Community ecology Chapter 53

Question 1

What are the two main outcomes due to species interactions - competition, consumption and mutualism

Answer 1

•(1) they affect the distribution and abundance of the interacting species, and

(2) they are agents of natural selection and thus affect the evolution of the interacting species. The nature of interactions between species frequently changes over time.

Question 2

A biological commuinity changes over time, what are the primary reasons for that change

Answer 2

climate

historical events

Question 3

Species is richer where

and lower where

Answer 3

richer in large islands near continents than small isolate islands - immigration and extinction

Richer in tropics - lower in the poles

Question 4

define biolobical comminity

Answer 4

•A biological community consists of interacting species, usually living within a defined area.

Question 5

What are biologists asking about comminities

Answer 5

how the work, how to manage them to preserve a species so that ppl will want to live there too

Question 6

define fitness

Answer 6

•fitness—the ability to survive and produce offspring—of the individuals involved.

Question 7

due to community interactions bt species, how does that affect the fate of a population

Answer 7

linked to other species that share its habitiat

Question 8

•A relationship between two species that provides a fitness benefit to members of one of the species is

Answer 8

a + interaction.

Question 9

•Such a relationship that hurts members of one of the species is a

Answer 9

– interaction.

Question 10

•A relationship that has no effect on the members of either species is a

Answer 10

0 interaction.

Question 11

• List the four general types of interactions among species in a community:

Answer 11

competition

consumption

mutualism

commensalism

Question 12

define competition

Answer 12

When individuals us the same resources - resulting in lower fitness for both (–)

Question 13

Define consumption

Answer 13

1.when one organism eats or absorbs nutrients from another, increasing the consumer’s fitness but decreasing the victim’s fitness (+/-).

Question 14

define mutualism

Answer 14

occurs when two species interact in a way that confers fitness benefits to both (+/+).

Question 15

define commensalism

Answer 15

1.when one species benefits but the other species is unaffected (+/0).

Question 16

define coevolutionary arms race

Answer 16

coevolutionary arms race occurs between predators and prey, between parasites and hosts, and between other types of interacting species.

Question 17

analyzing each type of species interaction - what are the three key themes

Answer 17

1. Species interactions may affect the distribution and abundance of a particular species.
2. Species act as agents of natural selection when they interact. In biology, a coevolutionary arms race occurs between predators and prey, between parasites and hosts, and between other types of interacting species
3. The outcome of interactions among species is dynamic and conditional.

Question 18

define competition

Answer 18

•is a –/– interaction that lowers the fitness of the individuals involved. When competitors use resources, those resources are not available to help individuals survive better and produce more offspring.

Question 19

define intraspecific competition

Answer 19

•occurs between members of the same species.
–Because intraspecific competition for resources intensifies as a population’s density increases, it is a major cause of density-dependent growth.

Question 20

define interspecific competition

Answer 20

when members of different species use the same limiting resourses

Question 21

define niche

Answer 21

•niche—the range of resources that the species is able to use or the range of conditions it can tolerate.

Question 22

•Interspecific competition occurs when the ____________________

Answer 22

niches of two species overlap.

Question 23

what is the competitive exclusion principle

Answer 23

it is not possible for species within the same niche to coexist.

Question 24

in developing the competitive exclusion principle, what experiments were run to develop this hypothesis

Answer 24

•species of the unicellular pond-dweller Paramecium.
–Grown in separate cultures, both species exhibited logistic growth.
–When the two species grew in the same culture together, only one species exhibited logistic growth; the other species was driven to extinction.

Question 25

define asymmetric competition

Answer 25

•when one species suffers a much greater fitness decline than the other.

Question 26

define symmetric competition

Answer 26

each species experiences a roughly equal decrease in fitness.

Question 27

•If _______________________occurs and the two species have completely overlapping niches, the stronger competitor is likely to drive the weaker competitor to extinction or to retreat to areas of nonoverlap.

Answer 27

asymmetric competition

Question 28

define fundamental niche

Answer 28

1.A species’ fundamental niche is the resources or areas used or conditions it tolerates in the absence of competitors.

Question 29

define realized niche

Answer 29

1.A species’ realized niche is the resources or areas used or conditions it tolerates when competition occurs.

Question 30

•If _________________ occurs and the niches of the two species do not overlap completely, the weaker competitor will move from its fundamental niche to a realized niche, ceding some resources to the stronger competitor.

Answer 30

asymmetric competition

Question 31

connell set experiments to test the competitive exclusion principle, what were they

Answer 31

• studies—removing one of the competitors and observing the response by the remaining species.
• exclusion of Chthamalus barnacles from the lower intertidal zone by Balanus barnacles.

Question 32

define fitness trade-off

Answer 32

If individuals are extremely good at competing for a particular resource, they are probably less good at enduring drought conditions, warding off disease, or preventing predation

Question 33

•Because competition is a ________________ interaction, there is strong natural selection on both species to avoid it.

Answer 33

negative negative

Question 34

define niche differentiation or resource partitioining

Answer 34

•The predicted eventual outcome is an evolutionary change in traits that reduces the amount of niche overlap and the amount of competition.

Question 35

•The change in species’ traits is called _______________

Answer 35

character displacement.

Question 36

Peter and Rosemary Grant recently documented character displacement in Galápagos finches - what did they find after the two droughts

Answer 36

1977 - Only those individuals with larger beaks were able to crack open the fruits of their major food source, Tribulus cistoides

• 2003; by this time the large ground finch, Geospiza magnirostris, had become established on the island.
• this time, only the smallest-beaked G. fortis individuals survived.

•Data on feeding behaviour indicated that G. magnirostris were outcompeting G. fortis for Tribulus cistoides; only G. fortis that could eat extremely small seeds efficiently could survive.

Question 37

what are one of the major threats to commuities

Answer 37

invasive species

Question 38

•One of the goals of conservation biology is to ______________

Answer 38

keep biological communities intact.

Question 39

experiments have shown that communities that contain a ________ number of different species are more resistant to invasion than communities with a ______ number of species

Answer 39

large

small

Question 40

___________ is a +/– interaction that occurs when one organism eats another.

Answer 40

•Consumption

Question 41

list the three major types of consumption

Answer 41

• herbivory
• parasitism
• predation

Question 42

define herbivory

Answer 42

1.the consumption of plant tissues by herbivores.

Question 43

define parasitism

Answer 43

the consumption of small amounts of tissues from another organism, or host, by a parasite

Question 44

define predation

Answer 44

1.Predation is the killing and consumption of most or all of another individual (the prey) by a predator.

Question 45

list the constitutive defences

Answer 45

avoidance

poison

fighting back

schooling and flocking behaviours

sposematic colouring

Question 46

define aposemmatic colouring

Answer 46

poisonous animials exhibit bright warning colouring

Question 47

•Some of the best-studied constitutive defences involve ___________—the close resemblance of one species to another.

Answer 47

mimicry

Question 48

what are the two forms of mimicry

Answer 48

mullerian

batesian

Question 49

define mullerian mimicry

Answer 49

1.the resemblance of two harmful prey species.

Question 50

define batesian mimicry

Answer 50

1.is the resemblance of an innocuous prey species to a dangerous prey species.

Question 51

•Many prey species have______________—defensive traits produced only in response to the presence of a predator.

Answer 51

inducible defences

efficient energetically, but slow

ie mussels

Question 52

•The data available to date indicate that in many instances, predators are efficient enough to_____________________ ______________________________

Answer 52

reduce prey populations below carrying capacity.

Question 53

•Biologists recently conducted a ____________—they compiled the results of more than 100 studies—and raised the question of why herbivores don’t eat more of the available plant food.

Answer 53

meta-analysis

Question 54

Why herbivores don’t eat more of the available plant food.

•Biologists consider two hypotheses to help answer the question:

1. The ___________ hypothesis suggests that predation or disease limits herbivores.
2. The ______________ hypothesis suggests that plants provide poor nutrition or are well-defended against herbivory.

Answer 54

top-down control

bottom-up limitation

Question 55

•Cottonwood trees and two of their herbivores, beavers and leaf beetles, provide an example of both top-down and bottom-up controls on herbivory.
state is the top-down example

Answer 55

• Top-down control, nitrogen limitation, and effective defence are all important factors in limiting the impact of herbivory.
• The mix of factors that keeps the world green varies from species to species and habitat to habitat.

Question 56

adaptations and arms races

When consumers and prey interact over time, a coevolutionary arms race begins - that happens

Answer 56

–Consumers evolve traits that increase their efficiency.

–In response, prey evolve traits that make them unpalatable or elusive.
–This leads to selection on consumers for traits that counter the prey adaptation, and so on.

•example is the interaction between the parasite Plasmodium (the consumer) and their host humans (the prey).

Question 57

•Plasmodium are unicellular protists that cause __________, which kills at least a million people a year.

Answer 57

malaria

Question 58

Recent data suggest that humans and Plasmodium are locked in a coevolutionary arms race

what is the evidence of this

Answer 58

–In West Africa, the HLA-B53 allele confers protection against malaria by displaying a signal that induces an immune response.
–Individuals with at least one HLA-B53 allele are better able to fight malarial infections.
–However, some Plasmodium populations appear to have evolved resistance to these defences.

Question 59

how do parasites manipulate their hosts

Answer 59

nematodes parasitize species of tree-dwelling ants - lay eggs in the posterior changing it`s colour

ants hold up their posterior - look like berries = birds eat them

nematodes complete their life cycle inside birds = feces = eaten by ants

increased likeliness parasite will be transmitted to a new host, whange the appearance of ants, and manipulatie their behaviour

Question 60

•________________________: strategies to maximize crop and forest productivity while using a minimum of insecticides or other types of potentially harmful compounds.

Answer 60

integrated pest management

Question 61

_____________ are +/+ interactions that involve a wide variety of organisms and rewards.

examples:

Answer 61

Mutualisms

•
–Flowering plants and their pollinators.
–Mycorrhizal fungi and plant roots.
–Bacteria that fix nitrogen and certain species of plants.
–Rancher ants and aphids.
–Farmer ants and fungi.
–Crematogaster ants and acacia trees.
–Cleaner shrimp and fish.

Question 62

•Even though mutualisms benefit both species, the interaction does not involve individuals from different species being _______________

Answer 62

altruistic.

Question 63

•The benefits received in a ____________ are a by-product of each individual pursuing its own self-interest by maximizing its ability to survive and reproduce.

Answer 63

mutualism

Question 64

mutualims - dynamic

Because the costs and benefits of species interactions are fluid, an interaction between the same two species may vary from ___________________________

Answer 64

parasitism to mutualism to competition

Question 65

predictability of communities

Clements argued that communities develop by passing through a series of predictable stages dictated by extensive interactions among species, and that this development culminates in a stable final stage called a_______________

Answer 65

climax community

experimental testing suggest that Clements`position was to extreme

Question 66

predictability of communities

Henry Gleason, in contrast, contended that the community found in a particular area is _______________________

Answer 66

neither stable nor predictable

•it is largely a matter of chance whether a similar community develops in the same area after a disturbance occurs.

experimental testing found that Gleason`s view is closer to accurate

Question 67

•A study of planktonic communities in experimental ponds showed that…..

Answer 67

identical communities do not develop in identical habitats. Each pond had a unique species assemblage.

Question 68

experimental testing has found that which species inhabit a particular site is influences by

Answer 68

biotice interations

climate

chance

history

Question 69

mapping current and past species`distributions

•Historical data on plant communities showed that groups of species change their ranges ______________ of one another; fossil pollen studies suggest that plant community composition has always been _________________

Answer 69

independently

dynamic, rather than static.

Question 70

•A_________________ is a species that has a much greater impact on the surrounding species than its abundance would suggest.

Answer 70

keystone species

Question 71

•A_____________________is any event that removes some individuals or biomass from a community.

Answer 71

disturbance

•it alters some aspect of resource availability.

Question 72

The impact of disturbance is a function of three factors

what are they

Answer 72

type

frequency

severity

Question 73

•Most communities experience a characteristic type of disturbance, and in most cases, disturbances occur with a predictable frequency and severity.
–This is called a community’s _____________

Answer 73

disturbance regime.

Question 74

•Ecologists use two approaches to determine the pattern of disturbance in a community:
what are they

Answer 74

1. Obtaining data in a short-term analysis and extrapolating to predict the longer-term pattern.
2. Reconstruction of the history of a particular site.

Question 75

•To maintain communities in good condition, biologists have to ensure that the ___________________occurs. Otherwise, community composition changes dramatically.

Answer 75

normal disturbance regime

Question 76

•____________________ is the recovery and development of communities following a severe disturbance.

Answer 76

Succession

Question 77

•_____________________ occurs when a disturbance removes the soil and its organisms, as well as organisms that live above the surface: Glaciers, floods, volcanic eruptions, and landslides.

Answer 77

Primary succession

Question 78

•_______________________ occurs when a disturbance removes some or all of the organisms from an area but leaves the soil intact: fires and logging.

Answer 78

Secondary succession

Question 79

•______________ are dominated by species that are short lived and small in stature, and that disperse their seeds over long distances.

Answer 79

Early successional communities

Question 80

•_______________________________ are dominated by species that tend to be long lived, large, and good competitors for resources such as light and nutrients.

Answer 80

Late successional communities

Question 81

•The specific sequence of species that appears over time is called the ______________
•

Answer 81

successional pathway.

Question 82

•Three factors determine the pattern and rate of species replacement during succession at a particular time and place:

list them

Answer 82

1. The particular traits of the species involved.
2. How the species interact.
3. Historical and environmental circumstances, such as the size of the area involved and weather conditions.

Question 83

•________________, the first organisms to arrive at a newly disturbed site, tend to be “weedy”; weeds are plants adapted for growth in disturbed soils.

Answer 83

Pioneering species

Question 84

•__________________species devote most of their energy to reproduction and little to competitive ability.

Answer 84

Early successional

•These species have good dispersal ability, being able to tolerate severe abiotic conditions, and high reproductive rates.

Question 85

role of species interactions

During succession, existing species can have one of three effects on subsequent species

what are they

Answer 85

facilitaion

tolerance

inhibition

Question 86

________________ occurs when early-arriving species make conditions more favourable for the arrival of certain later species by providing shade or nutrients.

Answer 86

1.Facilitation

Question 87

_________________ happens when existing species do not affect the probability that subsequent species will become established.

Answer 87

1.Tolerance

Question 88

______________ occurs when the presence of one species inhibits the establishment of another.

Answer 88

1.Inhibition

Question 89

•In addition to species traits and species interactions, the pattern and rate of succession depend on the _______________________ context in which they occur.

Answer 89

historical and environmental

Question 90

•Succession is also affected by the ________________ that occur during the process. Variation in weather and climate causes different successional pathways to occur in the same place at different times.

Answer 90

climate conditions

Question 91

•____________________ is the number of species present in a given community.

Answer 91

Species richness

Question 92

_________________________ is a weighted measure that incorporates a species’ relative abundance, as well as its presence or absence

Answer 92

Species diversity

Question 93

•The _______________ is usually positively correlated with habitat size. However, islands in the ocean have smaller numbers of species than do areas of the same size on continents.

Answer 93

number of species

Question 94

•The number of species present on an island is a product of just two events:

Answer 94

immigration and extinction.

Question 95

•Immigration rates should decline as the number of species on the island increases because:

Answer 95

–Individuals that arrive are more likely to represent a species that is already present.
–Competition should prevent new species from becoming established when many species are already present on an island.

Question 96

•______________________ should increase as species richness increases, because niche overlap and competition for resources will be more intense.

Answer 96

Extinction rates

Question 97

•MacArthur and Wilson formulated the model called the theory of island biogeography.
•
•Their theory makes two predictions—species richness should be higher on:

Answer 97

1. Larger islands than smaller islands.
2. Near shore islands versus remote islands.

Question 98

•The theory of island biogeography is important because:
•

Answer 98

1. It is relevant to a wide variety of island-like habitats such as alpine meadows, lakes and ponds, caves, and habitats isolated by human development.
2. It is relevant to species that have metapopulation structure.
3. It made specific predictions that could be tested.
4. It can help inform decisions about the design of natural preserves.

Question 99

•Biologists have long understood that__________________tend to be species rich, and the theory of island biogeography has been successful in framing thinking about how species richness should vary among island-like habitats.

Answer 99

large habitat areas

Question 100

Researchers have had a much more difficult time explaining what may be the most striking pattern in species richness

what was this

Answer 100

–In the mid-1800s, biologists recognized that communities in the tropics have more species than communities in temperate or subarctic environments.

Question 101

[*] Data compiled in the intervening years have confirmed the existence of a _________________ in species diversity—for communities as a whole as well as for many taxonomic groups.

Answer 101

strong latitudinal gradient

Question 102

latitudinal gradient in species diversity

to principles to explain the pattern

Answer 102

1. The causal mechanism must be abiotic.
2. The species diversity of a particular area is the sum of four processes: speciation, extinction, immigration, and emigration.

Question 103

latitudinal gradient

1.The _______________hypothesis proposes that high productivity promotes high diversity.

Answer 103

high-productivity

Question 104

Latitudinal Gradient

1.The____________ hypothesis contends that high temperature increases productivity and the likelihood that organisms can tolerate the physical conditions in a region.

Answer 104

energy

Question 105

Latitudinal Gradient

1.The___________________ hypothesis argues that the tropical regions have had more time and space for speciation than other regions.

Answer 105

area and age

Question 106

Latitudinal Gradient

The _______________________ hypothesis states that regions with a moderate type, frequency, and severity of disturbance should have high species richness and diversity

Answer 106

intermediate disturbance

Question 107

•You should be able to
–Explain how interactions among species affect the distribution and abundance of the interacting species.
–Describe the different interactions among species and how they act as agents of natural selection.
–Predict what might happen if a new species is introduced to an area and competes with an existing species.
–Describe the factors that influence the pattern of succession that occurs after a disturbance.
–Compare and contrast species richness and diversity.
–Calculate the Shannon index of species diversity.
–Explain why higher species richness is found in the tropics than in temperature regions.