Lecture 16

Question 1

Biogeography

Answer 1

• 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

Question 2

Lower Latitudes

Answer 2

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

Question 3

Species Richness and Composition

Answer 3

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

Question 4

Spatial Scales

Answer 4

• 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

Question 5

Global Scale

Answer 5

• 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

Question 6

Regional Scale

Answer 6

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

Question 7

Regional Species Pool

Answer 7

• 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

Question 8

Landscape

Answer 8

• topographic and environmental features of a region

Question 9

Species Composition and Diversity Vary Depending On

Answer 9

• how the landscape shapes rates of migration and extinction

Question 10

Local Scale

Answer 10

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

Question 11

Beta Diversity

Answer 11

• 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

Question 12

Global Biogeography

Answer 12

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

Question 13

Alfred Russel Wallace

Answer 13

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

Question 14

Overlaid species distributions and geographic regions and revealed two global patterns

Answer 14

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

Question 15

Continental Drift

Answer 15

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

Question 16

Pangaea/ Permian Period

Answer 16

• 251 million years ago
• one massive continent

Question 17

Cretaceous Period

Answer 17

• 100 million years ago
• 2 supercontinents- Laurasia, Gondwana

Question 18

Early Tertiary Period

Answer 18

• 60 million years ago

Question 19

Vicariance

Answer 19

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

Question 20

Most Oceans Have _____

Answer 20

• low nutrient availibility

Question 21

Global Patterns of Species Richness

Answer 21

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

Question 22

Species Diversification

Answer 22

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

Question 23

Species Diversification Rate

Answer 23

• 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

Question 24

Species Diversification Time

Answer 24

• 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

Question 25

Productivity or Carrying Capacity

Answer 25

- 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

Question 26

The Tropics

Answer 26

- 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

Question 27

Regional Biogeography

Answer 27

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

Question 28

Species-area Relationship

Answer 28

- species richness increases with the area sampled - an important concept in regional biogeography

Question 29

Species Area Curves

Answer 29

- 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

Question 30

Islands

Answer 30

- 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

Question 31

Island Species Diversity

Answer 31

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

Question 32

Equilibrium Theory of Island Biogeography

Answer 32

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

Question 33

Simberloff and Wilson

Answer 33

- 1969 - Manipulated mangrove islands in Florida by spraying with insecticides to remove all insects and spiders

Question 34

The Largest Ecological Experiment on Earth

Answer 34

- 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!

Question 35

Edge Effects

Answer 35

- 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

Question 36

In the Southern Amazon

Answer 36

- 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