A multi-scale approach to facultative paedomorphosis of European newts (Salamandridae) in the Montenegrin karst: Distribution pattern, environmental variables, and conservation

in Biological Conservation (2009), 142(3), 509-517

Facultative paedomorphosis, a process in which newt larvae can opt for reproduction before or after metamorphosis, is geographically heterogeneous. Despite numerous ecological studies and recent evidence ... [more ▼]

Facultative paedomorphosis, a process in which newt larvae can opt for reproduction before or after metamorphosis, is geographically heterogeneous. Despite numerous ecological studies and recent evidence of declines in paedomorphic populations, however, no attempt to model environmental variables that explain the presence of paedomorphs has been made at a multi-scale level. Our aim was to fill this gap in studying three newt species (Lissotriton vulgaris, Mesotriton alpestris, and Triturus macedonicus) of the Montenegrin karst as model species. To this end, we used multivariate analysis on three scales of habitat: the breeding pond, the land use and the climatologic features. Results show that the study area is both an important hotspot for paedomorphosis and where intraspecific diversity is quickly disappearing (20-47% extirpation) because of fish introductions. Other habitat variables (water permanency, PH or the habitat origin) were shown to act on paedomorphosis but not consistently across species, confirming complexity of the evolutionary and ecological processes. This study appeals for more long-term and detailed landscape studies of polyphenisms, a neglected but promising topic, to better understand and protect alternative modes of development. Particularly, measures should be taken to identify hotspots of intraspecific diversity at a global scale and stop fish introductions before we reach a point of no-return. (C) 2008 Elsevier Ltd. All rights reserved. [less ▲]

Ecological modeling and paedomorphosis: a study case in Montenegrin newts

Poster (2009)

Effects of widespread fish introductions on paedomorphic newts in Europe

in Conservation Biology (2005), 19(1), 162-170

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 ... [more ▼]

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. [less ▲]

Consequences of fish introductions on paedomorphic newts (Triturus alpestris and T. helveticus)

Poster (2005)

Fish stocking is largely recognized as a major thread to amphibian populations. Although it acts at a local level, it is widespread at a world scale. Despite this good knowledge, the effect of fish on ... [more ▼]

Fish stocking is largely recognized as a major thread to amphibian populations. Although it acts at a local level, it is widespread at a world scale. Despite this good knowledge, the effect of fish on alternative phenotypes has only been described in a few local studies. Our aim was to report on the loss of intraspecific heterochrony as a loss to diversity in determining the consequences of fish introductions on paedomorphs (morphs retaining gills at the adult stage) of two European species of newts. We surveyed almost all the main known paedomorphic populations of the Alpine (Triturus alpestris) and palmate (T. helveticus) newts, which all but one initially occupied fishless ponds and lakes in France, Italy, Slovenia, Bosnia, Montenegro, and Greece. Exotic fish were found in almost half of the studied aquatic habitats. Introductions involved several ornamental and large predatory species of fish. At all sites, in which fish were introduced, paedomorphs disappeared and metamorphs declined. The largest known populations of newts, including some endemic subspecies, were concerned. If measures are not taken to stop fish stocking, protect paedomorphs as conservation units, and restore natural habitats, all the largest paedomorphic populations may disappear in the near future. [less ▲]

Biogeography and ecology of paedomorphosis in Triturus alpestris (Amphibia, Caudata)

in Journal of Biogeography (2001), 28(10), 1271-1280

Aim Paedomorphosis is an evolutionary change in which larval structures are retained in adult animals. In newts and salamanders, this heterochronic process is widely represented and concerns the retention ... [more ▼]

Aim Paedomorphosis is an evolutionary change in which larval structures are retained in adult animals. In newts and salamanders, this heterochronic process is widely represented and concerns the retention of gill slits. We want to find out whether ecological and geographical determinants may be associated with paedomorphosis in the Alpine newt Triturus alpestris. Location Europe. Methods Determination of the main characteristics of all known aquatic sites containing paedomorphic Alpine newt individuals. Results Although metamorphs are common in Europe, paedomorphs are only found at the southern margin of the geographical range of the species: mainly in Italy and in the Balkans. They were recorded in eighty-seven aquatic sites. No single trend was outlined for the analysed ecological parameters of the aquatic and terrestrial habitats (e.g. altitude, maximum water depth, drying and presence of forest). Main conclusions Contrary to the first models of paedomorphosis, the main traits of aquatic and terrestrial habitat do not explain the occurrence of paedomorphs in natural populations. Although they were found in favourable aquatic habitats surrounded by hostile terrestrial landscapes, they also exist in temporary waters located at proximity of appropriate terrestrial environments. These results support models predicting paedomorphosis in varied environments, but require complementary investigations on the costs and benefits of the alternative ontogenetic pathways. On the other hand, the southern limitation of the heterochronic phenomenon suggests a genetic basis for paedomorphosis in the studied species. [less ▲]