Energy flow 4 Flashcards
Parasitoid
Any number of insects whose larvae live within and consume their hosts, usually another insect
Detritivore
An organism feeds on a freshly dead partially decomposed organic matter
Kleptoparasitism
A fundamental decision a foraging animal must make is how to obtain food and where to forage
Foraging in the presence of others- negatively impacting those others
General energy flow in boreal ecosystems
Populations and communities can be treated as thermodynamic systems
Energetics
Where energy goes when it enters the body and how much is lost
Ways energy is wasted
Not used
Urinary waste
Egested
Secondary production
Net primary production consumed by herbivores
1.5-2.5 percent in temperate deciduous forest
13 percent in Arctic tundra
60-90 percent in aquatic plankton communities
Assimilation efficiency
Percentage of food energy ingested that is assimilated across the gut wall and becomes available for metabolism
Nutritional content of plants as food
Body of green plants is quite different from body of animal
Plant cells are bound by cellulose, lignin and or other structural materials (high fiber)
Leads to carbon:nitrogen ratio of 40:1
Nutritional content of animals as food
8:1 to 10:1 CN ratio (little structural carbs or fiber components, but are rich in fats and proteins)
Why is assimilation efficiency so low
Mammals do not produce cellulolytic enzymes and cannot break down cellulose very efficiently
Many herbivores utilize microfauna that digest the cellulose and release nutrients
Basic approaches to assimilation
Foregut fermenters- Low quality, high fiber food, but can extract nutrients easily
Hindgut fermenters-Eats lots of food because they do not extract nutrients easily
Coprophagy
Eating faeces
Autocprophagy
Eating their own faeces
Caecotrophy
Eating soft faeces
Willow ptarmigan
Their gut length changes according to the season
Production efficiency
Percentage of assimilated energy incorporated into new growth and reproduction
Remaining energy goes into heat and repro
Ecological efficiency
Percentage of production available at a lower trophic level that goes into production of energy
Top down
Carnivores control number of herbivores
Bottom up
Herbivores control number of carnivores
In poor environments
Primary productivity will be too low to support herbivores
Bottom up
With more primary productivity
The system can support herbivores but is unable to support predators
When primary productivity can support herbivores and carnivores
The system should be dominated by the predatory-herbivore interaction
Top-down
Reciprocal interactions
Control by predators that are dependent on prey
Encountering predators when predator densities are high causes
Chronic stress on mother
Lower reproductive success
Passes on stress to child
Lower repro success in offspring
Regime shifts
An abrupt reorganization across trophic levels
Ecosystems can shift to new states characterized by different species compositions and dominating interactions
What controls primary production of boreal forests
Phosphorous
Climate change implications
Potentially makes our understanding of ecosystem structure and trophic interactions to be incorrect
Mismatch will have major implications for many species
