Ecological footprint of societies part 2

Question 1

Why is nutrient cycling important?

Answer 1

• Organisms are always limited by the availability of some nutrient.
• Patterns of nutrient availability and cycling can have profound impacts on ecosystem structure and function.

Question 2

why is nutrient cycling important - how are organisms involved in nutrient cycling?

Answer 2

All organisms are involved in nutrient cycling via trophic interactions

Question 3

what is the general question for nutrient cycling?

Answer 3

Do any social organisms have large-scale impacts on nutrient cycling, resulting in ecosystem-level changes?

Question 4

nitrogen cycling and societies - what is nitrogen essential for?

Answer 4

it is essential as a building block of amino acids, for building proteins, and DNA

Question 5

nitrogen cycling and societies - where is most nitrogen found

Answer 5

• in the atmosphere (N2)
• which is not a useable form for organisms

Question 6

nitrogen cycling and societies - Most nitrogen in biological systems originates from what?

Answer 6

• from the process of nitrogen fixation
• primarily via symbiotic Rhizobium bacteria associated with legume plants

Question 7

nitrogen cycling and societies - most ecological systems are what?

Answer 7

• nitrogen limited
• and an ecological system is shaped extensively by spatial and temporal patterns of Nitrogen availability.

Question 8

nitrogen cycling and socities - example

Answer 8

• legume plant species
• ungulate herbivores and termites

Question 9

nitrogen cycling and societies example - legume plant species

Answer 9

Nitrogen fixation is performed by legume plant species, including Acacia (ant plant) trees in African savanna systems.

Question 10

nitrogen cycling and societies example - ungulate herbivores and termites

Answer 10

Ungulate herbivores and termites are known to redistribute organic N across the landscape.

Question 11

nitrogen cycling and societies example - what do legume plant species, herbivores, and termites create?

Answer 11

create ’‘hotspots’’ of soil organic N in the African savanna ecosystem

Question 12

termite-mounds, Nitrogen, and habitat
structure

Answer 12

Termite mound soil has highest levels of plant-available N in the systems they are found in

Question 13

termite-mounds, Nitrogen, and habitat structure - what kind of nitrogen do nitrogen-fixing Acacia trees prefer?

Answer 13

they preferentially use N in mound soil in N fixation process, with cascading impact on other vegetation.

Question 14

termite-mounds, Nitrogen, and habitat structure - result of abundance of termite mound

Answer 14

results in a positive effect on growth for approximately 50% of Acacia trees in the ecosystem

Question 15

termite-mounds, nitrogen, and habitat structure - Regularity of termite mound spacing results in what?

Answer 15

results in consistent habitat heterogeneity, compared to areas with no termites.

Question 16

termite-mound, nitrogen, and habitat structure - what does the nitrogen concentration of termite mounds drive?

Answer 16

it drives spatial structuring of trees and associated nitrogen fixation within the savanna vegetation

Question 17

define landscape ecology

Answer 17

The study of the composition and spatial arrangement of habitats, both natural and anthropogenic, and how this influences ecological systems at all scales.

Question 18

Four major impacts on mound-building termites on the habitat composition of African savanna

Answer 18

1. Regulation and redistribution of usable organic Nitrogen.
2. Direct impact on vegetation cover via foraging (scale achieved by social foraging).
3. Indirect impact of mammal herbivore distribution (competitive superiority — indirect competition).
4. Fire frequency reduced via cascading effects of habitat alteration

Question 19

Ant mutualism experiment - Data contrast what areas?

Answer 19

1. no browsing mammals
2. only elephants excluded
3. all browsers present.

Question 20

ant mutualism experiment - protected Acacia

Answer 20

the tree retains tree cover regardless of elephant/browser pressure

Question 21

ant mutualism experiment - only elephants excluded

Answer 21

• Percentage cover of numerous other trees is much higher
• negligible effects of other browsers

Question 22

ant mutualism experiment - elephant and vegetation cover

Answer 22

elephants push percentage cover of other trees (non-Acacia) close to zero.

Question 23

ant mutualism experiment - landscape changes are all underpinned by what?

Answer 23

Landscape changes all underpinned by defensive services provided by mutualistic ants.

Question 24

define invasive species

Answer 24

A non-native species in an ecological system that causes economic or environmental harm, or harm to human health.

Question 25

What is the role of humans in biological invasions?

Answer 25

1. trade and travel
2. overcome natural dispersal barriers
3. mediated dispersal
4. free of natural predators
5. habitat alteration

Question 26

humans and invasion - trade and travel

Answer 26

Human trade and travel intentionally and unintentionally facilitate movement.

Question 27

humans and invasion - overcome natural dispersal barriers

Answer 27

Humans overcome natural dispersal barriers that organisms would otherwise not overcome

Question 28

humans and invasion - mediated dispersal

Answer 28

Human-mediated dispersal facilitates larger founding populations and multiple founding events in a short period of time.

Question 29

humans and invasion - freed of natural enemies

Answer 29

Invasive species freed of natural enemies in new locations.

Question 30

humans and invasions - habitat alteration

Answer 30

Human habitat alteration can facilitate establishment and growth of invasive species.

Question 31

Social biology and the invasion of the fire ant (Solenopsis invicta)

Answer 31

• Specialized in colonizing and surviving in disturbed habitat.
• Form large, territorial colonies with aggressive, stinging workers

Question 32

What makes the fire ants an invasive species?

Answer 32

• Human health
• Disrupts farming practices
• Loss of native species
• Alters trophic interactions

Question 33

Fire ants — Breaking the natural dispersal barrier

Answer 33

Human trade allowed for the leap-frogging of a major climatic and habitat barrier to natural dispersal.

Question 34

Fire ants — Human mediated dispersal

Answer 34

• Multiple introductions of a significant number of mature colonies and founding queens over a short period of time.
• Triggered rapid initial spread

Question 35

Fire ants: freed from natural enemies - what are the fire ant’s natural enemies

Answer 35

Parasitoid Phorid flies are the major enemies of fire ants in their native range.

Question 36

fire ants - freed from natural enemies

Answer 36

Fire ants have been freed from these enemies in their introduced range.

Question 37

fire ants: freed from natural enemies - how does the presence of the natural enemy alter the fire ant’s behavior

Answer 37

Presence of Phorid flies alters fire ant foraging behavior and colony growth rate

Question 38

Fire ants — human habitat modification

Answer 38

• Fire ants are disturbance specialists in their native range.
• Humans create similar habitat to floodplain areas

Question 39

fire ants: human habitat modification - how do humans create a similar habitat to floodplain areas

Answer 39

reduced vegetation and natural diversity, especially typical of human lawns and pasture.

Question 40

fire ants: human habitat modification - explain competition between fire ants and humans

Answer 40

• Evidence suggests that fire ants do not have an inherent competitive advantage
• human habitat modification tips the competitive balance in favor of fire ants

Question 41

fire ants: human habitat modification - fire ants in human modified habitats

Answer 41

Fire ants negatively impact insect diversity and reduce native ant diversity…only in human-disturbed habitat.

Question 42

fire ants: human habitat modification - fire ants in undisturbed habitats

Answer 42

fire ants struggle to become established and do not significantly impact native ant diversity if they do become established.