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Alexey А Moskalev, Anna V Kudryavtseva, Alexander S Graphodatsky, Violetta R Beklemisheva, Natalya A Serdyukova, Konstantin V Krutovsky, Vadim V Sharov, Ivan V Kulakovskiy, Andrey S Lando, Artem S Kasianov, Dmitry A Kuzmin, Yuliya A Putintseva, Sergey I Feranchuk, Mikhail V Shaposhnikov, Vadim E Fraifeld, Dmitri Toren, Anastasia V Snezhkina, Vasily V Sitnik
BACKGROUND: Gray whale, Eschrichtius robustus (E. robustus), is a single member of the family Eschrichtiidae, which is considered to be the most primitive in the class Cetacea. Gray whale is often described as a "living fossil". It is adapted to extreme marine conditions and has a high life expectancy (77 years). The assembly of a gray whale genome and transcriptome will allow to carry out further studies of whale evolution, longevity, and resistance to extreme environment. RESULTS: In this work, we report the first de novo assembly and primary analysis of the E...
December 28, 2017: BMC Evolutionary Biology
Mark S Springer, John Gatesy
MC5R is one of five melanocortin receptor genes found in placental mammals. MC5R plays an important role in energy homeostasis and is also expressed in the terminal differentiation of sebaceous glands. Among placental mammals there are multiple lineages that either lack or have degenerative sebaceous glands including Cetacea (whales, dolphins, and porpoises), Hippopotamidae (hippopotamuses), Sirenia (manatees and dugongs), Proboscidea (elephants), Rhinocerotidae (rhinos), and Heterocephalus glaber (naked mole rat)...
December 19, 2017: Molecular Phylogenetics and Evolution
Alexandra K Wright, Rebecca J Theilmann, Sam H Ridgway, Miriam Scadeng
Brain enlargement is associated with concomitant growth of interneuronal distance, increased conduction time, and reduced neuronal interconnectivity. Recognition of these functional constraints led to the hypothesis that large-brained mammals should exhibit greater structural and functional brain lateralization. As a taxon with the largest brains in the animal kingdom, Cetacea provides a unique opportunity to examine asymmetries of brain structure and function. In the present study, diffusion tensor imaging and tractography were used to investigate cerebral white matter asymmetry in the bottlenose dolphin (Tursiops truncatus)...
November 30, 2017: Brain Structure & Function
Robert W Boessenecker, Erum Ahmed, Jonathan H Geisler
We report five new specimens of xenorophid dolphins from North and South Carolina. Four of the specimens represent the xenorophid Albertocetus meffordorum, previously only known from the holotype skull. The other is a fragmentary petrosal from the upper Oligocene Belgrade Formation that we refer to Echovenator sp, indicating at least two xenorophids from that unit. Two of the Albertocetus meffordorum specimens are from the lower Oligocene Ashley Formation: 1) a partial skeleton with neurocranium, fragmentary mandible, ribs, vertebrae, and chevrons, and 2) an isolated braincase...
2017: PloS One
Klaas Post, Stephen Louwye, Olivier Lambert
Background: The family Pontoporiidae (Cetacea, Odontoceti, Inioidea) is currently represented in our oceans by just one species of diminutive dolphin (Pontoporia blainvillei, franciscana). Although P. blainvillei is limited to coastal waters of the South Atlantic along Brazil, Uruguay and Argentina, multiple Miocene and Pliocene fossils indicate the past presence of members of the family in the South Atlantic, South Paciifc and North Atlantic oceans. Our comprehension of the origin and diversity of this clade and of the relationships of its members with other inioids is hampered by the fact that part of the described fossil specimens, especially from the North Atlantic realm, are cranial fragments often associated to limited stratigraphic information...
2017: PeerJ
Lisa Noelle Cooper, Karen E Sears, Brooke A Armfield, Bhavneet Kala, Merla Hubler, J G M Thewissen
Cetaceans are the only mammals to have evolved hyperphalangy, an increase in the number of phalanges beyond the mammalian plesiomorphic condition of three phalanges per digit. In this study, cetaceans were used as a novel model to review previous studies of mammalian hyperphalangy and contribute new experimental evidence as to the molecular origins of this phenotype in embryos of the pantropical spotted dolphin (Stenella attenuata). Results show embryos of dolphins, mice, and pigs share similar spatiotemporal patterns of signaling proteins known to shape limbs of mammals (e...
October 25, 2017: Genesis: the Journal of Genetics and Development
Nozomi Kurihara, Yuko Tajima, Tadasu K Yamada, Ayaka Matsuda, Takashi Matsuishi
The genus Mesoplodon (Cetacea: Odontoceti: Ziphiidae) is one of the few cetacean genera with the karyotype 2n = 42. The 2n = 42 karyotype of M. europaeus and M. carlhubbsi is largely consistent with the general cetacean karyotype 2n = 44, although other 2n = 42 karyotypes do not exhibit clear homologies with the general cetacean karyotype. Therefore, the chromosomes of Mesoplodon species may be the key to understanding cetacean karyological evolution. In the present study, the male karyotypes of M. stejnegeri and M...
October 2017: Genetics and Molecular Biology
Anastasia A Proskuryakova, Anastasia I Kulemzina, Polina L Perelman, Alexey I Makunin, Denis M Larkin, Marta Farré, Anna V Kukekova, Jennifer Lynn Johnson, Natalya A Lemskaya, Violetta R Beklemisheva, Melody E Roelke-Parker, June Bellizzi, Oliver A Ryder, Stephen J O'Brien, Alexander S Graphodatsky
The phenomenon of a remarkable conservation of the X chromosome in eutherian mammals has been first described by Susumu Ohno in 1964. A notable exception is the cetartiodactyl X chromosome, which varies widely in morphology and G-banding pattern between species. It is hypothesized that this sex chromosome has undergone multiple rearrangements that changed the centromere position and the order of syntenic segments over the last 80 million years of Cetartiodactyla speciation. To investigate its evolution we have selected 26 evolutionarily conserved bacterial artificial chromosome (BAC) clones from the cattle CHORI-240 library evenly distributed along the cattle X chromosome...
August 31, 2017: Genes
Mónica Lopes-Marques, Raquel Ruivo, Elza Fonseca, Ana Teixeira, L Filipe C Castro
Gene duplication and loss are powerful drivers of evolutionary change. The role of loss in phenotypic diversification is notably illustrated by the variable enzymatic repertoire involved in vertebrate protein digestion. Among these we find the pepsin family of aspartic proteinases, including chymosin (Cmy). Previous studies demonstrated that Cmy, a neo-natal digestive pepsin, is inactivated in some primates, including humans. This pseudogenization event was hypothesized to result from the acquisition of maternal immune immunoglobulin G (IgG) transfer...
November 2017: Molecular Phylogenetics and Evolution
Gitanjali E Gnanadesikan, William D Pearse, Allison K Shaw
Many organisms migrate between distinct habitats, exploiting variable resources while profoundly affecting ecosystem services, disease spread, and human welfare. However, the very characteristics that make migration captivating and significant also make it difficult to study, and we lack a comprehensive understanding of which species migrate and why. Here we show that, among mammals, migration is concentrated within Cetacea and Artiodactyla but also diffusely spread throughout the class (found in 12 of 27 orders)...
August 2017: Ecology and Evolution
Hal Whitehead
Whales and dolphins (Cetacea) have excellent social learning skills as well as a long and strong mother-calf bond. These features produce stable cultures, and, in some species, sympatric groups with different cultures. There is evidence and speculation that this cultural transmission of behavior has affected gene distributions. Culture seems to have driven killer whales into distinct ecotypes, which may be incipient species or subspecies. There are ecotype-specific signals of selection in functional genes that correspond to cultural foraging behavior and habitat use by the different ecotypes...
July 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
Emily A Buchholtz, Jessica K Gee
Axial morphology was dramatically transformed during the transition from terrestrial to aquatic environments by archaeocete cetaceans, and again during the subsequent odontocete radiation. Here, we reconstruct the sequence of developmental events that underlie these phenotypic transitions. Archaeocete innovations include the loss of primaxial/abaxial interaction at the sacral/pelvic articulation and the modular dissociation of the fluke from the remainder of the tail. Odontocetes subsequently integrated lumbar, sacral, and anterior caudal vertebrae into a single torso module, and underwent multiple series-specific changes in vertebral count...
July 2017: Evolution & Development
Alexandra T Boersma, Matthew R McCurry, Nicholas D Pyenson
Many odontocete groups have developed enlarged facial crests, although these crests differ in topography, composition and function. The most elaborate crests occur in the South Asian river dolphin (Platanista gangetica), in which they rise dorsally as delicate, pneumatized wings anterior of the facial bones. Their position wrapping around the melon suggests their involvement in sound propagation for echolocation. To better understand the origin of crests in this lineage, we examined facial crests among fossil and living Platanistoidea, including a new taxon, Dilophodelphis fordycei, nov...
May 2017: Royal Society Open Science
Travis Park, Felix G Marx, Erich M G Fitzgerald, Alistair R Evans
The pygmy right whale, Caperea marginata, is the least understood extant baleen whale (Cetacea, Mysticeti). Knowledge on its basic anatomy, ecology, and fossil record is limited, even though its singular position outside both balaenids (right whales) and balaenopteroids (rorquals + grey whales) gives Caperea a pivotal role in mysticete evolution. Recent investigations of the cetacean cochlea have provided new insights into sensory capabilities and phylogeny. Here, we extend this advance to Caperea by describing, for the first time, the inner ear of this enigmatic species...
June 2017: Journal of Morphology
Mariana B Ebert, Maria I Mülller, Juliana Marigo, Ana L S Valente, Marta J Cremer, Reinaldo J da Silva
A new species of Synthesium from the bottlenose dolphin Tursiops truncatus in South Brazilian waters is described. Morphological and molecular identification was performed, and phylogenetic analyses were carried out using the ribosomal small subunit and internal transcribed spacer 1 and the mitochondrial NDH dehydrogenase subunit 3 and cytochrome c oxidase subunit 1 genes. The main characteristics of the new species are the subterminal round-shaped oral sucker, the anterior distribution of vitellaria reaching the level of the ovary and the oval-shaped testes...
May 2017: Parasitology Research
Rodrigo S Amaral, Vera M F DA Silva, Fabíola X Valdez Domingos, Anthony R Martin
The spermatozoa from seven adult Amazon river dolphins (Inia geoffrensis, CETACEA: INIIDAE) were analyzed by light and electron microscopy. The spermatozoa showed an elongated ellipsoid shaped head and a long tail with a well distinguishable midpiece. The head spermatozoa have a smooth surface like other odontocetes examined, with the exception of the Delphinidae family. The mean dimensions of the spermatozoa were within the range already reported for other cetaceans. The spermatozoa midpiece, as in other cetaceans, showed a random pattern of mitochondria, different from that described for other mammals...
March 3, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Sarah Z Dungan, Belinda S W Chang
Like many aquatic vertebrates, whales have blue-shifting spectral tuning substitutions in the dim-light visual pigment, rhodopsin, that are thought to increase photosensitivity in underwater environments. We have discovered that known spectral tuning substitutions also have surprising epistatic effects on another function of rhodopsin, the kinetic rates associated with light-activated intermediates. By using absorbance spectroscopy and fluorescence-based retinal release assays on heterologously expressed rhodopsin, we assessed both spectral and kinetic differences between cetaceans (killer whale) and terrestrial outgroups (hippo, bovine)...
March 15, 2017: Proceedings. Biological Sciences
Mark S Springer, John Gatesy
Various toothed whales (Odontoceti) are unique among mammals in lacking olfactory bulbs as adults and are thought to be anosmic (lacking the olfactory sense). At the molecular level, toothed whales have high percentages of pseudogenic olfactory receptor genes, but species that have been investigated to date retain an intact copy of the olfactory marker protein gene (OMP), which is highly expressed in olfactory receptor neurons and may regulate the temporal resolution of olfactory responses. One hypothesis for the retention of intact OMP in diverse odontocete lineages is that this gene is pleiotropic with additional functions that are unrelated to olfaction...
April 2017: Molecular Phylogenetics and Evolution
Maria Carla de Francesco, Anna Loy
Feeding adaptation, social behaviour, and interspecific interactions related to sexual dimorphism and allometric growth are particularly challenging to be investigated in the high sexual monomorphic Delphinidae. We used geometric morphometrics to extensively explore sexual dimorphism and ontogenetic allometry of different projections of the skull and the mandible of the bottlenose dolphin Tursiops truncatus. Two-dimensional landmarks were recorded on the dorsal, ventral, lateral, and occipital views of the skull, and on the lateral view of the left and the right mandible of 104 specimens from the Mediterranean and the North Seas, differing environmental condition and degree of interspecific associations...
2016: PloS One
J Y Lima, A P M Carvalho, C T Azevedo, L A Barbosa, L S Silveira
Variations of age and total length of Sotalia guianensis from the state of Espírito Santo, Brazil, were evaluated. Specimens were found stranded. Age and total length of 44 Guiana dolphins were assessed based on tooth analysis. Age varied between 0.5 year and 33 years (mean = 8.23 years). Most specimens were between zero and 6 years old (47%). Total length varied from 119 cm to 198 cm, with mean of 172.52 cm. Asymptotic length was reached at 185 cm and approximately 5-6 years of age. Mean total length and age were higher than in other regions of the distribution range of the species...
July 2017: Brazilian Journal of Biology, Revista Brasleira de Biologia
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