Lydekker Line — LLMpedia

Lydekker Line
Name	Lydekker Line
Location	New Guinea, Australia, Arafura Sea, Timor Sea
Established	1896
Named for	Richard Lydekker

Contents

Lydekker Line The Lydekker Line is a biogeographical boundary proposed in the late 19th century that separates the distinct faunal and floral provinces of Australia and New Guinea from the islands of western Wallacea, Southeast Asia, and the Malay Archipelago. It was articulated by Richard Lydekker as part of debates involving other naturalists and institutions such as Alfred Russel Wallace, the British Museum, the Royal Society, and the Zoological Society of London. The Line remains influential in studies by researchers affiliated with Cambridge University, the Natural History Museum, London, and regional museums in Jakarta and Port Moresby.

History and origin

Richard Lydekker proposed the Line during exchanges with contemporaries including Alfred Russel Wallace, Charles Darwin proponents, and curators at the British Museum (Natural History), informed by collections gathered during expeditions by Alfred Russel Wallace, James Cook's legacy voyages, and later surveys funded by institutions like the Royal Geographical Society and the Australian Museum. The concept arose amid 19th-century debates in publications associated with the Zoological Record and corresponded with taxonomic work by scholars at Oxford University, Cambridge University, and the Smithsonian Institution. Colonial administrations in Netherlands East Indies, British New Guinea, and Queensland influenced specimen flow to metropolitan centers such as London and Amsterdam, shaping Lydekker's synthesis. Debates over the Line were taken up in symposia convened by the British Association for the Advancement of Science and later revisited by ecologists at Harvard University and the University of California, Berkeley.

Geographically, the Lydekker Line runs close to the eastern edge of the Malay Archipelago, tracing a boundary near the eastern margin of the Sunda Shelf and the western edge of the Sahul Shelf, effectively placing islands such as New Guinea and the Aru Islands on the Australo-Papuan side while excluding islands of western Wallacea like Sulawesi, Borneo, and Timor. The Line corresponds with bathymetric features charted by surveys conducted by the Hydrographic Office and later by oceanographers at Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution, reflecting deep-water channels such as the Lombok Strait and deep trenches adjacent to the Arafura Sea and Timor Sea. Cartographers associated with the Royal Geographical Society and explorers like Alfred Russel Wallace used collections and maps from voyages by HMS Endeavour and other vessels to delineate the region's island groupings.

The Lydekker Line marks a major turnover in distributions documented by taxonomists at the Natural History Museum, London, curators at the American Museum of Natural History, and researchers affiliated with the Australian National University and the University of Papua New Guinea. It corresponds to genetic breaks observed in studies published by teams at Stanford University, University of Melbourne, and the Max Planck Institute and is central to zoogeographic frameworks used by authors of major checklists housed at the British Museum (Natural History) and the Smithsonian Institution. The Line is often invoked alongside concepts articulated by Alfred Russel Wallace and incorporated into faunal region schemes endorsed by organizations such as the International Union for Conservation of Nature and the World Wildlife Fund.

Faunal assemblages east of the Line are dominated by taxa closely allied to Australo-Papuan faunas, with representatives recorded in museum collections from New Guinea, the Aru Islands, and northern Australia that include marsupials, monotremes, and many bird lineages catalogued by ornithologists at the Royal Australasian Ornithologists Union, American Museum of Natural History, and Zoological Society of London. West of the Line, islands in Wallacea host faunas with stronger affinities to Southeast Asia and taxa described by explorers and taxonomists like Alfred Russel Wallace and Thomas Huxley, including diverse Primates and diverse reptile assemblages studied at the Natural History Museum, London and Leiden University Museum. Plant distributions tracked by botanists at Kew Gardens, Bogor Botanical Gardens, and the Royal Botanic Garden Edinburgh similarly reflect the boundary, with Australo-Papuan floras eastward and Malesian floras westward, influencing floristic treatments produced by the Flora Malesiana project and researchers at Harvard University Herbaria.

The Lydekker Line is one of three principal lines—alongside the Wallace Line and the Weber Line—used to describe the biogeographic transition across the Malay Archipelago; debates among proponents occurred in forums involving the Zoological Society of London, the British Association for the Advancement of Science, and publishers like the Journal of Biogeography and Transactions of the Royal Society. While the Wallace Line, associated with Alfred Russel Wallace and collections deposited at institutions such as the Natural History Museum, London and the British Museum, emphasizes an abrupt faunal break near the Lombok Strait, the Weber Line, advanced by Max Wilhelm Carl Weber, marks an intermediate zone acknowledged by the Royal Society and researchers at Leiden University. Comparative analyses by scholars at University College London, University of Oxford, and Yale University integrate paleogeographic reconstructions, plate tectonic models from the United States Geological Survey and the Geological Survey of Indonesia, and molecular data from laboratories at the Sanger Institute and the Max Planck Institute for Evolutionary Anthropology.

Conservation planning by agencies such as the International Union for Conservation of Nature, BirdLife International, and regional bodies in Indonesia and Papua New Guinea uses the Lydekker Line to prioritize endemic-rich areas and manage transboundary reserves involving partners like the World Wildlife Fund and the Australian Government Department of Agriculture, Water and the Environment. Protected-area designations administered by the Papua New Guinea National Museum and Art Gallery and Indonesia's Ministry of Environment and Forestry reflect patterns of endemism east of the Line, informing strategies promoted by organizations including the Convention on Biological Diversity and the United Nations Environment Programme. Ongoing research by teams at CSIRO, the Australian National University, and international consortia funded by the European Commission and National Science Foundation evaluates climate change impacts on island biotas, habitat fragmentation documented by satellite programs at NASA and European Space Agency, and invasive species management coordinated with the Australian Museum and regional conservation NGOs.

Category:Biogeography Category:Zoogeographic regions