Community Structure Flashcards
1
Q
Types of the effect of the change from one species to another
A
- Direct effects: impact of the presence of species A on species B in a two-species interaction
- Indirect effects: impact of the presence of species A on species C via an intermediary species (A –> B –> C)
- Cascading effects : those which extend across 3 or more trophic levels
- Keystone species : produce strong indirect effects
2
Q
Predator definition
A
- Any organism that consumes all of part of another living organism (prey or host) thereby benefits itself but reduces growth or survival of the prey.
3
Q
Name the different types of predators
A
- True predators - kill prey more or less immediately after attacking them - consume many prey items in course of life
- Grazers - Attack several or many prey items in course of their life, only consume part of the prey
- Parasites - Consume only part of each prey item (host) attack one or very few prey items in course of their life
4
Q
Why is predation important?
A
- Can affect the abundance and distribution of prey populations
- Major type of interaction that can influence organisation of communities
- Major selective force - many adaptation results from predation pressure
5
Q
What are the types of things animals think of when foraging?
A
- Resource quality and quantity
- Resource distribution
- Predator density
- Competition density
6
Q
What is the effect of predation on prey population
A
- Compensatory change in growth, survival and reproduction of surviving prey
- Predation is often not random - weakest, most vulnerable
7
Q
What regulates populations?
A
- Top-down control: Predation, parasites and disease
- Bottom-up control: Resources - food, nest sites
8
Q
What are the different types of prey defence?
A
- Vigilance - if not vigilant the target prey is captured 100% of the time
- Structural defence - spine length is an inducible defence
- Chemical defence - Use of poisonous chemical
- Suicidal altruism - Social insects use this, self-destruction acts benefits others in colony
9
Q
What is competition?
A
- Use or defence of a resource by one individual that reduces the availability of the resource to other individuals
1. Intraspecific - competition with members of own species
2. Intraspecific - competition between individuals of different species - reduces fitness of both
10
Q
Definition of resource
A
Resource: any substance or factor that is used by an organism and supports increased population growth rates as its availability in the environment increases
e.g. Food, water, nutrients, light, space
Non-consumable physical and biological factors are not resources e.g temperature
11
Q
Types of competition
A
- Exploitation competition - Mostly indirect, through shared resources (use of resources from one individual will decrease the amount for others)
- Interference competition - Direct interference over a resource (fight each other)
12
Q
What is the competitive Exclusion Principle?
A
- Principle: complete competitors can not coexist, one species must go extinct
- Complete competitors: two species that live in the same place and possess exactly the same ecological requirements
- Assumptions: Exactly the same resource requirement (no more, no less) environmental conditions remain the same
13
Q
Mutualisms definition
A
- Mutualisms: Organisms of different species interact to their mutual benefit
- Symbioses: Close physical association between species (living together)
- Obligate mutualisms: Co-evolved to a point at which neither member pair can persist without the other
- Facultative mutualisms: Association with other species is not essential but leads to positive effects on fitness
14
Q
Types of Mutualisms
A
- Protection - Trees provide food and shelter
e.g ants provide gardening services (obligate) - Transport - More than 3000 species of plant have seeds dispersed by ants, also pollination
