Chapter 8 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 –explains species diversity (by region) and the impact of exotic (introduced) species

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.

The major vegetation realms are also based on genetic factors

Biomes A biome is a kind of ecosystem. Similar environments provide similar opportunities for life and similar constraints. Characterized by a dominant vegetation type –Rainforest –Grasslands –Desserts

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

Convergent

Divergent

Geographic Patterns of Life within a Continent Plate Tectonics –mountain ranges –alterations in drainage patterns –paths of rivers Proximity to an ocean or other large body of water –heat capacity; cold and warm currents Location relative to mountain ranges, latitude and longitude

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 (pond, desert oasis, city park)

Biogeography and People Europe and Great Britain –climatic change –mountain ranges Exotic Species –species introduced into a new geographic area

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: arctic 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 than the boreal forest 4. Temperate Rainforest - moderate temperatures, over 250 cm/year of rain

5. Temperate Woodlands - Slightly drier climate than 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 prairies 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 (Pelagic region) - salinity variations (by latitude) - low in nitrogen and phosphorus - low productivity and algae diversity - many species of large animals but at low density - little “mixing” below 400 meters (thermocline) 15. Benthos - Bottom portion of the ocean - primary food input: dead organic matter - sunlight (no photosynthesis), temperature and pressure determine distribution of marine life

16. Upwellings - Upward flows of ocean water, rich in nutrients - allow abundant growth of algae and animals that depend on algae - occur off the west coast of North America, South America, West Africa, and the near the Arctic and Antarctic ice sheets - Westerlies can influence - among most important regions for the production of commercial fish 17. Hydrothermal Vents - Occur in the deep ocean were plate tectonic processes create vents - high concentration of sulfur compounds - chemosynthetic bacteria - high water pressure and extreme temperature ranges (4˚ - 100˚ C) - unusual life forms (giant clams, worms)