Showing papers on "Mantella published in 2006"

Mitochondrial evidence for distinct phylogeographic units in the endangered Malagasy poison frog Mantella bernhardi.

Abstract: Mantella bernhardi is an endemic species of Malagasy poison frog threatened by loss and fragmentation of its natural habitat and collection for the pet trade. It is classified as threatened according to the International Union for Conservation of Nature and Natural Resources (IUCN) categories and included in Appendix II of the Convention on the International Trade of Endangered Species (CITES). A recent survey has increased the known distributional range of the species from one to eight populations across southeastern Madagascar, but little is known about its biology and genetic diversity. Here we estimate inter- and intrapopulation mitochondrial genetic variation of four populations. Populations from the northern and southern parts of the distributional range showed a high degree of divergence (maximum of 11.35% in cytochrome b) and were recovered as reciprocally monophyletic groups. Nine haplotypes were detected in the northern and 12 in the southern populations. The population from Ranomafana National Park showed the lowest number of haplotypes and nucleotide diversity, and shared its most common haplotype with the second northern population from Tolongoina. All the other detected haplotypes were unique to each of the four populations. This suggests the existence of important barriers to gene flow, pre-dating human colonization of Madagascar at about 2000 years ago, in distinct contrast to other Mantella species that show a high degree of haplotype sharing throughout their range. The continued habitat fragmentation within the distribution range of M. bernhardi prevents any connection between its populations. Our data indicate the existence of at least two different management units for conservation in this species, corresponding to the North and South of its distribution range, and highlight the existence of strong regional endemism in southeastern Madagascar.

Individual variation in alkaloid content of poison frogs of Madagascar (Mantella; Mantellidae).

Abstract: Brightly colored Malagasy poison frogs, Mantella spp., sequester lipophilic, basic alkaloids from arthropod prey for their own chemical defense. Consequently, microsympatric prey diversity is expected to influence alkaloid diversity observed in poison frogs. Twenty-two specimens of three Mantella species from four localities in moist forests of southeastern Madagascar were analyzed individually via gas chromatography-mass spectrometry, revealing that they contain over 80 known alkaloids. Frogs within a locality possessed significantly similar alkaloid content and diversity, while frogs from areas that varied in disturbance, elevation, and/or species showed greater differences. Based on dietary data, the larger frog species Mantella baroni consumed more and larger prey, and showed greater diversity in skin alkaloids than significantly smaller Mantella bernhardi. Additionally, frogs from the most pristine locality had the greatest number of alkaloids, whereas individuals from the most disturbed localities had the least. In a comparison of frog alkaloid profiles over a 10- to 14-yr period, alkaloid turnover, and thus presumably alkaloid-source arthropod turnover, was high in a disturbed locality and low in the pristine primary forest locality. We demonstrate that the nonlethal transcutaneous amphibian stimulator (TAS) is effective for harvesting alkaloids from poison frogs; future studies using this device could obtain larger sample sizes without harming local frog populations.

The tadpoles of Scaphiophryne gottlebei (Microhylidae: Scaphiophryninae) and Mantella expectata (Mantellidae: Mantellinae) from Isalo Massif, south-central Madagascar

Abstract: The tadpoles of the microhylid Scaphiophryne gottlebei and of the mantellid Mantella expectata from the Isalo Massif (south-central Madagascar) are described and compared with already known tadpoles belonging to the same genera. The tadpole of S. gottlebei is peculiar in having the oral apparatus with a horny beak surrounded by dermal papillae, and a spiracle in intermediate position, between ventral and lateral. Furthermore, it shows unique feeding habits and a peculiar associated behaviour. During the day it stays close to the bottom and often burrows half of the body into the sand with the tail obliquely upwards; in this position it ingests organic material from among the substrate particles. During night time the tadpole leaves the bottom and swims throughout the water column. Since this tadpole cannot be included in any of the currently known ecomorphological categories we create a new category for this species, the ‘‘psammonektonic’’ tadpole. Mantella expectata was often found in the same environments, although it appears to prefer more open habitats. In some cases, tadpoles of both species were found together, although M. expectata usually prefers small and temporary streams for reproduction. The mantella tadpoles were also found in quite open savannah areas. The tadpole morphology agrees in general with that of other mantellas, mainly of the M. betsileo group, and is of the generalized ranoid type.

Genetic variation of an endangered Malagasy frog, Mantella cowani, and its phylogeographic relationship to the widespread M. baroni

Abstract: We investigated the degree and distribution of the genetic variation, and phylogeography, of two species of Malagasy poison frogs, Mantella cowani and M. baroni. The former is critically endangered due to its restricted distribution, habitat destruction and overcollection for the pet trade. Analysis of 526 bp of mtDNA (cytochrome b) resulted in separate haplotype networks for the two species, and discovered hybridization at a single locality. The two networks confirm the status of M. baroni and M. cowani as separate evolutionary species and units for conservation. Within both mitochondrial haplotype networks, specimens from di!erent localities shared numerous identical haplotypes, even those from the most distant sample sites of M. baroni. Most populations were characterized by high haplotype diversity and no haplotype clades exclusive to geographical regions were observed. Protection of a few large populations of these species is therefore likely to conserve much of the mtDNA genetic diversity found in the entire species. While M. baroni is widespread and occurs in many nature reserves, we recommend e"ci ent legal protection of some M. cowani habitats to protect this species against extinction.

Mitochondrial evidence for distinct phylogeographic units in the endangered Malagasy poison frog Mantella bernhardi

Abstract: Mantella bernhardi is an endemic species of Malagasy poison frog threatened by loss and fragmentation of its natural habitat and collection for the pet trade. It is classified as threatened according to the International Union for Conservation of Nature and Natural Resources (IUCN) categories and included in Appendix II of the Convention on the International Trade of Endangered Species (CITES). A recent survey has increased the known distributional range of the species from one to eight populations across southeastern Madagascar, but little is known about its biology and genetic diversity. Here we estimate inter- and intrapopulation mitochondrial genetic variation of four populations. Populations from the northern and southern parts of the distributional range showed a high degree of divergence (maximum of 11.35% in cytochrome b ) and were recovered as reciprocally monophyletic groups. Nine haplotypes were detected in the northern and 12 in the southern populations. The population from Ranomafana National Park showed the lowest number of haplotypes and nucleotide diversity, and shared its most common haplotype with the second northern population from Tolongoina. All the other detected haplotypes were unique to each of the four populations. This suggests the existence of important barriers to gene flow, pre-dating human colonization of Madagascar at about 2000 years ago, in distinct contrast to other Mantella species that show a high degree of haplotype sharing throughout their range. The continued habitat fragmentation within the distribution range of M. bernhardi prevents any connection between its populations. Our data indicate the existence of at least two different management units for conservation in this species, corresponding to the North and South of its distribution range, and highlight the existence of strong regional endemism in southeastern Madagascar.