Ecology - Nature of the Community Final

Question 1

what algal species spread rapidly in the 1980s after being introduced into the Mediterranean Sea

Answer 1

Caulerpa taxifolia

Question 2

What is species richness?

Answer 2

number of species in that community

Question 3

what are taxonomic and sampling problems associated with

Answer 3

measures of species richness

Question 4

Provide three ways in which subsets of species be defined.

Answer 4

1. affinity
2. guild
3. functional group

Question 5

describe affinity

Answer 5

all birds in a species

Question 6

describe guild

Answer 6

group of species that use same resources

Question 7

describe functional group

Answer 7

species that function in similar ways

Question 8

true or false:
food webs tell little about strength of interactions or importance in a community

Answer 8

true

Question 9

What are interaction webs and how do they describe both trophic (vertical) and non-trophic (horizontal) interactions in a community more accurately?

Answer 9

more
accurately describe both trophic (vertical) and non-trophic (horizontal) interactions

Question 10

What does species evenness measure?

Answer 10

Relative abundance of individuals among the species that make up the community

Question 11

Under what conditions is species evenness maximized?

Answer 11

Number of individuals in population are more evenly distributed

Question 12

What are species diversity indices?

Answer 12

Measure of species diversity that takes into account BOTH species richness ad evenness

Question 13

What kinds of communities have the greatest species diversity indices?

Answer 13

a community dominated by one or two species is less diverse than a community with the same numbers of species, each of which is well represented

Question 14

what plots the proportional abundance of each species relative to the others in rank order

Answer 14

abundance curves

Question 15

what can suggest what species interactions might be occurring

Answer 15

relative abundances

Question 16

what plots richness as a function of total number of individuals counted

Answer 16

species accumulation curves

Question 17

what is the function of species accumulation curves

Answer 17

help determine when most or all of the species in a community have been observed

Question 18

what are some examples of direct interactions

Answer 18

Direct interactions are those that occur between two species (e.g., competition, predation, etc.)

Question 19

How do indirect interactions different from direct interactions

Answer 19

With indirect interactions, the relationship between two species is mediated by a third (or more) species

Indirect effects are often discovered by accident when species are experimentally removed to study the strength of direct interactions.

Question 20

what is the decrease in herbivore abundance having a positive effect on a primary producer

Answer 20

trophic cascades

Question 21

How do sea otters have a positive effect indirect on kelp forests?

Answer 21

sea otters feed on sea urchins, which feed on the kelp

Question 22

What are some of the benefits of kelp forests to other organisms in the sea?

Answer 22

Kelp, in turn, can positively affect abundance of other seaweeds, which serve as habitat and food for marine invertebrates and fishes

Question 23

what occurs when a consumer is indirectly facilitated by a positive interaction between its prey and another species

Answer 23

trophic facilitation

Question 24

Give some examples of trophic facilitation in nature.

Answer 24

scavenging is a widespread behavior and an important process influencing food webs and ecological communities

Question 25

In what types of environments are trophic facilitations more likely to occur?

Answer 25

physically stressful environments than in favorable environments, where competition may be the most important interaction among species

Question 26

What service does the rush Juncus provide for marsh elders (Iva)?

Answer 26

Juncus shades the soil surface, decreasing evaporation and salt buildup * Juncus also has a type of tissue that allows oxygen to get to the roots

Question 27

true or false:
removing juncus decreases growth in iva and vice versa

Answer 27

false
the removal of iva DOES NOT decrease growth of juncus

Question 28

What effect does Juncus growth have on aphid growth in salt marshes?

Answer 28

Juncus has both positive and negative effects on the marsh elder (it improves soil conditions, but also facilitates the aphids)

Question 29

How do competitive networks differ from linear hierarchical systems?

Answer 29

In a competitive network, as opposed to a linear hierarchical system, no one species dominates the interaction, allowing for coexistence

Question 30

what is the magnitude of the effect of one species on the abundance of another species

Answer 30

interaction of strength

Question 31

how is the interaction of strength measured

Answer 31

removing one species (the interactor species) from the community and observing the effect on the other species (the target species)

Question 32

Give an example of how interaction strengths may depend on environmental factors.

Answer 32

Menge et al. (1996) measured interaction strength of sea star (Pisaster) predation on mussels (Mytilus) in wave-exposed versus wave- protected areas * Interaction strength was greater in protected areas * Pisaster was a less efficient predator when exposed to crashing waves

Question 33

what is responsible for creating, modifying or maintaining the physical habitat for themselves and other species

Answer 33

ecosystem engineers

Question 34

what are some ecosystem engineers

Answer 34

Coral reefs and kelp forests

Question 35

what is a species that is present in the greatest numbers / largest population in a community

Answer 35

dominant species

Question 36

what is a species that has a disproportionately large effect on its environment relative to its abundance

Answer 36

keystone species

Question 37

what is an example of a keystone species

Answer 37

beaver

Question 38

what is a ‘redundant species’

Answer 38

having the same function as other species within a larger functional group

Question 39

What is meant by some species interactions being context-dependent?

Answer 39

changeable under different environmental conditions