44.2 Biogeography
3 min read•june 14, 2024
explores how species spread across the globe, shaped by factors like climate and geography. It's a fascinating blend of biology and geography, helping us understand why certain plants and animals thrive in specific places.
Abiotic factors, like temperature and rainfall, play a huge role in determining where species can live. These non-living elements create the conditions that make or break an ecosystem, influencing everything from tiny microbes to massive forests.
Biogeography and Species Distribution
Concept of biogeography
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- Studies the distribution of species and ecosystems across geographic space and geological time
- Examines factors influencing the presence of plants, animals, and other organisms in different regions (historical events, ecological conditions)
- Provides insights into evolutionary history and adaptations of species to their environments
- Helps explain species distribution patterns and the underlying factors shaping them (climate, topography, biotic interactions)
Abiotic factors in species distribution
- Temperature affects metabolic rates, growth, and survival determining geographic ranges based on thermal tolerances (polar bears in Arctic, cacti in deserts)
- Precipitation influences water availability shaping the distribution of (rainforests, grasslands)
- Sunlight provides energy for photosynthesis in plants forming the basis of food webs and varies across latitudes (tundra, tropical forests)
- Topography creates diverse habitats and microclimates supporting different species and acts as barriers or corridors for dispersal (mountain ranges, valleys)
- Soil composition determines nutrients available for plant growth and associated animal communities influencing pH and water retention (serpentine soils, peat bogs)
- limit species movement and influence distribution patterns (oceans, mountain ranges)
Biogeographical processes and patterns
- has shaped the distribution of species over geological time scales
- explains on islands based on island size and distance from mainland
- describes changes in species composition over time following disturbances or in newly formed habitats
Abiotic Factors and Ecosystem Dynamics
Abiotic influences: aquatic vs terrestrial
- Aquatic ecosystems
- Dissolved oxygen can be limiting while water availability is not
- Temperature stratification creates distinct zones with different species (, epilimnion)
- Currents and water chemistry influence distribution (estuaries, coral reefs)
- Light penetration decreases with depth limiting photosynthesis (photic zone, benthic zone)
- Terrestrial ecosystems
- Water availability often limiting particularly in arid regions (deserts, grasslands)
- Temperature and precipitation patterns largely determine biome distribution (tundra, savanna)
- Soil composition and topography play significant roles (clay soils, karst landscapes)
- Light availability generally not limiting except in dense forests or extreme latitudes (rainforests, boreal forests)
Abiotic factors and primary productivity
- (NPP): rate at which primary producers convert solar energy into biomass
- Temperature
- NPP increases with temperature up to an optimum then declines
- Moderate temperature have higher NPP than extreme cold or hot ones (temperate forests vs tundra or deserts)
- Precipitation
- NPP increases with precipitation as water is essential for photosynthesis
- High precipitation biomes have the highest NPP (tropical rainforests, temperate rainforests)
- Sunlight
- NPP increases with sunlight availability as the primary energy source for photosynthesis
- High sunlight exposure biomes can have high NPP despite lower precipitation (grasslands, savannas)
- Nutrient availability
- NPP often limited by availability of essential nutrients (nitrogen, phosphorus)
- Nutrient-rich soil biomes can support high NPP (temperate grasslands, floodplains)
Key Terms to Review (35)
Above-ground biomass: Above-ground biomass is the total mass of living plants, excluding roots, above the soil surface in a given area. It includes stems, leaves, bark, and reproductive structures.
Adaptive radiation: Adaptive radiation is the evolutionary process in which a single ancestral species rapidly diversifies into a wide variety of forms to adapt to different environments and ecological niches. This phenomenon often occurs after the introduction of new habitats or following mass extinctions, enabling species to exploit various resources and reduce competition. It highlights the relationship between environmental factors and the diversification of life forms.
Alfred Russel Wallace: Alfred Russel Wallace was a British naturalist, explorer, and biologist who is best known for independently developing the theory of evolution through natural selection, concurrently with Charles Darwin. His work significantly contributed to the field of evolutionary biology and helped shape our understanding of species distribution and adaptation in relation to their environments.
Allopatric speciation: Allopatric speciation occurs when a population is divided by a geographical barrier, leading to reproductive isolation and the formation of new species. Over time, genetic differences accumulate making interbreeding between the separated populations impossible even if they come back into contact.
Allopatric speciation: Allopatric speciation is the process by which new species arise due to geographical isolation. When populations of a species become separated by physical barriers, such as mountains, rivers, or distance, they can evolve independently. This process often leads to the accumulation of genetic differences that can result in reproductive isolation, ultimately giving rise to distinct species.
Biogeographic analysis: Biogeographic analysis is the study of the distribution of species and ecosystems across geographic spaces and through geological time. This approach helps to understand how various factors, such as climate, geography, and evolutionary history, influence the distribution of life on Earth. By examining patterns of biodiversity, biogeographic analysis provides insights into ecological processes, conservation strategies, and the effects of environmental change.
Biogeography: Biogeography is the study of the geographic distribution of species and ecosystems in relation to historical, climatic, and ecological factors. It aims to understand patterns of biodiversity and the processes that result in these patterns.
Biogeography: Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. It helps explain how species and populations evolve and adapt in different environments, influenced by various factors such as climate, geography, and historical events. By understanding biogeography, we can grasp how barriers and corridors affect the formation of new species and how reconnection between habitats can lead to varying rates of speciation.
Biomes: Biomes are large regions of the Earth characterized by specific climate conditions, plant communities, and animal groups. They are distinct biological communities that have formed in response to a shared physical climate.
Biomes: Biomes are large ecological areas on Earth, characterized by distinct plant and animal groups adapted to their environment. They are defined primarily by their climate, geography, and the types of vegetation found within them, which influences the biodiversity and ecosystems present. Understanding biomes is crucial for studying how organisms interact with their environment and how these interactions are shaped by both biological and physical factors.
Biosphere: The biosphere is the global sum of all ecosystems, encompassing all living organisms and their relationships with each other and their environments. It includes land, water, and the atmosphere where life exists and interacts.
Charles Darwin: Charles Darwin was an English naturalist and biologist best known for his theory of evolution through natural selection, which he detailed in his 1859 work 'On the Origin of Species'. His ideas revolutionized our understanding of the development of life on Earth, linking the concept of species formation to the mechanisms of adaptation and survival in changing environments.
Cladistic analysis: Cladistic analysis is a method used in biological classification that groups organisms based on shared derived characteristics, helping to illustrate evolutionary relationships. This approach focuses on the branching patterns of evolution, known as cladograms, which depict how species are related through common ancestry. By analyzing traits and constructing these diagrams, cladistic analysis aids in understanding the diversity of life and the evolutionary processes that shape it.
Continental drift: Continental drift is the theory that continents have moved over geological time and were once part of a single supercontinent called Pangaea. This movement has influenced the distribution of species, climate changes, and the evolution of ecosystems across the globe.
Dispersal barriers: Dispersal barriers are natural or artificial features that prevent the movement of organisms from one area to another, influencing the distribution and diversity of species. These barriers can include geographic features like mountains and rivers, as well as human-made obstacles like roads and urban areas, which significantly affect the patterns of biodiversity and species interactions in ecosystems.
Dispersalism: Dispersalism is the ecological concept that focuses on the movement of organisms from their origin to new locations, which plays a crucial role in species distribution and biodiversity. This phenomenon helps explain how species colonize new areas, adapt to different environments, and contribute to the richness of ecosystems. Dispersal patterns can influence evolutionary processes and biogeographical patterns across the globe.
Ecological Succession: Ecological succession is the process by which ecosystems change and develop over time, leading to a series of progressive changes in the species composition and structure of a community. This process can occur in both terrestrial and aquatic environments and can be driven by various factors such as disturbances, climate changes, and species interactions. Understanding ecological succession helps illustrate how communities adapt to environmental changes and how biodiversity evolves over time.
Endemic species: An endemic species is one that is found in a specific geographic location and nowhere else in the world. These species often evolve unique traits due to their isolated environments.
Endemism: Endemism refers to the ecological state where a species is native to and restricted to a particular geographic area. This concept highlights the uniqueness of biodiversity in specific locations, often resulting from isolation, environmental factors, and evolutionary processes. Endemic species are crucial for understanding local ecosystems and can be indicators of ecological health and resilience.
Estivation: Estivation is a state of dormancy or torpor during hot and dry periods to conserve water and energy. It is seen in various animals, including amphibians, reptiles, and some mammals, as an adaptation to extreme environmental conditions.
Great American Biotic Interchange: The Great American Biotic Interchange refers to the significant ecological event that occurred during the Pleistocene epoch, around 3 million years ago, when the land bridge known as the Isthmus of Panama formed. This event allowed for the migration of flora and fauna between North and South America, resulting in a dramatic exchange of species, ecological communities, and evolutionary pressures that shaped the biodiversity of both continents.
Hibernation: Hibernation is a state of dormancy in animals characterized by low metabolic activity, reduced body temperature, and slowed physiological functions. It is an adaptation to survive periods of harsh environmental conditions, such as extreme cold or food scarcity.
Inorganic nutrients: Inorganic nutrients are essential chemical elements and compounds, excluding carbon-based substances, that organisms need to grow, reproduce, and maintain their biological functions. Common examples include minerals like nitrogen, phosphorus, potassium, calcium, and magnesium.
Island biogeography: Island biogeography is the study of the distribution and diversity of species on islands and how these factors are influenced by isolation, size, and habitat diversity. This concept explains how the number of species on an island is determined by a balance between immigration rates and extinction rates, shaping the unique ecosystems found on islands compared to mainland areas.
Net primary productivity: Net primary productivity (NPP) is the rate at which all the plants in an ecosystem produce net useful chemical energy. It is equal to the gross primary productivity (GPP) minus the energy used by the plants for respiration (R).
Net Primary Productivity: Net primary productivity (NPP) is the measure of the rate at which plants in an ecosystem produce net useful chemical energy through photosynthesis, minus the energy they expend during respiration. This concept is essential because it quantifies the amount of organic material available for consumption by herbivores and ultimately supports higher trophic levels in an ecosystem. Understanding NPP helps to explain energy flow through ecosystems and the distribution of biomass across different biogeographic regions.
Ocean upwelling: Ocean upwelling is the process where deep, cold, nutrient-rich water rises to the ocean's surface. This phenomenon supports high biological productivity and diverse marine ecosystems.
Phylogeography: Phylogeography is the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals. It combines phylogenetic analysis with geographic information to understand how species and populations have evolved and dispersed across different landscapes. This field sheds light on how geographical features, climate changes, and historical events like glaciation have influenced the genetic structure of populations.
Pleistocene epoch: The Pleistocene epoch is a geological time period that lasted from about 2.6 million to 11,700 years ago, characterized by repeated glacial cycles and significant climatic changes. During this time, large ice sheets covered vast areas of the Northern Hemisphere, influencing global climates and ecosystems, as well as the distribution and evolution of species.
Species richness: Species richness is the number of different species represented in an ecological community, landscape, or region. It provides a simple measure of biodiversity and helps in understanding the health and stability of ecosystems.
Species richness: Species richness refers to the number of different species present in a given ecological area, reflecting the diversity of life within that environment. This measure is crucial for understanding ecological dynamics, as higher species richness often leads to increased ecosystem stability and resilience. It also highlights the health of ecosystems and can influence conservation strategies and resource management.
Spring-and-fall turnover: Seasonal process in lakes where water layers mix due to changes in temperature. This occurs in both spring and fall, leading to nutrient redistribution and oxygenation of the water.
Thermocline: The thermocline is a distinct layer in a body of water, such as an ocean or lake, where the temperature changes more rapidly with depth compared to the layers above and below. It acts as a barrier to mixing between the warmer surface water and the colder deep water.
Vicariance: Vicariance refers to the process by which the geographical range of a species is split into separate populations due to a barrier, such as a physical geographic feature or an environmental change. This separation can lead to evolutionary divergence as populations adapt to their new environments, ultimately influencing biodiversity and species distribution. The concept highlights how geological events and climate shifts can impact the distribution of life on Earth.
Wallace's Line: Wallace's Line is an imaginary boundary that separates the ecozones of Asia and Australia, proposed by the naturalist Alfred Russel Wallace in the 19th century. It highlights the distinct differences in species composition on either side of the line, illustrating the impact of geographical barriers on biodiversity and evolution. The line runs through the islands of Indonesia, indicating how land and water can shape ecological diversity.