Studied by 10 people
Ecology
Study of relationships between organisms and the environment
Oikos
House
Logia
Study of
Ecological ignorance of Aswan Dam in Egypt
Schistosomiasis increased from 47% to 80%: snails can reproduce year round in the reservoir
Diminished flow of Nile into Mediterranean decreased phytoplankton blooms and fish harvest
Sardines dropped from 15,000 tons to 500 tons annually
Reduced silt deposition along floodplain increased need for commercialized fertilizers ($100M annually) -> New fertilizer plants use much of power produced by dam
Overwatering of land, causing salt to accumulate
Levels of ecological organization
Individuals
Population
Interactions
Community
Ecosystem
Landscape
Region
Biosphere
Individual level studies
Physiological ecology and Behavioral ecology
Physiological ecology
evolution of physiological and anatomical mechanisms by which organisms solve problems posed by physical and chemical variation in the environment
Behavioral ecology
focuses on evolution of behaviors that allow animals to survive and reproduce in the face of environmental variation
Population level studies
Groups of individuals of a single species inhabiting a defined area
Studies processes such as adaptation, extinction, distribution and abundance of species, population growth and regulation, variation in reproductive ecology of species
Interactions level studies
Predation, parasitism, competition
Emphasizes evolutionary effects of the interaction on species involved
Explores the effect of interactions on population structure or on properties of ecological communities
Ex. What evolutionary benefit do zebras gain by allowing birds to remove parasites?
Community level studies
Association of interacting species
Concentrate on the organisms inhabiting an area
Includes studies on species diversity, food webs
Ex. How does disturbance influence the number of mammal species in African grasslands?
Ecosystem level studies
Ecological community plus all of the physical and chemical factors influencing the community
Studies production and flow of energy, and the cycling of nutrients in the different compartments of the system
Ex. herbivory, passing of energy from one trophic level to another
How does fire affect the nutrient availability in grassland ecosystems?
Landscape level studies
Study of exchanges of materials, energy, and organisms between ecosystems
Ex. How do vegetated corridors affect the rate of movement by mammals among isolated forest fragments?
Region level studies
Studies geographical regions subject to large-scale and long-term regional processes
Includes studies on entire islands, biogeography, latitudinal gradients, historical and regional influences
Ex. How has geologic history influenced regional diversity within certain groups of organisms?
Biosphere level studies
Highest level of ecological organization
Includes studies on the atmosphere, global cycles, changes in global land cover
Ex. What role does concentration of atmospheric CO2 play in the regulation of temperature?
Robert MacArthur’s theory
Two species with identical ecological requirements could not coexist
Robert MacArthur test subjects and eco level
Warblers in interactions level
Douglass Morse Theory
Do warblers use the same feeding zones in the absence of one or more of the other species?
Nalini Nadkarni
Created an inventory of the rainforests in costa rica (ecosystem level)
Epiphyte mats
Storage of nutrients in the rainforest canopy
Gene Likens and Herbert Bormann experiment
Two stream valleys - one disturbed, one deforested
Before: 90% of nutrients were tied up in soil organic matter, 9.5% in vegetation
After: Nitrate losses, 40-50% higher; Other elements - 177% to 1,558% increase in streams draining landscape
Therefore, plants regulate the rate of nutrient loss in forests.
Margaret Davis
Collected information on pollen records (region level, paleoecology). Showed that during climate change, plants evolve, as well as disperse
Bruce Milne
Collected information on Theoretical modeling
Ecotones
transition from one type of ecosystem to another
Natural history
Study of how organisms in a particular area are influenced by factors such as climate, soils, predators, competitors, and evolutionary history
Terrestrial Biomes
Major divisions of terrestrial environment
Distinguished primarily by their predominant plants and are associated with particular climates
Distinctive plant formations
Large Scale Patterns of Climatic Variations
Seasons
Temperature
Precipitation
Atmospheric Circulation
Climate Diagrams
How do seasons happen?
Due to the tilt of the Earth’s axis (23.5 degrees)
Solstice (Winter, Summer) and Equinox (Autumn, Spring)
What affects the pattern of precipitation?
Uneven heating of earth’s surface
Solar driven air circulation, latitude and atmospheric circulation
Solstice (Winter, Summer) and Equinox (Autumn, Spring)
Coriolis Effect
Winds in the Southern hemisphere deflected to the left
Winds in the Northern hemisphere deflected to the right
Climate Diagrams
Developed by Heirich Walter
Summarizes the complicated differences in avg. climate
Soil horizons
O, A, B, C
Soil horizon O
Organic horizon
Soil horizon A
mineral soil mixed with organic matter
Soil horizon B
depositional horizon with materials leached from A horizon, forms banding patterns
Soil horizon C
weathered parent material that include rock fragments usually found on bedrock
Tropical Rain Forest
Precipitation exceeds 100 mm during most months.
Slight annual variation in temperature
Nutrient-poor due to too much rain, acidic soil
Highest biodiversity
ex. Belem, Brazil; Kisagani, Zaire; Kuala Lumpur, Malaysia
Tropical Dry Forest
Climate alternates between very wet and very dry seasons.
Temperature more variable than tropical rainforest
Plants are evolved to survive periods of drought
A bit nutrient-poor
ex. Acapulco, Mexico; Bumbay, India; Darwin, Australia (climate diagrams for sites in the Southern hemisphere order months from July to June)
Tropical Savanna
There is tropical savanna in some wet regions where impermeable subsoil creates conditions more favorable to grow grasses than trees.
Wet season is generally shorter and drier than that of the tropical dry forest.
Frequently with fires
Adaptation: herd together
ex. San Fernando, Venezuela; Taboua, Niger; Longreach, Australia (climate diagrams for sites in the Southern hemisphere order months from July to June)
Desert
Mean annual precipitation is lower than any other biome.
Year-round drought
Annual drought collides with pouring season.
Mean minimum temperature is above 0 degrees Celsius during May to September only.
Usually does not have the A soil horizon
Can still have high species diversity, particularly those with heat adaptations
Extreme temperatures (super hot during the day, super cold during the night)
ex. Yenna, Arizona USA; Faya Largens, Chad; Mongolia
Mediterranean Woodland and Shrubland (Chaparral/Fynbos/Mallee)
Moderate temperatures year round
The Mediterranean climate is summer drought, and a moist-cold season.
Some plants release aromatic compounds that lead to fires, making fires common
Trees with trunks that are fire-resistant are common here
ex. San Diego, California USA ; Taranto, Italy; Adelaide, Australia
Temperate Grassland (Prairies, Steppes)
Maximum precipitation and temperature coincide.
Several months have mean minimum temperatures below freezing.
Winters are usually cold and relatively dry.
Soil is relatively neutral or basic.
ex. Manhattan, Kansas USA; China
Temperate Forest
Can be temperature coniferous forests or temperate deciduous forests
Temperate coniferous forests are associated with seasonal drought, and a moderate variation in temperature.
Temperate deciduous forests are associated with low seasonal variation in precipitation, and a moderate variation in temperature.
Can be quite diverse.
Soil is relatively neutral or basic.
ex. J. Andrews Forest, Oregon USA; Philadelphia, Pennsylvania USA; Reims, France
Boreal Forest (Taiga)
Climate often shows great temperature variation
Modified temperatures and precipitation scales reflect cold, dry climate.
Tropic of Cancer, 23.5° N latitude
Northern summer solstice
Tropic of Capricorn, 23.5° S latitude
Northern winter solstice
Heating of Earth’s surface and atmosphere
Sun heats equator → hot air expands, rises → spreads northward, southward at high altitudes → high-altitude air cools, spreads toward the poles → air sinks down to surface
Rotation of the Earth on its axis breaks up atmospheric circulation into six major cells
Three each for Northern & Southern Hemisphere
Correspond to the trade winds north and south of the equator, westerlies bet. 30° and 60° N or S latitude, and polar easterlies above 60° latitude
Prevailing winds don’t blow directly south due to Coriolis effect
Precipitation from clouds produce
abundant rains in the tropics
Dry air descending across lands at ~30° latitude produces
deserts that ring the globe
Crossing between warm, moist air toward the poles and cold, polar air forms
clouds whose precipitation is linked with temperate environments
Microclimate
Small-scale variation in climate caused by a distinctive substrate, location, or aspect
Microclimate: Altitude
Higher areas are cooler because there is no atmosphere up there: lower chances of trapping the heat from the sun.
Less air pressure also allows the air to expand and move faster, absorbing the heat from the surroundings.
Microclimate: Aspect
Northern Hemisphere: Northern aspect is shaded and face away from the equator.
Southern Hemisphere: Southern aspect is shaded and face away from the equator.
Microclimate: Vegetation
Shading of soil surface by low shrubs lowers maximum temperature.
A layer of leaf litter lowers maximum temperatures even more.
Greater leaf area and numerous twigs of tall shrubs intercept more light, creating the coolest temperatures.
Microclimate: Ground Color
White sand reflects all wavelengths of visible light.
Black sand absorbs all wavelengths of visible light.
Microclimate: Boulders and Burrows
Lower temperatures in the soil, particularly in mammal burrows
Microclimate: Aquatic Temperatures
Temperature variation in air is highest, followed by the aquatic reed bed, then the shallow riffle, and lastly, the deep pool.
Rainbow trout’s Acetylcholinesterase
has two different forms: one that is activated in warmer temperatures, and one that is activated in cooler temperatures.
Baldwin & Hochachka studied what animal
Rainbow trout (Oncorhynchus mykiss)
Water takes a longer time to cool or heat up because of its
high heat capacity and latent heat of vaporization.
Acclimation
physiological changes in response to temperature; reversible
Poikilotherms
body temperature varies directly with environmental temperatures (cold-blooded)
Homeotherms
use metabolic energy to maintain a relatively constant body temperature (warm-blooded)
Ectotherms
regulate body temperature using external sources (Hc, Hr, and He)
Endotherms
rely heavily on internally derived heat energy (Hm)
Balancing heat gain against heat loss
Hs = Hm ± Hcd ± Hcv ± Hr – He
Hs - total heat stored
Hm - heat from metabolism
Hcd - heat through conduction
Hcv - heat through convection
Hr - heat through electromagnetic radiation
He - heat lost through evaporation
Temperature regulation by desert plants
Hs = Hcd ± Hcv ± Hr
Reflective leaves reduce heat gain by radiation
Reduce Hr by orienting leaves parallel to sunlight
Small leaves and open growth form increase exposure to wind
High convective heat loss to wind
Low conductive heat gain from ground
Temperature regulation by arctic and alpine plants
Hs = Hcd ± Hcv ± Hr
Dark pigmented leaves reduce reflection and increase heat gain by radiation
Compact hemispherical growth form decrease exposure of plant surface to wind
Orients leaves perpendicular to sunlight
Low convective heat loss to wind
Temperature regulation by ectothermic animals
Camnula pellucida
raise body temperature with access to light bask, about 10 C above air temp
body temp matches air temp when in the shade
Temperature regulation by endotherms: Mammals
Maintain constant metabolic rate;
Arctic species at a broad range, while tropical species at a narrow range
Thermal neutral zone
range of environmental temperatures over which rate of metabolism does not change
Temperature Regulation by Endotherms: Aquatic Animals
Dolphins have blubber and countercurrent heat exchange in their flippers
Blubber
Insulation of an animal’s body (ex: dolphin)
Countercurrent heat exchange in dolphin flippers
Blood vessels are side-by-side, allowing heat from warm blood to be absorbed by the returning cool blood
In each of many blood vessels, heat flows from warm incoming blood to cool returning blood due to conduction (Hcd) and convection (Hcv)
Temperature Regulation by Endotherms: Insects
A live moth keeps its thorax from overheating. The temperature of the abdomen and the thorax are related: blood circulation to the abdomen allows the thorax to cool down. If there is no circulation to the abdomen, the thorax overheats. Once the thorax overheats, it will be dead.
Metabolic heat from contraction of flight muscles.
Temperature Regulation by Thermogenic Plants
Symplocarpus foetidus
Starch is translocated from the taproot to the spadix. High metabolic rate of the spadix generates sufficient heat to melt the snow. Snow is melted by radiation and conduction.
Metabolic rate of this plant is higher in lower temperatures.
Sun-tracking behavior of plants (Dryas integrifolia): Keeps the flowers facing the sun for several hours each day. Sunlight reflected inward by parabolic-shaped Dryas heats the interior of the plant.
Surviving Extreme Temperatures: Inactivity
In the morning, when air temperature is 25oC and sand temperature is 35oC, all beetles are in the sun. As sand temperatures approach 70oC, most beetles are in the shade.
Beetles tip toe as temperatures increase.
Torpor
state of low metabolic rate and lowered body temperature
ex:
Amount of nectar available to a broad-tailed hummingbird determines whether it goes into torpor during the night.
Scarce nectar: go into torpor
Sufficient nectar: rest and save energy
Hibernation
lasts several months, occurs in winter
Aestivation
occurs in summer
Water Content of Air
Relative humidity = (Water vapor density / Saturation water vapor density) x 100
Vapor pressure deficit
difference between actual water vapor pressure and the saturation water vapor pressure at a particular temperature
As temperature increases, the amount of water vapor in air at saturation and saturation water vapor pressure
increase. (directly proportional)
Evaporative Water Loss
Higher water vapor pressure deficit (vpd), higher rate of water evaporation
Isosmotic
body fluids have same concentration of water and solids as external environment
Still requires energy to balance internal solutes
Hyperosmotic
higher internal salt concentration, lower internal water
Hypoosmotic
lower internal salt concentration, higher internal water
Plant water potential is reduced by:
(1) dissolved substances
(2) water’s tendency to adhere to cell walls or soil particles
(3) evaporation through the column of water from roots to leaves
Highest water potential is in the ___, while lowest water potential is in the ___
soil, air (dry air)
Water Regulation of animals
Wia = Wd + Wf + Wa - We - Ws
Wd: water from drinking
Wf: water from food
Wa: water absorbed (e.g. amphibians)
We: water evaporated
Ws: water secreted
Water Regulation of plants
Wia = Wr + Wa - Wt - Ws
Wr: water from roots
Wa: water absorbed (e.g. amphibians)
Wt: water transpirated
Ws: water secreted
An insect that sweats
Cicada
Diceroprocta apache: cicada that uses evaporative cooling
Hypoosmotic organisms in saltwater
Water diffuses from the gills of the fish to surrounding sea water, Cl and Na are also secreted by specialized cells in the gill
Marine fish drink water to compensate for water lost by osmosis
Hyperosmotic organisms in freshwater
Water diffuses into the gills of the fish, Cl and Na are also absorbed by specialized cells in the gill
Marine fish drink take in salt with their food
Their urine are diluted with a lot of water
Energy Sources
Light, Organic molecules, Inorganic molecules
Autotrophs
use inorganic sources of C and energy; could be photosynthetic or chemosynthetic
Photosynthetic autotroph
source of carbon is CO2, and source of energy is light
Chemosynthetic autotroph
source of carbon is CO2, and source of energy is inorganic chemicals (e.g. hydrogen sulfide)
Heterotrophs
use organic molecules as a source of C and energy
