2.5 Biogeographical consequences of plate tectonics
10 min read•august 21, 2024
Plate tectonics reshapes Earth's surface, driving species distribution and evolution. , mountain formation, and ocean basin changes create barriers and corridors for organisms, influencing biodiversity patterns globally.
These geological processes impact climate, form new habitats, and isolate populations. Understanding tectonic biogeography helps explain current species distributions, predict future changes, and guides conservation efforts in a dynamic world.
Continental drift theory
Explains the movement of Earth's continents over geological time scales, fundamentally reshaping our understanding of global biogeography
Provides a framework for understanding the distribution of species and ecosystems across the planet, linking geological processes to biological patterns
Early evidence for drift
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Matching coastlines of continents suggested they once fit together like puzzle pieces
Similar fossil records found on now-separated continents indicated past connections (Glossopteris flora in South America, Africa, India, and Australia)
Geological similarities across distant landmasses pointed to shared histories (mountain ranges, rock types)
Paleoclimatic evidence showed tropical plant fossils in now-polar regions, suggesting continental movement
Wegener's hypothesis
Alfred Wegener proposed the theory of continental drift in 1912, challenging prevailing views of static continents
Wegener's "supercontinent" Pangaea explained the distribution of fossils and geological features across modern continents
Proposed mechanisms for continental movement included centrifugal force and lunar tides, later proven incorrect
Faced significant scientific skepticism due to lack of a plausible mechanism for continent movement
Modern plate tectonics
Developed in the 1960s, integrating continental drift with seafloor spreading and processes
Explains continental movement through the interaction of rigid lithospheric plates floating on the asthenosphere
Supported by multiple lines of evidence including paleomagnetism, seafloor magnetic anomalies, and earthquake distributions
Provides a unifying theory for Earth's geological processes, including mountain building, volcanism, and earthquake activity
Plate boundaries and movements
Describes the interactions between tectonic plates, driving global geological processes and shaping Earth's surface
Influences the formation and evolution of habitats, creating barriers and corridors for species and evolution
Convergent vs divergent boundaries
Convergent boundaries occur where plates move towards each other, resulting in:
Subduction zones where oceanic crust sinks beneath continental or oceanic plates (Pacific Ring of Fire)
forming mountain ranges (Himalayas)
Divergent boundaries form where plates move apart, creating:
Mid-ocean ridges where new oceanic crust is formed (Mid-Atlantic Ridge)
Rift valleys in continental settings (East African Rift)
Impacts biogeography by creating or removing barriers to species movement and creating new habitats
Transform faults
Occur where plates slide horizontally past each other, neither creating nor destroying crust
Often result in earthquakes due to friction between moving plates (San Andreas Fault)
Can create localized habitats and influence species distributions through landscape changes
May act as barriers or corridors for species movement depending on their orientation and associated topography
Hot spots and mantle plumes
Stationary areas of upwelling magma from deep within the Earth's mantle
Create chains of volcanic islands as tectonic plates move over them (Hawaiian-Emperor seamount chain)
Provide opportunities for speciation and on newly formed islands
Influence ocean currents and climate patterns, affecting marine and terrestrial ecosystems
Biogeographical impacts of tectonics
Tectonic processes fundamentally shape the distribution and evolution of life on Earth
Create and destroy land bridges, isolate populations, and form new habitats, driving biodiversity patterns
Vicariance vs dispersal
involves the separation of populations by geological events:
Formation of mountain ranges or ocean basins splitting previously continuous populations
Results in allopatric speciation as populations evolve independently (marsupials in Australia and South America)
Dispersal occurs when organisms move across existing barriers:
Long-distance dispersal events (seeds carried by wind or birds)
Gradual range expansion along newly formed land bridges
Both processes contribute to biogeographical patterns, with their relative importance debated in different scenarios
Allopatric speciation
Occurs when populations become geographically isolated, leading to independent evolution
Tectonic events often create barriers that promote allopatric speciation:
Formation of islands (Galápagos finches)
Mountain building (Andean cloud forests)
Continental breakup (placental vs marsupial mammals)
Results in unique species assemblages in different regions, contributing to global biodiversity
Adaptive radiation
Rapid diversification of species from a common ancestor to fill diverse ecological niches
Often occurs following major tectonic events that create new habitats or isolate populations:
Hawaiian honeycreepers diversifying across different island habitats
Cichlid fish radiation in African rift lakes
Drives the evolution of novel traits and adaptations, increasing biodiversity in newly available environments
Formation of major biomes
Tectonic processes play a crucial role in shaping Earth's major biomes by influencing climate patterns and creating diverse landscapes
Understanding biome formation helps explain global biodiversity distribution and ecosystem functioning
Tropical rainforests
Develop in areas of consistent high rainfall and warm temperatures near the equator