Historical biogeography of Tyrrhenian land snails: the Marmorana-Tyrrheniberus radiation (Pulmonata, Helicidae).
ABSTRACT The few studies available on Tyrrhenian land snails support high diversification in the Italian Peninsula and groups structured mainly by vicariant events. Here we investigated the phylogeny of a conchologically diversified group of Tyrrhenian land snails assigned to the genera Marmorana and Tyrrheniberus. We constructed a molecular phylogeny by sequencing two commonly used mtDNA genes (cytochrome oxidase I and the large ribosomal subunit). We also carried out conchological and anatomical analysis. Morphological (shell and genitalia) and genetic data (mitochondrial genes) showed paraphyly of Marmorana. Plio-Pleistocene events in the Tyrrhenian area may have structured relationships between species at regional scale while isolation by distance probably played a role in diversification between populations on a local scale. Continental populations experienced dispersal during interglacial periods and fragmentation and reduction during the dry cold climatic phases. Areas inhabited by Apennine Marmorana could represent relict and/or glacial refugia, with extinction in some areas along the Apennines and survival in the south. The results support a reassessment of taxonomy both at genus and species level and call for further analysis.
- SourceAvailable from: Salem Busais[Show abstract] [Hide abstract]
ABSTRACT: Eobania vermiculata is a well-known circum-Mediterranean land snail having a cosmopolitan distribution that makes it suitable for phylogenetic studies. The present work examines the phylogenetic relationships of two populations of this land snail from Egypt and Saudi Arabia using mitochondrial markers (partial 16S rDNA and COI gene sequencing) in addition to traditional methods of shell’s shape analysis. The study highlights the extraordinary morphological variations between the two studied snail populations. This variation seems to be related to the geographic origin but not the colouration of the shell and may have caused the present changes in their mitochondrial genes. The molecular phylogenetic analysis of partial 16S rDNA and COI gene segments confirms the morphological findings. The two monophyletic populations of Egyptian and Saudi Arabian E. vermiculata were found to represent two distinct groups. The concordance of morphological and molecular results, that produced very clear separation of both populations, leads us to conclude that the two separate groups could be considered two separate subspecies.The Journal of Basic & Applied Zoology. 03/2012; 65(2):144–151.
- [Show abstract] [Hide abstract]
ABSTRACT: The phylogenetic relationships among genera of the subfamily Ariantinae (Pulmonata, Helicidae), especially the sister-group relationship of Cylindrus obtusus, were investigated with three mitochondrial (12S rRNA, 16S rRNA, Cytochrome c oxidase subunit I) and two nuclear marker genes (Histone H4 and H3). Within Ariantinae, C. obtusus stands out because of its aberrant cylindrical shell shape. Here, we present phylogenetic trees based on these five marker sequences and discuss the position of C. obtusus and phylogeographical scenarios in comparison with previously published results. Our results provide strong support for the sister-group relationship between Cylindrus and Arianta confirming previous studies and imply that the split between the two genera is quite old. The tree reveals a phylogeographical pattern of Ariantinae with a well-supported clade comprising the Balkan taxa which is the sister group to a clade with individuals from Alpine localities. Additional lineages representing samples from southern Alpine localities as well as from Slovakia split from more basal nodes, but their relationships are not clearly resolved. To achieve more definitive conclusions concerning the geographical origin of Ariantinae, still more sequence data are needed to obtain a tree with better resolution of basal nodes. The genetic data also provided new insights concerning the genus Cepaea, which was used as one of the outgroup taxa. Cepaea vindobonensis is only distantly related to Cepaea nemoralis and Cepaea hortensis, the latter two being more closely related to Eobania vermiculata. Thus, in our tree, the genus Cepaea is paraphyletic. Key words: Cylindrus obtusus – phylogeny – phylogeography – Alpine land snails – shell morphology – histone genes – Cytochrome c oxidase subunit 1 – rRNAJournal of Zoological Systematics and Evolutionary Research 01/2013; · 1.80 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The Helicoidea is one of the most diverse superfamilies of terrestrial land snails. In this study we present a molecular phylogeny of the western Palaearctic Helicoidea obtained by means of Neighbor Joining, Maximum Likelihood and Bayesian analysis of the mitochondrial 16S rRNA gene fragment and the nuclear rRNA gene cluster including the 3'end of the 5.8S gene, the complete ITS2 region and 5'end of the large subunit 28S. Most of the morphologically-defined families were confirmed. We propose a revised phylogenetic classification so that families, subfamilies and tribes are monophyletic. The family Hygromiidae sensu Hausdorf and Bouchet (2005) is divided into three clades which are here given familial rank: Canariellidae and Geomitridae, which are recognized for the first time at familial rank, and Hygromiidae s.str. (including Ciliella and Trochulus) that is here restricted. The subfamilies Ciliellinae, Geomitrinae, Hygromiinae, Monachainae and Trochulinae recognized in current classifications were not recovered as monophyletic groups. The familily Cochlicellidae is here given tribe rank (Cochlicellini) belonging to the Geomitridae. We describe a new tribe, Plentuisini. Three subfamilies are recognized within Helicidae: Ariantinae, Helicinae (including Theba) and Murellinae. New classification indicates that free right ommatophore retractor muscle arose only once within Geomitridae. The anatomy of the auxiliary copulatory organs of the reproductive system of families, subfamilies and tribes is highlighted. We estimate the origin of the Helicoidea at the end of the Early Cretaceous and its families as Late-Cretaceous to Paleogene. Western Palaearctic Helicoidea belongs to two different lineages that diverged around 86 Ma ago, both starting their diversification at the end of the Cretaceous (around 73-76 Ma). Radiation of some western Helicoidean families started during the Eocene. Copyright © 2014. Published by Elsevier Inc.Molecular Phylogenetics and Evolution 12/2014; · 4.02 Impact Factor