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Ecology 2483 > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

Biogeography

A
  • the study of patterns of species composition and diversity across geographic locations
    Ex. The Amazon rainforest is the most species-rich forest in the world – with approximately 1,300 tree species
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2
Q

Lower Latitudes

A
  • closer to the equator
  • Have many more and a wider variety of species than higher latitudes
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3
Q

Species Richness and Composition

A
  • ​​vary from continent to continent
  • same community type or biome can vary in species richness and composition depending on its location on Earth
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4
Q

Spatial Scales

A
  • Interconnected in a hierarchical way
  • Patterns of species diversity and composition at one spatial scale setting the conditions for patterns at smaller spatial scales
  • Not the same for all organisms
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5
Q

Global Scale

A
  • the entire world
  • Species have been isolated from one another on different continents or in different oceans by long distances and over long periods
  • Rates of speciation, extinction and dispersal help determine differences in species diversity and composition
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6
Q

Regional Scale

A
  • areas with uniform climate
  • species are bound by dispersal to that region
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7
Q

Regional Species Pool

A
  • all the species contained within a region
  • Gamma diversity (whole region)
  • Provides raw material for local assemblages and sets the theoretical upper limit on species diversity for communities
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8
Q

Landscape

A
  • topographic and environmental features of a region
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9
Q

Species Composition and Diversity Vary Depending On

A
  • how the landscape shapes rates of migration and extinction
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10
Q

Local Scale

A
  • equivalent to a community
  • Species physiology and interactions with other species are important factors in species diversity
  • alpha diversity
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11
Q

Beta Diversity

A
  • Change in species number and composition, or turnover of species, from one community type to another
  • Connects local and regional scales
  • How different one community is from another
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12
Q

Global Biogeography

A
  • Global patterns of species diversity and composition are controlled by geographic area and isolation, evolutionary history, and global climate change
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13
Q

Alfred Russel Wallace

A
  • 1923-1913
  • Father of biogeography
  • Main contribution: was the study of species distributions across large spatial scales
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14
Q

Overlaid species distributions and geographic regions and revealed two global patterns

A

1) there is a gradient of species diversity with latitude
2) Earth’s land mass can be divided into six biogeographic regions
- Six biogeographic regions correspond roughly to Earth’s six major tectonic plates

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15
Q

Continental Drift

A
  • Can be found in the fossil record and in existing taxonomic groups
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16
Q

Pangaea/ Permian Period

A
  • 251 million years ago
  • one massive continent
17
Q

Cretaceous Period

A
  • 100 million years ago
  • 2 supercontinents- Laurasia, Gondwana
18
Q

Early Tertiary Period

A
  • 60 million years ago
19
Q

Vicariance

A
  • evolutionary separation of species by barriers such as those formed by continental drift
20
Q

Most Oceans Have _____

A
  • low nutrient availibility
21
Q

Global Patterns of Species Richness

A
  • If we assume dispersal rates are similar everywhere, then species richness should reflect a balance between extinction and speciation
22
Q

Species Diversification

A
  • Speciation rate - extinction rate = species diversification
  • net increase/ decrease of species over time
  • should be controlled by speciation, extinction, and dispersal
23
Q

Species Diversification Rate

A
  • Tropics have the most land area on Earth and temperatures are very stable
  • Large thermally stable areas should decrease extinction rates:
  • Speciation by geographic isolation would be more likely
24
Q

Species Diversification Time

A
  • Tropics are thought to have been more climatically stable over time
  • Species have had more time to evolve
  • Temperate and polar regions have undergone severe climatic changes:
    Glaciation
    Disrupting species
    Diversification
  • Most species originate in the tropics and then move to other regions during warm climatic periods
25
Q

Productivity or Carrying Capacity

A
  • Highest in the tropics (terrestrial)
  • High productivity promotes large population sizes due to carrying capacity being larger
  • Higher productivity leads to lower extinction rates
  • Greater coexistence
  • Overall higher species richness
  • Some very productive habitats have low species diversity
    Ex; estuaries
26
Q

The Tropics

A
  • Have the most land area
  • The southern hemisphere has more oceans than the northern hemisphere
  • Can be seen as a “cradle” of diversity
  • Can also be a “museum” – species that diversify there tend to stay there
  • Loss of biodiversity could cut off the supply of new species to higher latitudes in the future
  • Species diversity peaks during ‘icehouse’ conditions
27
Q

Regional Biogeography

A
  • regional differences in species diversity are influenced by area and distance, which determine the balance between immigration and extinction rates
28
Q

Species-area Relationship

A
  • species richness increases with the area sampled
  • an important concept in regional biogeography
29
Q

Species Area Curves

A
  • Plot species richness (S) of a sample against area (A) of the sample
  • Relationship between S and A is estimated by linear regression:
  • S = zA + c
    z = slope
    c = y-intercept
  • Species area data not usually linear
  • S and A are transformed into logarithmic values to obtain a straight line
30
Q

Islands

A
  • all display the same basic pattern
  • Large islands have more species than small islands
  • Can be any kind of isolated area surrounded by dissimilar habitats (matrix habitat)
    Ex. Habitat fragments such as in the Amazon rainforest, can be considered islands
31
Q

Island Species Diversity

A
  • shows a strong negative relationship to distance from a source of species
  • Island size and degree of geographic isolation are always confounded
32
Q

Equilibrium Theory of Island Biogeography

A
  • Developed by MacArthur and Wilson
  • The number of species on an island depends on a balance between immigration or dispersal rates and extinction rates
33
Q

Simberloff and Wilson

A
  • 1969
  • Manipulated mangrove islands in Florida by spraying with insecticides to remove all insects and spiders
34
Q

The Largest Ecological Experiment on Earth

A
  • The number of fish species in the Amazon River exceeds the total number found in the entire Atlantic Ocean
  • One hectare of rainforest in the Amazon contains more plant species than all of Europe!
35
Q

Edge Effects

A
  • Large Habitat fragmentation created
  • The transition between forest matrix habitat
    Ex; trees at the edge are exposed to more light, higher temperatures, wind, fire, and diseases
  • Can contribute to local extinctions
36
Q

In the Southern Amazon

A
  • Burning is used regularly, and keeps the forest edges in a constant state of disturbance
  • Fire-tolerant species increase and edge effects extend into the fragment, reducing its effective size

Ecology 2483 (21 decks)

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