Lecture 7 Flashcards
What are some characteristics of predators?
- they consume more than one prey per predator
- predator usually larger than prey
- predators are usually more generalists than parasitoids
- predators may be omnivorous
What is the sit and wait predation strategy?
predator sits still and ambushes prey
What are active hunters?
search out their prey and are often highly mobile, sometimes incorporate collaboration in strength by numbers
How do predators optimize energy intake?
Energy reward of the prey E, should be larger than the cost of searching (s) and handling (h) time
E / (s+h)
What determines if a predator is a specialist or a generalist?
if s is small - predator is a specialist
if s is large - predator is a generalist
How do spatial aspects affect time hunting?
important in decision making by predators, take into account travel time and searching for prey
What are some prey defence to predators?
hiding
aposematism
mimicry of baits
mimicry of muller
chemical defense
gregarious lifestyle
What is hiding?
prey defence to predators
leaf rolling, camoflage and protection, galls and leaf mines
What is aposematism?
brightly coloured insects advertise their toxicity and are avoided by predators, toxins can be sequestered from plants are produced by insects themselves
What is mimicry of bates?
a non-toxic species (mimic) copies the appearance of a toxic species (model), the non toxic mimic benefits from the toxicity of the model with similar appearance
mimicry of muller
a toxic species (mimic) copies the appearance of another toxic species (model)
both species benefit from resemblance in appearance and toxicity
What is chemical defence?
e.g. bombardier beetles produce a spray (stored in two reservoirs in beetles abdomen
when aqueous solution of hydroquinones and hydrogen peroxide reach rxn chamber, catalysts facilitate the decomposition of the hydrogen peroxide and the oxidation of the hydroquinone
What is a gregarious lifestyle?
prey live in aggregations to be better able to defend themselves, strength by numbers and risk spreading
What is a cyclical pattern between a single predator and prey species?
predators inhibit prey population growth and are dependent on prey populations for their own population growth
(food web complexity causes stability in prey/predator interactions)
What is apparent competition?
Apparent competition is an ecological phenomenon where two or more prey species indirectly affect each other’s populations through the influence of a shared predator. This type of competition occurs not because the prey species are directly competing for resources, but because the presence and abundance of one prey species can affect the predation pressure on the other prey species.
What is intraguild predation?
occurs when two species that share a host/prey (may compete) also engage in a trophic interaction with each other
What is cannabalism?
The act of consuming ones own kind e.g. preying mantids eat their partner to enhance fitness
What is kleptoparasitism?
a feeding strategy where one animal deliberately steals food from another e.g. kleptoparasitic flies that profit from prey caught by spider
What is a non consumptive effect?
predators create a landscape of fear that influences changes in prey behaviour and performance
What is an example of non-consumptive effects?
exposure to risk predator (mandibles non functional) causes reduction in caterpillar survival (caterpillars stop eating and hide)
