Previous studies of relationships among the subspecies of snapping turtles (Chelydra serpentina) based on morphological and osteological characters have been inconclusive. We investigated relationships among the four currently recognized subspecies using restriction endonuclease fragment patterns of mtDNA and protein electrophoresis. Sixteen six-based recognizing restriction endonucleases yielded 90 variable fragments that define 11 different haplotypes. Individuals of the two North American subspecies, C. s. osceola and C. s. serpentina, are closely related, differing by a maximum of 0.5% sequence divergence. The Central American subspecies, C. s. rossignonii and C. s. acutirostris, are more distinct, both from each other (a minimum of 1.7% sequence divergence) and from the North American samples (an average of 4.45% sequence divergence). The degree of allozymic variation among the four subspecies was found to be limited and could not be used to diagnose the four recognized subspecies. The mtDNA data presented here support the species-level distinctness of C.s. rossignoii and C. s. acutirostris from each other and from a C. s. serpentina-C. s. osceola complex. The recognition of three distinctive groups of Chelydra rather than one widespread polytypic species has important conservation implications because it focuses attention on the poorly known middle and South American species.
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文章 : 英语