Courtship Behavior and Systematics in the Subtribe Nectemydina 2. A Comparison above the Species Level and Remarks on the Evolution of Behavior Elements

Based on a literature review and unpublished data of the author, the male courtship behavior of turtles of the genera Chrysemys, Graptemys, Malaclemys , Pseudemys, Trachemys ( = subtribe Nectemydina), and Deirochelys is analyzed and its significant elements are applied to systematics above the species level. The results are discussed in a zoogeographic-evolutionary context. Head-nodding in a vertical plane is widely distributed in chelonian courtship and is a plesiomorphic character. Claw vibration is a synapomoll>hy of the subtribe Nectemydina, and claw vibration from a position above the female is a shared derived character of Pseudemys species. The different courtship modes represented by the species of the subtribe Nectemydina evolved from a common ancestral behavior pattern consisting of head-nodding plus claw vibration . Manifold variations of thi s basic pattern developed as character displacements. Today the highest diversity of courtship patterns occurs in the area with the highest species diversity, the southeastern United States. Differences in courtship which probably function as isolating mechanisms are listed . Introduction Behavioral characters have long been used to distinguish between closely related , morphologically similar, or otherwise indistinguishable species. However, only a few cases are known where strictly inherited behavior patterns are characteristic for higher taxa (Mayr, 1975). As a herpetological example, Zimmermann 'and Zimmermann (1988) recently presented a remarkable study which has encouraged intense, constructive discussions and highlighted the often impressive value of behavioral characters in taxonomic studies above the species level. In the first part of this study (Fritz, 1990; also the English translation in Bull. Chicago Hell>. Soc. 33(11):225-236, 1998), the utility of courtship behavior in the taxonomy of the turtle genus Trachemys was examined at the species level. Herein , in the second part of the study, it will be demonstrated that the complex courtship of turtles in the subtribe Nectemydina [the New World terrapins , in a broader sense than usually applied], also yields interesting conclusions pertaining to the higher taxonomy of these chelonians. [Editors' note: in this translation , "terrapin" is used for the German "Schmuckschildkrote ," the vernacular term for a turtle of the genus Trachemys, Pseudemys, Deirochelys, or, less frequently, ChrysemysJ. Claw vibration as a characteristic behavioral trait of the subtribe Nectemydina Several authors have demonstrated over the years that the long-known characteristic claw vibration behavior of the redeared slider (Trachemys scripta elegans) is a common behavior in the courtship display of aquatic turtles of the subfamily Emydinae (see Appendix). Moreover, until now , this behavior has been described only for species of the subtribe Nectemydina sensu Smith and Smith (1980), with the possible exception of the chicken turtle (Deirochelys reticularia; see Krefft , 1951) . It is highly improbable that the most complicated motion patterns displayed during claw vibration behavior would have developed independently several times through evolutionary convergence at the subfamily level or a lower taxonomic level. Taking this into account, the claw vibration behavior clearly proves to be a shared derived character, a synapomorphy of the subtribe Nectemydina (possibly including Deirochelys). This character, in addition to many morphological criteria, serves to unite this subtribe as a natural group (Figure 1) . Krefft ( 1951) published anecdotal observations on the courtship of a single captive Deirochelys . However, the claw vibra1 Citation of original article: FriLZ, Uwe. 1991. Balzverhalten und Systematik in der Subtribus Nectemydina 2. Vergleich oberhalb des Armiveaus und rirungen zur Evolution. Salamandra 27(3): 129-142. Figures have been reprinted with permission. srudy is based upon the material of an MA thesis prepared at the Institute for Zoology at the University of Stuttgart-Hohenheim . This work was s:x'~h~ ~ a grant from the Srudiensrijrung des deurschen Volkes. 3 PrlI .; addresJ: Staarliches Museum fur Tierkunde, Forschungss telle, A.-B.-Meyer-Bau, Kiinigsbriicker Landstrasse 159, 0-01109 Dresden, Germany. E-maIl: museum.fuer.tie rkunde@sz·online.de 4. T ransla n was edited by lames N. Stuart and Mic hael Dloogatch.