What is the Wallace Line?
- Proposed by Alfred Russel Wallace in the 19th century.
- Marks a sharp boundary in species distribution between Asia and Australia.
- Runs between Bali and Lombok, northward between Borneo and Sulawesi, then curving south of Mindanao.
- Wallace observed distinct species on either side—Asian species like tigers and orangutans versus Australian species like kangaroos and cockatoos.
- Relevance : GS 1(Geography)
Key Findings on Sulawesi
- Sulawesi, despite being close to Borneo, hosts unique species from both Asian and Australian origins.
- Example: Tarsiers and anoas (Asian lineage) vs. dwarf cuscus (Australian marsupial).
- Wallace struggled to categorize Sulawesi, redrawing his line multiple times.
Geological and Evolutionary Explanations
- Tectonic Movements:
- Malay Archipelago formed due to the breakup and drift of landmasses.
- Australia separated from Antarctica, drifting north toward Asia, creating Indonesia’s volcanic islands.
- Climatic and Environmental Factors:
- Oceanic cooling affected species migration.
- Asian species could migrate via tropical islands, while Australian species faced harsher routes.
- Study (2023) on 20,000 species confirmed that environmental conditions influenced species dispersal.
Modern Relevance
- Wallace Line is more of an ecological gradient than a fixed boundary.
- New technologies (evolutionary modeling, computer simulations) refine our understanding of species adaptation.
- Conservation concerns:
- Indo-Malayan archipelago faces high habitat destruction rates.
- Understanding historical species distribution helps predict responses to climate change and habitat loss.
- Experts argue redrawing the line is unnecessary; focus should be on biodiversity conservation instead.
