Stick or grip? Co-evolution of adhesive toepads and claws in Anolis lizards.

Exploring the relationship between phenotype and performance in an ecological and evolutionary context is crucial to understanding the adaptive nature of phenotypic traits. Despite their ubiquity in vertebrates, few studies have examined the functional and ecological significance of claw morphologies. Here we examine the adhesive toepad and claw system of Anolis lizards. Claw characters are significantly different between lizards classified as arboreal (perch height≥1m) and non-arboreal (perch height<1m). Arboreal species possess significantly higher and longer claws, and show trends toward decreased claw curvature and wider claw tip angles. Toepad size and claw length and height are tightly correlated with each other and with perch height, suggesting that the adhesive toepad and gripping claw have co-evolved to accommodate different habitats. The functional morphology and evolution of claws are ripe areas for future investigation.

[1]  J. Losos,et al.  DETERMINISM IN THE DIVERSIFICATION OF HISPANIOLAN TRUNK‐GROUND ANOLES (ANOLIS CYBOTES SPECIES COMPLEX) , 2013, Evolution; international journal of organic evolution.

[2]  G. Burghardt.  Lizard Ecology: Studies of a Model Organism, Raymond B. Huey, Eric R. Pianka, Thomas W. Schoener (Eds.). Harvard University Press, Cambridge, Massachusetts (1983), 501 , 1984 .

[3]  A. Grafen.  The phylogenetic regression. , 1989, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[4]  Peter H. Niewiarowski,et al.  The effect of surface water and wetting on gecko adhesion , 2012, Journal of Experimental Biology.

[5]  Andrew M. Smith.  Biological Adhesives , 2016, Springer International Publishing.

[6]  Jonathan E. Clark,et al.  Towards Penetration-based Clawed Climbing , 2005 .

[7]  A. Herrel,et al.  The interplay between claw morphology and microhabitat use in neotropical iguanian lizards. , 2009, Zoology.

[8]  Duncan J. Irschick,et al.  Evolutionary correlations among morphology, habitat use and clinging performance in Caribbean Anolis lizards , 2004 .

[9]  Zani.  The comparative evolution of lizard claw and toe morphology and clinging performance , 2000 .

[10]  Kellar Autumn,et al.  Properties, Principles, and Parameters of the Gecko Adhesive System , 2006 .

[11]  D. Pincheira‐Donoso.  Lizards in an evolutionary tree: ecology and adaptive radiation of anoles , 2011 .

[12]  Peter H. Niewiarowski,et al.  Sticky Gecko Feet: The Role of Temperature and Humidity , 2008, PloS one.

[13]  Matt Wilkinson,et al.  Changes in materials properties explain the effects of humidity on gecko adhesion , 2010, Journal of Experimental Biology.

[14]  Matt Wilkinson,et al.  Effects of humidity on the mechanical properties of gecko setae. , 2011, Acta biomaterialia.

[15]  Ronald S. Fearing,et al.  ADHESION FORCE MEASUREMENTS ON SINGLE GECKO SETAE , 2000 .

[16]  A. Feduccia,et al.  Evidence from Claw Geometry Indicating Arboreal Habits of Archaeopteryx , 1993, Science.

[17]  M. Cartmill.  2 – Pads and Claws in Arboreal Locomotion , 1974 .

[18]  Yu Tian,et al.  Gecko adhesion pad: a smart surface? , 2009, Journal of physics. Condensed matter : an Institute of Physics journal.

[19]  A. Russell,et al.  Between a rock and a soft place: microtopography of the locomotor substrate and the morphology of the setal fields of Namibian day geckos (Gekkota: Gekkonidae: Rhoptropus) , 2014 .

[20]  Duncan J. Irschick,et al.  Ecomorphological Differences in Toepad Characteristics between Mainland and Island Anoles , 2003 .

[21]  Bieke Vanhooydonck,et al.  Effects of substrate structure on speed and acceleration capacity in climbing geckos , 2005 .

[22]  S. J. Arnold,et al.  Morphology, Performance and Fitness , 1983 .

[23]  K. Queiroz**,et al.  Phylogeny of the Dactyloa Clade of Anolis Lizards: New Insights from Combining Morphological and Molecular Data , 2013 .

[24]  E. Williams.  15. ECOMORPHS, FAUNAS, ISLAND SIZE, AND DIVERSE END POINTS IN ISLAND RADIATIONS OF ANOLIS , 1983 .

[25]  J. Felsenstein.  Phylogenies and the Comparative Method , 1985, The American Naturalist.

[26]  AN ALTERNATIVE EXPLANATION OF THE EFFECT OF HUMIDITY IN GECKO ADHESION: STIFFNESS REDUCTION ENHANCES ADHESION ON A ROUGH SURFACE , 2010 .

[27]  S. Poe,et al.  Patterns of ecomorphological convergence among mainland and island Anolis lizards , 2010 .

[28]  R. Full,et al.  Adhesive force of a single gecko foot-hair , 2000, Nature.

[29]  A. Biewener.  Scaling body support in mammals: limb posture and muscle mechanics. , 1989, Science.

[30]  Ws. Rasband.  ImageJ, U.S. National Institutes of Health, Bethesda, Maryland, USA , 2011 .

[31]  Beni Charan Mahendra.  Contributions to the bionomics, anatomy, reproduction and development of the indian house-gecko,Hemidactylus flaviviridis Rüppel , 1941, Proceedings / Indian Academy of Sciences.

[32]  A. Garrod.  Animal Locomotion , 1874, Nature.

[33]  R. Reisz,et al.  Histological microstructure of the claws of the African clawed frog, Xenopus laevis (Anura: Pipidae): implications for the evolution of claws in tetrapods. , 2007, Journal of experimental zoology. Part B, Molecular and developmental evolution.

[34]  Bebni Charan Mahendra,et al.  Contributions to the bionomics, anatomy, reproduction and development of the Indian house-gecko,Hemidactylus flaviviridis RÜPpel. Part I , 1936, Proceedings / Indian Academy of Sciences.

[35]  Robert N. Fisher,et al.  A comparative analysis of clinging ability among pad‐bearing lizards , 1996 .

[36]  J. Losos,et al.  Mainland colonization by island lizards , 2005 .

[37]  R. Full,et al.  Evidence for van der Waals adhesion in gecko setae , 2002, Proceedings of the National Academy of Sciences of the United States of America.

[38]  A. Herrel,et al.  Ecomorphology of Anolis lizards of the Choco′ region in Colombia and comparisons with Greater Antillean ecomorphs , 2007 .

[39]  Stanislav N. Gorb,et al.  The effect of surface roughness on the adhesion of elastic plates with application to biological systems , 2003 .

[40]  J. Losos,et al.  MORPHOLOGICAL DIVERSIFICATION AND ADAPTIVE RADIATION: A COMPARISON OF TWO DIVERSE LIZARD CLADES , 1999, Evolution; international journal of organic evolution.

[41]  L. Vitt,et al.  A COMPARISON OF EVOLUTIONARY RADIATIONS IN MAINLAND AND CARIBBEAN ANOLIS LIZARDS , 1997 .

[42]  S. Gorb,et al.  Roughness-dependent friction force of the tarsal claw system in the beetle Pachnoda marginata (Coleoptera, Scarabaeidae). , 2002, The Journal of experimental biology.

[43]  Jonathan B. Losos,et al.  Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles , 2009 .

[44]  Luke J. Harmon,et al.  GEIGER: investigating evolutionary radiations , 2008, Bioinform..