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331The reliable data on paedomorphosis in two subspecies of the common newt Triturus vulgaris lantzi (Abkhazia, western Caucasus) and T. v. vulgaris (the vicinity of St. Petersburg) are given for the first time for the former Soviet Union. Data on the appearance, occurrence, development and distribution of paedomorphic larvae are given based on field and laboratory observations beginning in 1986. The life cycles of paedomorphic and metamorphosed newts are discussed.
We studied spatial niche metrics of large-bodied newts (Triturus cristatus and T. marmoratus) in three breeding ponds in western France. Adults and larvae were sampled with underwater funnel traps. Larvae were identified to the species with diagnostic microsatellite DNA markers. The distribution of adult T. cristatus and T. marmoratus across pond regions differed in one out of six cases, no differences were observed between larvae (two ponds studied). Niche overlap and niche breadth indices across resource states defined as pond regions or individual traps were high (Schoener’s C: pond regions 0.60–0.98, traps 0.35–0.71; Levins’ B: pond regions 0.71–0.98, traps 0.35–0.76). Adults of large-bodied newts significantly differed in resource use from small-bodied newts (T. helveticus). The results are discussed in view of the occurrence of interspecific breeding attempts, and the unpredictable ecological characteristics of newt breeding ponds.
Under sperm competition, paternity is apportioned by polyandrous females according to the order of matings and the genetic quality of the inseminating males. In order to distinguish between these two effects, we sequentially paired 12 female smooth newts (Lissotriton vulgaris) with each of two males and, where possible, repeated the same procedure in reverse order of the identical males after assumed sperm depletion. For a total of 578 offspring, amplified fragment length polymorphisms genetic markers revealed multiple paternities in all matings, without significant first- or second-male sperm precedence. The paternity share of individual males was transitive across the two trials with male order switch, and successful males had a significantly higher genetic dissimilarity to the female than expected by chance. We argue that patterns of paternity in natural newt populations are determined through a combination of goodgenes and relatedness.
Pond-breeding amphibians are deme-structured organisms with a population genetic structure particularly susceptible to demographic threats. We estimated the effective number of breeding adults (Nb) and the effective population size (Ne) of the European urodele amphibians Triturus cristatus (the crested newt) and T. marmoratus (the marbled newt), using temporal shifts in microsatellite allele frequencies. Eight microsatellite loci isolated from a T. cristatus library were used, five of which proved polymorphic in T. marmoratus, albeit with high frequencies of null alleles at two loci. Three ponds in western France were sampled, situated 4–10 kilometres apart and inhabited by both species. Parent–offspring cohort comparisons were used to measure Nb; samples collected at time intervals of nine or 12 years, respectively, were used to measure Ne. The adult population census size (N) was determined by mark–recapture techniques. With one exception, genetic distances (FST) between temporal samples were lower than among populations. Nb ranged between 10.6 and 101.8 individuals, Ne ranged between 9.6 and 13.4 individuals. For the pond where both parameters were available, Nb / N(overall range: 0.10–0.19) was marginally larger than Ne/N (overall range: 0.09–0.16), which is reflected in the temporal stability of N. In line with the observed differences in reproductive life-histories between the species, Nb/N ratios for newts were about one order of magnitude higher than for the anuran amphibian Bufo bufo. Despite of the colonization of the study area by T. cristatus only some decades ago, no significant genetic bottleneck could be detected. Our findings give rise to concerns about the long-term demographic viability of amphibian populations in situations typical forEuropean landscapes.
Review of data on the state of Triturus cristatus populations in the former Soviet Union is presented. In large areas the newt is a common amphibian. These are the regions of leafed and mixed forests in the south-western part of the area of occupancy in the former USSR. The overall abundance decreases in the zones of forest steppe and steppe as well as the taiga in the north. The areas, from where declines were documented, comprise less than a half of the total area of the species occupancy. Majority of the declines and extinctions concern the landscapes disturbed by anthropogenic activity: destruction, pollution, the shallowing and eutrophication of the ponds, drainage and pollution of water bodies, melioration of meadows, destruction of forests, construction of dams on large rivers and the introduction of the exotic fish Perccottus glehni. In general, T. cristatus in the former Soviet Union deserves conservation in many regions where it is rare and/or threatened species. The measures for protection should include, first of all, conservation of the habitats from destruction, pollution and introductions of exotic fish. However, the general situation with this newt on the territory seems not to be alarming and the species seems not to be threatened there in general. This part of the range composes about a half of the total range of the species. Thus, T. cristatus at present does not meet the requirements for the inclusion in the IUCN Red List and should be protected only at various regional levels.
Facultative paedomorphosis is an environmentally induced polymorphism that is well known for many caudate species including newts. Although facultative paedomorphosis has been documented in some smooth-newt populations, records of entirely paedomorphic populations outside the Balkans are limited. Here we present the first evidence of a paedomorphic population of the smooth newt in the Czech Republic with discussion of potential causes that need to be further tested.
In a field study in south central Sweden, we analysed the diversity of macrophytes in paired samples of ponds in a total of five geographically separated sites. Each pair of ponds involved one pond with presence of great crested newts (Triturus cristatus) and one pond in which newts were absent. Ponds with presence of great crested newts had a significantly higher mean number of plant species than ponds without newts. Newts occurred in ponds that tended to have a lower amount of pond area covered by surface vegetation, although this difference was not statistically significant. Macrophyte diversity also tended to increase more steeply in ponds with T. cristatus, compared with ponds without newts. Broad-leaved pond weed (Potamogeton natans) and square-leaved liverwort (Chiloscyphus pallescens) were among the plants that were most associated with presence of great crested newts. Plant diversity had a slightly more nested structure for ponds with great crested newts than for those without, which indicates a more homogeneous plant species assemblage in the former group of ponds. Overall, the results indicate that the great crested newt may be a reliable and useful indicator species for high plant species richness in ponds and small wetlands, which may be valuable for environmental monitoring and conservation in pond landscapes.
This study examined the hypothesis that numbers of newts captured were correlated with the phase of the moon. During the spring of 2008 smooth newts and great crested newts were captured in bottle traps laid in two ponds at Riseholme Park, University of Lincoln, UK. Highest rates of capture for smooth newts were either side of the new moon but for great crested newts the highest rate was immediately before the new moon. Identification of individuals showed that during the observation period smooth newts regularly moved between aquatic and terrestrial habitats, but great crested newts appeared to leave ponds and did not return. This is the first report that numbers of newts captured are affected by the lunar cycle. Activity during the darkest nights may limit the risk of predation as individuals leave breeding ponds to forage on land or to move between ponds. These results have implications for surveys of newt breeding sites because lack of individual identification and trapping events at the wrong time of the month can both seriously undermine estimates of population sizes.
