Lecture 22: Biodiversity & Global Ecology: Biodiversity equilibrium

Question 1

________________ can be seen as ____________________ from the balancing of mechanistic factors that ______________________ from a location.

Answer 1

• Biodiversity
• equilibrium reached
• add and subtract species

Question 2

4 broad factors that add and subtract species

Answer 2

1. Speciation rate
2. Extinction rate
3. Colonization
4. Local extinction

Question 3

4 broad factors that add and subtract species - speciation rate

Answer 3

ultimate source of diversity

Question 4

4 broad factors that add and subtract species - extinction rate

Answer 4

ultimate loss of species

Question 5

4 broad factors that add and subtract species - colonization and local extinction

Answer 5

determined by local interactions

Question 6

Speciation is the ultimate source of biodiversity, but _______________________________

Answer 6

requires larger areas and long timescales

Question 7

The biodiversity of ___________, like islands, is ____________________________________ and ______________________________________

Answer 7

• small areas
• limited to additions from colonization
• loss from subsequent local extinctions

Question 8

_________ are useful for limiting biodiversity studies to the processes of _______________________

Answer 8

• Islands
• colonization and local extinction

Question 9

The____________________________________________________ by Robert MacArthur and E. O. Wilson – the number of species on an island balances processes of colonization and local extinction

Answer 9

equilibrium theory of island biogeography

Question 10

_________________ for new species _____________, as the island _______

Answer 10

• Colonization rate
• declines over time
• fills up

Question 11

ultimate limits to colonization

Answer 11

when all regional species are on the island, colonization must be zero

Question 12

_________________ of species drives _____________________________ – more species means more likelihood of local extinction due to local interactions

Answer 12

• Accumulation
• increasing rate of local extinction

Question 13

Balance of colonization and extinction on islands

Answer 13

Where the decreasing colonization rate and the increasing extinction rate cross is the equilibrium state for biodiversity on the island

Question 14

Why does the rate of colonization decelerate to zero as island diversity increases?

Answer 14

If an island is adding species through time, at some point if that island has every single species, the colonization rate must be zero

Question 15

Why does the rate of local extinction accelerate as island diversity increases?

Answer 15

It gets more and more hostile as more species are present

Question 16

Balance of colonization and extinction on smaller islands

Answer 16

• Smaller islands increase the likelihood of chance extinctions, and amplify the negative effects of more species arriving on the island
• lower equilibrium biodiversity

Question 17

Balance of colonization and extinction on closer islands

Answer 17

• Chances of colonization decrease with increasing distance from sources of colonizing species – reduced “species rain”
• Equilibrium biodiversity is higher

Question 18

Simberloff and Wilson’s classic test in the Florida keys

Answer 18

• Islands that are further away colonize at a slower rate and level off at a lower equilibrium biodiversity.
• All islands return to close to original biodiversity.

Question 19

The ___________________ of biodiversity also applies to _________________

Answer 19

• equilibrium view
• continental landmasses

Question 20

____________________ are _____________________________ on continents

Answer 20

• Speciation and extinction
• extra sources of additions and subtractions

Question 21

Large islands or any location on continents have _____________________________________________

Answer 21

higher species richness than expected by colonization alone

Question 22

The ______________ richness comes from the __________________________________________ — endemic speciation and extinction rate.

Answer 22

• extra species
• net balance of speciation rate and extinction rate

Question 23

The balance of speciation and extinction

Answer 23

• Speciation rate starts very low and accelerates then plateaus
• Extinction rate accelerates through time
• Equilibrium point is at the top where the extinction and speciation rate meet - species “rain”

Question 24

Why does speciation rate decelerate and plateau?

Answer 24

• It starts very low when there is no species bc you need species to produce more species
• It declines bc landmass becomes filled up and there is no space for it to diversify

Question 25

Interactions that mechanistically influence both species production and extinction through time (net species accumulation), and local colonization and local extinction rates

Answer 25

1. Structural complexity
2. Solar energy and precipitation
3. Biotic mechanisms

Question 26

influencing biodiversity interactions - structural complexity

Answer 26

• Biodiversity increases with structural complexity/heterogeneity
• Structural complexity is typically more important than productivity for producing and supporting high biodiversity

Question 27

Why is structural complexity good for producing more species?

Answer 27

Structural complexity provides more niche spaces for different kinds of species to evolve and coexist.

Question 28

influencing biodiversity interactions - solar energy and precipitation

Answer 28

• Solar inputs matters that most in regions with strong solar gradients – moving through temperate zones towards the poles
• Precipitation matters the most in regions with relatively uniform solar inputs – the tropics

Question 29

influencing biodiversity interactions - biotic mechanisms

Answer 29

• niche specialization
• Disturbance dynamics
• Consumers and pathogens

Question 30

biotic mechanisms on species accumulating and sorting - niche specialization

Answer 30

Heterogeneity interacts with niche specialization and the process of competition to facilitate an increase in biodiversity.

Question 31

biotic mechanisms on species accumulating and sorting - disturbance dynamics

Answer 31

Disturbance dynamics drive environmental heterogeneity and species turnover through time.

Question 32

biotic mechanisms on species accumulating and sorting - Consumers and pathogens

Answer 32

Consumers and pathogens have greater impact on common species than on rare species, creating turnover of species through time.

Question 33

Biotic mechanisms: environmental heterogeneity and niche specialization

Answer 33

Competition and specialization may result in tighter packing into overall niche space, further increasing biodiversity

Question 34

Intermediate disturbance hypothesis

Answer 34

Inhabitable heterogeneity is greatest at intermediate rates of disturbance

Question 35

Biotic mechanisms: Consumer and pathogen impact and species abundance

Answer 35

Common species may be eaten more, while rarer species escape detection — A possible outcome of consumption by a keystone species.

Question 36

One army ant species also consistently reduces the abundance of the __________________ non-ant leaf litter arthropods.

Answer 36

most common

Question 37

Another army ant species ___________ arthropod abundance in _________________

Answer 37

• only reduces
• high-abundance areas

Question 38

Local diversity = regional diversity

Answer 38

• Theoretical relationship that would pertain if all species within a region were found in all communities

Question 39

Proportional sampling

Answer 39

• If species are added to a community independently of its existing species richness
• Then the local community should sample the regional species pool proportionally

Question 40

local ecological saturation

Answer 40

• if local interactions among species limit membership in a community
• then the number of species in the community should level off at an upper limit, or saturation point, above which regional diversity has no effect

Question 41

define Convergent evolution

Answer 41

• Distantly related species evolve a functional resemblance to each other in response to similar environments.
• Convergence in composition of whole animal communities is also common

Question 42

Convergent evolution has played a major role in shaping dominant vegetation in types of __________

Answer 42

biomes

Question 43

________________ in species accumulation and ecological function is also seen in the ___________________________________

Answer 43

• Convergence
• biodiversity of large islands

Question 44

If _____________________ to allow species production, they act as _________________ from the perspective of biodiversity accumulation.

Answer 44

• islands are big enough
• mini continents

Question 45

Often see repeated evolution of the same ___________ on different islands

Answer 45

“ecotypes”

Question 46

define ecotype

Answer 46

a distinct phenotype with a well-defined ecological function

Question 47

Equilibrium biodiversity production is ____________ when conditions are ______________ — convergent evolution of species phenotype, ecology, and composition of whole communities

Answer 47

• repeatable
• similar