Authors: Luciana Cecilia Belver And Luciano Javier Ayila

Authors: N. J. L. Heideman

Authors: Jan C. Malmgren

Abstract: Migration patterns across a drift 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.

Keywords: Amphibia, behaviour, conservation, dispersion, circular statistics

Authors: Frank Glaw And Miguel Vences

Abstract: A new species of the Mantidactylus domerguei species group in the subgenus Blommersia is described from central eastern Madagascar. Mantidactylus sarotra sp. n. is morphologically similar to the syntopic M. blommersae but differs by smaller size, vocal sac coloration, advertisement cal Is and habitat of calling males. A phylogenetic analysis of 565 nucleotides of the mitochondrial l 6S rRNA gene of all described species of the M. domerguei group revealed that M. sarotra and M. blommersae are not sister species but are genetical ly highly differentiated (9.73% sequence divergence). M. sarotra was grouped with high bootstrap support as a sister species of M. kely. The two species share a general advertisement calI structure, vocal sac col oration and small size, but differ from each other in terms of skin texture, dorsal coloration, and pulse rate of vocalizations. The high differentiation among all species of the group (4.96% divergence between the closest relatives, M. blommersae and M. domerguei) indicate that speciation of the currently recognized taxa probably occurred several million years before the present.

Keywords: Mantidactylus sarotra sp. n., Blommersia, Madagascar, phylogeny, mitochondrial DNA, advertisement calls

Authors: Jon Loman

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 1 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.

Keywords: amphibian development, competition, frog tadpoles, drying ponds

Authors: R. Jehle And J. W. Arntzen

Abstract: Recent technical advances allow straightforward access to genetic information directly drawn from DNA. The present article highlights the suitability of high variation molecular genetic markers, such as microsatellites, for studies relevant to amphibian conservation. Molecular markers appear particularly useful for i) measuring local gene flow and migration, ii) assigning individuals to their most likely population of origin, iii) measuring effective population size through the between-generation comparison of allele frequencies, and iv) detecting past demographic bottlenecks through allele frequency distortions. We demonstrate the use of some newly developed analytical tools on newt (Triturus sp.) microsatellite data, discuss practical aspects of using microsatellites for amphibians, and outline potential future research directions.

Keywords: amphibians, conservation, microsatellites, Triturus cristatus