Lec 10- heterotrophs Flashcards
heterotrophy diversity
found across all organismal groups
herbivores
eats plants
carnivores
eats animals
detritivores
eat nonliving (dead) organic matter
What is food economics
the balance between ease of getting food and the quality of food
Ecological stoich
elements relationships in food
- relative abundance of C and N varies
- dictates what and how each type of heterotroph eats
plant stoich
high C:N ratio
- C used to build up structure and for photosynthesis
C>N
animals, fungi and bacteria stoich
low C:N ratio
less C needed
N>C
what 5 elements make 93-97% of biomass of plants, animals, etc?
C
O
N
P
H
carbon fxn
structure
oxygen fxn
part of water molecules
hydrogen fxn
part of water molecules
nitrogen fxn
part of amino and nucleic acids
phosphorus fxn
essential for cellular processes- ATP energy transfer
herbivory- food stoich
easy to get food- abundant
low quality food- rich in C but poor in N- difficult to digest
herbivory food
substantial nutritional chem challenges
- low N, high C
- cellulose and lignin strenthen tissue but increase C:N ratio = difficult to ingest and digest
- overcome plant physical and chemical defenses
physical: spines/thorns
chemical: toxins/digesting reducing compounds
- plants are poor food and animals must generally consume large amounts of food
koala diet
eucalyptus
- long digesting organs
- gut microbes
- long sleep
elephants diet
large amounts of food
10% of food to obtain nutrients
porcupines
defense strategies against predators (quills)
carnivory stoich
hard to get food but high quality of food
- nutritionally rich prey
- little variation in C:N ratio: prey available and have varied diet
- selection on nutritional requirements less strong, selection stronger on ability and efficiency of capturing and consuming diff preys
- adaptions to hunt effectively
detritivory stoich
easy to access but high and low quality
difference between detritivory and decomposition
both contribute to decomp and nutrient recycling
- detritivores = ingest and digest dead matter via internal processes (sea cucs)
- decomposers = directly absorb nutrients through chemical and bio processes (fungi)
detritivory
feed on nonliving organic matter
dominant food source is dead plant matter
dead plants rich in C and energy but poor in N
- N limiting to living plants
Nitrogen Use Efficiency in plants to reabsorb N before dropping leaves
- fresh detritus may have physical and chemical defenses present
- not limited by food
- abiotic and chemical composition more direct impacts (soil moisture)
mixotrophy
exploit more than one C source
omnivores
gain energy from plants and animals
mixotrophs
gain energy from photosynthesis (inorganic) and from consuming organic material
saprophytes
feed on dead matter
pinesap
parasites
feed on living plant host
dodder
epiphytes
grow on other plants
- DOES NOT parasitize on them
epiphytic fern
insectivorous plants
additional nutrients from trapped insects
- venus fly trap
functional response
relationship b/w food availability and feeding rate
- relationship b/w food density and food intake levels off
what influences feeding rate?
- animals can only eat so much in mouth
- time to digest (make room for more)
- time to find food (easier for herb)
- time to handle/process food (herb needs more time)
- safer to hide than eat
functional response curve (1)
feeding rate increases linearly up to incipient limiting concentration
- due to quick processing
ILC- feeding rate levels off abruptly, max feeding rate. prey density at which food intake levels off into aymptote
- zooplankton
- rare kind of curve
functional response curve (2)
feeding rate increases linearly at low concentrate at slow rate at moderate concentrations then levels off at high concentrations
- limited by search and low densities
- at hgiher densities then food is widely available
- more common
- large animals (moose)
functional response curve (3)
s-shaped
low at low food densities
increases at intermediate food densities and then levels off at high food densities
- juveniles
optimal foraging theory
max or min some factors to optimize feeding process
- what
- where
- when
- costs vs benefits
- allocated energy
- approach to understand behavior
marginal value theorem
where and when to eat
how long should animal forage in food patch b/f moving to a new location?
- graph
slope = energy gain per unit time
red line = total energy gained by organism as it forages in a patch
- optimal time to spend in a patch is one that maximizes energy gain per unit time across a landscape of patches
diet composition - what to eat
rate of energy intake or predator feeding on ONE prey
E/T = Ne1E1- Cs/ 1 + Ne1H1
Ne1 = # of prey per unit time
Cs = energy expended searching
H1 = handling time
energy predictions
if 1 prey was not enough they add a second prey so 2 prey E/T»_space; 1 E/T
if 1 pray enough then 1 prey E/T > 2 prey E/T
Bluegill sunfish
support the optimal foraging theory
- size distribution of prey in natural habitat
- predicted intake of prey by size (big prey = more food per unit effort)
- actual intake of prey by size, measured in natural habitat
