The use of isozyme characters in systematic studies of turtles: preliminary data for Australian Chelids

In this study we explore how various treatments of a small isozyme data set may be used to generate phylogenetic hypotheses for comparison with the results of allozyme analysis involving some of the same taxa. The isozyme data were collected from various tissue samples representing eight species of four genera of Australian chelid turtles: Chelodina, Elseya, Elusor, and Emydura. Treatments of the allozyme components of these data employed a chord distance in a Distance Wagner analysis and particulate characters (“locus-as-character”) for a Wagner parsimony analysis. Treatments of a tissue expression data set included coding as presence–absent in a given tissue and as tissue arrays; a maximum parsimony analysis was used for both coded data sets. The resultant phylogenetic hypotheses were then compared with the current hypotheses of relationships among these turtles arising from morphological data as well as an independent and much larger allozyme data set. Our results support the conclusions of previous studies that the genus Elseya is polyphyletic. However the schema as to which species-level taxa in this genus are allied to the other chelid genera vary in our study with type of data and their encoding method. The relationship of Elseya dentata to other chelid turtles varied considerably with respect to different data sets and different means of coding and analysis.