Evolution, Biogeography and Systematics of the Western Palaearctic Zamenis Ratsnakes
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Received: 25 February 2018 | Revised: 23 April 2018 | Accepted: 1 May 2018 DOI: 10.1111/zsc.12295 ORIGINAL ARTICLE Evolution, biogeography and systematics of the western Palaearctic Zamenis ratsnakes Daniele Salvi1,2 | Joana Mendes2,3 | Salvador Carranza3 | David James Harris2,4 1Department of Health, Life and Environmental Sciences, University of Abstract L'Aquila, L'Aquila, Italy The phylogenetic relationships between western Palaearctic Zamenis and Rhinechis 2CIBIO Research Centre in Biodiversity and ratsnakes have been troubled, with recent estimates based on the supermatrix ap- Genetic Resources, InBIO, Universidade do proach questioning their monophyly and providing contradictory results. In this Porto, Vairão, Vila do Conde, Portugal study, we generated a comprehensive molecular data set for Zamenis and closely re- 3Institute of Evolutionay Biology (CSIC‐ Universitat Pompeu Fabra), Barcelona, lated ratsnakes to assess their phylogenetic and systematic relationships and infer Spain their spatial and temporal modes of diversification. We obtained a fully resolved and 4 Departamento de Biologia, Faculdade de well‐supported phylogeny, which is consistent across markers, taxon‐sets and phylo- Ciências, Universidade do Porto, Porto, genetic methods. The close phylogenetic relationship between Rhinechis and Zamenis Portugal is well‐established. However, the early branching pattern within this clade, and the Correspondence position of R. scalaris and Z. hohenackeri, remains poorly supported. The Persian Daniele Salvi, Department of Health, Life and Environmental Sciences, University of ratsnake Z. persicus is sister to the Mediterranean species Z. situla, Z. longissimus L'Aquila, 67100 Coppito, L'Aquila, Italy. and Z. lineatus, of which Z. situla is sister to a clade containing the latter two species. Email: [email protected] These results are consistent with a recent phylogenomic study on ratsnakes based on Funding information hundreds of loci. Whereas, topological tests based on our data and evidence from Fundação para a Ciência e a Tecnologia, Grant/Award Number: IF/01627/2014 such phylogenomic study strongly rejected previous phylogenetic estimates based on and SFRH/BD/81528/2011; Ministero the supermatrix approach and demonstrate that these “mega phylogenies”, with hun- dell'Istruzione, dell'Università e dreds of taxa and high levels of missing data, have recovered inconsistent relation- della Ricerca; Consejo Superior de Investigaciones Científicas, Grant/Award ships with spurious nodal support. Biogeographical and molecular dating analyses Number: CGL2015‐70390 suggest an origin of the ancestor of Rhinechis and Zamenis in the Aegean region with early cladogenesis during the Late Miocene associated with the Aegean arch forma- tion and support a scenario of east‐to‐west diversification. Finally, while we have little morphological and phylogenetic evidence for the distinctiveness between Rhinechis and Zamenis, a classification of them in a single genus, and the designation of Zamenis scalaris (Schinz, 1822), reflects better their evolutionary relationships. KEYWORDS Colubridae, fast radiation, multilocus phylogeny, Rhinechis, species tree, supermatrix 1 | INTRODUCTION sometimes considered as a tribe or as a distinct subfamily, Coronellini, January 1863 (Utiger, Schatti, & Helfenberger, Ratsnakes represent an evolutionary lineage of the subfam- 2005). Some 82 species and 17 genera of ratsnakes are cur- ily Colubrinae Oppel, 1811, within Colubridae Oppel, 1811, rently recognized (Uetz, Freed, & Hošek, 2018; not includ- ing Gonyosoma and Coelognathus, Chen, Mckelvy, et al., Daniele Salvi and Joana Mendes have contributed equally to this work. 2014), mainly distributed in the Holarctic region but also in Zoologica Scripta. 2018;47:441–461. wileyonlinelibrary.com/journal/zsc © 2018 Royal Swedish Academy of Sciences | 441 442 | SALVI ET AL. the Oriental and northern portions of the Neotropical region. Rhinechis Michahelles, 1833 for the western Mediterranean Over the last decades, molecular studies have contributed to species R. scalaris (Schinz, 1822). Utiger et al. (2002), based a drastic reconsideration of ratsnakes’ systematics and evo- on mitochondrial DNA (mtDNA) sequence data, established lution. Until the end of the last century, most species distrib- the monophyletic genus Zamenis Wagler, 1830 including the uted in the Northern Hemisphere were included in a single Mediterranean species Z. longissimus Laurenti, 1768, Z. lin- genus (Elaphe) based on shared morphological features (see eatus Camerano, 1891 and Z. situla Linnaeus, 1758, and the Schulz, 1996). Extensive research based on DNA sequence species Z. persicus Werner, 1913 and Z. hohenackeri Strauch, data restricted the genus Elaphe Fitzinger, 1833 to a dozen 1873 from south‐western Asia (Figure 1). of Palaearctic species and provided strong phylogenetic ev- Phylogenetic estimates of the relationships between idence for a monophyletic origin of New World ratsnakes Zamenis and Rhinechis have been contradictory in differ- (Lampropeltini), which were assigned to distinct genera (e.g., ent studies (Figure 2). First molecular studies based mainly Burbrink & Lawson, 2007; Rodríguez‐Robles & De Jesús‐ on mtDNA showed R. scalaris either branching off early Escobar, 1999; Utiger et al., 2002, 2005). in a solitary phylogenetic lineage within the European Western Palaearctic ratsnakes belong to four distinct lin- ratsnakes (Lenk et al., 2001; Utiger et al., 2002) or sister to eages (Helfenberger, 2001; Lenk, Joger, & Wink, 2001; Schulz, the Zamenis clade (Burbrink & Lawson, 2007; Utiger et al., 1996; Utiger et al., 2002). These include representatives of 2002), although these phylogenetic relationships received the genera Coronella Laurenti, 1768, Elaphe and two other low statistical support. In contrast, recent studies based on recently designated genera. Helfenberger (2001), based on an- the supermatrix approach, with hundreds or thousands of atomical and allozyme data, resurrected the monotypic genus Colubridae or Squamata taxa, recovered R. scalaris deeply FIGURE 1 Distribution of the ratsnakes genera Zamenis, Rhinechis and Coronella in the Palaearctic (based on IUCN, 2017; Salvi et al., 2017): (a) distribution of Zamenis species; (b) distribution of R. scalaris; (c) distribution of Coronella species [Colour figure can be viewed at wileyonlinelibrary.com] SALVI ET AL. | 443 (a) Lenk et al. 2001 (weightedMP mtDNAtree) (d) Pyronet al. 2011 (ML supermatrix tree)* 98 Zamenis longissimus 100 Rhinechis scalaris 97 Zamenislineatus 99 Zamenis situla 98 Zamenis situla 100 Zamenis longissimus 91 Zamenispersicus Zamenislineatus 97 82 Zamenis hohenackeri Zamenispersicus 100 Oreocryptophis porphyraceus 67 Zamenis hohenackeri 100 Elaphe spp. (3) 99 Rhinechis scalaris (e) Pyronet al. 2013 (ML supermatrix tree) Zamenis hohenackeri 99 Zamenis persicus (b) Utigeret al. 2002 (weightedMP mtDNAtree) 100 Zamenis longissimus 64 100 Zamenis lineatus 97 Elaphe spp. (10) Rhinechisscalaris Lampropeltini (13) 100 Zamenis situla Oreocryptophis porphyraceus Rhinechis scalaris (f) 77 Figueroa et al. 2016 (ML supermatrix tree) Orthriophis spp. (4) Zamenis hohenackeri Zamenis hohenackeri 47 89 Zamenis longissimus 99 Zamenis persicus Zamenis situla Rhinechis scalaris 75 93 Zamenis lineatus Zamenis situla Zamenis persicus 99 Zamenis lineatus 99 Oocatochus rufodorsatus Zamenis longissimus 58 Coronella spp. (2) 100 Ptyaskorros (c) Burbrink & Lawson 2007 (ML mtDNA+cmos tree) (g) Zheng & Wiens 2016 (ML supermatrix tree) Rhinechis scalaris Zamenis hohenackeri 91 Zamenis hohenackeri Zamenispersicus Zamenispersicus 38 100 Zamenislineatus 44 46 Zamenislineatus 100 Zamenis longissimus 100 Zamenis situla 100 Rhinechisscalaris Zamenis situla FIGURE 2 Summary of the previous phylogenetic hypotheses on Zamenis and Rhinechis based on molecular data (mainly mitochondrial data) and different taxon‐sets: ratsnakes taxon‐sets (a–c), Serpentes taxon‐sets (d, f), and Squamata taxon‐sets (e, g). Branch lenghts in each tree are scaled as in the original study; trees are simplified by collapsing some clades (in brackets is reported the number of species included in each collapsed clade); bootstrap values as in the original studies are reported. (* the tree from Zaher et al., 2012 is identical to the tree of Pyron et al., 2011 as it is based on the same data‐matrix with sequences added for a single species) nested within Zamenis in a highly supported clade with re- ratsnake, Ptyas korros. This precipitate taxonomic change solved intraclade relationships (Figueroa, McKelvy, Grismer, is not justified in the light of the current phylogenetic insta- Bell, & Lailvaux, 2016; Pyron, Burbrink, & Wiens, 2013; bility of Rhinechis and Zamenis across available studies, and Pyron et al., 2011; Zheng & Wiens, 2016; Zaher et al., 2012; has been hardly ever accepted in recent literature (e.g., Chen, see Figure 2). These “mega‐phylogenies” questioned the Lemmon, Lemmon, Pyron, & Burbrink, 2017; Speybroeck, monophyly of Zamenis and its distinction from Rhinechis and Beukema, Bok, & Van Der Voort, 2016; Zheng & Wiens, prompted taxonomic instability of these taxa. Wallach’s cata- 2016; a Google Scholar search showed that the synonymiza- logue of world’s snakes (2014) synonymized Rhinechis with tion of Rhinechis with Zamenis has been adopted in only three Zamenis based on the re‐analysis of the Pyron et al. (2011) studies since 2014, compared to over 140 hits for the binomen supermatrix by Zaher et al. (2012), who however did not rec-