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Clasp and dance: Mating mode promotes variable sexual size and shape dimorphism trajectories in crocodile newts (Caudata: Salamandridae)
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  • Peter Pogoda,
  • Marcus Zuber,
  • Tilo Baumbach,
  • Alexander Kupfer
Peter Pogoda
Stuttgart State Museum of Natural History
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Marcus Zuber
Karlsruhe Institute of Technology
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Tilo Baumbach
Karlsruhe Institute of Technology
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Alexander Kupfer
Stuttgart State Museum of Natural History
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Abstract

Sexual dimorphism (SD) is a main source of intraspecific morphological variation, however sexual shape dimorphism (SShD) was long time neglected in evolutionary research. Especially in cold-blooded animal groups only subtle shape differences are expressed between males and females and the selective forces behind it are poorly understood. Crocodile newts of the genera Echinotriton and Tylototriton are highly polymorphic in their reproductive ecology and hence, are a highly suitable model system to investigate potential evolutionary forces leading to SShD differences. We applied 3D geometric morphometrics to the cranial and humerus morphology of nine species of crocodile newts to investigate patterns of SShD in relation to the different mating modes. Trajectories of shape differences between males and females differ in both, cranium and humerus but mating mode does explain differences in SShD trajectories between species only in cranial morphology. Nevertheless, cranial morphology shape differed between the amplecting and circle dancing species. Hence, other selective forces must act here. Variable interspecific allometric trajectories are a potential source of shape differences whereas these trajectories are quite stable for the sexes irrespective of the species.

Peer review status:UNDER REVIEW

16 Jul 2021Submitted to Ecology and Evolution
17 Jul 2021Assigned to Editor
17 Jul 2021Submission Checks Completed
26 Jul 2021Reviewer(s) Assigned
11 Aug 2021Review(s) Completed, Editorial Evaluation Pending