Population Ecology

Question 1

What is a biological community

Answer 1

An assemblage of populations of various species living close enough for a potential interaction (competition, predation, herbivory, symbiosis, and disease)

Question 2

Fitness effect

Answer 2

Influence of competition of reproduction (fitness of offspring)

Question 3

Competitive exclusion

Answer 3

Local elimination of a competing species

Question 4

Competitive exclusion principle

Answer 4

two species competing for exactly the same limiting resources cannot coexist in the same place

Question 5

Ecological Niche

Answer 5

The total of a species use of biotic and abiotic resources

Question 6

Fundamental niche

Answer 6

entire set of conditions under which an animal can survive and reproduce

Question 7

Realised Niche

Answer 7

Set of conditions actually used by animal after interaction with other species (competition) has been accounted for

Question 8

Barnacle example of fundamental niche and realised niche

Answer 8

once a competitive species was removed from the rock base, another barnacle was able to expand into entire rock - can tolerate entire rock.

Question 9

Resource partitonisn

Answer 9

The differentiation of ecological niches, enables similar species to coexist in a community. (i.e. adaptations for tree-dwelling, floor dwelling, etc)

Question 10

Character displacement

Answer 10

Two competing species in the same environment develop divergent traits to reduce competition between the species

Question 11

Example of character displacement (Galapagos finches)

Answer 11

Beak size related to range of seeds that can be eaten, allowing each species to exploit differing resources (thereby reducing competition as they aren’t competing for the same resource) - When living on islands separately - they have similar beak sizes (lots of overlap). When living together on islands - their beak size is remarkably different = Character displacement (result of competition over many generations which lead to specialisation)

Question 12

Batesian Mimicry

Answer 12

Harmless/palatable species mimics and unpalatable or harmful model

Question 13

Mullerian Mimicry

Answer 13

Two or more unpalatable/harmful species resemble each other

Question 14

Herbivory

Answer 14

Interaction where herbivore eats SOME parts of plants or alga

Question 15

Parasitism

Answer 15

One organism (parasite) derives nourishment/structure from another organism (host), which is harmed in the process

Question 16

Dominant species

Answer 16

Ecological dominance is the degree to which one or several species have a major influence controlling other species in their ecological community (more often species with large biomass)

Question 17

Example of dominant species

Answer 17

mangroves, high abundance, high influence

Question 18

Keystone

Answer 18

Not the most abundant species in their community but have a disproportionate influence on community structure

Question 19

Sea star example of keystone species

Answer 19

In the absence of sea stars, the mussels (its prey) dominated the community as their expansion was not limited by predator.

Question 20

Otter example of keystone species

Answer 20

Otters eat sea urchins, allow kelp forest to flourish. Due to overfishing, orca turned to eating otters, urchins became abundant, kelp forests died. Otters are therefore keystone species for kelp forest diversity.

Question 21

What are keystone species often (predator, prey etc??)

Answer 21

Predator, keep population in check

Question 22

Ecosystem “Engineers”

Answer 22

Some organisms exert influence by causing physical changes in the environment that affect community structure

Question 23

Example of ecosystem engineers

Answer 23

Beaver dams can transform landscapes on a very large scale

Question 24

Non-equilibrium model

Answer 24

Decades ago, most ecologists favoured the view that communities are in a state of equilibrium. * Recent evidence of change has led to a non-equilibrium model, which describes communities as constantly changing after being buffeted by disturbances.