posted on 2011-12-31, 09:33authored byLaura J May-Collado, Ingi Agnarsson, Douglas Wartzok
Copyright information:
Taken from "Phylogenetic review of tonal sound production in whales in relation to sociality"
http://www.biomedcentral.com/1471-2148/7/136
BMC Evolutionary Biology 2007;7():136-136.
Published online 10 Aug 2007
PMCID:PMC2000896.
One conspicuous outlier (arrow) represents a contrast including the killer whale () which forms relatively small social groups but produces highly modulated whistles. It has been proposed that the killer whale uses whistles in a manner different from any other delphinid to indicate motivational state. That multiple factors are at work shaping tonal sounds in cetaceans may obscure and make difficult to discover true co-evolutinary histories of characters. Accordingly when is removed from the analysis the regression between the two characters becomes stronger.