The role of vicariance vs. dispersal in shaping genetic patterns in ocellated lizard species in the western Mediterranean

The schism between North Africa and Southern Europe caused by the opening of the Strait of Gibraltar and the consequent refilling of the Mediterranean basin at the end of Messinian salinity crisis (MSC), 5.33 million years ago, has been advocated as the main event shaping biogeographical patterns in the western Mediterranean as exemplified by the distribution of species and subspecies and genetic variation within the ocellated lizard group. To reassess the role of the MSC, partial sequences of three mitochondrial DNA genes (cytochrome b, 12S and 16S ribosomal RNA) and two nuclear genes (beta-fibrinogen and C-mos) from species of the ocellated lizard group were analysed. Three alternative hypotheses were tested: that divergence was initiated (i) by post-MSC vicariance as the basin filled, (ii) when separate populations established either side of the strait by pre-MSC overseas dispersal, and (iii) by post-MSC overseas dispersal. The pattern and level of divergence detected clearly refute the post-MSC vicariance hypothesis, and support a model of divergence initiated by earlier overseas dispersal. Indeed, our best estimate is that the basal Euro-African divergence predates the MSC event by several million years. The estimated divergence times among the populations in former Miocene Mediterranean islands, the current Betic and Rifian mountains, from adjacent mainland populations suggest overseas dispersal for the former and overland dispersal, or perhaps vicariance, for the latter. These results suggest that the MSC may have played a much less important role in shaping the current western Mediterranean biogeographical patterns than might have been anticipated from the dramatic nature of the episode

Molecular Phylogenetics of the New-World Crocodylia

During the late twentieth and early twenty-first centuries, there has been a revolution in evolutionary biology. Traditional methods that had been applied to understanding relationships and natural history for hundreds of years have been supplemented (and sometimes replaced) by biochemical and molecular techniques that now allow us to examine the entire genomes of non-model organisms. Herein we review the use of these new technologies as they apply to crocodylians in general and specifically to the New-World members of the Alligatoridae and Crocodylidae. While generally concordant with traditional analyses, in some cases they have permitted cryptic species to be recognized. In addition, they have allowed crocodylian biologists to detect hybridization events between species, both in captivity and in the wild, that would not have been possible before their use. Hybridization may lead to the formation of new species, but it may also allow a common species to “swamp out” a rarer one. Because there appears to be little hybrid dysgenesis between many of the potential hybridizing forms, hybridization is potentially a serious problem for several New-World species

An Amphisbaenian Skull from the European Miocene and the Evolution of Mediterranean Worm Lizards

<div><p>The evolution of blanid amphisbaenians (Mediterranean worm lizards) is mainly inferred based on molecular studies, despite their fossils are common in Cenozoic European localities. This is because the fossil record exclusively consists in isolated elements of limited taxonomic value. We describe the only known fossil amphisbaenian skull from Europe – attributed to <i>Blanus mendezi</i> sp. nov. (Amphisbaenia, Blanidae) – which represents the most informative fossil blanid material ever described. This specimen, from the Middle Miocene of Abocador de Can Mata (11.6 Ma, MN7+8) in the Vallès-Penedès Basin (Catalonia, NE Iberian Peninsula), unambiguously asserts the presence of <i>Blanus</i> in the Miocene of Europe. This reinforces the referral to this genus of the previously-known, much more incomplete and poorly-diagnostic material from other localities of the European Neogene. Our analysis – integrating the available molecular, paleontological and biogeographic data – suggests that the new species postdates the divergence between the two main (Eastern and Western Mediterranean) extant clades of blanids, and probably precedes the split between the Iberian and North-Western African subclades. This supports previous paleobiogeographic scenarios for blanid evolution and provides a significant minimum divergence time for calibrating molecular analyses of blanid phylogeny.</p></div

The taxonomic impediment: A shortage of taxonomists, not the lack of technical approaches

For almost 30 years, there have been active discussions about the taxonomic impediment and the challenge this represents to address the current human-induced biodiversity crisis. From the start (Systematics Agenda 2000, 1994), the term ‘taxonomic impediment’ has been ambiguous, designating both the insufficiency and inadequacy of the resources put to the service of taxonomy (the taxonomic impediment sensu stricto) and its main consequence, the wide discrepancy between the reality of specific biodiversity and our knowledge of it (the taxonomic gap; Dubois, 2010; Raposo et al., 2020). The total number of species on our planet is unknown, and its various estimates (using different methods) are widely divergent, but consensus exists that we are far from having inventoried half, and most likely one-tenth, of the species still present on earth today (González-Oreja, 2008)