Mating system drives negative associations between morphological features in Schistosomatidae

<p>Abstract</p> <p>Background</p> <p>Sexual morphological features are known to be associated with the mating systems of several animal groups. However, it has been suggested that morphological features other than sexual characteristics could also be constrained by the mating system as a consequence of negative associations. <it>Schistosomatidae </it>are parasitic organisms that vary in mating system and can thus be used to explore links between the mating system and negative associations with morphological features.</p> <p>Results</p> <p>A comparative analysis of <it>Schistosomatidae </it>morphological features revealed an association between the mating system (monogamous <it>versus </it>polygynandrous) and morphological characteristics of reproduction, nutrition, and locomotion.</p> <p>Conclusions</p> <p>The mating system drives negative associations between somatic and sexual morphological features. In monogamous species, males display a lower investment in sexual tissues and a higher commitment of resources to tissues involved in female transport, protection, and feeding assistance. In contrast, males of polygynandrous species invest to a greater extent in sexual tissues at the cost of reduced commitment to female care.</p

Molecular evolution of the crustacean hyperglycemic hormone family in ecdysozoans

<p>Abstract</p> <p>Background</p> <p>Crustacean Hyperglycemic Hormone (CHH) family peptides are neurohormones known to regulate several important functions in decapod crustaceans such as ionic and energetic metabolism, molting and reproduction. The structural conservation of these peptides, together with the variety of functions they display, led us to investigate their evolutionary history. CHH family peptides exist in insects (Ion Transport Peptides) and may be present in all ecdysozoans as well. In order to extend the evolutionary study to the entire family, CHH family peptides were thus searched in taxa outside decapods, where they have been, to date, poorly investigated.</p> <p>Results</p> <p>CHH family peptides were characterized by molecular cloning in a branchiopod crustacean, <it>Daphnia magna</it>, and in a collembolan, <it>Folsomia candida</it>. Genes encoding such peptides were also rebuilt <it>in silico </it>from genomic sequences of another branchiopod, a chelicerate and two nematodes. These sequences were included in updated datasets to build phylogenies of the CHH family in pancrustaceans. These phylogenies suggest that peptides found in Branchiopoda and Collembola are more closely related to insect ITPs than to crustacean CHHs. Datasets were also used to support a phylogenetic hypothesis about pancrustacean relationships, which, in addition to gene structures, allowed us to propose two evolutionary scenarios of this multigenic family in ecdysozoans.</p> <p>Conclusions</p> <p>Evolutionary scenarios suggest that CHH family genes of ecdysozoans originate from an ancestral two-exon gene, and genes of arthropods from a three-exon one. In malacostracans, the evolution of the CHH family has involved several duplication, insertion or deletion events, leading to neuropeptides with a wide variety of functions, as observed in decapods. This family could thus constitute a promising model to investigate the links between gene duplications and functional divergence.</p

Picoeukaryotic sequences in the Sargasso Sea metagenome

Many sequences from picoeukaryotes were found in DNA sequence data assembled from Sargasso seawater

Monogeneans of West African Cichlid Fish: Evolution and Cophylogenetic Interactions

The goals of this paper were to investigate phylogenetic and evolutionary patterns of cichlid fish from West Africa and their Cichlidogyrus and Scutogyrus monogenean parasites, to uncover the presence of host-parasite cospeciation and to assess the level of morphological adaptation in parasites. This required the following steps, each one representing specific objectives of this paper: (1) to build phylogenetic trees for Cichlidogyrus and Scutogyrus species based on ribosomal DNA sequences, (2) to investigate phylogenetic relationships within West African cichlid fish based on the analysis of mitochondrial cytochrome b DNA sequences, (3) to investigate host-parasite cophylogenetic history to gain clues on parasite speciation process, and (4) to investigate the link between the morphology of the attachment apparatus and parasite phylogeny. Phylogenetic analyses supported the monophyletic origin of the Cichlidogyrus/Scutogyrus group, and suggested that Cichlidogyrus is polyphyletic and that Scutogyrus is monophyletic. The phylogeny of Cichlidae supported the separation of mouthbrooders and substrate-brooders and is consistent with the hypothesis that the mouthbrooding behavior of Oreochromis and Sarotherodon evolved from substrate-brooding behavior. The mapping of morphological characters of the haptor onto the parasite phylogenetic tree suggests that the attachment organ has evolved from a very simple form to a more complex one. The cophylogenetic analyses indicated a significant fit between trees using distance-based tests, but no significant cospeciation signal using tree-based tests, suggesting the presence of parasite duplications and host switches on related host species. This shed some light on the diversification process of Cichlidogyrus species parasitizing West African cichlids

Review of the phylogenetic reconstruction of the diatoms using molecular tools with an analysis of a seven gene data set using multiple outgroups and morphological data for a total evidence approach

Medlin tested multiple outgroups with 18S rRNA dataset and found that haptophytes, ciliates, prasinophytes and chlorophytes recovered monophyletic Coscinodiscophyceae, Mediophyceae, Bacillariophyceae with strong BT support. Theriot et al. added six plastid genes to the diatom dataset but with only one outgroup, Bolidomonas and omitted most of the V4 region of that gene and bases beyond position 1200. They recovered a grade of clades from radial into polar centrics, into araphid pennates into the monophyletic raphid pennates. Their structural gradation hypothesis (SGH) contrasts to the CMB hypothesis of Medlin and Kaczmarska. We selected only those species with all seven genes from their dataset and added the entire 18S RNA gene to make a new dataset to which we sequentially added heterokont, haptophyte, and prasinophyte/chlorophyte outgroups. We analysed it using 1) evolutionary models with parameters relaxed across genes and codon positions for coding sequences (codon partition analysis scheme = CP) and 2) no partitions or evolutionary models as applied to each gene, using only optimised models of evolution for the entire dataset (NCP). CP recovered a monophyletic mediophycean and bacillariophycean clade and three coscinodiscophycean clades. Sequentially adding more outgroups did not change clade topology but dramatically increased BT support. NCP recovered a monophyletic Coscinodiscophyceae and Bacillariophyceae and three Mediophyceae clades, each with strong bootstrap support. Morphological data was added and analyzed similarly. NCP recovered three monophyletic classes and CP recovered the Bacillariophyceae arising from within the Mediophyceae, making the subphylum monophyletic but the class was paraphyletic. Each analysis was tested with SH tests in PAUP and IQTree. Plastid inheritance in the diatoms is not homogenous and thus their phylogenies may not be homologous. If so, then our application of gene models may be overparametrising the data. The application of no partitioning models with morphological data supported the CMB hypothesis

Prasinovirus distribution in the Northwest Mediterranean Sea is affected by the environment and particularly by phosphate availability

AbstractNumerous seawater lagoons punctuate the southern coastline of France. Exchanges of seawater between these lagoons and the open sea are limited by narrow channels connecting them. Lagoon salinities vary according to evaporation and to the volume of freshwater arriving from influent streams, whose nutrients also promote the growth of algae. We compared Prasinovirus communities, whose replication is supported by microscopic green algae, in four lagoons and at a coastal sampling site. Using high-throughput sequencing of DNA from a giant virus-specific marker gene, we show that the environmental conditions significantly affect the types of detectable viruses across samples. In spatial comparisons between 5 different sampling sites, higher levels of phosphates, nitrates, nitrites, ammonium and silicates tend to increase viral community richness independently of geographical distances between the sampling sites. Finally, comparisons of Prasinovirus communities at 2 sampling sites over a period of 10 months highlighted seasonal effects and the preponderant nature of phosphate concentrations in constraining viral distribution

L'justice en Espagne au Dix-huitème siècle

Extrait de la Revue des Pyrinées-Année 189

Host-microbiota-parasite interactions in two wild sparid fish species, Diplodus annularis and Oblada melanura (Teleostei, Sparidae) over a year: a pilot study

peer reviewed[en] BACKGROUND: The microbiota in fish external mucus is mainly known for having a role in homeostasis and protection against pathogens, but recent evidence suggests it is also involved in the host-specificity of some ectoparasites. In this study, we investigated the influence of seasonality and environmental factors on both fish external microbiota and monogenean gill ectoparasites abundance and diversity and assessed the level of covariations between monogenean and bacterial communities across seasons. To do so, we assessed skin and gill microbiota of two sparid species, Oblada melanura and Diplodus annularis, over a year and collected their specific monogenean ectoparasites belonging to the Lamellodiscus genus. RESULTS: Our results revealed that diversity and structure of skin and gill mucus microbiota were strongly affected by seasonality, mainly by the variations of temperature, with specific fish-associated bacterial taxa for each season. The diversity and abundance of parasites were also influenced by seasonality, with the abundance of some Lamellodiscus species significantly correlated to temperature. Numerous positive and negative correlations between the abundance of given bacterial genera and Lamellodiscus species were observed throughout the year, suggesting their differential interaction across seasons. CONCLUSIONS: The present study is one of the first to demonstrate the influence of seasonality and related abiotic factors on fish external microbiota over a year. We further identified potential interactions between gill microbiota and parasite occurrence in wild fish populations, improving current knowledge and understanding of the establishment of host-specificity

Diversity and structure of sparids external microbiota (Teleostei) and its link with monogenean ectoparasites.

peer reviewed[en] BACKGROUND: Animal-associated microbial communities appear to be key factors in host physiology, ecology, evolution and its interactions with the surrounding environment. Teleost fish have received relatively little attention in the study of surface-associated microbiota. Besides the important role of microbiota in homeostasis and infection prevention, a few recent studies have shown that fish mucus microbiota may interact with and attract some specific parasitic species. However, our understanding of external microbial assemblages, in particular regarding the factors that determine their composition and potential interactions with parasites, is still limited. This is the objective of the present study that focuses on a well-known fish-parasite interaction, involving the Sparidae (Teleostei), and their specific monogenean ectoparasites of the Lamellodiscus genus. We characterized the skin and gill mucus bacterial communities using a 16S rRNA amplicon sequencing, tested how fish ecological traits and host evolutionary history are related to external microbiota, and assessed if some microbial taxa are related to some Lamellodiscus species. RESULTS: Our results revealed significant differences between skin and gill microbiota in terms of diversity and structure, and that sparids establish and maintain tissue and species-specific bacterial communities despite continuous exposure to water. No phylosymbiosis pattern was detected for either gill or skin microbiota, suggesting that other host-related and environmental factors are a better regulator of host-microbiota interactions. Diversity and structure of external microbiota were explained by host traits: host species, diet and body part. Numerous correlations between the abundance of given bacterial genera and the abundance of given Lamellodiscus species have been found in gill mucus, including species-specific associations. We also found that the external microbiota of the only unparasitized sparid species in this study, Boops boops, harbored significantly more Fusobacteria and three genera, Shewenella, Cetobacterium and Vibrio, compared to the other sparid species, suggesting their potential involvement in preventing monogenean infection. CONCLUSIONS: This study is the first to explore the diversity and structure of skin and gill microbiota from a wild fish family and present novel evidence on the links between gill microbiota and monogenean species in diversity and abundance, paving the way for further studies on understanding host-microbiota-parasite interactions