Module 2

Question 1

Bio geographical regions

Answer 1

Nearctic, Palearctic,oceanian, neotropical, antarctic, afro tropical, indomalayan, australasian

Question 2

Holarctic

Answer 2

north temperate region, very little organisms are holarctic because it spans the whole north temperate zone

Question 3

pan tropical

Answer 3

everywhere in the tropics, very few organisms are pantropical

Question 4

How did organisms disperse?

Answer 4

• drifted on the continents from where their ancestors evolved (Pangea broke apart)
• dispersed from one place to another (swam, flew, were carried…)
• newly evolved on-site

Question 5

vicariance

Answer 5

geographic separation

Question 6

paleogeography

Answer 6

the study of geological features at particular times in the geological past

Question 7

When did the Pangea supercontinent form?

Answer 7

300-200 mya

Question 8

When did Pangea break apart into Gondwana and Laurasia

Answer 8

200-150 mya

Question 9

When did Laurasia break to North aAmerican and Asia, and when did Gondwana break into South America, Africa, India, Australia, Antarctica?

Answer 9

150-50 mya

Question 10

When did the central american land bridge form?

Answer 10

3-8 mya

Question 11

Wallaces line

Answer 11

In indonesia area, separates Laurasia (asian origin) species from Gondwanaland (Australian origin) species, actually more of a gradual filter than a strict barrier

Question 12

South American flora

Answer 12

Gondwana origins for basically all of the lowland plant taxa, Laurasian species colonized the Andes when they uplifted

Question 13

Endemism

Answer 13

taxa that are restricted to a single area

Question 14

Why is there high continental endemism?

Answer 14

• vicariance (geographic separation) by continental drift, mountain uplift, water
• allopatric speciation

Question 15

Allopatric speciation

Answer 15

speciation resulting from reproductive isolation due to geographic selection

Question 16

Central American Land Bridge

Answer 16

lead to the “great american biotic interchange”. Laurasian taxa moved into S. America, Gondwana taxa moved into N. America. Marine species experienced allopatric speciation, there was profound changes to the continental climate (like the Gulf Stream strengthening).

Question 17

Great American Biotic Interchange

Answer 17

From south to north:
- opossums, porcupines, armadillos, anteaters, ground sloths
From north to south:
- rodents, foxes, bears, raccoons, cats, peccaries, deer, rapier, primates, camelids, horses

more animals survived in the South than the North as the climate cooled: 10% of N. American animals have S. American origin, but >50% of S. American specials have N. American origin

Question 18

What is the #1 country for total species richness?

Answer 18

Brazil

Question 19

What is the #1 country for species per unit area?

Answer 19

Colombia

Question 20

What bio regions are the most diverse?

Answer 20

First Neotropical, then Indo-Malaysian then Afrotropical

Question 21

Latitudinal biodiversity gradient

Answer 21

Species diversity is negatively correlated with latitude. The farther away from the equator, the less species diversity. Almost all taxa show this. Only exceptions are salamanders and some butterfly groups

Question 22

Biodiversity and area

Answer 22

Biodiversity is positively correlated with island size or habitat area: with more area, there is more diversity

Question 23

Biodiversity and precipitation

Answer 23

there is more diversity with higher rainfall

Question 24

Biodiversity and elevation

Answer 24

Biodiversity is negatively correlated with altitude: fewer species as altitude increases

Question 25

Biodiversity and time

Answer 25

Geological time: species tend to accumulate over time if there is not a crisis going on Intermediate disturbance hypothesis

Question 26

Intermediate disturbance hypothesis

Answer 26

the highest species diversity occurs when there are intermediate levels of disturbance (both with frequency, time after, and disturbance intensity)

Question 27

The productivity hypothesis

Answer 27

Higher solar energy input leads to higher precipitation which leads to higher production which leads to larger populations which leads to more species…can be opposed by the paradox of enrichment

Question 28

Paradox of enrichment

Answer 28

the best competitors win out so diversity goes down

Question 29

Stability-time hypothesis

Answer 29

Higher biodiversity in the tropics is supported by - a warm, stable climate over long period - a year round growing season (faster generation times, faster evolution) - no glaciation (more total time for evolution to occur)

Question 30

Competition/Niche-diversification hypothesis

Answer 30

- biotic interactions, such as competition, are stronger in the tropics - competition leads to niche partitioning which leads to speciation which leads to tighter species packing

Question 31

Predation/Parasitism hypothesis

Answer 31

- there are more predators, herbivores, and pathogens in the tropics - predators reduce the numbers of the most abundant prey, which prevents competitive exclusion among prey species - more prey species can coexist (reduced extinction)

Question 32

Tropics as a cradle

Answer 32

there is higher speciation in the tropics which leads to higher biodiversity

Question 33

Tropics as a museum

Answer 33

there is less extinction in the tropics which increases biodiversity

Question 34

Article: Why the tropics are so diverse

Answer 34

- warm, humid, large area, isolated - isolation of regions with the same climate from each other, large total area

Question 35

Human footprint

Answer 35

- 72% of the world’s land is used - 96% of mammals on Earth are humans and their livestock - livestock takes up 83% of agricultural land

Question 36

Global threats to biodiversity

Answer 36

#1: habitat loss and degradation #2: overexploitation #3: climate change #4: invasive species and disease #5: pollution

Question 37

Habitat loss

Answer 37

Tropics are disproportionally affected by habitat loss, deforestation is driven mostly by agriculture

Question 38

Deforestation

Answer 38

Beef, soy, palm oil, wood are the commodities that drive tropical deforestation International markets drive deforestation, except in Africa

Question 39

Which forests are most threatened by deforestation?

Answer 39

dry forests

Question 40

Habitat fragmentation

Answer 40

when habitats are reduced into smaller sizes… - smaller habitats mean small populations = genetic drift, inbreeding - causes spatial isolation of populations = reduced gene flow, risk for crossing bad areas - edge effects

Question 41

edge effects

Answer 41

edges of habitats have more wind, more light, lower humidity…this changes the community composition, and is unsuitable for the “core” species that need the interior habitat

Question 42

Overexploitation

Answer 42

#1 threat to large mammals, big threat to tropical trees, marine fish, pet trade animals Primarily due to commercial use (sale), not subsistence

Question 43

Global carbon stocks

Answer 43

- Tropical forests hold the most carbon in the biomass - Boreal forests hold the most carbon in the soil - Tropical forests absorb about 30% of carbon emissions

Question 44

Global irrecoverable carbon stocks

Answer 44

stocks that are if lost, they cannot be recovered in a short period of time, AND they are manageable. Lots of these in tropical regions

Question 45

Local climate change effects

Answer 45

drought, forest fires, heating due to deforestation (reduced evapotranspiration)

Question 46

Tropical expansion

Answer 46

Tropical climates are expanding about 30 miles per decade. The ITCZ is expanding (there is a wider belt of low pressure, which pushes the Hadley cells apart)

Question 47

Pollution in tropical ecosystems

Answer 47

- pesticides, insect collapse - mercury from gold-mining - plastics, marine life

Question 48

Threats to insects

Answer 48

Pesticides kill insects, natural gas flares kill insects. Lose insects means lose things that depend on insects

Question 49

Invasive species

Answer 49

there are fewer non-native invasives (NNIs) in the tropics - light limitation (understory’s dark due to canopy blocking light) - phosphorous limitation - higher diversity (fewer open niches) - human modification of natural areas in the tropics is more recent (less time to bring in non-native species) - less studies about invasive species in the tropics - islands are especially inviasible

Question 50

Invasibility

Answer 50

the ability to be invaded

Question 51

disease

Answer 51

Disease is overall a minor threat to biodiversity but has had big impacts on some groups. - Chytrid fungus: decimated amphibians globally - climate change is becoming a bigger threat than disease for amphibians now though