As a result of factors such as global warming, habitat destruction, and species introduction, amphibians are declining worldwide. No one, however, has analyzed the status of polymorphic amphibian species at a national or continental scale, although some local reports exist. Our aim was to report on the loss of intraspecific heterochrony as a loss to diversity in determining the consequences of fish stocking on European populations of paedomorphic newts. Paedomorphosis is a polymorphism in which larval traits are retained in the adult stage. We surveyed 39 paedomorphic populations of the alpine ( Triturus alpestris) and palmate ( T. helveticus) newts, all but one of which initially occupied fishless ponds and lakes in France, Italy, Slovenia, Bosnia, Montenegro, and Greece. Exotic fishes were found in 44% of the studied aquatic habitats, with a 100% presence in Montenegro. At all sites paedomorphs disappeared and metamorphs declined. Only fish explained these population changes because alternative factors such as drying were not significant. More catastrophically, fish introductions occurred in habitats known to support the largest populations of newts and even some endemic subspecies. If management and legislative measures are not taken to stop fish stocking, protect paedomorphs as conservation units at national and international levels, and restore natural habitats, all the largest paedomorphic populations may disappear in the near future. Their disappearance would represent a loss of one of the rare, fascinating examples of intraspecific heterochrony. Resumen: Los anfibios están declinando mundialmente debido a causas como calentamiento global, destrucción de hábitat e introducción de especies. Sin embargo, nadie ha analizado el estatus de especies polimórficas de anfibios a una escala nacional o continental, aunque existen algunos reportes locales. Nuestro objetivo fue reportar la pérdida de heterocronía intraespecífica como una pérdida de diversidad al determinar las consecuencias del aprovisionamiento de peces sobre poblaciones europeas de tritones pedomórficos. La pedomórfosis es un polimorfismo en el que se retienen características larvarias en la etapa adulta. Muestreamos 39 poblaciones pedomórficas de los tritones Triturus alpestris y T. helveticus, que, excepto una, inicialmente habitaban charcas y lagos sin peces en Francia, . Encontramos peces exóticos en 44% de los hábitats acuáticos estudiados, con presencia de 100% en Montenegro. Los pedomorfos desaparecieron y los metamorfos declinaron en todos los sitios. Solo peces explicaron estos cambios poblacionales porque factores alternativos como desecación no fueron significativos. Más catastróficamente, las introducciones de peces ocurrieron en hábitats conocidos por sostener a las mayores poblaciones de tritones incluyendo algunas subespecies endémicas. Todas las poblaciones pedomórficas grandes pueden desaparecer en el futuro cercano si no se toman medidas de gestión y legislativas para detener el aprovisionamiento de peces, proteger a pedomorfos como...

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BackgroundGenetic architecture of a species is a result of historical changes in population size and extent of distribution related to climatic and environmental factors and contemporary processes of dispersal and gene flow. Population-size and range contractions, expansions and shifts have a substantial effect on genetic diversity and intraspecific divergence, which is further shaped by gene-flow limiting barriers. The Balkans, as one of the most important sources of European biodiversity, is a region where many temperate species persisted during the Pleistocene glaciations and where high topographic heterogeneity offers suitable conditions for local adaptations of populations. In this study, we investigated the phylogeographical patterns and demographic histories of four species of semifossorial slow-worm lizards (genus Anguis) present in the Balkan Peninsula, and tested the relationship between genetic diversity and topographic heterogeneity of the inhabited ranges.ResultsWe inferred phylogenetic relationships, compared genetic structure and historical demography of slow worms using nucleotide sequence variation of mitochondrial DNA. Four Anguis species with mostly parapatric distributions occur in the Balkan Peninsula. They show different levels of genetic diversity. A signature of population growth was detected in all four species but with various courses in particular populations. We found a strong correlation between genetic diversity of slow-worm populations and topographic ruggedness of the ranges (mountain systems) they inhabit. Areas with more rugged terrain harbour higher genetic diversity.ConclusionsPhylogeographical pattern of the genus Anguis in the Balkans is concordant with the refugia-within-refugia model previously proposed for both several other taxa in the region and other main European Peninsulas. While slow-worm populations from the southern refugia mostly have restricted distributions and have not dispersed much from their refugial areas, populations from the extra-Mediterranean refugia in northern parts of the Balkans have colonized vast areas of eastern, central, and western Europe. Besides climatic historical events, the heterogeneous topography of the Balkans has also played an important role in shaping genetic diversity of slow worms.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0669-1) contains supplementary material, which is available to authorized users.

As with many other amphibians, Triturus species are characterized by a biphasic life cycle with abrupt changes in the cranial skeleton during metamorphosis. The post-metamorphic shape changes of the cranial skeleton were investigated using geometric morphometric techniques in six species: Triturus alpestris, T. vulgaris, T. dobrogicus, T. cristatus, T. carnifex, and T. karelinii. The comparative analysis of ontogenetic trajectories revealed that these species have a conserved developmental rate with divergent ontogenetic trajectories of the ventral skull shape that mainly reXect phylogenetic relatedness. A striking exception in the ontogenetic pattern was possibly found in T. dobrogicus, characterized by a marked increase in the developmental rate compared to the other newt species. The size-related shape changes explained a large proportion of shape change during postmetamorphic growth within each species, with marked positive allometric growth of skull elements related to foraging.

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