| 1. |
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| 2. |
- Elmberg, Johan, et al.
(author)
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Movements and habitat choice of resident and translocated adult female Grass Snakes (Natrix natrix) during the egg-laying period
- 2019
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In: Herpetological Journal. - : BRITISH HERPETOL SOC. - 0268-0130. ; 29:4, s. 244-250
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Journal article (peer-reviewed)abstract
- We used externally applied transmitters to study movements of female grass snakes (Natrix natrix) during the egg-laying period in a near-urban landscape in Sweden. Half of the studied snakes were residents while the other half were translocated individuals with no previous experience of the area. As predicted, resident females moved more goal-oriented and shorter distances than did translocated individuals. Habitat use did not differ between resident and translocated snakes; they were typically found in bushes, reeds, and tall vegetation. Habitat preference (use in relation to availability) showed that bushy habitats, tall grassy vegetation and reedbeds were over-used in proportion to availability, whereas forest and open grass lawns were used less than expected based on availability. Our study highlights the importance of preserving and restoring linear habitat components providing shelter and connectivity in conservation of grass snakes. We suggest that externally applied transmitters are a better option than surgically implanted ones in movement studies of grass snakes, and that translocation as a conservation method for snakes has drawbacks.
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| 3. |
- Gustafson, Daniel H., et al.
(author)
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Great crested newts (Triturus cristatus) as indicators of aquatic plant diversity
- 2006
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In: Herpetological Journal. - 0268-0130. ; 16:4, s. 347-352
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Journal article (peer-reviewed)abstract
- 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.
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| 4. |
- Hagman, Mattias, et al.
(author)
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Grass snakes (Natrix natrix) in Sweden decline together with their anthropogenic nesting-environments
- 2012
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In: Herpetological Journal. - : British Herpetological Society. - 0268-0130. ; 22:3, s. 199-202
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Journal article (peer-reviewed)abstract
- In this paper we show that the number of grass snake (Natrix natrix L.) specimens deposited in Swedish museum collections has declined in the last eighty years, and that this is correlated with a dramatic national decrease in the number of livestock holdings. These results support the hypothesis that Swedish grass snakes are declining and that this may be linked to a loss of important nesting-environments provided by open manure heaps in small-scale farming. Our study suggests that information obtained from museum databases potentially may be used to explore population trends for snakes and other reptiles.
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| 5. |
- Litvinchuk, Spartak N., et al.
(author)
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Taxonomic status and distribution of common toads in Iran
- 2012
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In: Herpetological Journal. - 0268-0130. ; 22:4, s. 271-274
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Journal article (peer-reviewed)abstract
- We report several new localities of common toads from northern Iran. Based on the study of external morphology and a fragment of the mitochondrial 16S rRNA gene, the Iranian common toads were identified as Bufo eichwaldi. Maximum entropy modelling was used to estimate the effects of altitude, precipitation and temperature on the distribution of B. eichwaldi. The distribution of the species is linked to a forest zone on the slopes of the Talysh and Elburz mountains.
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| 6. |
- Loman, Jon
(author)
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When crowded tadpoles (Rana arvalis and R-temporaria) fail to metamorphose and thus fail to escape drying ponds
- 2002
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In: Herpetological Journal. - 0268-0130. ; 12:1, s. 21-28
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Journal article (peer-reviewed)abstract
- Do moor frog (Rana arvalis) and common frog (R. temporaria) tadpoles increase developmental rate if there is a risk of their pond drying up before metamorphosis? To study this, I performed an experiment designed to mimic natural conditions in many drying ponds. The number of tadpoles per tank was constant during the experiment but the water level was lowered in experimental tanks so that crowding increased. Experimental tadpoles grew and developed more slowly than control tadpoles that were in constant water volume. Also, metamorphosis was delayed (i.e. a smaller proportion had metamorphosed when the experiment was concluded on I August) and the metamorphs were smaller. I conclude that, due to crowding, the tadpoles in this experiment were not able to speed up development rate adaptively. Performance of the tadpoles in the experiment was compared to that of R. temporaria tadpoles in the field. These lived in a pond where desiccation resulted in division of the water body into a small pool and a large pool. The small pool dried out completely before the rest of the pond. Tadpoles in this pool were smaller and had relatively smaller hind legs, suggesting slower development. This pattern confirms the result of the experiment, supporting my suggestion that the experimental set-up mimicked many natural situations. Of particular interest is the fact that other studies-carried out both in the same geographical area and elsewhere-have shown R. temporaria to have the ability to respond adaptively to pond drying. The fact that it did not do so in this particular experiment, as well as in the field pond studied here, shows that care must be exercised when extrapolating from one study to the properties of a species. Different conditions, both in the field and in experiments, may well give different responses.
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| 7. |
- Malmgren, Jan C.
(author)
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How does a newt find its way from a pond? : Migration patterns after breeding and metamorphosis in great crested newts (Triturus cristatus) and smooth newts (T-vulgaris)
- 2002
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In: Herpetological Journal. - 0268-0130. ; 12:1, s. 29-35
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Journal article (peer-reviewed)abstract
- Migration patterns across adrift fence with pitfall traps were studied between 1997 and 1999 at a breeding pond with populations of great crested newts, Triturus cristatus, and smooth newts, T. vulgaris, at a study site in south-central Sweden. Metamorphs and older newts emigrated from the pond non-randomly and seemed to avoid exiting where open fields adjoined, but were oriented towards a patch of forest immediately to the east of the pond. Movement patterns changed slightly over the years, but metamorphs were more dispersed and less concentrated than older newts, and did not choose directions identical to those of older newts. Older great crested and smooth newts showed similar directional orientation. Great crested newt metamorphs dispersed towards both edges of the forest patch, and possible explanations for this are discussed. The results suggest that orientation in relation to cues from the surroundings of a breeding pond may be used by newts to make migratory decisions.
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| 8. |
- Nadachowska, Krystyna, et al.
(author)
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Characterization of microsatellite loci in the Carpathian newt (Lissotriton montandoni)
- 2010
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In: Herpetological Journal. - 0268-0130. ; 20:2, s. 107-110
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Journal article (peer-reviewed)abstract
- Seven polymorphic microsatellite loci were developed for the Carpathian newt (Lissotriton montandoni) and tested for cross-amplification in multiple geographic groups of its sister species L. vulgaris. Genetic variation was characterized for 52 L. montandoni from two sites from Poland and Romania, reflecting the geographic range of the species. The number of alleles per locus ranged from six to 13 and the observed heterozygosity ranged from 0.20 to 0.87. Significant excess of homozygotes detected at two loci may suggest the presence of null alleles. No evidence for linkage disequilibrium between loci was detected. The cross-amplification success was variable, suggesting that the use of the markers developed in the present study may be limited to geographically restricted groups of the smooth newt.
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| 9. |
- Nadachowska, Krystyna
(author)
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Divergence with gene flow : the amphibian perspective
- 2010
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In: Herpetological Journal. - 0268-0130. ; 20:1, s. 7-15
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Journal article (peer-reviewed)abstract
- Advances in molecular and computational biology as well as in population genetics theory open new avenues in the study of speciation, for example enabling the explicit estimation of the amount of gene flow that has occurred during population divergence. Developments in two areas seem particularly important. First, novel coalescent-based methods can be applied to multilocus sequence data to infer the time of population divergence, long-term effective population sizes and their changes and the extent of gene flow between diverging populations. Second, the advent of ultra high-throughput sequencing technologies enable the inexpensive generation of vast amount of sequence data for any organism. Many amphibian species have been shown to be incompletely reproductively isolated and can hybridize for prolonged periods of time, making them ideal models to study the divergence of populations to form new taxa despite ongoing gene flow. Here I discuss the new findings emerging from multilocus DNA sequence-based approaches that have already been applied in amphibian population genetics. I also outline future directions of research, emphasizing the utility of parallel sequencing technologies together with methods of population genetic and phylogenetic inference, which are likely to provide a better understanding of the process of population differentiation and divergence to ultimately form new species.
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