L10 + L11 - Predator Prey Interactions Flashcards
(18 cards)
In taxonomic classification of predators, what are the 3 kinds?
Carnivore, Omnivores, Herbivores
In functional classification of predators, what are the 4 types?
True predators, grazers, parasites, parasitoids
Describe how a grazer feeds
Grazers attack many prey, only taking part of each, attacks are usually not lethal
E.g.: herbivores such as sheep or cattle, flies that bite
Give 3 examples of parasites
Tapeworm, TB bacterium, measles virus
Describe how a parasitoid attacks it prey
A parasitoid attacks 1 prey and its attack is always lethal
Usually Diptera (flies) or Hymenoptera (wasps)
Account for 25% of the world’s species
When can herbivores have a serious effect on plants?
Germination or seed setting time
How do plants compensate for herbivores by shading?
The top leaves shade lower leaves, if eaten by a herbivore this lets light through to other leaves below and may even increase photosynthesis levels.
What 2 things can herbivores do that has a disproportionately harmful effect on the plant?
Ring barking, transfer of plant diseases, e.g.: Dutch elm disease and beetles
Give an example of how plant interactions are effected by the abiotic environment
Plants stressed by pollutants provide a better food source for herbivores as they have a high nitrogen content
What defensive methods do plants employ against herbivores?
After a herbivore attacks a plant increases the production of defensive structures or chemicals. Such as have delayed leaf production, tougher leaves, higher fibre and resin content, lower nitrogen content
Why are the effects on a population targeted by predators not predictable?
The survivors might compensate for the loses - reduced intraspecific competition
targets aren’t random they are usually on the weak, ill or young, which generally haven’t yet or aren’t giving much to the population as a whole - least likely to survive or reproduce
How does an unlimited supply of food effect a natural enemies growth?
They continue to grow as a population until the limit is reached as they cant only eat so much and grow so much
Define Monophagous, Oligophagous and Polyphagous
Monophagous - is a specialist and only eats one kind of food
Oligophagous - eats a few different food
Polyphagous - is a generalist and eats many kinds of food
Describe the functional response of a Type 1 natural enemy
Type 1 consumption rate rises linearly as prey density increases. At a certain level consumption levels off and remains constant
Describe the functional response of a Type 2 natural enemy
Type 2 consumption rate rises non-linearly as prey density increases as it is easier to catch. At a certain level consumption levels off and remains constant`
Describe the functional response of a Type 3 natural enemy
At high prey densities Type 3 is like Type 2 - the causes are the same
At low densities Type 3 response has an acceleration phase – curve is sigmoidal
State what will happen to herbivore population levels if there is no predator
It will fluctuate but population will persist
What occurs when predator levels are too high/strong?
Predator will kill all the prey and then itself go extinct
