Niches

Question 1

Ecological niche and the ecological niche concept

Answer 1

Ecological niche: total structural and functional role of a species in an ecosystem

Ecological niche concept: habitat occupancy (where), ecological niche (what you do)

Question 2

Niche breadth

Answer 2

generalist vs specialist

Question 3

Species with overlapping ecological niches interact in 1 of 3 ways:

Answer 3

1) negative: competition - -, predation + -, herbivory + -, parasitism + -
2) positive/symbiosis: commensalism + 0, mutualism + +
3) neutral (no effect)

Question 4

Define niche

Answer 4

the role of an organism in the ecosystem

Question 5

Define fundamental niche

Answer 5

theoretical limit for a species determined by the optimal requirements for all environmental factors in the absence of competition

Question 6

Competitive exclusion (Gause 1930)

Answer 6

2 species requiring approximately the same resources are not likely to remain long evenly balanced in numbers in the same habitat unless…

1) There are refuges from competition (potential loser hangs on in marginal habitats)
2) The loser can re-immigrate from elsewhere
3) Disturbances in the environment prevent the winner from gaining complete monopoly

Question 7

How can niche overlap be reduced?

Answer 7

habitat segregation (ex. upper/lower canopy, forest floor, etc.)

Question 8

Define realized niche

Answer 8

actual habitats where the organism is found due to interactions and limitations on resources in the presence of competition

Question 9

Define habitat

Answer 9

place where an organism lives

Question 10

Define niche compression

Answer 10

realized niches are narrower than fundamental niches, therefore the species occupies a narrower range of habitats than it would in the absence of competition (allopatry isolation vs sympatry together)

Question 11

Define character displacement

Answer 11

phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur but are minimized or lost where the species distributions do not overlap

Question 12

Define competitive release

Answer 12

when a niche is absent, the 2 species occupying the periphery of that niche expand their ranges until they meet

Question 13

Define adaptive radiation

Answer 13

a rapid evolution characterized by an increase in the morphological and ecological diversity of a single, rapidly diversifying lineage, adaptive radiations often occur as a result of an organism arising in an environment with unoccupied niches, such as newly formed lake or isolated chain. Colonizing population may diversify rapidly to take advantage of all possible niches

Question 14

Define community

Answer 14

a group of interacting organisms living together in a specific geographical area or habitat

Question 15

Biocencus/community

Answer 15

term used by Karl Mobius (1877) to describe the interacting organisms of the oyster and mussel bearing tidal flats of the North Sea

Question 16

3 components of community structure

Answer 16

1) closed/open
2) ecotones (boundaries)
3) continuum concept