STENO ORGANISMS
• They are specialists. • Advantage ??? • Disadvantage ???
EURY ORGANISMS
• They are generalists (“jack of all trades”) • Advantage ??? • Disadvantage ???
• Virtually anything can be Limiting / Regulating .
• Nutrients (or other minerals), Temperature, Light, Water, Atmospheric Gases, Currents and Pressures, Soil, Fire, Biotic Factors (just to name some)
• Temp. varies with altitude and latitude; it is temp. rather than these factors which is REALLY regulating
• Temp. decreases 5.5oC for every 1,000 m (3oF for every 1,000 ft.)
• a particular organism may have narrow ranges of tolerance for some factors, medium for others and wide for yet others
• these ranges / limits may vary seasonally, geographically (ecotypes), and/or with the stage of the life cycle (age)
• Pedicularis groenlandica (Colorado rockies) not above 10,000 ft. not altitude directly temp. --- but not directly on the plant obligate outcrosser --- temp. on its pollinator (bee)
• Some spores can tolerate these conditions (and even worse in laboratory studies)
• Some living organisms can be active at the upper natural extremes but few anywhere near the lower
• Maritime equatorial area may be as little as 0.5o
TEMPERATURE (III)
• Regulating temp. may vary depending on other abiotic environmental factors or with the stage in the life cycle
• Sp. B doesn’t need (as such) the unusual nutrient conditions in the serpentine soils
• Sp. B does well in ‘normal’ soils that have been autoclaved
• bacterial toxins from bacteria that live only in the ‘normal’ soils inhibit Sp. B
LIEBIG’S LAW OF THE MINIMUM
• Justus Liebig (1830’s-1840’s, agronomist)
• From his work we get what some call Liebig’s Law of the Minimum
• The size of a crop is determined by the essential nutrient that is present in minimal amount.
TEMPERATURE (IV)
(Is it altitude and latitude?)
TEMPERATURE (V)
• North / South temp. cline similar to the Altitudinal temp. cline
• Limiting effect of temp. --- Sequoia sempervirens (the coast redwood) pacific coast fogbelt to s. Oregon (temp.) --- freezing of seedlings c. coastal California (moisture)
• High or low temp. may be regulating but seasonal fluctuations are often regulating; Midcontinental areas (Minnesota) may have 35o (some areas of Tibet reported to be 80o)
• transplant them to the other’s habitat and they die?
• Why ?????
WHICH REGUALTORY FACTOR IS HAVING THE EFFECT ????
• Sp. A cannot tolerate the unusual nutrient conditions in the serpentine soils
• Steno • (narrow range)
• Meso • (middle or a bit wider range)
• Eury • (wide range)
SOME IMPORTANT SUFFIXES
• thermal • hydric • haline • phagic • oecious or ecious
• when conditions are not optimal for one factor this may influence other factors (? domino effect ?)
MORE RIDERS / AFTERTHOUGHTS
• organisms rarely (IF EVER!) live under optimal conditions for all (or even most) factors
NUTRIENTS
• most material covered previously
• too much of a nutrient as well as too little can be harmful
• Too little (???)
• Too much (???)
• Synergisms and extrapolation (fertilizer experiment) • + NaNO3 --- 10% increase in yield • + K2SO4 --- 10% increase in yield • + both --- doubled the yield
• Majority are found active between 0 o and 40o. WHY?
TEMPERATURE (II)
• Highest temp. in some ecosystems
• 36o in normal seawater
• Land shade temp. often reaches 46o for a month or more; sometimes 55o
SHELFORD’S LAW OF TOLERANCE
• the absence or poor performance of a species may be controlled by the qualitative or quantitative deficiency or excess of any factor that approaches the limit of tolerance
• did not take into account Biblioteka and – synergisms
• SYNERGISM –-- result of an interaction of two or more factors so that the combined effect is greater (+ or -) than the sum of their separate effects
WATER (I)
BIOLOGY 403: PRINCIPLES OF ECOLOGY
(Regulatory / Limiting Factors)
LIMITING / REGULATING FACTORS
• Limiting Factor ??? Is Regulatory Factor a better term?
TEMPERATURE (I)
• Sometimes difficult to determine if this is the major factor --- WHY?
• Often interacts with moisture
• Temps on the earth (oC): -70 to +100 or more
• in ‘real’ systems it is often difficult (and unrealistic) to single out ONE thing as the major regulatory factor (WHY ?????)