Detecting non-tree-like signal using multiple tree topologies

要旨

Abstract Recent applications of phylogenetic methods to historical linguistics have been criticized for assuming a tree structure in which ancestral languages differentiate and split up into daughter languages, while language evolution is inherently non-tree-like ( François 2014 ; Blench 2015 : 32–33). This article attempts to contribute to this debate by discussing the use of the multiple topologies method ( Pagel & Meade 2006a ) implemented in BayesPhylogenies ( Pagel & Meade 2004 ). This method is applied to lexical datasets from four different language families: Austronesian ( Gray, Drummond & Greenhill 2009 ), Sinitic ( Ben Hamed & Wang 2006 ), Indo-European ( Bouckaert et al. 2012 ), and Japonic ( Lee & Hasegawa 2011 ). Evidence for multiple topologies is found in all families except, surprisingly, Austronesian. It is suggested that reticulation may arise from a number of processes, including dialect chain break-up, borrowing (both shortly after language splits and later on), incomplete lineage sorting, and characteristics of lexical datasets. It is shown that the multiple topologies method is a useful tool to study the dynamics of language evolution.

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