Bio 160 - First exam

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