Chapter 7 - Predation, Grazing & Disease Flashcards
What are the 3 types of predators?
- True predator
- Grazers
- Parasites
Not every organism can fit into one of these 3 categories, creating other categories, like parasitoids
What are true predators?
They kill their prey and so immediately after attacking them. They consume many prey throughout their life.
ex. many species from lions to zooplankton
What are grazers?
They attack several/many prey items through out their life and consume only part of each prey, meaning they usually do not kill their prey
ex. from cattle to blood-sucking leeches
What are parasites?
They consume only part of each prey (known as the host) and don’t kill their prey in the short term (can in the long term) and they will attack one or few prey in their lifetime.
ex. bad bacteria and tapeworms
What are parasitoids?
They are flies and wasps whose larvae consume their host (another insects larvae) from within (as they were laid there by their mother), so they have only one host, which they always kill.
What is compensation?
It is a common response to predation
ex. plant compensation after a herbivory attack occurs to compensate loss - like the removal of top leaves causes lower leaves to increase their rate of photosynthesis and/or dormant buds are stimulated to develop.
What is “sit and wait”?
It is the foraging behaviour of predators to find their prey in a location of their selection.
ex. spiders
What is transmission?
It is a predator behaviour that depends on infectious and uninfected hosts bumping into one another. The overall rate of parasite transmission depends on the density of uninfected susceptible hosts and the density of infectious hosts.
What is optimal foraging theory?
It is a viewpoint that seeks to understand why particular foraging patterns have been favoured by natural selection.
ex. the best bird wing structure is selected for a species
ex 2. a bee will choose one complex flower species (specializes in it) and some other noncomplex ones as well.
Describe generalist predators in regards to their handling and searching times?
They have typically short handling times compared to their search times.
ex. a bird has something to gain and nothing to lose by consuming an item once found because it doesn’t know when it will find food again
Describe specialist predators in regards to their handling and searching times?
They have handling times that are relatively long compared to their search times.
ex. lions live in sight of their prey but catching them can be a long and energy-consuming process
What happens when there is an increase or decrease in predators?
- An increase in predators means a decrease in prey because more prey items are being consumed
- A decrease in predators means an increase in prey because fewer prey items are being consumed
What is mutual interference?
It refers to the consumption rate per individual being reduced with increases in predator density by a number of processes, even when food is not limited.
ex. predators interact behaviourally with other members of their pop, leaving less time for feeding, like hummingbirds defending a rich source of nectar
What is a metapopulation?
It is when an overall pop is divided by the patchiness of an environment into a series of subpopulations, and each has their own internal dynamics, but are still linked to other subpops through dispersal b/w patches
Predation is a force acting on communities that can be described as:
a disturbance!
ex. a predator creates a gap for colonization by other organisms
What is predator-mediated coexistence?
It is when predation promotes the coexistence of species that might otherwise exclude one another.
ex. owls reducing the competitive dominance of smaller birds that exist when the owl is absent
What is symbiosis?
Meaning “living together”, it is the term for close physical associations between species in which a symbiont occupies a habitat provided by a host (excluding parasites)
What is mutualism?
It is when organisms of different species interact to their mutual benefit, so it does not require a symbiont
ex. birds disperse plant seeds by the plant offering the reward of fruit
ex 2. pollination occurs through offering insects/birds the reward of nectar
What are mycorrhizae?
They are fungi that have mutualistic relationships with roots
What are nectaries?
They are sugar-secreting organs on vegetative parts of a plant that attracts insects
ex. nectar from nectaries on Acacia trees attract ants
What is pollen?
It is a nutritionally rich food resource and is offered freely and abundantly to species
What is nectar?
It has no value to plant other than for attracting animals. Nectaries are usually unprotected, but specialized plant species enclose them so only the right visitors can access them
What is gut microbiota?
They are microorganisms that occupy parts of various animals alimentary canals. They are known as extracellular symbionts
What is a predator defined as?
It is any organism that consumes all or part of another living organism thereby benefitting itself, but reducing the growth, fecundity or survival of the prey
Is grazing always bad for the prey?
No, because the plant can adjust chemicals for production of flowers (meaning more seeds) when a top is clipped off.
ex. limited food causes intense intraspecific competition has compensation when grasshoppers are preyed on
ex 2. added food reduces competition so the predation decreases the number of grasshoppers
Can pollination be mutualism?
Yes, because there is reproduction of the flowers and energy/protein is provided for insects. However, it can be seen as predation as well because the insect keeps the pollen & nectar, essentially killing that individual flower
Describe generalist flowers in regards to their handling and searching times?
They have low handling times and low rewards for predators because the anthers are easily accessible, making the pollen easy to collect, so there is little nectar.
Describe specialist flowers in regards to their handling and searching times?
They have greater handling times and higher rewards for predators because they have to have knowledge on how to access the pollen, so there is more nectar.
ex. insect may have to shake the flower to get the pollen/nectar
