1 1 ORIGINAL RESEARCH 2 3 TITLE: A biogeographic reversal in sexual size dimorphism along a continental temperature 4 gradient 5 6 AUTHORS 7 Simon Tarr 8 School of Geography, University of Nottingham, Nottingham, NG7 2RD, UK 9
[email protected] 10 Orcid ID: 0000-0001-8464-1240 11 12 Shai Meiri 13 Department of Zoology, Tel-Aviv University, Tel-Aviv, 69978, Israel 14
[email protected] 15 Orcid ID: 0000-0003-3839-6330 16 17 James J. Hicks 18 School of Geography, University of Nottingham, Nottingham, NG7 2RD, UK 19
[email protected] 20 Orcid ID: 0000-0001-5154-5615 21 22 Adam C. Algar (Corresponding Author) 23 School of Geography, University of Nottingham, Nottingham, NG7 2RD, UK 24
[email protected] 25 Orcid ID: 0000-0001-8095-0097 26 27 28 KEYWORDS 29 Body size, sexual size dimorphism, sexual selection 30 31 ACKNOWLEDGEMENTS 32 Thanks to Daniel Pincheira-Donoso and Andrew MacColl for thoughts on the early stages of this 33 work. The University of Nottingham’s Biogeography, Ecology and Evolution Research group 34 supplied valuable feedback on an earlier draft. 35 36 2 37 ABSTRACT 38 The magnitude and direction of sexual size dimorphism (SSD) varies greatly across the animal 39 kingdom, reflecting differential selection pressures on the reproductive and/or ecological roles of 40 males and females. If the selection pressures and constraints imposed on body size change along 41 environmental gradients, then SSD will vary geographically in a predictable way. Here, we uncover a 42 biogeographical reversal in SSD of lizards from Central and North America: in warm, low latitude 43 environments, males are larger than females, but at colder, high latitudes, females are larger than 44 males.