Testing Convergent and Parallel Adaptations in Talpids Humeral Mechanical Performance by means of Geometric Morphometrics and Finite Element Analysis P. Piras, 1,2 * G. Sansalone, 1,2,3 L. Teresi, 4 T. Kotsakis, 1,2 P. Colangelo, 3 and A. Loy 1,5 1 Center for Evolutionary Ecology, Largo San Leonardo Murialdo 1, 00146 Roma, Italy 2 Dipartimento di Scienze Geologiche, Universita ` Roma Tre, Largo San Leonardo Murialdo 1, 00146 Roma, Italy 3 Dipartimento di Biologia e Biotecnologia ‘‘Charles Darwin’’, ‘‘Sapienza’’ Universita ` di Roma,Via Borelli 50, I-00161 Rome, Italy 4 LaMS - Modelling & Simulation Lab Universita ` Roma Tre, Via Corrado Segre, 6 I-00146 Roma, Italy 5 Environmetrics Lab, Dipartimento STAT, Universita ` del Molise, Pesche I-86090, Italy ABSTRACT The shape and mechanical performance in Talpidae humeri were studied by means of Geometric Morphometrics and Finite Element Analysis, including both extinct and extant taxa. The aim of this study was to test whether the ability to dig, quantified by humerus mechanical performance, was characterized by conver- gent or parallel adaptations in different clades of com- plex tunnel digger within Talpidae, that is, Talpi- nae1Condylura (monophyletic) and some complex tun- nel diggers not belonging to this clade. Our results suggest that the pattern underlying Talpidae humerus evolution is evolutionary parallelism. However, this insight changed to true convergence when we tested an alternative phylogeny based on molecular data, with Condylura moved to a more basal phylogenetic position. Shape and performance analyses, as well as specific comparative methods, provided strong evidence that the ability to dig complex tunnels reached a functional opti- mum in distantly related taxa. This was also confirmed by the lower phenotypic variance in complex tunnel dig- ger taxa, compared to non-complex tunnel diggers. Evo- lutionary rates of phenotypic change showed a smooth deceleration in correspondence with the most recent common ancestor of the Talpinae1Condylura clade. J. Morphol. 000:000–000, 2012. Ó 2012 Wiley Periodicals, Inc. KEY WORDS: talpid humerus; geometric morphometrics; finite element analysis; comparative methods; parallel evolutionary trajectories INTRODUCTION Ever since Darwin (1859), the concept of adapta- tion has been a central topic in evolutionary biol- ogy. During the past 30 years, it was the focus of many disputes (Gould and Lewontin, 1979) and of changes in semantics (Gould and Vrba, 1982). The term ‘‘adaptation’’ itself has many different defini- tions (Dobzhansky, 1956; Dobzhansky et al., 1968; Dobzhansky, 1970; Gould, 2002, among others). Patterns of shared adaptations among phylogeneti- cally distant taxa are described in terms of either convergence or parallelism. Specifically, independ- ently evolved similar character states could have originated through true adaptation (i.e., the func- tion at the first appearance of a character and its current function coincide), exaptation (i.e., the cur- rent function is different from the original; Gould and Vrba, 1982), convergence (i.e., starting from different ancestral states, different taxa reach the same character state by means of opposite devia- tions relative to their original phenotypic states; Stayton, 2006) or parallelism (i.e., starting from different ancestral states, different taxa follow a parallel evolution toward the current phenotypic state by means of equal deviations relative to their original phenotypic states; Stayton, 2006). A key aspect of these issues is to consider phylo- genetic relationships as a central factor in explain- ing the above mentioned patterns. In some case, shared ancestry channels the phenotypes that, being adapted to a particular function, are posi- tively selected (Revell et al., 2007). Specific hypotheses about convergence and par- allelism need specific tests that have been rarely applied in experimental studies (Stayton, 2006; Revell et al., 2007; Stayton, 2008; Adams and Collyer, 2009). Characters which are adapted to a particular function and are shared by different Additional Supporting Information may be found in the online version of this article *Correspondence to: Paolo Piras, Center for Evolutionary Ecology, Largo San Leonardo Murialdo 1, 00146 Roma, Italy. E-mail: ppiras@uniroma3.it Received 27 September 2011; Revised 6 January 2012; Accepted 29 January 2012 Published online in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/jmor.20015 JOURNAL OF MORPHOLOGY 000:000–000 (2012) Ó 2012 WILEY PERIODICALS, INC.