Climatic niche differences among Zootoca vivipara clades with different parity modes: implications for the evolution and maintenance of viviparity.

Parity mode (oviparity/viviparity) importantly affects the ecology, morphology, physiology, biogeography and evolution of organisms. The main hypotheses explaining the evolution and maintenance of viviparity are based on bioclimatic predictions and also state that the benefits of viviparity arise during the reproductive period. We identify the main climatic variables discriminating between viviparous and oviparous Eurasian common lizard (Zootoca vivipara) occurrence records during the reproductive period and over the entire year.Analyses based on the climates during the reproductive period show that viviparous clades inhabit sites with less variable temperature and precipitation. On the contrary, analyses based on the annual climates show that viviparous clades inhabit sites with more variable temperatures.Results from models using climates during reproduction are in line with the "selfish-mother hypothesis", which can explain the success of viviparity, the maintenance of the two reproductive modes, and why viviparous individuals cannot colonize sites inhabited by oviparous ones (and vice versa). They suggest that during the reproductive period viviparity has an adaptive advantage over oviparity in less risky habitats thanks to the selfish behaviour of the mothers. Moreover, the results from both analyses stress that hypotheses about the evolution and maintenance of viviparity need to be tested during the reproductive period.

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.

Development and characterization of 79 nuclear markers amplifying in viviparous and oviparous clades of the European common lizard.

The European common lizard (Zootoca vivipara) is a widely distributed species across Europe and Asia exhibiting two reproductive modes (oviparity/viviparity), six major lineages and several sublineages. It has been used to tackle a large variety of research questions, nevertheless, few nuclear DNA sequence markers have been developed for this species. Here we developed 79 new nuclear DNA sequence markers using a clonation protocol. These markers were amplified in several oviparous and viviparous specimens including samples of all extant clades, to test the amplification success and their diversity. 49.4% of the markers were polymorphic and of those, 51.3% amplified in all and 94.9% amplified in 5-7 of the extant Z. vivipara clades. These new markers will be very useful for the study of the population structure, population dynamics, and micro/macro evolution of Z. vivipara. Cross-species amplification in four lizard species (Psammodromus edwardsianus, Podarcis muralis, Lacerta bilineata, and Takydromus sexlineatus) was positive in several of the markers, and six makers amplified in all five species. The large genetic distance between P. edwardsianus and Z. vivipara further suggests that these markers may as well be employed in many other species.

Forensic assignment to geographic origin, a useful tool in seafood fraud control.

Seafood fraud is an economically motivated and widely spread problem encompassing drastic consequences in both public health and species conservation. In Northern Spain, only the first Atlantic salmon (Salmo salar) catch of the angling season (named Campanu) can be sold. In the year 2011, an angler denounced it on regional Court claiming that the Campanu (which was sold in 6000€) was fraudulent because it had been caught from another river than the fisherman ("the seller") stated. Here, we report the first judicial case of application of geographical genetic assignment in a fish species in Spain. In order to accomplish this, genetic assignments to their rivers of origin of the Campanu and another three following salmon catches of the angling season of the year 2011 were performed. A panel of eight microsatellite loci together with a comprehensive genetic baseline of the rivers of the region were employed. Results showed that the Campanu was the only case in which genetic assignment and fisherman declaration of the river of origin did not match. The methodology here employed showed to be very useful as a reinforcement of other evidences contributing to fight against seafood fraud in Courts.

Long-term effects of stock transfers: synergistic introgression of allochthonous genomes in salmonids.

The genus Salmo was employed as a model to study introgression of genes between species due to secondary contacts. Seven microsatellite loci, the LDH-C1* locus and the 5S ribosomal DNA were studied. Results showed the mutually enhanced introgression of allochthonous genomes into southern European salmonids. This phenomenon appears to go beyond a simple consequence of the altered behaviour of domestic individuals. Invasions of autochthonous genomes by allochthonous genes would be enhanced by human activities such as stock transfers, which would simultaneously promote allochthonous and allospecific (from other species) introgressions in a synergistic process in Atlantic salmon Salmo salar and brown trout Salmo trutta. As a minor result, the data do not support the value of the microsatellite locus SsaD486 as a species-specific marker.

'Representative Genes', is it OK to use a small amount of data to obtain a phylogeny that is at least close to the true tree?

Despite the problems associated with the one-gene-constructed phylogenetic relationships, recently it has been shown that merely adding more sequences to the analyses is not enough to resolve all the inconsistencies present in these relationships. In this work, the existence of 'representative' genes for groups of species is evaluated in terms of efficiency (costs/benefits), employing the cytochrome c oxidase subunit I (COI) and the penguins' phylogeny as a case study. 'Representative' genes are very useful and they could produce good results for first approaches or humble laboratories, especially if the gene is chosen depending on the time scale and objectives of our work.

Same old Salmo? Changes in life history and demographic trends of North Iberian salmonids since the Upper Palaeolithic as revealed by archaeological remains and beast analyses.

Life history traits determine fitness and hence the ability of populations and species to survive through adverse conditions. Therefore, identifying temporal changes in life history traits over large timescales is necessary to understand and predict the effect of current global change on wild populations. In this study, we compare life history traits between Palaeolithic and present-day vertebrates, analysing the number of winters spent in the river and at sea by North Iberian salmonids (Salmo salar and Salmo trutta) from two separate time frames: the Upper Palaeolithic, based on archaeological remains, and the present day, based on sport catches. The river stage did not change significantly, but the marine period has been shortened in modern anadromous specimens, accordingly shortening mean generation time. Population growth rates have been estimated through Bayesian analyses of the mitochondrial DNA control region of modern specimens for the two Salmo species using two different mutation rates (1% and 3.6%). Coincidence of coalescent N(e) estimates with independent N(e) calculated from catches suggests that the 3.6% mutation rate fits better the evolution of the studied populations. Population growth rate declines would have occurred in the last millennium and could be explained by a combination of climatic events and anthropogenic activities.