Biogeography Flashcards
What is biogeography? Why is it a composite science?
Study of species’ distributions in space and time. It is a composite of ecology (niche theory, community ecology), evolution (speciation), and earth sciences (geology)
How are spatial patterns of biodiversity explained by physical and biological processes?
History: origination, extinction, dispersal, evolution of physical environment
Ecology:
- biotic and abiotic interactions
Where organisms live, it is related to their environment. How?
Abiotic characters, such as climate and substrate or temperature, salinity, light, pressure
Biotic factors such as interactions (competition, mutualism, parasitism etc)
What does it mean by referring to the “geographic template?”
The geographic template is the foundation of all biogeographical patterns, characterized by PREDICTABLE PATTERNS OF CHANGE ALONG MAJOR GRADIENTS (latitude, elevation, salinity, depth, etc)
What are the two Great Engines?
- Energy from the Earth’s core (plate tectonics - mountains & volcanoes)
- The Sun (primary productivity and heat from radiant energy -> wind, precipitation); higher latitudes cooler due to solar radiation dispersing over greater surface area
What is convection? Describe the basic pattern across the hemispheres and each cell name
Convection is when heated tropical air rises, is replaced by cooler surface winds and then descends (so from 0 degrees to 30 degrees; Hadley - then 30-60; Ferrel and 60-90; Polar)
What is the Coriolis Effect? Explain the types of winds and their directions
Coriolis effect: points at higher latitudes travel shorter distances per rotation, so winds to the N or S deflect to the right above the equator and left below it.
Trade Winds: westward approaching equator
Westerlies: Eastward Winds between 30-60 deg. latitude
What are Trade Winds? What are Westerlies?
Trade Winds: westward approaching equator
Westerlies: Eastward Winds between 30-60 deg. latitude
Explain how ocean currents are affected by Trade Winds and Westerlies
Trade Winds: make currents westwards at equator
Westerlies: cause currents to go eastward at higher latitudes
Explain directions of oceanic gyres in different hemispheres
N: Clockwise
S: Counterclockwise
Explain precipitation and elevation relationship
Hot air rises, cools (losing density and pressure - like refrigerators - reduced greenhouse effect); condenses and causes precipitation and then dry air
What is the greenhouse effect?
Retention of radiant heat from the Earth’s surface
Explain precipitation pattern across latitude
Warm air equator -> rainfall at low latitudes & mid-elevations = tropical rainforests
30N/S -> cool air descends and causes aridification (deserts and mediterranean)
How does soil form?
Weathering: mechanical breakdown (wind, water, heat)
chemical breakdown (water, CO2 - dissolve solutes)
Biological breakdown: CO2 and organic acids from lichens
Also: Organic material decay
Names of soil formation and the regions
Temperate: Podzolization (cool and precipitation)
Tropical: Laterization (warm and precip)
Arid Grasslands: Calcification (cool to hot, no precip)
Tundra (cold; moist)
When did biogeographers accept plate tectonics?
mid 1900’s
Who was Alfred Wegener, what did he do?
Developed continental drift theory; Pangea-> but did not have the mechanism!
What is the mechanism behind continental drift?
plate tectonics; CONVECTIVE forces of molten rock in asthenosphere -> pushing and pulling
Explain the major plate patterns through time
220 MYA
80 MYA
65 MYA
40 MYA
10 MYA
30 thousand YA
220: Gondwana (Triassic)
80: Tethyan Seaway (Cretaceous)
65: Cretaceous-Paleocene boundary
40: Eocene (Mediterranean N Africa)
10: Mid-Miocene, similar today
30-18 TYA: Last Glacial Maximum
What is vicariance biogeography? What inspired it?
Vicariance Biogeo: Study of disjunct distributions to find the treelike historical signal of continental breakup
Inspired by: Plate tectonics
What were the tectonics and climate of the Cenozoic like?
Gondwana collides with Eurasia = HIMALAYAS (Alps, Pyrenees etc)
Wallacea contact & Land bridge of North
Diversification of mammals, birds, plants
What were the tectonics and climate of the Paleocene?
66-65 MA
- Tropical climate (Ice-free poles)
EXTENSIVE tropical rainforests
What were the tectonics and climate of the Eocene?
56-34 MA
- Thermal maximum = ocean acidification
- Tropical climate at high latitude (think palm trees wyoming)
- Cooled later = antarctic ice sheet
- Mediterranean sea forms
What were the tectonics and climate of the Oligocene?
34-23 MA
- MAJOR cooling, ice expansion, seasonality
- C4 photosynthesis origin (CAM too)
- S America and Africa isolated
What were the tectonics and climate of the Pliocene?
5.3 - 2.58 MA
- Climate warmer, sea levels higher
- Climatic oscillations
- Arctic Ice Cap
- GABI!
- Homo
What were the tectonics and climate of the Quaternary?
2.58 - 0 MA
Glacial-Interglacial Cycles
- Milankovitch Cycles drive these cycles
What feedback effects occur during milankovitch cycles?
- Albedo (from ice extent), changes in CO2 with plant productivity
Explain the Milankovitch Cycles
Varies from a circular to elliptical orbit which lasts 90,000, 41,000, and 22,000 years
In a more elliptical orbit, there is a greater difference in solar radiation between summer and winter.
What is geographic range?
Locations where all individuals of a species occur; An emergent property; product of a species’ physiology, ecology, and evolutionary history; fundamental unit underlying biogeographic patterns
What is an irruption?
Movement in years of resource change
Why is range tricky regarding the concept of species?
Because defining a species is tough! Range is an emergent property (group thing), so you have to decide what the group is
What is the basis of range? Specifically, the “atomic basis”
Record of occurrence (like photo, museum specimen, etc)
- Surveys, Community Science, inventories, museums
What are the types of maps?
Dot
Outline
Contour
Predictive
What are dot maps?
Precise locations; biased; fixed in time
What are outline maps?
Informed subjective estimate of occurrence -> occurrence, geography, climate, ecosystem, physiology included in the making
What are Contour Maps?
Maps of abundance; hard to do unless a lot of sampling; interpolation required
What are predictive maps?
Species distribution models -> correlate occurrence with environmental variables and predicts suitable habitat areas
What are some problems and considerations for making range maps?
- Quality of data inconsistent; sampling bias (roads)
- Core range vs outliers
- Native vs invasive ranges
What is a Wallacean Shortfall?
For most species we know very little about range, esp. thru time.
What are the 2 quantities for measuring geographic range? Measuring is important for comparison!
- Extent of Occurrence (along a dimension; distance, latitude, elevation)
- Area of Occupancy (2D; ellipse, hull, area over grid)
What questions can be answered with comparing the extent of occupancy of a species?
- Ecological niche relationship
- Extinction Risk
- Gene Flow
- Dispersal Ability
- Phenotypic Plasticity
What are ways to measure area of occupancy?
Ellipse
Convex Hull
Grid Cells
What is Spatial Dispersion? What are the patterns?
- Distribution of points (organisms)
- Clumped, Random, Even
SCALE-DEPENDENT
What is important about cells and grids for area of occupancy?
It is SCALE-DEPENDENT! Think about the spatial dispersion
What size are most ranges?
Small!
What is something that determines range sizes?
Body Size (constraint against large body and small range)
What is Rapoport’s Rule?
Range increases with latitude (and elevation, sea depth)
Why are ranges bigger at higher latitudes and elevations?
Physiological limits (fitness)
What is Hutchinson’s Niche Concept
Curve over all relevant aces of variation -> n-dimensional hypervolume = Fundamental Niche!
What did Janzen say about mountains and what is the reasoning?
Mountain passes are higher in the tropics; the seasonality of temperate mountains is greater, so species have wider niches and can cross mountains more easily vs highly specialized tropical species
What is the fundamental niche?
the full range of environmental conditions under which an organism can live