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Flashcards in Final Deck (170)
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1

What is nutrition mutualisms?

Two species exchange nutrients, or one species is rewarded in some way for improving the nutritional status of another

2

What are some examples of nutrition mutualisms?

-mycorrhizae and N2 fixing bacteria
-Corals- symbiosis with zooxanthellae
-deep sea tube worms

3

Mutualism will only arise if

pw(sm) + qw(um) > w(nm)
-w(nm): fitness of individuals in a nonmutualistic population
-p: proportion of successful mutualists (W(sm))
-q: proportion of unsuccessful mutualists (w(um))

4

The major exploitative interactions include

predation, herbivory, and parasitism

5

Key predator adaptations affect the ___, ___, and ___ of prey.

detection, capture, consumption

6

Mutualisms generally evolve to facilitate

reproduction, energy/nutrient acquisition, or protection from exploitative interactions

7

Mutualisms can be

obligate or facultative; specialized or general

8

What is an ecological community?

a group of interacting species that co-occur in a particular place

9

What parameters describe communities?

-composition: what species are present?
-structure: how do those species interact with each other?

10

What is direct filtering determined by?

environmental tolerances of the species

11

What is indirect filtering mediated by?

interactions with other species that are subject to filtering

12

What do neutral models of community composition assume?

-communities are random combos of species physiologically able to live in the same place
-two mechanisms determine species membership in communities- dispersal in ecological time and speciation in evolutionary time
-if communities are altered, they do not necessarily recover the same community structure

13

What do niche-based models of community composition assume?

-biological interactions (ex: competition) shape (and are shaping) the niches of coexisting species and so determine community composition
-"ghost of competition past" may give the appearance of competition not being important in the current community (i.e. that niches are already well separated or even randomly distributed) via competitive exclusion and character displacement some time in the past

14

Under a neutral model of community structure

species associate at random

15

In a neutral model

the niches are arranged at random, so that some niches are very similar, and others very different

16

In a niche-based model

the niches are over- or hyper-dispersed in niche space

17

Which is more likely: competitive hierarchy or competitive networks?

competitive networks

18

Coexistence is possible by ___ the niche

subdividing

19

Coexistence is also possible is resources are ___ and OVERALL niche overlap is ___

abundant; small

20

What are some ways to pack species into diverse communities?

-increase overlap: possible if resources (k) are large enough and overlap does not exceed some threshold
-decrease niche breadth: a.k.a. become more specialized
*can happen via character displacement
-extend range along resource axis: a.k.a exploiting resources not used by other species
*can happen via character displacement/directional selection

21

Environmental filtering and competition have ___ effects on community composition

opposing

22

If environmental filtering dominates over competition,

phylogenetic clustering is more likely
-closely related groups will have similar traits and so pass through environmental filter together

23

If competition dominates over environmental filtering,

phylogenetic over- dispersion is more likely
-only phylogenetically and therefore ecologically different species are found within guilds in the community

24

What is community heritability?

the proportion of the variation in a characteristic of the community (such as herbivore diversity) that is explained by genetic variation in the population of a particular species (e.g. plants)

25

How does community heritability affect community structure?

via "community genetics"

26

What is facilitation?

a process in which the presence of one species INCREASES the probability that another occurs in the community, usually by mediating competition

27

How does mutualism operate like facilitation?

lessens the effects of competitive interactions

28

What are keystone predators?

eat other competitively dominant predators, thus allowing coexistence of a diverse community

29

What is apparent competition?

two similar species are negatively impacted by the action of a shared predator or herbivore
-good example of an indirect interaction between two species (one that is mediated via another species)

30

Any process that increases the resource base or decreases the degree to which a resource is limiting will ___ the impact of competition

reduce