Showing papers on "Mantella published in 2019"

A new genus of polystomatid parasitic flatworm (Monogenea: Polystomatidae) without free-swimming life stage from the Malagasy poison frogs.

Abstract: Madapolystoma n. g. (Monogenea, Polystomatidae), is proposed for a new genus of polystomatid from the urinary bladder of the Malagasy poison frogs of the genus Mantella (family Mantellidae), with the description of one new species. This is the second anuran polystome to be described from Madagascar. The parasites are small with a maximum body length of less than 3 mm. The two gut caeca have a few diverticulae but no prehaptoral anastomoses and are confluent posteriorly. The haptor bears six well-developed suckers and one pair of hamuli. A single small ovary lies in mid-body while the single follicular testis lies posteriorly in the body. Vaginae are present. The new genus is unique among all known polystomes in that it apparently has no free-swimming ciliated larvae but instead is characterized by advanced intra-uterine development with larvae developing hamuli and even suckers while still in utero . Based on molecular phylogenetic data, the closest relative of Madapolystoma is the genus Eupolystoma from Africa. Madagascar has a very diverse anuran fauna with a 100% level of endemicity at the species level, and more Madapolystoma species from other mantellid hosts await description.

Mitochondrial Introgression, Color Pattern Variation, and Severe Demographic Bottlenecks in Three Species of Malagasy Poison Frogs, Genus Mantella .

Abstract: Madagascar is a biodiversity hotspot particularly rich in amphibian diversity and only a few charismatic Malagasy amphibians have been investigated for their population-level differentiation. The Mantella madagascariensis group is composed of two rainforest and three swamp forest species of poison frogs. We first confirm the monophyly of this clade using DNA sequences of three nuclear and four mitochondrial genes, and subsequently investigate the population genetic differentiation and demography of the swamp forest species using one mitochondrial, two nuclear and a set of nine microsatellite markers. Our results confirm the occurrence of two main mitochondrial lineages, one dominated by Mantella aurantiaca (a grouping supported also by our microsatellite-based tree) and the other by Mantella crocea + Mantella milotympanum. These two main lineages probably reflect an older divergence in swamp Mantella. Widespread mitochondrial introgression suggests a fairly common occurrence of inter-lineage gene flow. However, nuclear admixture seems to play only a limited role in this group, and the analyses of the RAG-1 marker points to a predominant incomplete lineage sorting scenario between all five species of the group, which probably diverged relatively recently. Our demographic analyses show a common, severe and recent demographic contraction, inferred to be in temporal coincidence with the massive deforestation events that took place in the past 1000 years. Current data do not allow to conclusively delimit independent evolutionary units in these frogs, and we therefore refrain to suggest any taxonomic changes.

Phenotypic and genetic diversity in aposematic Malagasy poison frogs (genus Mantella).

Abstract: Intraspecific color variation has long fascinated evolutionary biologists. In species with bright warning coloration, phenotypic diversity is particularly compelling because many factors, including natural and sexual selection, contribute to intraspecific variation. To better understand the causes of dramatic phenotypic variation in Malagasy poison frogs, we quantified genetic structure and color and pattern variation across three closely related species, Mantella aurantiaca, Mantella crocea, and Mantella milotympanum. Although our restriction site-associated DNA (RAD) sequencing approach identified clear genetic clusters, they do not align with current species designations, which has important conservation implications for these imperiled frogs. Moreover, our results suggest that levels of intraspecific color variation within this group have been overestimated, while species diversity has been underestimated. Within major genetic clusters, we observed distinct patterns of variation including: populations that are phenotypically similar yet genetically distinct, populations where phenotypic and genetic breaks coincide, and populations that are genetically similar but have high levels of within-population phenotypic variation. We also detected admixture between two of the major genetic clusters. Our study suggests that several mechanisms-including hybridization, selection, and drift-are contributing to phenotypic diversity. Ultimately, our work underscores the need for a reevaluation of how polymorphic and polytypic populations and species are classified, especially in aposematic organisms.

Microhabitat preference of the critically endangered golden mantella frog in Madagascar

Abstract: The golden mantella (Mantella aurantiaca) is a critically endangered (CR) frog, endemic to the eastern rainforests of Madagascar. Although the species is very popular in the pet trade and widely bred in captivity, its specific habitat requirements in the wild are poorly understood. Ten forested sites in the Moramanga district of Madagascar were surveyed for microhabitat and environmental variables, and the presence or absence of golden mantellas in quadrats positioned along transects in the vicinity of breeding sites. Mixed models were used to determine which variables best explained microhabitat use by golden mantellas. Sites where golden mantellas were found tended to have surface temperatures of 2023 ˚C, UVI units at about 2.9, about 30 % canopy cover, and around 30 % herbaceous cover. Within sites, golden mantellas preferred microhabitats that had 70 % leaf litter coverage and relatively low numbers of tree roots. This information can be used to improve the identification and management of habitats in the wild, as well as to refine captive husbandry needs

Activation of the Bile Acid Pathway and No Observed Antimicrobial Peptide Sequences in the Skin of a Poison Frog.

Abstract: The skin secretions of many frogs have genetically-encoded, endogenous antimicrobial peptides (AMPs). Other species, especially aposematic poison frogs, secrete exogenously derived alkaloids that serve as potent defense molecules. The origins of these defense systems are not clear, but a novel bile-acid derived metabolite, tauromantellic acid, was recently discovered and shown to be endogenous in poison frogs (Mantella, Dendrobates, and Epipedobates). These observations raise questions about the evolutionary history of AMP genetic elements, the mechanism and function of tauromatellic acid production, and links between these systems. To understand the diversity and expression of AMPs among frogs, we assembled skin transcriptomes of 13 species across the anuran phylogeny. Our analyses revealed a diversity of AMPs and AMP expression levels across the phylogenetic history of frogs, but no observations of AMPs in Mantella We examined genes expressed in the bile-acid metabolic pathway and found that CYP7A1 (Cytochrome P450), BAAT (bile acid-CoA: amino acid N-acyltransferase), and AMACR (alpha-methylacyl-CoA racemase) were highly expressed in the skin of M. betsileo and either lowly expressed or absent in other frog species. In particular, CYP7A1 catalyzes the first reaction in the cholesterol catabolic pathway and is the rate-limiting step in regulation of bile acid synthesis, suggesting unique activation of the bile acid pathway in Mantella skin. The activation of the bile acid pathway in the skin of Mantella and the lack of observed AMPs fuel new questions about the evolution of defense compounds and the ectopic expression of the bile-acid pathway.

Complete mitochondrial genome of the Malagasy poison frog Mantella baroni through RNAseq

Abstract: Within the Malagasy endemic family of Mantellidae, the only completely sequenced mitochondrial genome (mitogenome) is that of Mantella madagascariensis. Yet, this genome has proven to be th...