Correction: Genetic introgression among differentiated clades is lower among clades exhibiting different parity modes.

The original version of this Article contained an error in the spelling of the author Y. Surget-Groba, which was incorrectly given as J. Surget-Groba. This has now been corrected in both the PDF and HTML versions of the Article.

Genetic introgression among differentiated clades is lower among clades exhibiting different parity modes.

Mechanisms leading to sympatric speciation are diverse and may build up reproductive isolation. Reproductive isolation among differentiated clades may exist due to genetic incompatibilities, sexual selection, differences in parity mode, reduced post-zygotic survival or reproductive success of hybrids. Here, we test whether differences in parity mode lead to reproductive isolation by investigating introgression in Zootoca vivipara, a lizard species exhibiting oviparous and viviparous reproduction. We measured introgression in transects spanning different viviparous clades, different oviparous subclades, transects containing oviparous and viviparous clades, and transects within the same subclade (control transects). Introgression in transects spanning oviparous and viviparous clades was one order of magnitude smaller than transects spanning the same reproductive mode and no statistical differences existed between transects spanning the same reproductive mode and control transects. Among types of transects, no significant differences existed in genetic and geographic distances, nor number of detected alleles. Moreover, hybrids were detected in all types of transects, showing that parity mode alone does not necessarily lead to complete reproductive isolation, which suggests that reinforcement may play an important role. The evolution of different parity modes together with reinforcement may thus promote reproductive isolation and rapid speciation, potentially explaining why only six of the almost 40,000 vertebrates belonging to groups consisting of viviparous and oviparous species exhibit bimodal reproduction.

Adaptive radiation in Lesser Antillean lizards: molecular phylogenetics and species recognition in the Lesser Antillean dwarf gecko complex, Sphaerodactylus fantasticus.

The time associated with speciation varies dramatically among lower vertebrates. The nature and timing of divergence is investigated in the fantastic dwarf gecko Sphaerodactylus fantasticus complex, a nominal species that occurs on the central Lesser Antillean island of Guadeloupe and adjacent islands and islets. This is compared to the divergence in the sympatric anole clade from the Anolis bimaculatus group. A molecular phylogenetic analysis of numerous gecko populations from across these islands, based on three mitochondrial DNA genes, reveals several monophyletic groups occupying distinct geographical areas, these being Les Saintes, western Basse Terre plus Dominica, eastern Basse Terre, Grand Terre, and the northern and eastern islands (Montserrat, Marie Galante, Petite Terre, Desirade). Although part of the same nominal species, the molecular divergence within this species complex is extraordinarily high (27% patristic distance between the most divergent lineages) and is compatible with this group occupying the region long before the origin of the younger island arc. Tests show that several quantitative morphological traits are correlated with the phylogeny, but in general the lineages are not uniquely defined by these traits. The dwarf geckos show notably less nominal species-level adaptive radiation than that found in the sympatric southern clade of Anolis bimculatus, although both appear to have occupied the region for a broadly similar period of time. Nevertheless, the dwarf gecko populations on Les Saintes islets are the most morphologically distinct and are recognized as a full species (Sphaerodactylus phyzacinus), as are anoles on Les Saintes (Anolis terraealtae).

Intraspecific phylogeography of Lacerta vivipara and the evolution of viviparity.

The lacertid lizard Lacerta vivipara is one of the few squamate species with two reproductive modes. We present the intraspecific phylogeny obtained from neighbor-joining and maximum-parsimony analyses of the mtDNA cytochrome b sequences for 15 individuals from Slovenian oviparous populations, 34 individuals from western oviparous populations of southern France and northern Spain, 92 specimens from European and Russian viviparous populations, and 3 specimens of the viviparous subspecies L. v. pannonica. The phylogeny indicates that the evolutionary transition from oviparity to viviparity probably occurred once in L. vivipara. The western oviparous group from Spain and southern France is phylogenetically most closely related to the viviparous clade. However, the biarmed W chromosome characterizing the western viviparous populations is an apomorphic character, whereas the uniarmed W chromosome, existing both in the western oviparous populations and in the geographically distant eastern viviparous populations, is a plesiomorphic character. This suggests an eastern origin of viviparity. Various estimates suggest that the oviparous and viviparous clades of L. vivipara split during the Pleistocene. Our results are discussed in the framework of general evolutionary models: the concept of an oviparity-viviparity continuum in squamates, the cold climate model of selection for viviparity in squamates, and the contraction-expansion of ranges in the Pleistocene resulting in allopatric differentiation.

Further evidence of the existence of oviparous populations of Lacerta (Zootoca) vivipara in the NW of the Balkan Peninsula.

The lizard Lacerta (Zootoca) vivipara, which is viviparous in the greatest part of its distribution range, has however some oviparous populations on the southern margin of its range. The present study aimed at determining the reproductive mode and the ATA (aspartate transaminase) enzyme characteristics of four populations in Slovenia and one population in Croatia. The Slovenian females studied here presented an oviparous reproductive mode which strongly resembled those observed in the oviparous populations of south-western France and north-western Spain. Our electrophoresis analyses revealed the existence of two distinct alleles, ATA-150 and ATA-200, in the oviparous populations of Slovenia. These alleles were identical to those observed in the French and Spanish oviparous group and were distinct from the allele ATA-100 characterizing the viviparous populations that we had previously studied. Although we did not study the reproductive mode of Croatian females, the allele ATA-200 observed in one population of Croatia strongly suggested that this population might also be oviparous.

Comparisons of mitochondrial DNA (mtDNA) sequences (16S rRNA gene) between oviparous and viviparous strains of Lacerta vivipara: a preliminary study.

The lizard Lacerta vivipara has allopatric oviparous and viviparous populations. The mitochondrial DNA (mtDNA) gene coding for the 16S rRNA was sequenced for several viviparous lizard populations from France, Switzerland, Bulgaria, Czech Republic, The Netherlands, Sweden, and for oviparous lizard populations from the Pyrenean and Cantabric Mountains. Seven distinct groups (three oviparous and four viviparous) were identified. The net nucleotide divergence between oviparous and viviparous haplotypes was 1.3% +/- 0.5 (mean +/- standard deviation). These results on mtDNA, together with other data obtained previously, led us to formulate a biogeographical scenario that could be tested by further research.