Transcript Ch08
Chapter 8 News story CBS News Biogeography Why Were Introductions of New Species into Europe So Popular Long Ago? • Biogeography: – The large scale geographic pattern in the distribution of species, and the causes and history of this distribution Wallace’s Realms: Biotic Provinces • Realm: – Major biogeographic regions of Earth that are based upon fundamental features of the plants and animals found in those regions • Taxa: – Categories that identify groups of living organisms based upon evolutionary relationships or similarity of characteristics (ex: species, families, orders) • Biotic Provinces: – A geographical region (realm) inhabited by a characteristic set of taxa, bounded by barriers that prevent the spread of those distinctive kinds of life to other regions. The main biogeographic realms for animals are based on genetic factors. Why is this so? The major vegetation realms are also based on genetic factors. Why do you suppose this is the case? Biomes • A biome is a kind of ecosystem. Similar environments provide similar opportunities for life and similar constraints. – Rainforest – Grasslands – Deserts Here you can see the relationship between precipitation and latitude. Convergent Evolution • The process by which species evolve in different places of times and, although they have different genetic heritages, develop similar external forms and structures as a result of adaptation to similar environments • Ex: shapes of sharks Divergent Evolution • Organisms with the same ancestral genetic heritage migrate to different habitats and evolve into species with different external forms and structures, but continue to use the same type of habitats • Ex: Ostrich Geographic Patterns of Life within a Continent Island Biogeography • Theory of Island Biogeography – Islands have fewer species than continents – The smaller the island, the fewer the species • Adaptive Radiation: – The process that occurs when a species enters a new habitat that has unoccupied niches and evolves into a group of new species, each adapted to one of these niches. • Ecological Island: – An area that is biologically isolated so that a species occurring within the area rarely mixes with any other population of the same species Environmental stress and biogeography. Explain this diagram in terms of immigration, population & extinction. Earth’s Biomes • The Earth has 17 major biomes , each with its own characteristic dominant shapes and forms of life. • Most biomes have been heavily altered by human action. • People have introduced exotic species to new habitats – sometimes creating benefits, often creating problems • Primary Rule: Unless there is a clear and good reason to introduce an exotic species into a new habitat, don’t do it. 17 Major Biomes 1. Tundras - treeless plains that occur in the harsh climates of low rainfall and low average temperature - two types: artic tundra and alpine tundra - parts have permafrost: permanently frozen ground 2. Taiga or Boreal Forests - includes the forests of the cold climates of high latitudes and high altitudes - dominant life forms including moose and other large mammals, small flowering plants and trees 3. Temperate Deciduous Forests - occur in warmer climates that the boreal forest 4. Temperate Rainforest - moderate temperatures, over 250 cm/year of rain 5. Temperate Woodlands - Slightly drier climate that the deciduous forests - fire is common and species adapt to it 6. Temperate Shrublands - also called chaparral: miniature woodlands 7. Temperate Grasslands - include many North American parries 8. Tropical Rain Forests - high average temperature and rainfall 9. Tropical Seasonal Forest and Savannas - high average temperature, low latitudes, abundant but seasonal rainfall 10. Deserts - The driest region that vegetation can survive. 11. Wetlands - Include freshwater swaps, ,marshes and bogs – all have standing water 12. Freshwaters - Have phytoplankton and estuaries 13. Intertidal Areas - Areas exposed to alternately to air during low tide and high tide 14. Open Ocean - Also called the pelagic region 15. Bethos - Bottom portion of the ocean 16. Upwellings - Upward flows of ocean water 17. Hydrothermal Vents - Occur in the deep ocean were plate tectonic processes create vents