BIOL 121 Exam 3

Ecology

the study of the interactions between organisms and the environment

Organism Ecology

How do form, physiology, and behavior lead to survival?

• Focus is on adaptations and modifications of structure and function

  • Adaptations result from evolutionary change by natural selection

  • A natural link to the population approach

Population Ecology

What determines the numbers of individuals and their variations in time and space?

• Focus is on processes of birth and death, immigration and emigration, influenced by:

  • The physical environment

  • Evolutionary processes

  • Interactions with other populations

  • A natural link to the community approach

Community Ecology

How are communities structured from their component populations?

• Focus is on the diversity and relative abundance of different kinds of organisms living together, affected by:

  • Population interactions, promoting and limiting coexistence

  • Feeding relationships are responsible for fluxes of energy and materials

  • A natural link to the ecosystem approach

Ecosystem Ecology

How can we account for the activities of populations in the common “currencies” of energy and materials?

• Focus is on movements of energy and materials and influences of:

  • Organisms large and small

  • Climate and other physical factors, including those acting on a global scale

  • A natural link to the biosphere approach

Biosphere Ecology

How can we understand the global movements of air and water, and the energy and chemical elements they contain?

• Focus is on the global circulation of matter and energy, affecting:

  • Distributions of organisms

  • Changes in populations

  • Compositions of communities

  • Productivity of ecosystems

Sun Intensity

The more the sun is relative to the spot on Earth, the warmer it will be

• As the angle of the sun becomes more direct, the warmer it gets

Hadley Cells and Wind Patterns

• Hadley cells are responsible for trade winds and the distribution of moisture across the globe

  • The movement of these cells leads to major wind patterns

• Larger air masses move over 30 degrees of latitude, leading to rainforests and deserts

Axis/Tilt

As the sun moves around the orbit, we are closer or farther away from the sun, and the tilt affects the angle of the sunlight

Ocean Currents

Warm/cold currents affect terrestrial coastal climate

Biome

a major type of ecological community

Tropical Biomes: Tropical Forest

• 20-34°C (68-93°F)

• 125-660 cm precipitation (50-200 in)

• Equatorial/Subequatorial

• High biodiversity

• High human impact

  • Population growth, deforestation for agriculture and development, fragmentation due to roads, etc.

Tropical Biomes: Tropical Savanna

• 24-29°C (75-84°F)

• 10-40 cm (3.9-15.7 in) precipitation

• Equatorial/Subequatorial

• High human impact

  • Ranching, overhunting, and fires

Temperate Biomes: Desert

• 0-60°C (32-140°F)

  • Variable

• <30 cm (12 in) precipitation

• Latitude ~30° N and S

• High human impact 

  • Diversion of water, deep groundwater wells allow human populations in the desert

  • Urbanization (example: Las Vegas) and converting land to irrigated farmland (California Central Valley) 

Temperate Biomes: Chaparral (WILL BE ON EXAM)

• Shrub land 

• Kind of fire-resistant 

• Like a wetter desert 

• 10-40°C seasonal

• 65-75 cm (25.6-29.5 in) precipitation

• Latitude ~30° coastal

• High human impact

  • Large human population/settlements, urbanization and agriculture, and fires

Temperate Biomes: Temperate Grassland

• -10-30°C (14-86°F) seasonal

• 25-75 cm (9.8-29.5 in) precipitation

  • Seasonal

• Mid latitude 

• High human impact

  • Habitat loss to agriculture/ranching 

Temperate Biomes: Temperate Broadleaf Forest

• -30°-30°C (-22-86°F)

  • Seasonal

• 75-150 cm (29.5-59 in) precipitation

  • Seasonal

• Mid latitude

• High human impact

  • Massive logging, land clearing for agriculture, and urban

• New England, Wisconsin, and the southern states 

Northern Coniferous Forest/Boreal

• -50-20°C (-58-68°F)

  • Seasonal

•  40-100 cm (15.7-39 in) precipitation

• High latitude

• Severe winters, short growing season

• High human impact

  • Logging, loss of old growth

Tundra

• -34-12°C (29-52°F)

  • Seasonal

• 20-60 cm (7.9-23.6 in) precipitation

• Highest latitudes

• Permafrost – the soil/dirt is always frozen

• High human impact

  • Oil/mineral extraction, melting of permafrost due to climate change

Permafrost

the soil/dirt is always frozen

Aquatic Biomes

A large ecosystem found in water environments characterized by…

1. Light

2. Temperature

3. Water movement

4. Salinity (salt concentration)

5. Oxygen

Lakes

• Divided into zones by depth, distance to shore, and light

• Nutrient classification

  • Oligotrophic – low nutrients, high O2

  • Eutrophic – high nutrients, low O2

• High human impact

  • Nutrient runoff = eutrophication

Littoral

Close to shore

Limnetic

Far from shore

Photic

light

Aphotic

no light

Benthic

bottom

Pelagic

open water

Wetlands

• Inundated by water

• High nutrients/productivity 

• Low oxygen

• High diversity

• Water purification

• High human impact

  • Draining and filling have destroyed up to 90% of wetlands worldwide

Streams and Rivers

• Flow speed, volume

• Headwaters to mouth

  • Temperature

  • Oxygen

  • Nutriends 

• High human impact

  • Municipal, agricultural, and industrial pollution

  • Damming and flood control affect the ecosystem and migratory species

Estuaries

• Transition of river and sea

• Salinity gradients

• High nutrients/productivity

• Nursery grounds

• High human impact

  • Filling/dredging and pollution

Intertidal Zone

• Vertical zones based on tides

• Steep physical and chemical gradients

• High human impact

  • Oil pollution, spills

  • Building cement/rock walls and barriers to reduce erosion

Ocean Pelagic Zone

• 70% of Earth’s surface

• Divided into zones by depth, distance to shore, and light

• Stable temperatures

• High human impact

  • Overfishing, dumping wastes, plastics

Coral Reefs

• Near shore 

  • Light dependent

• Highly diverse and productive 

• High human impact

  • Coral collecting, overfishing, climate change, pollution, and the development of coastal mangrove agriculture decimated reef fishes

(Deep) Marine Benthic Zone

• Offshore seafloor

• Dark, cold, and high pressure

• Deep-sea vents

• High human impact

  • Overfishing, dumping organic wastes 

Population

A group of individuals of the same species in the same area at the same time

• Rely on the same resources

• Interact

• Interbreed

Closed Population

zero immigration and emigration

• B - D = N

Open Population

allows for immigration and emigration 

• (B - D) + (I - E) = N

Distribution/Dispersion

pattern of spacing

Uniform

allelopathic plants

• All compete with each other

Clumped

plants that drop seeds, schools of fish

• Working together

Random

wind-blown seeds

• Neutral interactions

Intraspecific Competition

members of the same species are competing with each other

Demographics

Statistical data relating to the population and particular groups within it 

1. Age structure

2. Birthrate/fecundity (ability to give birth) 

3. Death rate

4. Generation time

5. Sex ratio

6. Other (any characteristics that affect the growth or decline of a population)

   1. Genetic diversity, disease susceptibility, etc. 

Type I Graph

low juvenile loss rate because of lots of parental care

• Humans

Type II Graph

constant rate of death throughout life

• Ground squirrels

• Rodents

• Invertebrates 

• Lizards

• Annual plants

Type III Graph

rate of juvenile loss is high and levels out once they live past the initial period of high death

• Little parental investment 

• Die within their first year of life

  • Fish and marine inverts

  • Barnacles

  • Moths

  • Insects and plants

Exponential Population Growth

the unrestricted increase in population (density independent)

• Recovering from a disturbance or moving to a new area (more resources)

Rev. Thomas Malthus (KNOW HIS NAME)

• 1978: An Essay on the Principle of Population

• “Malthusian catastrophe”

  • The population of England is growing too fast, and it will run out of supplies eventually

• Influences Charles Darwin

  • “Nature is red in tooth and claw.”

    • Only those that win will survive and reproduce 

Carrying Capacity (K)

the maximum population size that the environment can support with no degradation of habitat 

• Varies with changes in resources

Demographic Transition

 the Industrial Revolution led to a drop in death rates, and cultural changes, especially women’s rights, led to lower birth rates

• Stage 1: Pre-Transition

  • High birth rates 

  • High death rates 

• Stage 2: Early Transition

  • High birth rates 

  • Lowering death rates

• Stage 3: Late Transition

  • Lowering birth rates

• Stage 4: Post-Transition

  • Stability
    

Fertility Rate

the average number of children a woman has in her lifetime based on the childbearing rates of women in a population in a given year

• Between 2007 and 2020, the TFR in the United States declined from 2.12 to 1.64

  • 2008 recession 

  • Postponement of marriage

  • Delaying childbearing, but that never happens

  • Women’s labor force participation

Issues with Declining Birth Rates

1. The population is older

2. Social security

3. Shrinking labor force

4. Economic/social/cultural concerns 

Community

a group of populations of different species living close enough to interact

Niche

 an organism is found based on all of its needs (fundamental niche), plus the interactions with other organisms (realized niche) 

Fundamental Niche

a full range of environmental conditions and resources that a species can theoretically utilize without competition or other limiting factors (ideal conditions)

Realized Niche

actual range of conditions and resources a species occupies in nature

• Often smaller than the fundamental niche

Competition Exclusion

no two similar species can occupy the same niche at the same time

Resource Partitioning

to reduce competition, an organism starts to take on different niches

Competition (-/-)

the struggle between organisms for the same limited resources necessary for survival and reproduction (both organisms end up harmed)

Predation (+/-)

one organism, the predator, kills and consumes another organism, the prey, to obtain energy and sustain life

Parasitism (+/-)

one organism, the parasite, benefits at the expense of the other organism, the host

• The host is not always dead; the parasite is most likely living off of the host while it’s alive

Mutualism (+/+)

each species benefits from the relationship, playing a crucial role in maintaining biodiversity and ecosystem health

Commensalism (+/0)

one species benefits while the other is neither helped nor harmed

Coevolution

two (or more) species reciprocally affect each other’s evolution

Mechanical Defense

physical adaptations that help prey avoid detection and predation

• Quills in a porcupine

• Spikes/thorns on vegetation

Chemical Defense

releasing a chemical to deter predators

• Skunk spray

• Chemical toxins in plants

Warning Coloration

organisms can change color to scare off predators

Crypsis

camouflage/blending in to hide from predation

Batesian Mimicry (IMPORTANT)

a harmless species looks like a harmful one

• Only one is harmful

Mullerian Mimicry (IMPORTANT)

Two unpalatable species mimic each other

• Both are harmful

• Two poisonous species look identical

  • The more you fit in, the more predators know to stay away from you

Species Diversity

incorporates richness (number of different species) and evenness (what percent of the community is made up of each species)

Species Composition

relative abundance

• same as evenness

Trophic Structure

the hierarchical arrangement of various trophic levels within an ecosystem, which includes producers, primary consumers, secondary consumers, and tertiary consumers

Food Chain

a linear sequence showing how energy and nutrients flow from one organism to another (who eats who)

Food Webs

a complex network of interconnected food chains that illustrates how energy and nutrients flow through an ecosystem, showing the feeding relationships among all organisms

Terrestrial Biomes

• Climate – temperature, precipitation, seasonality, latitude (most important)

• Soil – nutrient source

• Vegetation type

• Vegetation structure

• Distribution – follows patterns of climate, topography, and oceans

Adaptations to being a better predator

• Keen eyesight

• Sharp beak

• Sharp talons

• Fast flight

• Good hearing

Adaptations for better defense mechanisms

• Quills in porcupines

• Spikes/thorns on vegetation

• Skunk spray or other chemical toxins

• Warning coloration 

• Crypsis (camouflage)

• Mimicry