B.Biogeography - Climate Biogeography Biogeographic realms...

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Heyer BioGeography Tropic of Cancer (23.5 ° N) Equator Nearctic Neotropical Ethiopian Oriental Australian Palearctic (23.5 ° S) Tropic of Capricorn Biogeographic realms • By 1800s, many naturalists began to identify broad patterns of distribution biogeographic realms Figure 50.5 Environmental components affect the distribution and abundance of organisms Figure 50.2 Kangaroos/km 2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Climate in northern Australia is hot and wet, with seasonal drought. Red kangaroos occur in most semiarid and arid regions of the interior, where precipitation is relatively low and variable from year to year. Southeastern Australia has a wet, cool climate. Southern Australia has cool, moist winters and warm, dry summers. Tasmania Factors that Limit Population Size Abiotic (nonliving) Limiting Factors – Temperature – Water – Soil type – Sunlight – Salinity – Wind stress – Altitude, depth Biotic (living) Limiting Factors – Food source – Competition – Predators – Social factors, mates – Pathogens, parasites – Vegetation Factors that Limit Population Size Density Dependent Limiting Factors – Limited resources • Food • Water • Safe refuge • Predation • Competition • Living space – Disease, Pollution Density Independent Limiting Factors – Natural disasters • Hurricanes • Floods, landslides, volcanoes • Drought, frost – Environmental insult • Deforestation • Pesticide • Fire – Climatic change Climate • The prevailing weather conditions in a particular area • Four major abiotic components: – Temperature, water, sunlight, and wind • Macroclimate: patterns on • Microclimate: very fine, small-scale patterns – e.g., conditions encountered by the community of organisms underneath a fallen log
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Heyer Latitude is an important correlate for temperature, photoperiod, and rainfall The equator receives maximal solar heating producing predictable patterns of wind and rainfall WET and DRY • Uneven heating causes wet and dry areas GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS Seasons Figure 50.10 June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere;
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B.Biogeography - Climate Biogeography Biogeographic realms...

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