Chapter 17-Biogeography

study of variation of species composition and diversity among geographical locations

occur no where else on Earth

entire world

• 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

physical geography of a region

• essentially equivalent to community
• alpha diversity: diversity at local scale

• 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

limit of species richness for the community

• 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

• species diversity is greatest at equator and decreases towards poles
• seabirds defy rule

sections of Earth's crust that move across Earth's surface due to currents generated by moltened rock mantel

• boundary beween tectonic plates
• seafloor spreading: new crust forcing olates apart

• one plate is forced downward under another another
• associated with earthquake, volcanos, and mountain ranges

where 2 plates meet and slide side ways past each other

evolutionary separation of species due to barriers such as those formed by comtinential drift

areas of high species richness

• 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

• 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

species richness increases with the area sampled

• smaller the island smaller species diversity
• islands closer to pop source have higher species diversity
• equilibruim found b/c of extinction and immigration

• 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

potential hazards that effect the edge of forest including harsh environmental conditions, fire hunting, predators, disease, and invasive species

• 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