chapter 7 energy relations

Chapter 7 Energy relations

Energy sources and trophic biology:

light, organic molecules, or inorganic molecules

Announcements?

• Meetings?

• Photosynthesis = autotrophic– Plants, bacteria, protists

Energy sources and trophic biology

• Chemosynthesis = autotrophic– Bacteria


• Consume organic matter = heterotrophic– Bacteria, fungi, protists, animals, plants


Trophic diversity across biological kingdoms

Figure 7.2

3 biochemical pathways for photosynthesis:

• C3

• In dry environments:– C4

– CAM

• Cool/moist, low light environ

• Energy efficient

• Less efficient water use

• Less efficient CO2 uptake

Different photosynthesis types in different environments - C3

• Hot/dry, high light environ

• Less energy efficient

• More efficient water use

• More efficient CO2 uptake

Different photosynthesis types in different environments - C4

• Desert - succulents

• Less energy efficient

• Most efficient water use

• Efficient CO2 uptake at NIGHT

Different photosynthesis types in different environments - CAM

Energy Relations In Plants (All measured by CO2 flux)

• Gross Photosynthesis (Pgross )

– Total amount of CO2 fixed into glucose

• Respiration (R)– Total amount of glucose utilized for energy

• Net Photosynthesis (Pnet )

– Pgross - R

Generalized Light Response Curve

Irradiance

Pn

et (=

Pg

ross

- R

)

0

-

+

CompensationPoint

SaturationPoint

Contrasting photosynthetic response curves

Figure 7.21

Light response curve:

• 1 = range of irradiance where P limited by low light


• 2 = optimum irradiance (max Pnet)


• 3 = range of irradiance where P limited by high light; breaks down photosynthetic apparatus faster than repaired

Light Response Curves

Irradiance

Pn

et (=

Pg

ross

- R

)

0

-

+

C4 Plant Species Sugar Cane Sorghum Corn

C3 Plant Species Trees Wheat AlgaeC3 Species Have Higher

Pnet in Low Light

Light response curve for different species

Generalized Nutrient Response CurveG

row

th R

ate

Nutrient Concentration

<<<< Deficiency >>>> Toxicity >>>>

Saturation

Optimum

Nutrient Response CurvesG

row

th R

ate

Nutrient Concentration

Macro-Nutrient

Micro-Nutrient C

OHPKNSMgCa

FeMnZnCuMoBCl..

Required in large quantities

Rarely toxic at concentrationsthat occur in Nature

Required in small quantities

Become toxic at higherconcentrations

Energy/nutrients usually in limited supply

• Environment-plant relations:– Photosynthesis only with appropriate T,

light, water, nutrients (based on climate/soil)

Energy/nutrients usually limited supply

• Plant-Herbivore relations– Plants are numerous– Easy to find, catch– Low nutritional value– Available seasonally

Energy/nutrients usually Energy/nutrients usually limited supplylimited supply

• Plant-Herbivore relations– Plants use physical and chemical

defenses• Thorns• Toxins• Digestion-reducing compounds

Energy/nutrients usually Energy/nutrients usually limited supplylimited supply

• Predator-Prey relations:– Prey animals less numerous than plantsPrey animals less numerous than plants– difficult to find, catchdifficult to find, catch– Higher nutritional valueHigher nutritional value


• Predator-Prey relations:– Evolution of defenses by plants and

prey animals– NS pressure on herbivores/predators to

evolve alternative methods


• Detritivores:– Majority of food plant material

Predation

1 search

2 recognition

3 catching

4 consumption

Table of adaptationsTable of adaptations

• Pred activityPred activity

• SearchingSearching

• Pred Pred adaptationadaptation

• Sensory Sensory acuityacuity

• Search where Search where prey are prey are abundantabundant

• Search imageSearch image

• Prey counter-adaptationPrey counter-adaptation• Improved sensory Improved sensory

acuityacuity• Space outSpace out

• PolymorphismPolymorphism

Table cont.Table cont.

• Pred activity

• Recognition of prey

• Pred adaptation

• Learning

• Prey counter-adaptation

• Warning signals, mimicry

• Pred activity

• Catching

• Pred adaptation

• Improved motor skills

• Weapons of offense

• Prey counter-adaptation• Improved motor skills,

startle responses, aggregation formation

• Weapons of defense



• Pred activity

• Handling prey

• Pred adaptation

• Subduing skills

• Detoxification ability

• Prey counter-adaptation• Active defense, tough

integument, autotomy• Toxins

Anglerfish: Anglerfish: Frogfish:Frogfish:

Cryptic against rocky background.Cryptic against rocky background.

Lure to attract prey.Lure to attract prey.

Harris HawkHarris HawkTo detect small prey, extremely good To detect small prey, extremely good

eyesight. For capturing prey, has sharp eyesight. For capturing prey, has sharp beak and talons.beak and talons.

SEA ANEMONES - SEA ANEMONES -

poisonous tentacles.poisonous tentacles.

Counter-adaptation, CLOWNFISH coat Counter-adaptation, CLOWNFISH coat themselves with chemical inhibitor -themselves with chemical inhibitor -prevents anemone stings, avoid prevents anemone stings, avoid predation from anemone and other fish.predation from anemone and other fish.

FLOUNDERFLOUNDER

Lies on one side of its body - prevents Lies on one side of its body - prevents shadow. Chromatophores modify color to shadow. Chromatophores modify color to match background. Throws sand on the match background. Throws sand on the top of their flattened body to increase top of their flattened body to increase concealment.concealment.

What do these What do these BUTTERFLIES BUTTERFLIES

mimic?mimic?

Some INSECTS resemble twigs in Some INSECTS resemble twigs in physical structure and behavior. physical structure and behavior. They can branch off a limb and They can branch off a limb and remain motionless.remain motionless.

AUSTRALIAN AUSTRALIAN

TAWNYTAWNY

FROGMOUTH FROGMOUTH

Resembles part of the tree in Resembles part of the tree in which it rests. This bird is which it rests. This bird is active at night and remains active at night and remains motionless during dayight motionless during dayight hours.hours.

GRAY TREEFROGS occur as GRAY TREEFROGS occur as two different color morphs two different color morphs within the same population: a within the same population: a brown morph...brown morph...

. . . and a green morph. . . . and a green morph.

Predators generally avoid snakes with Predators generally avoid snakes with a bright banding pattern of black, a bright banding pattern of black, yellow, and red. ~ 70 spp. of New yellow, and red. ~ 70 spp. of New World snakes have this "coral" type World snakes have this "coral" type of banding. of banding.

EASTERN CORAL EASTERN CORAL

SNAKE SNAKE

is highly venomousis highly venomous

Warning signals need not always be Warning signals need not always be visual. RATTLESNAKES possess a visual. RATTLESNAKES possess a highly venomous bite and give a highly venomous bite and give a warning noise with their rattle.warning noise with their rattle.

Warning signals can be olfactory: Warning signals can be olfactory:

SKUNKS- warning coloration and bad SKUNKS- warning coloration and bad odor warn predators. Spray temporarily odor warn predators. Spray temporarily blinds close predators; offensive odor blinds close predators; offensive odor lingers long after discharge.lingers long after discharge.

MONARCHMONARCH BUTTERFLY feeds as larva BUTTERFLY feeds as larva on milkweed plants - contain toxins. on milkweed plants - contain toxins. Toxins are sequestered in tissues of Toxins are sequestered in tissues of adult. Distinctive colors of adult adult. Distinctive colors of adult Monarch warns birds not to eat them.Monarch warns birds not to eat them.

VICEROY (left) VICEROY (left) closely resembles closely resembles Monarchs. Monarchs. Although not Although not distasteful, birds distasteful, birds avoid Viceroy.avoid Viceroy.

Katydids employ two types of defense. First, Katydids employ two types of defense. First, coloration resembles leaves - crypsis coloration resembles leaves - crypsis decreases chances of detection.decreases chances of detection.

If detected, second line of defense decreases If detected, second line of defense decreases probability of being captured - it hops away.probability of being captured - it hops away.

PEACOCK BUTTERFLY from Ireland PEACOCK BUTTERFLY from Ireland has spots resembling eyes. These has spots resembling eyes. These "eyes" frighten away "eyes" frighten away insectivorous birds.insectivorous birds.

Squids deter predation by Squids deter predation by forming a group. Group forming a group. Group formation may decrease per formation may decrease per capita predation risk incapita predation risk innumber of ways: selfish number of ways: selfish

herd herd behavior, confusion behavior, confusion effects, effects, or by having more or by having more individuals individuals on look out for on look out for approaching predator. This may explain approaching predator. This may explain why large ungulates travel in herds.why large ungulates travel in herds.

ELK have keen sense of smell, good ELK have keen sense of smell, good hearing, and are swift runners to hearing, and are swift runners to avoid most predators. If trapped in avoid most predators. If trapped in deep snow, antlers are a match for deep snow, antlers are a match for most predators.most predators.

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.

Six-lined Racerunner has a bright Six-lined Racerunner has a bright colored tail that distracts predators colored tail that distracts predators from its head. When caught, the tail from its head. When caught, the tail breaks off allowing the lizard to breaks off allowing the lizard to escape = AUTOTOMY.escape = AUTOTOMY.

HEDGEHOGS are covered with sharp HEDGEHOGS are covered with sharp spines similar to the porcupine. spines similar to the porcupine. When attacked, they curl up into a When attacked, they curl up into a ball exposing a sphere of spines.ball exposing a sphere of spines.

LIONFISH have long, poisonous LIONFISH have long, poisonous spines that are used as a defense spines that are used as a defense against predators.against predators.

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.

Counter-adaptations of preyCounter-adaptations of prey

• 1. Crypsis:–Increases recognition time

–Only have to make prey less profitable than other prey item

2. rarity2. rarity

• Most predators eat more than one type of prey

• Most target more common species, or PT (= apostatic selection)

• Example: prey choice of bird

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

Optimal “Foraging” by Plants

Environment

Low light

Limited water

or nutrients

Optimal Growth Pattern

Produce more leaves (less roots)

Produce more roots (less leaves)

Optimal foraging

• Herbivores, carnivores– Optimize foraging by:

• Minimize energy/water use in search, chase, subdue, eating prey

• Select prey based on availability and value

Size of pumas and their preyFigure 7.19

Fig 7.25

Optimal foraging theory predicts maximum energy

intake

• But, many studies do not find animals behave optimally

• Why?

chapter 7 energy relations

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