ch 22 : landscape ecology, biogeography, and global biodiversity

Question 1

the field of study that considers the spatial arrangement of habitats at different scales and examines how they influence individuals, populations, communities, and ecosystems

Answer 1

landscape ecology

Question 2

current habitat heterogeneity is a reflection of what?

Answer 2

recent and historical events caused by natural human forces

Question 3

long-lasting influence of historical processes on the current ecology of an area.

Answer 3

legacy effects

Question 4

what can continue to cause habitat heterogeneity?

Answer 4

natural forces

Question 5

how has human activity influenced natural forces?

Answer 5

human activity has influenced the intensity, frequency, and ecological influence of natural forces.

Question 6

why does species richness often increase from the local to landscape scale?

Answer 6

because habitat diversity increases along this gradient

Question 7

the number of species in a relatively small area of homogenous habitat, such as a stream

Answer 7

local (i.e. alpha) diversity

Question 8

the number of species in all of the habitats that comprise a large geographic area

Answer 8

regional (i.e. gamma) diversity

Question 9

the number of species that differ in occurrence between two habitats

Answer 9

beta diversity

Question 10

the collection of species that occurs within a region; serves a source of species of all local sites within a region

Answer 10

regional species pool

Question 11

the process of sorting species in the regional pool among localities according to their adaptations and interactions

Answer 11

species sorting

Question 12

a graphical relationship in which increases in area (A) are associated with increases in the number of species (S)

Answer 12

species area curve

Question 13

equation for species-area curve

Answer 13

S = cA^z where c and z are constants fitted to the data

or

log S = log c + z log A

Question 14

across many different groups of organisms, the slope (z) ranges from 0.20 to 0.35 across scales of 1 m2 to the area of an entire country.

Answer 14

slide 12 !!

Question 15

what have human activities caused throughout the world?

Answer 15

widespread fragmentation of large habitats

Question 16

what are the effects of fragmentation?

Answer 16

• it decreases habitat area and increases patch number, edge size, and isolation
• small habitats have small populations which are more likely to go extinct

Question 17

specifically, how does fragmentation effect fragment edges?

Answer 17

• fragmentation causes an increase in the amount of edge habitat compared to the original unfragmented habitat
• an increase in edge habitat changes the abiotic conditions (e.g., ground temperatures in a forest) and the species composition of a habitat.

Question 18

what happens to species that prefer edge habitats when fragmentation occurs?

Answer 18

they increase in abundance

Question 19

how can declining populations in habitat patches be sustained?

Answer 19

by the dispersal of organisms between patches via habitat corridors

Question 20

how do habitat corridors help declining populations?

Answer 20

they increase gene flow and genetic diversity

Question 21

what purposes can habitat corridors serve?

Answer 21

1. pieces of preserved habitats
2. constructed for the specific purpose of allowing species dispersal

Question 22

small intervening habitat patches that dispersing organisms can use to move between large favorable habitats; useful for flying organisms that do not need continuous corridors to disperse

Answer 22

stepping stones

Question 23

what can help determine whether organisms can move between fragments?

Answer 23

the quality of habitat between fragments (i.e. matrix habitat)

Question 24

are all habitats in the matrix the same?

Answer 24

no; some habitats in the matrix may contain favorable conditions for dispersal, whereas others might be inhospitable.

Question 25

CONCEPT : the equilibrium theory of island biogeography incorporates both _____ and ________

Answer 25

area and isolation

Question 26

what did MacArthur and Wilson find?

Answer 26

1. species richness increases with island area 2. islands closer to the mainland appeared to receive more colonizing species

Question 27

how did MacArthur and Wilson test their hypothesis? what did they find?

Answer 27

- to test the hypothesis that species richness is determined by both island area and isolation, they measured bird species richness on 25 islands in the South Pacific. - they found that larger islands contained more species - among islands of similar sizes, near islands contained more bird species than far islands

Question 28

t/f the effects of patch size and isolation are very different across multiple types of habitat

Answer 28

false, they are similar

Question 29

Daniel S and E.O Wilson's experiment

Answer 29

- Daniel Simberloff and E. O. Wilson conducted a manipulative experiment to test effects of habitat size and isolation. - on a set of islands in the Florida Keys, they observed that islands closer to the mainland had more insect species than islands farther from the mainland. - they built tents over selected islands, and fumigated them to kill all insects. - they removed the tents and allowed species to naturally recolonize.

Question 30

what did Daniel S and E.O Wilson's experiment result in?

Answer 30

they found that more insects recolonized islands closer to the mainland, and species richness of islands was similar to values before fumigation.

Question 31

a theory stating that the number of species on an island reflects a balance between the colonization of new species and the extinction of existing species.

Answer 31

equilibrium theory of island biogeography

Question 32

according to the equilibrium theory of island biogeography, what would happen on an uninhabited island?

Answer 32

many species from a nearby source habitat (e.g. mainland) could potentially colonize the island

Question 33

assuming the species pool of potential colonizers is a fixed size, what could be said about the rate of new species colonizing the island?

Answer 33

the rate of new species colonizing the island declines as a function of how many species have already colonized the island

Question 34

what happens as more species colonize the island?

Answer 34

more species are subject to possible extinction due to change and negative interactions (e.g. competition, predation, parasitism)

Question 35

given that the island continues to experience colonization and extinction of species, what would the opposing forces result in?

Answer 35

these opposing forces should result in an equilibrium point of species richness on the island Ŝ.

Question 36

theory of island biogeography: this model only predicts what?

Answer 36

- this model only predicts the number of species at equilibrium—not the species composition at equilibrium. - at equilibrium, there is a continuous turnover of species, resulting in a temporally variable species composition.

Question 37

theory of island biogeography : smaller islands should have________ extinction rates; islands nearer to a source habitat should have ________ colonization rates.

Answer 37

higher; higher

Question 38

what reveals predictions regarding Ŝ?

Answer 38

combining the effects of island area and isolation

Question 39

understanding the effects of what has helped to design nature reserves?

Answer 39

island size and shape

Question 40

since large areas can support large populations with low extinction rates, setting aside a single, _________ will better protect biodiversity than will several small areas.

Answer 40

large area

Question 41

what are some other things that need to be considered when designing nature reserves?

Answer 41

- reserves also need to be close enough to allow dispersal, but far enough to reduce dispersal of diseases and parasites. - the benefits and disadvantages of edge habitat must be considered; round areas have less edge-to-area ratios than rectangular areas. - nature reserves are typically a compromise among various options.

Question 42

_________ _______ in diversity are pervasive and extend even to the oceans

Answer 42

latitudinal trends

Question 43

in the Northern Hemisphere, species richness of most animal and plant groups increase from __________ to _________

Answer 43

north to south

Question 44

in what direction does mammal species richness increase

Answer 44

mammal species richness also increases to the west, likely due to the habitat heterogeneity of mountains

Question 45

oceans also have increased species richness at _________ ________

Answer 45

lower latitudes

Question 46

at any given latitude, there are________ species where there is a greater ecological heterogeneity

Answer 46

more

Question 47

among habitats with _________ __________ ______ ___________, less heterogeneous habitats will support fewer species.

Answer 47

similar levels of productivity

Question 48

what rose in response to past environmental conditions?

Answer 48

current diversity

Question 49

movement of landmasses across Earth’s surface

Answer 49

continental drift

Question 50

the single landmass that existed on Earth ~250 Mya and subsequently split into Laurasia and Gondwana

Answer 50

pangaea

Question 51

the northern landmass that separated from Pangaea ~150 Mya and subsequently split into North America, Europe, and Asia

Answer 51

laurasia

Question 52

the southern landmass that separated from Pangaea and split into South America, Africa, Antarctica, and India

Answer 52

gondwana

Question 53

what did the separation of continents allow species to do?

Answer 53

independently evolve in different regions of the Earth; the joining of continents allowed groups of organisms unique to one landmass to move into new areas

Question 54

what did the separation and joining of continents establish?

Answer 54

six distinct biogeographic regions that contain unique groups of organisms

Question 55

over the past 250 million years, what have the climates on earth experienced?

Answer 55

- dramatic changes as the continents drifted - these changes have had profound effects on the distributions of plants and animals

Question 56

about 2 Mya, gradual cooling of the Earth produced oscillations in climate known as the _______ _______

Answer 56

Ice Age

Question 57

what did alternating periods of cooling and warming cause?

Answer 57

the advance and retreat of ice sheets over north America and cycles of cool, dry climates and warm, wet climates in the tropics

Question 58

what did the advance and retreats of ice sheets cause?

Answer 58

the composition of plant species to change as species migrated back and forth across the landscape