zones.

What is the intertidal zone?

Shoreline that is alternately submerged and exposed by the tides.

What is the abyssal zone?

Bottom sediments that lie permanently below deeper water.

What are salt marshes and magrove swamps characterized by?

Intertidal estuarine waters with emergent vegetation.

Salt marshes have nonwoody emergent vegetation.

Mangrove swamps have mangrove trees.

What are estuaries?

Coastal regions where seawater mixes with fresh water from rivers, streams, and runoff (hence lower salinity). With constant input of nutrients, estuaries have exceptionally high productivity.

What is the rocky intertidal zone characterized by?

Intertidal, marine waters, on a steep rocky coastline.

Where are coral reefs, seagrass beds, and kelps forests found?

The neritic zone - shallow region of the ocean overlying continental shelf.

What is Earth’s largest biome?

The open ocean (pelagic zone).

What is the benthic zone?

The bottom surface of an aquatic environment.

Creatures in this zone include microorganisms (bacteria/fungi) and larger invertebrates (crustaceans/polychaete worms).

Most common food for benthic communities = organic matter (detritus) that has fallen from the shallower photic depths.