Exploring fluctuating asymmetry in two recovering populations of the Eurasian otter.

The Eurasian otter is a wide-ranging semi-aquatic mammal that underwent a significant population decline in the last century, leading to local extinctions, reduction and fragmentation of populations. The individuals of populations exposed to both external and internal stress may present the inability to produce a specific developmental outcome, generating developmental 'noise' (developmental instability (DI)). Factors contributing to DI include inbreeding depression, population bottlenecks, habitat loss and exposure to pollution.

The three-dimensionally articulated oral apparatus of a Devonian heterostracan sheds light on feeding in Palaeozoic jawless fishes.

Attempts to explain the origin and diversification of vertebrates have commonly invoked the evolution of feeding ecology, contrasting the passive suspension feeding of invertebrate chordates and larval lampreys with active predation in living jawed vertebrates. Of the extinct jawless vertebrates that phylogenetically intercalate these living groups, the feeding apparatus is well-preserved only in the early diverging stem-gnathostome heterostracans. However, its anatomy remains poorly understood.

The oldest three-dimensionally preserved vertebrate neurocranium.

The neurocranium is an integral part of the vertebrate head, itself a major evolutionary innovation. However, its early history remains poorly understood, with great dissimilarity in form between the two living vertebrate groups: gnathostomes (jawed vertebrates) and cyclostomes (hagfishes and lampreys). The 100 Myr gap separating the Cambrian appearance of vertebrates from the earliest three-dimensionally preserved vertebrate neurocrania further obscures the origins of modern states.

Testing heterochrony: Connecting skull shape ontogeny and evolution of feeding adaptations in baleen whales.

Ontogeny plays a key role in the evolution of organisms, as changes during the complex processes of development can allow for new traits to arise. Identifying changes in ontogenetic allometry-the relationship between skull shape and size during growth-can reveal the processes underlying major evolutionary transformations. Baleen whales (Mysticeti, Cetacea) underwent major morphological changes in transitioning from their ancestral raptorial feeding mode to the three specialized filter-feeding modes observed in extant taxa.

The ontogeny of asymmetry in echolocating whales.

Extreme asymmetry of the skull is one of the most distinctive traits that characterizes toothed whales (Odontoceti, Cetacea). The origin and function of cranial asymmetry are connected to the evolution of echolocation, the ability to use high-frequency sounds to navigate the surrounding environment. Although this novel phenotype must arise through changes in cranial development, the ontogeny of cetacean asymmetry has never been investigated.

Evolution: Killer whale bites and appetites.

A newly discovered fossil dolphin shows that modern killer and false-killer whales evolved from fish-eating ancestors. While today both species occasionally feed on large warm-blooded prey, including seals and other whales, this diet specialization has evolved only recently.

Enhancing CT imaging: A safe protocol to stain and de-stain rare fetal museum specimens using diffusible iodine-based staining (diceCT).

Computed tomography (CT) scanning is being increasingly employed in the study of natural history, particularly to investigate the internal anatomy of unique specimens in museum collections. Different techniques to enhance the contrast between tissues have been developed to improve the quality of the scans while preserving the integrity of these rare specimens. Diffusible iodine-based contrast enhanced computed tomography (diceCT) was found to be particularly effective and reversible for staining tissues in formalin preserved specimens.

Prenatal developmental sequence of the skull of minke whales and its implications for the evolution of mysticetes and the teeth-to-baleen transition.

Baleen whales (Mysticeti) have an extraordinary fossil record documenting the transition from toothed raptorial taxa to modern species that bear baleen plates, keratinous bristles employed in filter-feeding. Remnants of their toothed ancestry can be found in their ontogeny, as they still develop tooth germs in utero. Understanding the developmental transition from teeth to baleen and the associated skull modifications in prenatal specimens of extant species can enhance our understanding of the evolutionary history of this lineage by using ontogeny as a relative proxy of the evolutionary changes observed in the fossil record.

Prenatal Development of the Humpback Whale: Growth Rate, Tooth Loss and Skull Shape Changes in an Evolutionary Framework.

Extant baleen whales (Mysticeti) share a distinct suite of extreme and unique adaptations to perform bulk filter feeding, such as a long, arched skull, and mandible and the complete loss of adult dentition in favor of baleen plates. However, mysticetes still develop tooth germs during ontogeny. In the fossil record, multiple groups document the transition from ancestral raptorial feeding to filter feeding.

From Teeth to Baleen and Raptorial to Bulk Filter Feeding in Mysticete Cetaceans: The Role of Paleontological, Genetic, and Geochemical Data in Feeding Evolution and Ecology.

The origin of baleen and filter feeding in mysticete cetaceans occurred sometime between approximately 34 and 24 million years ago and represents a major macroevolutionary shift in cetacean morphology (teeth to baleen) and ecology (raptorial to filter feeding). We explore this dramatic change in feeding strategy by employing a diversity of tools and approaches: morphology, molecules, development, and stable isotopes from the geological record. Adaptations for raptorial feeding in extinct toothed mysticetes provide the phylogenetic context for evaluating morphological apomorphies preserved in the skeletons of stem and crown edentulous mysticetes.

Inactivation of C4orf26 in toothless placental mammals.

Previous studies have reported inactivated copies of six enamel-related genes (AMBN, AMEL, AMTN, ENAM, KLK4, MMP20) and one dentin-related gene (DSPP) in one or more toothless vertebrates and/or vertebrates with enamelless teeth, thereby providing evidence that these genes are enamel or tooth-specific with respect to their critical functions that are maintained by natural selection. Here, we employ available genome sequences for edentulous and enamelless mammals to evaluate the enamel specificity of four genes (WDR72, SLC24A4, FAM83H, C4orf26) that have been implicated in amelogenesis imperfecta, a condition in which proper enamel formation is abrogated during tooth development. Coding sequences for WDR72, SCL24A4, and FAM83H are intact in four edentulous taxa (Chinese pangolin, three baleen whales) and three taxa (aardvark, nine-banded armadillo, Hoffmann's two-toed sloth) with enamelless teeth, suggesting that these genes have critical functions beyond their involvement in tooth development.