Life Histories: Energy Budgets, Seed Dispersal, and Plant Classification, Study notes of Ecology and Environment

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LIFE HISTORIES

Chapter 12

ENERGY BUDGETS

 Principle of Allocation  (^) Investment of energy in one endeavor reduces the investment in another  (^) Trade offs in reproduction  (^) Number and Quality of offspring

 Conclusions?

SEED DISPERSAL IN PLANTS

 Unassisted: No specialized structures.  (^) Adhesion: Hooks, spines, or barbs.  Wind: Wings, hair, (resistance structures).  (^) Ant: Oil surface coating (elaisome).  Vertebrate: Fleshy coating (aril).  Scatter-hoarded: Gathered, stored in caches

SEED SIZE AND NUMBER OF PLANTS

SEED SIZE AND NUMBER IN PLANTS

BEFORE AND AFTER SEXUAL

MATURITY

 Before - maintenance or growth.  (^) After - maintenance, growth, or reproduction.  (^) Individuals delaying reproduction will grow faster and reach a larger size.  (^) Increased reproduction rate (usually, unless you’re dead)

CONTRASTING R AND K SELECTION

 Intrinsic Rate of Increase:  (^) Highest in r selected species.  Competitive Ability:  (^) Highest in K selected species.  Reproduction:  (^) r: Numerous individuals rapidly produced.  (^) K: Fewer larger individuals slowly produced.  (^) Gestation period and period to sexual maturity

PLANT LIFE HISTORIES

 Grime proposed two most important variables exerting selective pressures in plants:  (^) Intensity of disturbance:  (^) Any process limiting plants by destroying biomass.  (^) Intensity of stress:  (^) External constraints limiting rate of dry matter production.

PLANT TYPES

 Ruderals (highly disturbed habitats)  (^) Grow rapidly and produce seeds quickly.  Stress-Tolerant (high stress - no disturbance)  (^) Grow slowly - conserve resources.  Competitive (low disturbance low stress)  (^) Grow well, but eventually compete with others for resources.