15 - Species Diversity

Question 1

the number of species increases from ____ to ____ latitudes

Answer 1

high

low

Question 2

low prey diversity promotes ____ population dynamics

Answer 2

unstable

Question 3

less species redundancy ____ ecosystem resilience

Answer 3

lowers

Question 4

more species redundancy _____ ecosystem resilience

Answer 4

increases

Question 5

this latitudinal gradient includes what animals?

Answer 5

mammals, land birds, ants, butterflies, marine coastal fish, marine bivalves, copepods, snakes, almost universal

Question 6

species richness may also vary with what other factors?

Answer 6

longitude, elevation, depth, topography, aridity

Question 7

what hypotheses exist regarding the latitudinal gradient?

Answer 7

history 
spatial heterogeneity
competition
predation
productivity
environmental stability
disturbance

Question 8

describe the history/time hypothesis

Support?

Argument??

Answer 8

topical habitats are older TF more stable and less disturbed.
had time for adaptation and speciation

Support: geological past of boreal less constant that tropics. All communities diversity with time

Argument: as glaciers moved in, species moved south to escape. This hyp cannot be tested

Question 9

describe the spatial heterogeneity hypothesis

Answer 9

higher diversity in tropics bc of increase in # of potential habitats

decrease in envr complexity moving away from equator

the more heterogenous and complex the physical envr, the more diverse the plant and animal communities

Question 10

describe the competition hyp

Answer 10

less competition in boreal envr compared to tropics

northern pop regulated by extreme envr conditions, not biological factors. in tropics, pop’s increase to densities where comp for resources is necessary

sources of mortality are abiotic

high competition results in higher rates of speciation

Question 11

alpha diversity

Answer 11

overall species richness

Question 12

beta diversity

Answer 12

number of unique species in diff habitats

Question 13

where is alpha and beta diversity highest why?

Answer 13

tropics

organisms more specialized to habitats

Question 14

ex of competition leading to speciation?

Answer 14

darwin’s finches

comp for food led to specialized beak morphology (feeding specialization)

Question 15

describe predation hypothesis

Answer 15

increase species in tropics in function of increased number of predators that regulate the prey species

decrease comp among prey species

allows co-existence of prey species and potential for new

stronger selective pressure on avoiding predation than becoming better competitors

Question 16

describe the cropping principle

what hyp is this under?

Answer 16

predation increases diversity by reducing intraspecific competition among prey species

Question 17

example of cropping principle

Answer 17

presence of herbivores creates more niches for plants

Question 18

under cropping principle, what happens if predators are removed?

Answer 18

prey start competing –> one/few may dominate

Question 19

two species competing for the same limiting resources cannot exist

What law??

Answer 19

Gause’s law of competitive exclusion

Question 20

effect on community disproportionate to their abundance

Answer 20

keystone predator

Question 21

describe cropping principle in lakes

Answer 21

top predators feed on zooplankton
if TP removed, community diversity decreases. Dominated by a few species of large grazing zooplankton

add fish, diversity of small zooplankton and their invert predators increase

Question 22

describe mesopredator release?

why hyp is this under?

Answer 22

apex predators affect diversity as well as abundance of lower trophic levels

predation hypothesis

Question 23

describe the productivity hyp

Answer 23

tropics support a greater number of species bc of more resources

*increased production leads to increased diversity

Question 24

what are the exceptions to the productivity hyp?

Answer 24

marshes

desert

Question 25

TF there is a correlation between productivity and vertebrate biodiversity

Answer 25

False

Question 26

environmental stability hypothesis

Answer 26

constant climate --> finer specialization and adaptations, shallower niches don't have to deal with such a large amount of envr changes

Question 27

disturbance hypothesis

Answer 27

if community disturbance freq is high --> local extinction --> decrease in species diversity if very low --> competitive exclusion by dominant species --> decrease in species diversity ECOLOGICAL TIME SCALE intermediate disturbance will maximize diversity and lead to patches at local scale

Question 28

what are some limitations of all these hypotheses?

Answer 28

circular (based on the assumption of greater diversity in tropics), some no supported by sufficient evidence (no consistent correlation btwn species diversity and envr stability, productivity, physical heterogeneity

Question 29

role of ice-age extinctions

Answer 29

slow speciation and colonization after glaciations

Question 30

role of polar harshness

Answer 30

high extinction rates, slow population growth

Question 31

role of tropical climatic stability

Answer 31

low extinction rates allow specialization and speciation

Question 32

role of tropical productivity

Answer 32

greater evenness, narrow niches

Question 33

role of structural heterogeneity

Answer 33

finer niche subdivision, microclimate heterogeneity

Question 34

role of interspecific interactions

Answer 34

competition, predation, and mutualism promote specialization

Question 35

TF primitive species are not abundant in the arctic

Answer 35

F - they ARE particularly abundant | --> think about plants

Question 36

Rapoport's rule

Answer 36

taxa have larger ranges in polar regions

Question 37

provide 2 examples of "super dominant" species that are generally plastic

Answer 37

willow lemmings

Question 38

____ ____ is the environmental variable that best predicts plant diversity in the arctic

Answer 38

summer temperature

Question 39

in general, what is expected to happen with a warming climate?

Answer 39

species diversity should increase

Question 40

what species are most vulnerable?

Answer 40

those that are most abundant in the northernmost part of the tundra or polar deserts best adapted to climate conditions of high arctic where more competitive species are absent

Question 41

TF/ southern limits of turn see less specialization among microhabitats

Answer 41

False, greater

Question 42

what determines the northern borders of the geographic distribution of most animals?

Answer 42

temperatures lower than the species-specific tolerance limits

Question 43

what determines the southern borders of the geographic distribution of terrestrial arctic animals

Answer 43

biotic factors --> competitors and natural enemies

Question 44

T/F high temps determine the southern border of terrestrial arctic animals

Answer 44

F

Question 45

why is biodiversity important in the arctic

Answer 45

there is little functional redundancy among species in the arctic and species redundancy enhances ecosystem resilience

Question 46

what are the two types of research?

Answer 46

fundamental research - understand generally how the world works applied research - solve problems - conservation/management and such

Question 47

why is northern research important

Answer 47

rate of change may be more important than its magnitude | science of change is easier to study in the arctic