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Biogeography
study of variation of species composition and diversity among geographical locations
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Endemic
occur no where else on Earth
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Global Scale
entire world
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Regional Scale
- smaller geographical areas in which climate is roughly uniform and species are restricted by dispersal limitations
- Regional Species Pool: aka gamma diversisty, all species in given region
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Landscape
physical geography of a region
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Local Scale
- essentially equivalent to community
- alpha diversity: diversity at local scale
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Beta diversity
- connection between local and regional scale of species diversity
- turnover: told by beta diversity, change in species composition across landscape as one moves from one local community to another
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Saturation Point
limit of species richness for the community
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Biogeographical Regions
- Earth's landmass divided into 6 parts containing distinct biotas that differ markedly in species composition and diversity
- Neartic- North Am
- Neotropic- central and South Am
- Paleartic- Europe, parts of Asia/Africa
- Ethiopian- Africa
- Oriental- china, india, southeast Asia
- Australasian- Austrailia, Indo-pacific, New Zealand
- correspond roughly to tectonic plates
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Gradient of Species
- species diversity is greatest at equator and decreases towards poles
- seabirds defy rule
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Continental Drift
sections of Earth's crust that move across Earth's surface due to currents generated by moltened rock mantel
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mid-ocean ridges
- boundary beween tectonic plates
- seafloor spreading: new crust forcing olates apart
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Subduction zones
- one plate is forced downward under another another
- associated with earthquake, volcanos, and mountain ranges
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Fault
where 2 plates meet and slide side ways past each other
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vicariance
evolutionary separation of species due to barriers such as those formed by comtinential drift
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Hot spots
areas of high species richness
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Species Diversification
- net increase or decrease of species over time
- larger land area and steady temperatures leads to higher diversity
- allows for increase in size of species population decreasing risk of extinction due to chance events and increasing the geographical range of species thus spreading risk over larger area
- cause less drastic climate condition
- tropics serve for the cradle of diversity
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Productivity Hypothesis
- species diversity is highest at tropics b/c greatest productiviy occurs there for terrestrial systems
- promotes larger population size
- marine organisms have shift b/c higher productivity at poles in aquatic environments
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Species-Area Relationship
species richness increases with the area sampled
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Islands
- smaller the island smaller species diversity
- islands closer to pop source have higher species diversity
- equilibruim found b/c of extinction and immigration
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Equilibrium Theory of Island Biogeography
- number of species on an island depends on balance between immigration or dispersal rates and extinction rates
- occurs b/c competition increase causeing decrease inpopulation size as need same space and resources or predation increases as more consumer species are added to Island
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Edge Effects
potential hazards that effect the edge of forest including harsh environmental conditions, fire hunting, predators, disease, and invasive species
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Ecosystem Services
- produced by natural systems that help sustain human health and well-being
- ex. drugs and food products made from products that come from Tropical Rainforest plants
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