Biogeography: Biomes, Biodiversity, and Distribution

Introduction

Biogeography is the study of the distribution of species and ecosystems across geographical space and geological time. It integrates concepts from geography, ecology, evolution, and climatology to explain why organisms are found where they are. Major biomes - large-scale ecological communities shaped by climate - form the building blocks of biogeographic classification.

Factors Influencing Biogeographic Distribution

Abiotic Factors

1. Climate: Temperature, precipitation, sunlight - most important determinant
2. Geology: Soil type, parent rock, mineral availability
3. Topography: Altitude, aspect, slope
4. Water availability: Freshwater vs. marine; depth, currents
5. Disturbance regimes: Fire, floods, volcanic activity, glaciation

Biotic Factors

1. Competition: Interspecific and intraspecific
2. Predation: Controls population sizes
3. Mutualism: Symbiotic relationships
4. Dispersal ability: Seeds, spores, migratory capacity

Historical Factors

1. Plate tectonics: Continental drift separated biota (Gondwana breakup)
2. Glacial cycles: Pleistocene ice ages caused range shifts
3. Evolution and speciation: Adaptation to local conditions
4. Extinction events: Mass extinctions reshape distributions

Major Terrestrial Biomes