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Chapter 7 Energy relations Energy sources and trophic biology: light, organic molecules, or inorganic molecules
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Announcements? Meetings?
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Photosynthesis = autotrophic –Plants, bacteria, protists Energy sources and trophic biology
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Chemosynthesis = autotrophic –Bacteria Energy sources and trophic biology
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Consume organic matter = heterotrophic –Bacteria, fungi, protists, animals, plants Energy sources and trophic biology
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Trophic diversity across biological kingdoms Figure 7.2
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3 biochemical pathways for photosynthesis: C 3 In dry environments: –C 4 –CAM
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Cool/moist, low light environ Energy efficient Less efficient water use Less efficient CO 2 uptake Different photosynthesis types in different environments - C 3
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Hot/dry, high light environ Less energy efficient More efficient water use More efficient CO 2 uptake Different photosynthesis types in different environments - C 4
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Desert - succulents Less energy efficient Most efficient water use Efficient CO 2 uptake at NIGHT Different photosynthesis types in different environments - CAM
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Energy Relations In Plants ( All measured by CO 2 flux) Gross Photosynthesis (P gross ) –Total amount of CO 2 fixed into glucose Respiration (R) –Total amount of glucose utilized for energy Net Photosynthesis (P net ) –P gross - R
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Generalized Light Response Curve Irradiance P net (= P gross - R) 0 - + Compensation Point Saturation Point
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Contrasting photosynthetic response curves Figure 7.21
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Light response curve: 1 = range of irradiance where P limited by low light
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Light response curve: 2 = optimum irradiance (max P net )
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Light response curve: 3 = range of irradiance where P limited by high light; breaks down photosynthetic apparatus faster than repaired
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Light Response Curves Irradiance P net (= P gross - R) 0 - + C4 Plant Species Sugar Cane Sorghum Corn C3 Plant Species Trees Wheat Algae C3 Species Have Higher P net in Low Light
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Light response curve for different species
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Generalized Nutrient Response Curve Growth Rate Nutrient Concentration >>>Toxicity >>>> Saturation Optimum
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Nutrient Response Curves Growth Rate Nutrient Concentration Macro- Nutrient Micro- Nutrient C O H P K N S Mg Ca Fe Mn Zn Cu Mo B Cl. Required in large quantities Rarely toxic at concentrations that occur in Nature Required in small quantities Become toxic at higher concentrations
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Energy/nutrients usually in limited supply Environment-plant relations: –Photosynthesis only with appropriate T, light, water, nutrients (based on climate/soil)
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Energy/nutrients usually limited supply Plant-Herbivore relations –Plants are numerous –Easy to find, catch –Low nutritional value –Available seasonally
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Energy/nutrients usually limited supply Plant-Herbivore relations –Plants use physical and chemical defenses Thorns Toxins Digestion-reducing compounds
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Energy/nutrients usually limited supply Predator-Prey relations: –Prey animals less numerous than plants –difficult to find, catch –Higher nutritional value
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Energy/nutrients usually limited supply Predator-Prey relations: –Evolution of defenses by plants and prey animals –NS pressure on herbivores/predators to evolve alternative methods
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Energy/nutrients usually limited supply Detritivores: –Majority of food plant material
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Predation 1 search 2 recognition 3 catching 4 consumption
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Table of adaptations Pred activityPred activity SearchingSearching Pred adaptationPred adaptation Sensory acuitySensory acuity Search where prey are abundantSearch where prey are abundant Search imageSearch image Prey counter-adaptationPrey counter-adaptation Improved sensory acuityImproved sensory acuity Space outSpace out PolymorphismPolymorphism
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Table cont. Pred activity Recognition of prey Pred adaptation Learning Prey counter- adaptation Warning signals, mimicry
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Pred activity Catching Pred adaptation Improved motor skills Weapons of offense Prey counter-adaptation Improved motor skills, startle responses, aggregation formation Weapons of defense Table cont.
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Pred activity Handling prey Pred adaptation Subduing skills Detoxification ability Prey counter-adaptation Active defense, tough integument, autotomy Toxins
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Anglerfish: Frogfish: Cryptic against rocky background. Lure to attract prey.
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Harris Hawk To detect small prey, extremely good eyesight. For capturing prey, has sharp beak and talons.
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SEA ANEMONES - poisonous tentacles. Counter-adaptation, CLOWNFISH coat themselves with chemical inhibitor - prevents anemone stings, avoid predation from anemone and other fish.
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FLOUNDER Lies on one side of its body - prevents shadow. Chromatophores modify color to match background. Throws sand on the top of their flattened body to increase concealment.
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What do these BUTTERFLIES mimic?
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Some INSECTS resemble twigs in physical structure and behavior. They can branch off a limb and remain motionless.
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AUSTRALIANTAWNYFROGMOUTH Resembles part of the tree in which it rests. This bird is active at night and remains motionless during dayight hours.
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GRAY TREEFROGS occur as two different color morphs within the same population: a brown morph...... and a green morph.
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Predators generally avoid snakes with a bright banding pattern of black, yellow, and red. ~ 70 spp. of New World snakes have this "coral" type of banding. EASTERN CORAL SNAKE is highly venomous
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Warning signals need not always be visual. RATTLESNAKES possess a highly venomous bite and give a warning noise with their rattle.
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Warning signals can be olfactory: SKUNKS- warning coloration and bad odor warn predators. Spray temporarily blinds close predators; offensive odor lingers long after discharge.
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MONARCH BUTTERFLY feeds as larva on milkweed plants - contain toxins. Toxins are sequestered in tissues of adult. Distinctive colors of adult Monarch warns birds not to eat them.
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VICEROY (left) closely resembles Monarchs. Although not distasteful, birds avoid Viceroy.
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Katydids employ two types of defense. First, coloration resembles leaves - crypsis decreases chances of detection. If detected, second line of defense decreases probability of being captured - it hops away.
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PEACOCK BUTTERFLY from Ireland has spots resembling eyes. These "eyes" frighten away insectivorous birds.
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Squids deter predation by forming a group. Group formation may decrease per capita predation risk in number of ways: selfish herd behavior, confusion effects, or by having more individuals on look out for approaching predator. This may explain why large ungulates travel in herds.
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ELK have keen sense of smell, good hearing, and are swift runners to avoid most predators. If trapped in deep snow, antlers are a match for most predators.
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Turtles have tough integument which is virtually impenetrable. BOX TURTLES have broad hinge across plastron, allows them to completely close shell so tightly - not even a knifeblade can be inserted.
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Six-lined Racerunner has a bright colored tail that distracts predators from its head. When caught, the tail breaks off allowing the lizard to escape = AUTOTOMY.
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HEDGEHOGS are covered with sharp spines similar to the porcupine. When attacked, they curl up into a ball exposing a sphere of spines.
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LIONFISH have long, poisonous spines that are used as a defense against predators.
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POISON ARROW FROGS of C. and S. America produce mucous covering - one of most potent natural poisons known. Mucous used by native people to poison arrow points. Frog has warning coloration.
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Counter-adaptations of prey 1. Crypsis: –Increases recognition time –Only have to make prey less profitable than other prey item
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2. rarity Most predators eat more than one type of prey Most target more common species, or PT (= apostatic selection) Example: prey choice of bird
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Optimal foraging theory Maximize benefit/cost ratio of energy Natural selection should result in traits that allow species to shift behavior / growth patterns to maximize efficiency of resource acquisition under changing environmental conditions
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Optimal “Foraging” by Plants Environment Low light Limited water or nutrients Optimal Growth Pattern Produce more leaves (less roots) Produce more roots (less leaves)
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Optimal foraging Herbivores, carnivores –Optimize foraging by: Minimize energy/water use in search, chase, subdue, eating prey Select prey based on availability and value
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Size of pumas and their prey Figure 7.19
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Fig 7.25
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Optimal foraging theory predicts maximum energy intake But, many studies do not find animals behave optimally Why?
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