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PubMed1991

Catecholaminergic amacrine cells in the dog and wolf retina.

Catecholaminergic (presumed dopaminergic) amacrine cells in the retinae of Beagle dogs (canis lupus f. familiaris) and wolves (canis lupus) were visualized with an antiserum against tyrosine hydroxylase (TH). In both species, TH immunoreactivity is found in a population of amacrine cells with large somata (about 14 microns diameter) and large, moderately branched dendritic trees. Somata are located in the proximal inner nuclear layer (normal amacrines) or in the ganglion cell layer (displaced amacrines). Most dendrites stratify in a narrow band in the inner plexiform layer close to the inner nuclear layer, where they form a dense plexus with the characteristic pattern of "dendritic rings." The displaced cells have some of their dendrites in a proximal stratum of the inner plexiform layer. A few immunopositive processes are found in the outer plexiform layer (interplexiform processes). In Beagle dogs, the cell density of catecholaminergic amacrines varies from less than 1/mm2 in far periphery to 40-55/mm2 in central retina (mean density 21/mm2). The proportion of displaced amacrines varies locally from 10 to 85% (overall proportion 41% in one retina). In the wolf, densities of catecholaminergic cells range between about 3/mm2 in peripheral and up to 35/mm2 in central retina. The proportion of displaced cells is somewhat lower than in dogs, varying between 11 and 31% across the retina. The morphology and density distribution of canine catecholaminergic amacrines resemble that of other mammalian retinae. A marked difference, however, is the high percentage of displaced cells in both dog and wolf retina; it is the highest found in any mammal so far. The displaced and normal cells appear to be members of a single functional population. A comparison of the topographic distributions of catecholaminergic amacrines, rods, and ganglion cells in the dog retina shows no consistent density correlations between these neurons that are all part of the rod pathway.

Animals↗

PubMed2001

(Z)-3-hexenyl (R)-3-hydroxybutanoate: a male specific compound in three North American decorator wasps Eucerceris rubripes, E. conata and E. tricolor.

The males of the decorator wasps Eucerceris have been observed to display abdomen-dragging behavior on plants surrounding their nest. It is thought that this applies a territorial-marking sex pheromone that serves to alert females to the males' territory for courtship and mating. The extracts of three species E. rubripes, E. conata, and E. tricolor have been analyzed by GC-MS. The gas chromatograms revealed the presence, in large quantities, of one common volatile compound in the male head extracts. By analogy with the closely related bee wolves Philanthus, we believe the pheromone is produced in the mandibular glands. Utilizing mass spectrometry, microreactions, FT-IR, and 1H and 13C NMR spectroscopy the structure of the pheromone was proposed to be (Z)-3-hexenyl 3-hydroxybutanoate, which was confirmed by synthesis. The absolute configuration of the chiral center was determined to be R for the three species by preparing the Mosher esters of the insect samples and comparing their GC retention times with a synthetic sample of known absolute configuration. In addition 2- and 3-hexenoic acid and some aromatic compounds were also found in varying quantities in both males and females along with hydrocarbons and fatty acids, although no species-specific profiles emerged.

Animals↗

PubMed1997

Individual differences and their relation to social structure in domestic cats.

Two groups of domesticated cats with established social structures were tested for their response to novel stimuli in a variety of test situations. Clear individual differences in responses were consistent over a series of test sessions and remained stable despite regular environmental changes. Individual differences in behavioral response were not related to object dominance (food competition) or social dominance (freedom of movement in social encounters) unlike similar studies with social animals. No relationship was found in either group between a cat's rank in object dominance and its rank in social dominance. Significant correlations were demonstrated in the individual cat's latency to approach a novel stimulus, behavioral rank in test situations, and attention span in both groups of cats. Comparisons were made between similar studies with wolves, and inferences were drawn about the relationship between individual differences and social structure in social and nonsocial species.

Animals↗

PubMed1991

Food caching in captive coyotes: stereotypy of action sequence and spatial distribution of cache sites.

This paper describes some aspects of the food caching behaviour of four captive coyotes. Detailed observations of the actions used by coyotes to cache food revealed them to be strikingly similar to those previously described for timber wolves. The similarities included the identity of the movements used, their temporal sequencing, and their susceptibility to interruption. This suggests that there exists a stereotypy across canids in the action sequences used in caching. Second, an examination of the distribution of cache sites revealed that each coyote scattered cache sites widely within a wooded region of their enclosure and preferentially in terrains close to exposed tree roots.

Animals↗

PubMed1989

DNA phylogeny of the extinct marsupial wolf.

The phylogenetic affiliation of the extinct marsupial wolf (Thylacinus cynocephalus), which once was widespread in Australia, has been uncertain. On the basis of morphology, some systematists argue that the thylacine was most closely related to an extinct group of South American carnivorous marsupials, the borhyaenids, whereas others consider it to be closer to Australian carnivorous marsupials. Here we use direct sequencing by means of the polymerase chain reaction (PCR) to compare 219 bases of mitochondrial (mt) DNA from museum specimens of the marsupial wolf and representatives of six genera of extant marsupials. In agreement with the results of an antigenic study of albumin, our genetic data suggest that the marsupial wolf was more closely related to other Australian marsupial carnivores than to those of South America. Thus, the marsupial wolf represents an example of convergent morphological evolution to South American carnivorous marsupials as well as to true wolves.

Amino Acid Sequence↗

PubMed1987

Growth stage dependent expression of MHC antigens on the canine transmissible venereal sarcoma.

Canine transmissible venereal sarcoma (CTVS) is a naturally occurring contagious neoplasm which can be transplanted with intact viable cells across major histocompatibility (MHC) barriers within the species and even to other members of the canine family, such as foxes, coyotes, and wolves. After 2 to 4 months of progressive growth the tumour regresses spontaneously in adults but metastasizes in immunosuppressed hosts and neonates. The mechanisms of how the tumour cells manage to overcome histocompatibility barriers so successfully for such a long period and yet succumb later are not known. In the present study we found that CTVS cells were not stimulatory to the lymphocytes of normal or tumour-bearing animals in mixed lymphocyte-tumour reaction (MLTR), although the lymphocytes from tumour-bearing animals in mixed lymphocyte-tumour reaction (MLTR), although the lymphocytes from tumour-bearing hosts responded well to either phytohaemagglutinin (PHA) or third-party allogeneic lymphocytes. Immunofluorescent antibody (IFA) assay of MHC antigens by monoclonal antibodies (MoAb) to monomorphic Class I and Class II MHC antigens showed that progressor tumour cells lacked the expression of the antigens whereas 30 to 40% of regressor tumour cells expressed them.

Animals↗

PubMed2026

Skull morphology of the extinct Tasmanian tiger suggests unique biting style.

The recently extinct thylacine (Tasmanian tiger) was the largest modern marsupial predator. It is considered a classic example of evolutionary convergence due to striking similarities with placental canids (e.g., foxes and wolves), particularly in the skull, despite ~160 million years of evolutionary separation. However, we here present geometric and linear morphometric evidence that the thylacine's cranial form arises from a mosaic of traits not represented among canids or other living mammalian carnivores. Thylacines had disproportionately large heads, tall and gracile snouts with a flared canine region, and conspicuously large infraorbital foramina. Many of these traits suggest adaptations to fast, high-impact snapping behaviour in prey capture, as proposed for several living and extinct predatorial vertebrates with similar trait combinations. The thylacine's cranial function may therefore not be inferable from observation of living mammals. However, genomic progress presents new opportunities for future insights into the evolution and development of thylacine cranial adaptation.

Animals↗

PubMed2004

North Spain (Burgos) wild mammals ectoparasites.

Twenty-seven species of arthropods were collected from 105 wild mammals, six wolves Canis lupus (Linnaeus, 1758) included. A total of 87 animals (82.8%) harboured some ectoparasites. Ticks were found in 60% of the samples, fleas in 51.4%, chewing-lice in 3.8%, and others (Mesostigmata and hippoboscids) in 3.8%. Moreover, 42.5% were single infestation and 57.5% mixed. Some of the species were new records for a host in spanish country such as Trichodectes canis (De Géer, 1778), Ixodes trianguliceps (Birula, 1895), Ceratophyllus (Monopsyllus) S. sciurorum (Schrank, 1803) and Paraceras melis melis (Walker, 1856) on several mammals. Two species were new records for Spain: Chaetopsylla matina (Jordan, 1925) and Archaeopsylla erinacei erinacei (Bouché, 1835).

Animals↗

PubMed1994

Influence of body morphology on turning behavior in carnivores.

The present work illustrates how three carnivore species with different body morphologies differ in the performance of a basic motor component-turning. Marbled polecats, which have an elongated and slender trunk, turn while sharply bending the trunk laterally. Grey wolves possess elongated legs and turn by maneuvering with their legs while slightly bending the trunk laterally and lowering the head to contact the ground. Honey badgers feature a wide and massive bear-like shape and rarely bend the trunk, but rather turn either by maneuvering with their legs or while elevating parts of the trunk in the vertical domain. It is suggested that these strategies shorten the radius of turning and thus reduce the moment of inertia. A lower moment of inertia may optimize turning behavior in terms of speed, energy cost, and the smoothness of transition between turning and bouts of forward progression or arrest.

Journal Article↗

PubMed2003

Canine transmissible venereal tumour: cytogenetic origin, immunophenotype, and immunobiology. A review.

Canine transmissible venereal tumour (CTVT) is the only known naturally occurring tumour that can be transplanted as an allograft across major histocompatibility (MHC) barriers within the same species, and even to other members of the canine family, such as foxes, coyotes and wolves. The progression of this tumour is unique in that, it follows a predictable growth pattern. In natural and experimental cases, the growth pattern includes progressive growth phase, static phase and regression phase, and this is followed by transplantation immunity in immunocompetent adults, while metastasis occurs in puppies and immunosuppressed dogs. Because of the uniqueness of CTVT transmission and progression, experimental investigations of various aspects of the biology of CTVT have been used to provide clues to the immunobiology of both animal and human tumours. This review examines the current state of knowledge of the aspects of the cytogenetic origin, immunophenotype, immunobiology and immunotherapy of CTVT.

Animals↗

PubMed1994

Transfer of 210Po and 210Pb through the lichen-caribou-wolf food chain of northern Canada.

Natural background activity and food chain transfer of the uranium decay products, 210Po and 210Pb, were examined in the lichen-caribou-wolf food chain at two locations in the Northwest Territories of Canada. 210Po and 210Pb activities in lichens differed with species and location. Both 210Po and 210Pb were markedly higher in caribou bone than in wolf bone. 210Po activities in liver, kidney, and muscle were similar in both species. Caribou fetuses had lower activities of 210Po but higher activities of 210Pb than maternal muscle and placenta, suggesting greater placental transport of 210Pb than 210Po. Concentration ratios (CR = Bq kg-1 in consumer/Bq kg-1 in its food source) and ff values (ff in d kg-1 = Bq kg-1 in muscle/Bq d-1 ingested) showed that wolves retain more 210Po and less 210Pb from their diet than do caribou. 210Po CRs averaged 0.38 for caribou/lichens, 0.26 for caribou/rumen contents, and 0.40 for wolves/caribou. 210Pb CRs averaged 0.36 for caribou/lichens, 0.57 for caribou/rumen contents, and 0.13 for wolves/caribou.

Animals↗

PubMed2024

Evolutionary consequences of domestication on the selective effects of new amino acid changing mutations in canids.

The domestication of wild canids led to dogs no longer living in the wild but instead residing alongside humans. Extreme changes in behavior and diet associated with domestication may have led to the relaxation of the selective pressure on traits that may be less important in the domesticated context. Thus, here we hypothesize that strongly deleterious mutations may have become less deleterious in domesticated populations. We test this hypothesis by estimating the distribution of fitness effects (DFE) for new amino acid changing mutations using whole-genome sequence data from 24 gray wolves and 61 breed dogs. We find that the DFE is strikingly similar across canids, with 26-28% of new amino acid changing mutations being neutral/nearly neutral (|s| < 1e-5), and 41-48% under strong purifying selection (|s| > 1e-2). Our results are robust to different model assumptions suggesting that the DFE is stable across short evolutionary timescales, even in the face of putative drastic changes in the selective pressure caused by artificial selection during domestication and breed formation. On par with previous works describing DFE evolution, our data indicate that the DFE of amino acid changing mutations depends more strongly on genome structure and organismal characteristics, and less so on shifting selective pressures or environmental factors. Given the constant DFE and previous data showing that genetic variants that differentiate wolf and dog populations are enriched in regulatory elements, we speculate that domestication may have had a larger impact on regulatory variation than on amino acid changing mutations.

Journal Article↗

PubMed2025

The distribution of fitness effects varies phylogenetically across animals.

The distribution of fitness effects (DFE) describes the selection coefficients () of newly arising mutations and fundamentally influences population genetic processes. However, the extent and mechanisms of DFE variation have not been systematically investigated across species with divergent phylogenetic histories and ecological functions. Here, we inferred the DFE in natural populations of eleven animal (sub)species, including humans, mice, fin whales, vaquitas, wolves, collared flycatchers, pied flycatchers, halictid bees, Drosophila, and mosquitoes. We find that the DFE co-varies with phylogeny, where the expected mutation effects are more similar in closely related species (). Additionally, mammals have a higher proportion of strongly deleterious mutations (22% to 47% in mammals; 0.0% to 5.4% in insects and birds) and a lower proportion of weakly deleterious mutations than insects and birds. Population size is significantly negatively correlated with the expected impact of new deleterious mutations (), and the proportion of new beneficial mutations (). These findings align with Fisher's Geometric Model (FGM), which defines organismal complexity as the number of phenotypes under selection. Consistent with the FGM's predictions, we observe that mutations are more deleterious in complex organisms, while beneficial mutations occur more frequently in smaller populations to compensate for the drift load. Our study demonstrates strong phylogenetic constraints in the evolution of a fundamental population genetics parameter, and proposes that, through mechanisms of global epistasis, long-term population size and organismal complexity drive variation in the DFE across animals.

Fisher’s geometric model↗

PubMed2005

The canine genome.

The dog has emerged as a premier species for the study of morphology, behavior, and disease. The recent availability of a high-quality draft sequence lifts the dog system to a new threshold. We provide a primer to use the dog genome by first focusing on its evolutionary history. We overview the relationship of dogs to wild canids and discuss their origin and domestication. Dogs clearly originated from a substantial number of gray wolves and dog breeds define distinct genetic units that can be divided into at least four hierarchical groupings. We review evidence showing that dogs have high levels of linkage disequilibrium. Consequently, given that dog breeds express specific phenotypic traits and vary in behavior and the incidence of genetic disease, genomic-wide scans for linkage disequilibrium may allow the discovery of genes influencing breed-specific characteristics. Finally, we review studies that have utilized the dog to understand the genetic underpinning of several traits, and we summarize genomic resources that can be used to advance such studies. We suggest that given these resources and the unique characteristics of breeds, that the dog is a uniquely valuable resource for studying the genetic basis of complex traits.

Animals↗

PubMed1980

Evolution of canine information processing under conditions of natural and artificial selection.

The paper first argues that under conditions of domestication animals are necessarily selected (incidentally or otherwise) for (1) responsitivity to a broad band of stimuli and (2) behavioral plasticity. The consequent tractability of domestic animals is contrasted with the stimulus-boundness and response stereotypy of the fixed action patterns observed in wild animal behavior. It is suggested that this difference accounts for the differential trainability of wolves and dogs. The second section of the paper presents observational evidence that although capacity for observational learning. It is then noted that since observational learning requires recognition of means-ends relationships this conclusion is inconsistent with the claim that wolf behavior is largely instinct-bound. Finally, these conclusions are reconciled by hypothesizing that the wolf possesses a "duplex" information-processing system, a primitive "instinctual" system that mediates basic survival responses and a more recently acquired "cognitive" system that evolved as the wolf became a group hunter. Neurobehavioral and developmental comparisons of wolf and dog suggest that these two systems have become integrated into a single scheme in the course of the dog's domestication.

Animals↗

PubMed1972

Peripheral thermoregulation: foot temperature in two Arctic canines.

Arctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory. Proportional thermoregulation stabilized the subcutaneous temperature of the foot pad to a precision of +/- 0.7 degrees C (largest deviations). Selective shunting of blood-borne body heat through a cutaneous vascular plexus in the foot pad accounted for more than 99 percent of measured heat loss from the pad surface. Maximum energetic efficiency is achieved because the unit of heat exchange is located in the pad surface which contacts the cold substrate rather than throughout the pad.

Animals↗

PubMed1982

Development of rotation of mandibular premolar tooth germs in the dog.

The development of premolar tooth germs in dogs, particularly their rotation and crowding, was examined on radiographs, dissected specimens of tooth germs, serial sections stained by Masson-Goldner's technique and reconstructed models. The materials used were the mandibles of 32 puppies from birth to 6 months, and the species was a highly pedigreed Shiba Inu which has no crowding of the premolars in the mature stage. The results obtained are as follows. (1) Rotations and crowdings of premolars, similar to those in brachygnathus dogs and wolves raised in captivity, were observed during ontogenesis of dolichocephalic dogs, whose adult state exhibits no crowding of teeth. (2) The type of rotation was B (the mesial portion is rotated buccally) for the second and third premolars and L (the mesial portion lingually) for the fourth premolar. (3) The rotations of the premolars did not coincide with those of their deciduous predecessors. (4) These rotations appeared in the bud and cap stages of premolars, before the formation of roots of deciduous molars. The premolars developed crowding at 5 months when they increased in dimension.

Aging↗

PubMedDate not supplied

Differentiation of the Italian wolf and the domestic dog based on microsatellite analysis.

The Italian wolf is in the process of regaining the Alpine region which comes into conflict with the extensive sheep keeping practiced in Switzerland during the summer. As in Switzerland, the wolf is a protected species, the government reimburses losses caused by wolves. Therefore we wanted to know whether the Italian wolf could be distinguished from the domestic dog by microsatellite analysis if DNA samples of the predators could be secured. The evaluation of combined genotypes for the microsatellites CanBern6, CPH4, CPH7, CPH9, CPH12, CPH22 and ZuBeCa1 made it possible to identify an individual as either a domestic dog or an Italian wolf. The assignment of an individual to either one of the two populations is based on the logarithm of the likelihood ratio of an individual being an Italian wolf rather than a domestic dog, given a specific combined genotype. The distribution of the Italian wolf combined genotypes (n=42) is clearly distinct from the distribution of the domestic dog combined genotypes (n=90). The likelihood ratio for the "worst" Italian wolf combined genotype was 2.3 E+5 and for the "worst" domestic dog combined genotype was 3.8 E-5.

Journal Article↗