A test for paedomorphism in domestic pig cranial morphology

Domestic animals are often described as paedomorphic, meaning that they retain juvenile characteristics into adulthood. Through a three-dimensional landmark-based geometric morphometric analysis of cranial morphology at three growth stages, we demonstrate that wild boar (n = 138) and domestic pigs (n = 106) (Sus scrofa) follow distinct ontogenetic trajectories. With the exception of the size ratio between facial and neurocranial regions, paedomorphism does not appear to be the primary pattern describing the observed differences between wild and domestic pig cranial morphologies. The cranial phenotype of domestic pigs instead involves developmental innovation during domestication. This result questions the long-standing assumption that domestic animal phenotypes are paedomorphic forms of their wild counterpart

Evolution of Matrix Gla and Bone Gla Protein Genes in Jawed Vertebrates

Matrix Gla protein (Mgp) and bone Gla protein (Bgp) are vitamin-K dependent proteins that bind calcium in their gamma-carboxylated versions in mammals. They are recognized as positive (Bgp) or negative (Mgp and Bgp) regulators of biomineralization in a number of tissues, including skeletal tissues of bony vertebrates. The Mgp/Bgp gene family is poorly known in cartilaginous fishes, which precludes the understanding of the evolution of the biomineralization toolkit at the emergence of jawed vertebrates. Here we took advantage of recently released genomic and transcriptomic data in cartilaginous fishes and described the genomic loci and gene expression patterns of the Mgp/Bgp gene family. We identified three genes, Mgp1, Mgp2, and Bgp, in cartilaginous fishes instead of the single previously reported Mgp gene. We describe their genomic loci, resulting in a dynamic evolutionary scenario for this gene family including several events of local (tandem) duplications, but also of translocation events, along jawed vertebrate evolution. We describe the expression patterns of Mgp1, Mgp2, and Bgp in embryonic stages covering organogenesis in the small-spotted catshark Scyliorhinus canicula and present a comparative analysis with Mgp/Bgp family members previously described in bony vertebrates, highlighting ancestral features such as early embryonic, soft tissues, and neuronal expressions, but also derived features of cartilaginous fishes such as expression in fin supporting fibers. Our results support an ancestral function of Mgp in skeletal mineralization and a later derived function of Bgp in skeletal development that may be related to the divergence of bony vertebrates

On the Relationship between Zaprionus spinipilus Chassagnard & McEvey and Z. vittiger Coquillett, the Type Species of the Genus Zaprionus (Diptera: Drosophilidae)

Zaprionus vittiger Coquillett is the type species of the genus Zaprionus Coquillett. However, the species is only known from five old museum specimens collected from South Africa and Malawi. It has often been confused with many other Zaprionus species, especially with Z. spinipilus Chassagnard & McEvey, a widespread species in Africa known from Madagascar, Malawi, Ethiopia and Cameroon. We have recently collected flies from the type localities of both species (South Africa and Madagascar, respectively). This has prompted us to test the taxonomic boundaries of these two nominal species using molecular (the mitochondrial COII and the nuclear Amyrel genes), chromosomal, morphological (internal and external genitalia), and reproductive isolation analyses. The results suggest Z. spinipilus to be a junior synonym to Z. vittiger.Agence Universitaire de la Francophonie (AUF)Agence Universitaire de la Francophonie (AUF)La Fondation des TreillesLa Fondation des TreillesComité Français d´Evaluation de la Coopération Universitaire avec le Brésil (COFECUB)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)French-Brazilian cooperative agreement CAPES-COFECU

Thyroid hormone-dependent apoptosis during metamorphosis in Ciona robusta involves both bilaterian-ancestral and vertebrate-derived processes

Chordate metamorphosis is a postembryonic larva-to-juvenile transition triggered by thyroid hormones and their specific receptors (TR). This crucial developmental event shows a wide morphological diversity among different chordate lineages and is characterized by ecological, morphological, metabolic and behavioral changes that can be drastic. One of the most studied models is the amphibian Xenopus, whose tadpole metamorphosis includes apoptosis-induced tail regression dependent on the thyroid hormone pathway. In an evolutionary context, we used the ascidian model, the extant closest group to vertebrates, in which the swimming larva transforms to a sessile filter-feeding juvenile during metamorphosis, to study the role of thyroid hormones in this transformation. The ascidian metamorphosis is also characterized by an apoptosis-driven tail regression as in Xenopus. However, whether this apoptosis-driven process is dependent on the thyroid hormone has not yet been elucidated. In this study, we interfered with thyroid hormone signaling during tail regression of the ascidian Ciona robusta to investigate whether (i) thyroid hormone is involved in the regulation of developmental apoptosis, and (ii) apoptosis leading to tail regression involves its classical molecular pathways. We described specific gene expression landmarks as well as apoptosis dynamics during larva metamorphosis under thyroid hormone exposure and thyroid hormone inhibition treatments. We provide evidence that Ciona robusta metamorphosis involves thyroid hormone-dependent apoptosis, similar to other studied chordates. However, the mode of action of thyroid hormone shows great variation compared to the classically described scheme in chordates, both in thyroid hormone/TR interactions and in the apoptotic pathway