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Tropical ecosystems (botany 575) > Module 2 > Flashcards

Module 2 Flashcards

1
Q

Bio geographical regions

A

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

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2
Q

Holarctic

A

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

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3
Q

pan tropical

A

everywhere in the tropics, very few organisms are pantropical

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4
Q

How did organisms disperse?

A
  • 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
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5
Q

vicariance

A

geographic separation

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6
Q

paleogeography

A

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

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7
Q

When did the Pangea supercontinent form?

A

300-200 mya

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8
Q

When did Pangea break apart into Gondwana and Laurasia

A

200-150 mya

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9
Q

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

A

150-50 mya

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10
Q

When did the central american land bridge form?

A

3-8 mya

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11
Q

Wallaces line

A

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

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12
Q

South American flora

A

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

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13
Q

Endemism

A

taxa that are restricted to a single area

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14
Q

Why is there high continental endemism?

A
  • vicariance (geographic separation) by continental drift, mountain uplift, water
  • allopatric speciation
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15
Q

Allopatric speciation

A

speciation resulting from reproductive isolation due to geographic selection

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16
Q

Central American Land Bridge

A

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).

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17
Q

Great American Biotic Interchange

A

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

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18
Q

What is the #1 country for total species richness?

A

Brazil

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19
Q

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

A

Colombia

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20
Q

What bio regions are the most diverse?

A

First Neotropical, then Indo-Malaysian then Afrotropical

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21
Q

Latitudinal biodiversity gradient

A

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

22
Q

Biodiversity and area

A

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

23
Q

Biodiversity and precipitation

A

there is more diversity with higher rainfall

24
Q

Biodiversity and elevation

A

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

25
Q

Biodiversity and time

A

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

26
Q

Intermediate disturbance hypothesis

A

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

27
Q

The productivity hypothesis

A

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

28
Q

Paradox of enrichment

A

the best competitors win out so diversity goes down

29
Q

Stability-time hypothesis

A

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)

30
Q

Competition/Niche-diversification hypothesis

A
  • 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
31
Q

Predation/Parasitism hypothesis

A
  • 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)
32
Q

Tropics as a cradle

A

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

33
Q

Tropics as a museum

A

there is less extinction in the tropics which increases biodiversity

34
Q

Article: Why the tropics are so diverse

A
  • warm, humid, large area, isolated
  • isolation of regions with the same climate from each other, large total area
35
Q

Human footprint

A
  • 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
36
Q

Global threats to biodiversity

A

1: habitat loss and degradation

#2: overexploitation
#3: climate change
#4: invasive species and disease
#5: pollution

37
Q

Habitat loss

A

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

38
Q

Deforestation

A

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

39
Q

Which forests are most threatened by deforestation?

A

dry forests

40
Q

Habitat fragmentation

A

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

41
Q

edge effects

A

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

42
Q

Overexploitation

A

1 threat to large mammals, big threat to tropical trees, marine fish, pet trade animals

Primarily due to commercial use (sale), not subsistence

43
Q

Global carbon stocks

A
  • 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
44
Q

Global irrecoverable carbon stocks

A

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

45
Q

Local climate change effects

A

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

46
Q

Tropical expansion

A

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)

47
Q

Pollution in tropical ecosystems

A
  • pesticides, insect collapse
  • mercury from gold-mining
  • plastics, marine life
48
Q

Threats to insects

A

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

49
Q

Invasive species

A

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

50
Q

Invasibility

A

the ability to be invaded

51
Q

disease

A

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

Tropical ecosystems (botany 575) (2 decks)

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