The Evidence for the Timing of Speciation of Modern Continental Birds and the Taxonomic Ambiguity of the Quaternary Fossil Record

摘要

Modern continental bird species evolution is discussed from the perspective of the Quaternary fossil record. An alternative interpretation of the fossils-that they are taxonomically ambiguous at the species level and below-is proposed. Evidence for this ambiguity is offered in the form of an analysis of the published diagnoses of extinct species and subspecies from the Quaternary Europe. This analysis showed that characters used to describe new species are often identical to those used to describe new subspecies. This indicates that no consensus exists as to what character differences define those taxonomic levels. Finally, an alternative non-taxonomic approach to the fossil record is outlined, which highlights patterns in time and space of different adaptive morphologies with a view of shedding light on evolutionary processes that may be taking place. This approach suggests that a Pleistocene origin for the species pairs Lagopus lagopus/L. mutus and Sturnus vulgaris/S. uncolor is highly likely and that allopartic speciation, whether by simple geographic isolation or isolation due to variations in relative migratory/sedentary behaviour, is implicated.