Marine biogeographic boundaries and human introduction along the European coast revealed by phylogeography of the prawn Palaemon elegans

11 páginas, 5 figuras, 6 tablas.A phylogeographic analysis is carried out for the widely distributed European littoral prawn Palaemon elegans in order to test for potential genetic differentiation and geographic structure. Mitochondrial sequences were obtained from 283 specimens from the northeastern Atlantic, the Baltic, Mediterranean, Black and Caspian Seas. Our study revealed a surprisingly complex population structure. Three main haplogroups can be separated: one from the Atlantic (Type I) and two from the Mediterranean (Types II and III). While the Mediterranean types occur in sympatry, a clear phylogeographic break was observed along the Almería-Oran Front separating Type I and giving evidence for a genetic isolation of Atlantic and Mediterranean populations. Type III represents the most distinct haplogroup with high levels of nucleotide divergence, indicating the occurrence of a cryptic species with a Messinian origin. The colonization of the southeastern Baltic Sea is most likely due to human introduction.For financial support we like to thank the European Union funding (FEDER), the Spanish “Ministerio de Educación y Ciencia, Plan Nacional I+D” (Project CGL2004-01083), the DAAD (D/03/40344) and the Spanish “Ministerio de Ciencia y Tecnología—Acciones Integradas (HA2003-078).Peer reviewe

Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry

Dermatophytoses represent a major health burden in animals and man. Zoophilic dermatophytes usually show a high specificity to their original animal host but a zoonotic transmission is increasingly recorded. In humans, these infections elicit highly inflammatory skin lesions requiring prolonged therapy even in the immunocompetent patient. The correct identification of the causative agent is often crucial to initiate a targeted and effective therapy. To that end, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The objective of this study was to evaluate the reliability of species identification of zoophilic dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based identification of the most common zoophilic dermatophyte Microsporum canis. Trichophyton (T.) spp. usually achieved scores only around the cutoff value for secure species identification because of a small number of reference spectra. Moreover, these results need to be interpreted with caution due to the close taxonomic relationship of dermatophytes being reflected in very similar spectra. In our study, the analysis of 50 clinical samples of hedgehogs revealed no correct identification using the provided databases, nor for zoophilic neither for geophilic causative agents. After DNA sequencing, adaptation of sample processing and an individual extension of the inhouse database, acceptable identification scores were achieved (T. erinacei and Arthroderma spp., respectively). A score-oriented distance dendrogram revealed clustering of geophilic isolates of four different species of the genus Arthroderma and underlined the close relationship of the important zoophilic agents T. erinacei, T. verrucosum and T. benhamiae by forming a subclade within a larger cluster including different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the identification of zoophilic dermatophytes provided fresh cultures are used and the reference library was previously extended with spectra of laboratory-relevant species. Performing independent molecular methods, such as sequencing, is strongly recommended to substantiate the findings from morphologic and MALDI-TOF MS analyses, especially for uncommon causative agents

Comparative phylogeographic studies of three marine and one amphidromous decapod species clarifying the mechanisms of generation and maintenance of genetic diversity and identifying cryptic species

The aim of this study was to determine the influence of biogeography, oceanography and ecology on the population structure of different crustacean species with emphasis on their larval development. It is predicted that the duration of larval development influences the dispersal capability and therefore the level of genetic differentiation. In addition, the results should provide answers if there are cryptic species. The two atlanto-mediterranean crab species Xantho hydrophilus (Herbst, 1790) and Xantho poressa (Olivi, 1792) and the European prawn Palaemon elegans (Rathke, 1837) were included as marine species. Xantho has a shorter larval development with four zoeal stages than Palaemon with nine larval stages. Therefore, a higher gene flow within Palaemon was expected. We used also the amphidromous species Xiphocaris elongata (Guérin-Méneville, 1856) which occurs in freshwater systems of the Caribbean islands. The life cycle of amphidromous X. elongata is intermediate between freshwater and marine species and thus, high genetic differentiation was predicted. A comparative population genetics analyses was conducted to reveal differences in the population structure due to the distinct larval development and the amphidromous life-cycle. In the case of X. hydrophilus, results show a restricted gene flow between the populations of the Atlantic and the Mediterranean Sea. However, the taxonomic status of the Mediterranean subspecies X. h. granulicarpus is not valid as long as no single mutation step was detected to distinguish constantly between the two subspecies X. hydrophilus and X. h. granulicarpus. In addition, morphological transitional forms of X. hydrophilus are found within the Western Mediterranean Sea. X. poressa is suggested to reproduce panmictically because no differences are found between the populations of the Mediterranean Sea and the Atlantic Ocean and a mark recapture experiment showed that the species reaches high population densities. This species is well adapted to its habitat due to its variability in colouration and size which is the result of passive defence (camouflage). A pattern of allometric growth in the carapace shape was observed. Phylogenetic analyses revealed that X. sexdentatus is very closely related to X. hydrophilus. This could be either due to hybridization or introgression. Despite the fact that Palaemon elegans has nine larval stages, there is surprisingly high genetic differentiation. Normally such strong differences are only found between species and thus a cryptic species within the P. elegans complex is suggested. Three types of haplotype groups are found: Type I from the Atlantic and the Alboran Sea, Type II only within the Mediterranean Sea and Type III within the Mediterranean, Black, Caspian, Baltic and East Sea. Type III could be a relict of the Messinian crisis due to its high genetic differentiation, while Type II has recolonized the Mediterranean Sea after the crisis and ongoing separation mechanisms have established restricted gene flow between Type I and II. The barrier to gene flow between the Atlantic Type and the two Mediterranean Types is the Almería-Oran-Front. The Almería-Oran-Front is an important phylogeographic break, where restricted gene flow is possible. An isolation-by-distance pattern could be detected within the Atlantic Ocean. Furthermore, there is significant genetic differentiation between the Northern Atlantic and the North-East Atlantic due to the English Channel. These results provide evidence that dispersal play a minor role in determining the genetic structure of a species, compared to the biogeographic history and physical factors. This becomes even more obvious by comparison with the shrimp Xiphocaris elongata, for which a higher genetic differentiation due to the isolated freshwater systems and the amphidromous life cycle was expected. Although there is a high genetic differentiation, no geographic pattern emerges. The amphidromous life cycle enhance the dispersal capability and gene flow. It displays rather patterns of a marine species than of an exclusively freshwater species. The species is characterized by its variability in the rostrum length, but the results give no evidence for a genetic differentiation of the phenotypes. Thus, adaptive plasticity due to predators and in part allometric growth could be an explanation for the variability

Marine biogeographic boundaries and human introduction along the European coast revealed by phylogeography of the prawn Palaemon elegans

11 páginas, 5 figuras, 6 tablas.A phylogeographic analysis is carried out for the widely distributed European littoral prawn Palaemon elegans in order to test for potential genetic differentiation and geographic structure. Mitochondrial sequences were obtained from 283 specimens from the northeastern Atlantic, the Baltic, Mediterranean, Black and Caspian Seas. Our study revealed a surprisingly complex population structure. Three main haplogroups can be separated: one from the Atlantic (Type I) and two from the Mediterranean (Types II and III). While the Mediterranean types occur in sympatry, a clear phylogeographic break was observed along the Almería-Oran Front separating Type I and giving evidence for a genetic isolation of Atlantic and Mediterranean populations. Type III represents the most distinct haplogroup with high levels of nucleotide divergence, indicating the occurrence of a cryptic species with a Messinian origin. The colonization of the southeastern Baltic Sea is most likely due to human introduction.For financial support we like to thank the European Union funding (FEDER), the Spanish “Ministerio de Educación y Ciencia, Plan Nacional I+D” (Project CGL2004-01083), the DAAD (D/03/40344) and the Spanish “Ministerio de Ciencia y Tecnología—Acciones Integradas (HA2003-078).Peer reviewe

Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry

Dermatophytoses represent a major health burden in animals and man. Zoophilic dermatophytes usually show a high specificity to their original animal host but a zoonotic transmission is increasingly recorded. In humans, these infections elicit highly inflammatory skin lesions requiring prolonged therapy even in the immunocompetent patient. The correct identification of the causative agent is often crucial to initiate a targeted and effective therapy. To that end, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The objective of this study was to evaluate the reliability of species identification of zoophilic dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based identification of the most common zoophilic dermatophyte Microsporum canis. Trichophyton (T.) spp. usually achieved scores only around the cutoff value for secure species identification because of a small number of reference spectra. Moreover, these results need to be interpreted with caution due to the close taxonomic relationship of dermatophytes being reflected in very similar spectra. In our study, the analysis of 50 clinical samples of hedgehogs revealed no correct identification using the provided databases, nor for zoophilic neither for geophilic causative agents. After DNA sequencing, adaptation of sample processing and an individual extension of the inhouse database, acceptable identification scores were achieved (T. erinacei and Arthroderma spp., respectively). A score-oriented distance dendrogram revealed clustering of geophilic isolates of four different species of the genus Arthroderma and underlined the close relationship of the important zoophilic agents T. erinacei, T. verrucosum and T. benhamiae by forming a subclade within a larger cluster including different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the identification of zoophilic dermatophytes provided fresh cultures are used and the reference library was previously extended with spectra of laboratory-relevant species. Performing independent molecular methods, such as sequencing, is strongly recommended to substantiate the findings from morphologic and MALDI-TOF MS analyses, especially for uncommon causative agents

Identification of Zoophilic Dermatophytes Using MALDI-TOF Mass Spectrometry

Dermatophytoses represent a major health burden in animals and man. Zoophilic dermatophytes usually show a high specificity to their original animal host but a zoonotic transmission is increasingly recorded. In humans, these infections elicit highly inflammatory skin lesions requiring prolonged therapy even in the immunocompetent patient. The correct identification of the causative agent is often crucial to initiate a targeted and effective therapy. To that end, matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) represents a promising tool. The objective of this study was to evaluate the reliability of species identification of zoophilic dermatophytes using MALDI-TOF MS. The investigation of isolates from veterinary clinical samples suspicious of dermatophytoses suggests a good MALDI-TOF MS based identification of the most common zoophilic dermatophyte Microsporum canis. Trichophyton (T.) spp. usually achieved scores only around the cutoff value for secure species identification because of a small number of reference spectra. Moreover, these results need to be interpreted with caution due to the close taxonomic relationship of dermatophytes being reflected in very similar spectra. In our study, the analysis of 50 clinical samples of hedgehogs revealed no correct identification using the provided databases, nor for zoophilic neither for geophilic causative agents. After DNA sequencing, adaptation of sample processing and an individual extension of the inhouse database, acceptable identification scores were achieved (T. erinacei and Arthroderma spp., respectively). A score-oriented distance dendrogram revealed clustering of geophilic isolates of four different species of the genus Arthroderma and underlined the close relationship of the important zoophilic agents T. erinacei, T. verrucosum and T. benhamiae by forming a subclade within a larger cluster including different dermatophytes. Taken together, MALDI-TOF MS proofed suitable for the identification of zoophilic dermatophytes provided fresh cultures are used and the reference library was previously extended with spectra of laboratory-relevant species. Performing independent molecular methods, such as sequencing, is strongly recommended to substantiate the findings from morphologic and MALDI-TOF MS analyses, especially for uncommon causative agents