Ecology Exam 219 cards

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Resources Required for Life

1. Water 2. Energy: light, organic molecules (C), inorganic molecules 3. Nutrients (N,P, etc) raw materials for development, maintenance, and reproduction Life: energy&nutrients->offspring



-The capacity to do work (e.g. motion) -Neither created or destroyed-changes form (e.g. heat and chemical bonds)



-Solar energy (rays)-chemical bonds (glucose) :Photosynthesis->used by plant or stored for other organisms (loss at each level)->Glucose to ATP, eventually converted to heat energy (random molecular motion) not available for the most part by biologic


Two ultimate pathways that energy enters biological systems

-photosynthesis: (solar energy + CO2 -> Glucose) -Chemosythesis: (inorganic molecule + CO2 -> Glucose) H2S: deep sea vents NH2 & NO2: Nitrifying bacteria in soil. Great ecological importance. -Autotrophs-make their own organic C molecule (glucose


Photosynthesis "Carbon Fixation"

Photosythesis (e.g. cyanobacteria, algae, plants) sunlight CO2+H2O -> C6H12O6 (sugar) +O2+H2O -visible light is just right at 45% solar energy -light quality and quantity change spatially and temporally . Heterogenity



1. herbivores-eat living plants & plant parts 2. carnivores-eat animals 3. detritivores-eat non-living organic matter (dead plants) decomposers -more specialized catagorization (omnivores, insectivores, piscivores, etc) -various ways of maximizin


Chemical composition and nutrient requirements

-C, O, H, N, P, comprise 93-97% of biomass in organisms (proportion varies) N-amino acids; nucleotides, nucleic acid P-ATP, nucleotides/nucleic acid, phospholipids Plants-C from air nutrients from soil Animals-C and nutrients from food they eat



Consume plants and living parts Overcome 2 main problems -low nutritional value and hard to digest plants -physical and chemical defenses of plants


Herbivores Low nutritional values and hard to digest plants

-strengthening compounds-cellulose and lignin -make C&N ration even higher --most animals cannot digest cellulose and lignin --require help of bacteria,fungi, protists in digestive tract (ruminant stomach) --long digestive tract-eat a whole lot


Herbivores Physical and chemical defense of plants

physical:thorns, spines, etc chemical:toxins (kill, impair, or repel) -1,000s isolated by chemicals -more common and higher toxicity in tropics -tobacco plants-nicotine



-consume nutrient rich food (prey) -complex predator/prey interactions -carnivores (predators) must overcome prey defenses -camouflage, mimicry -anatomical defenses-spines, shells -behavioral defenses-flight, run, refuges, f


Carnivores-predator/prey interactions

-predator is the force driving selection and therefore refining the prey's defense -prey size consumed is usually correlated with predator size (size-selection predation)



feed on non-living organic matter (dead plant material) food is rich in carbon and energy but very low in N -Macro-decomposers millipedes, some beetles -isopods -earthworms -aquatic insect larvae -Micro-decomposers -bacteria -fungi


Energy Limitations

availablity of energy is not the only issue organisms face. The rate at which an organism can take up energy is limited. -individual internal constraints-digestion, handling time(time it takes to process food-chasing prey, cracking shells) -eternal


Energy Acquisition Limitations in Plants

plants cannot fix an unlimited amount of carbon even when CO2 and light are in abundance. Shade vs Sun Species-the shaded plant is adapted to be more efficient at fixing C at low light levels


Energy Acquisition Limitations in Animals

-all things equal, animals cannot consume an unlimited amount of prey per unit time -3 primary functional response patterns observed as you increase prey density. 1. filter feeding organisms that require very little handling time. 2. most common,


Energy Acquisition Limitation in Animals Cont.

Type 2: functional response is most commonly observed in nature. (occurs in both herbivores and carnivores)


Energy Economics: the energy budget

Life: energy & nutrients -> offspring principle of allocation:if energy uptake is limited an organism cannot fully meet all energy demands -compromise between competing demands -growth -reproduction -food acquisition -de


Optimal Foraging Theory

So predators are selective-search for the perfect prey item