Genetic regulation of canine skeletal traits: trade-offs between the hind limbs and forelimbs in the fox and dog

Genetic variation in functionally integrated skeletal traitscan be maintained over 10 million years despite bottlenecksand stringent selection. Here, we describe an analysis of thegenetic architecture of the canid axial skeleton using populationsof the Portuguese Water Dog Canis familiaris) and silver fox(Vulpes vulpes). Twenty-one skeletal metrics taken from radiographsof the forelimbs and hind limbs of the fox and dog were usedto construct separate anatomical principal component (PC) matricesof the two species. In both species, 15 of the 21 PCs exhibitedsignificant heritability, ranging from 25% to 70%. The secondPC, in both species, represents a trade-off in which limb-bonewidth is inversely correlated with limb-bone length. PC2 accountsfor approximately 15% of the observed skeletal variation, 30%of the variation in shape. Many of the other significant PCsaffect very small amounts of variation (e.g., 0.2–2%)along trade-off axes that partition function between the forelimbsand hind limbs. These PCs represent shape axes in which an increasein size of an element of the forelimb is associated with a decreasein size of an element of the hind limb and vice versa. In mostcases, these trade-offs are heritable in both species and geneticloci have been identified in the Portuguese Water Dog for manyof these. These PCs, present in both the dog and the fox, includeones that affect lengths of the forelimb versus the hind limb,length of the forefoot versus that of the hind foot, musclemoment (i.e., lever) arms of the forelimb versus hind limb,and cortical thickness of the bones of the forelimb versus hindlimb. These inverse relationships suggest that genetic regulationof the axial skeleton results, in part, from the action of genesthat influence suites of functionally integrated traits. Theirpresence in both dogs and foxes suggests that the genes controllingthe regulation of these PCs of the forelimb versus hind limbmay be found in other tetrapod taxa.     

Age- and sex-associated variations in the directional asymmetry of rhesus macaque forelimb bones

Several investigators have questioned the significance of handedness as an explanation of directional forelimb asymmetries, yet little has been done to isolate other explanatory factors. In this investigation, we analyze 61 female and 76 male rhesus macaque skeletons for evidence of age- and/or sex-associated variations in ten forelimb bone measurements. All significant directional asymmetries are found to favor the right side. Although some of these asymmetries are found to favor the right side. Although some of these asymmetries are compatible with the interpretation of muscle hypertrophy associated with preferential use of the right forelimb, the overall pattern suggests that age- and sex-related ontogenetic factors deserve equal consideration. Significant sex differences in asymmetry means are present within and across age groups (juveniles, subadults, and adults), and numerous changes in asymmetry with age are also found. A pattern of decreasing asymmetry with age was found in males, with 40% of the ten measures being asymmetrical in juveniles, 30% in subadults, and 20% in adults. Among females, this pattern is reversed. No significant asymmetries were found for juvenile or subadult females, whereas 40% of the measures were asymmetrical in adult females. We conclude that greater consideration of age- and sex-related factors is necessary when drawing samples for the purpose of investigating asymmetries, and an awareness of trait-specific age and sex patterns of variation is necessary when citing forelimb asymmetries in demographically nonrepresentative populations as evidence of handedness or other behavioral asymmetries.     

北极狐GHR基因单核苷酸多态性及其与生长性状的相关性分析

文章采用单链构象多态性(PCR-SSCP)和DNA测序的方法检测了北极狐生长激素受体(Growth hormne receptor, GHR)基因的单核苷酸多态性(SNPs), 并针对该群体的特点建立合适的统计分析模型, 对GHR基因多态性与生长性状的相关性进行了分析。结果表明, 在北极狐GHR基因的外显子1和外显子5上发现了4个多态位点, 分别为5′UTR上的G3A和外显子1上的C99T突变, 外显子5上的T59C和G65A突变; GHR基因G3A和C99T多态性与母狐的体重性状显著相关(P<0.05), T59C和G65A多态性与公狐的体重性状显著相关(P<0.05), 与母狐的皮张长度性状极显著相关(P<0.01)。因此, 可以利用以上点突变对北极狐的体重及皮张长度性状进行标记辅助选择研究, 以达到快速选育出快大、优质的北极狐的目的。     

Directional asymmetry in the forelimb of Macaca mulatta

Asymmetry was investigated in the forelimbs of 150 rhesus monkey (Macaca mulatta) skeletons using measurements of right and left humerii, radii, ulnae, second metacarpals, and femora. Seven of the ten forelimb dimensions were larger on the right than on the left side. Paired t-tests revealed that the mean of the right side was significantly larger than that for the left for two measurements of the ulna and two of the humerus. No measurement was significantly larger on the left than on the right side. These results indicate a small but significant asymmetry in the forelimb bones of rhesus monkeys and, as is the case for humans, the direction of asymmetry favors the right side. Our findings are consistent with an interpretation of hypertrophy of certain muscles and opens the question of whether rhesus monkeys preferentially use their right forelimbs for manipulative tasks that require manual dexterity, as is the case for humans. These forelimb skeletal asymmetries are discussed in light of the recent literature on cortical asymmetry and handedness in nonhuman primates.     

Flying foxes as carriers of pathogenic Leptospira species

Recent serologic studies have identified flying foxes (Pteropus spp.) as carriers of leptospirosis; however, little is known about the role of flying foxes as carriers of pathogenic Leptospira spp. To determine if Australian Pteropus spp. are carriers of pathogenic Leptospira spp., TaqMan real-time polymerase chain reaction (PCR) was used to detect leptospiral DNA in kidney and urine specimens from four species of flying fox, including the spectacled flying fox (Pteropus conspicillatus), black flying fox (Pteropus alecto), grey-headed flying fox (Pteropus poliocephalus), and little red flying fox (Pteropus scapulatus). Of the 173 kidney samples tested, 19 (11%) were positive for leptospiral DNA. Positive individuals were detected in all four species; significant differences in prevalence were not detected between species, between species within the same geographic area, or between geographically separated samples from the same species. Of the 46 urine samples tested, 18 (39%) tested positive by PCR, confirming that flying foxes shed leptospires into the environment. The detection of leptospiral DNA in the kidneys and urine of flying foxes suggests that flying foxes are carriers of pathogenic Leptospira spp. No evidence collected in the present study, however, suggests that flying foxes pose a significant risk of leptospirosis to the wider community or that humans who are in regular, close contact with flying foxes are at risk for leptospirosis.     

Brief communication: Locomotor limb preferences in captive chimpanzees (Pan troglodytes): implications for morphological asymmetries in limb bones

Understanding the evolutionary origins of hemispheric specialization remains a topic of considerable interest in a variety of scientific disciplines. Whether nonhuman primates exhibit population-level limb preferences continues to be a controversial topic. In this study, limb preferences for ascending and descending locomotion were assessed as a means of examining the hypothesis that asymmetries in forelimb bones might be attributed to asymmetries in posture. The results indicated that captive chimpanzees showed a population-level leftward asymmetry in descending locomotion but no group bias for ascending locomotion. The results are consistent with previous behavioral studies in captive chimpanzees as well as studies on skeletal asymmetries of the forelimbs of chimpanzees.     

Space use and resting site selection of red foxes (<Emphasis Type="Italic">Vulpes vulpes</Emphasis>) living near villages and small towns in Southern Germany

In 2005–2008, we radio-tracked 17 foxes in rural areas of Southern Germany. The mean home range size was 76.6 ha (95% MCP) or 138.9 ha (95% fixed kernel), and the built-up area formed an integral part of the home range. Home ranges of juvenile foxes were significantly smaller than home ranges of adult foxes. Gender-specific differences among adult foxes were not established. A minimum population density of 2.7 foxes per km² and summer densities of up to 13.4 foxes per km² were calculated. Therefore, the fox density was three to eight times higher than that of strictly rural foxes. Daytime resting sites of foxes were mostly found in forests (62.2%) and reedbed areas (20.6%). Of the resting sites, 14.8% were situated inside settlements, in fallow gardens or gardens of residents. During the day, foxes exhibited habitat preferences for forests and reedbed areas. A habitat structure that offers plenty of cover or dense vegetation is essential for its selection as a safe resting site. If this basic requirement is fulfilled, foxes also choose resting sites within settlements, and are not disturbed by human presence.     

长江源区同域分布兔狲、藏狐和赤狐的时空重叠度

兔狲(Otocolobus manul)、藏狐(Vulpes ferrilata)和赤狐(V. vulpes)是青藏高原三江源区域分布的重要小型食肉兽。本研究于2014年6月至2019年9月在青海省长江源区沱沱河和通天河沿岸选取208个位点布设红外相机, 通过所获取的时空分布数据比较了上述3种同域分布小型食肉兽的时空利用情况。通过空间重叠度系数的比较分析, 兔狲和藏狐、兔狲和赤狐以及藏狐和赤狐之间的空间重叠度系数分别为0.25、0.48和0.17, 这表明兔狲、藏狐和赤狐三者在空间利用上存在一定的差异。通过核密度估计方法分析, 兔狲和藏狐属典型的昼行性动物, 而赤狐以夜行性活动为主。兔狲、藏狐和赤狐每个物种在冷暖两季的日活动节律重叠指数分别为0.83、0.78和0.88。两两比较分析表明, 兔狲和藏狐二者的日活动节律重叠指数最高(0.84), 兔狲和赤狐在夜间活动时段存在一定重叠(0.63), 而藏狐和赤狐的时间生态位分化最明显, 重叠指数最低(0.48)。此外, 在暖季, 两两物种之间的日活动节律重叠指数均小于其冷季的重叠指数。综上所述, 长江源区兔狲、藏狐和赤狐3种小型食肉兽可通过空间和时间资源的利用差异来降低物种间的干扰和竞争, 从而达到同域物种共存的目的。     

Development of fluctuating asymmetry in tail feathers of the barn swallow Hirundo rustica

Fluctuating asymmetry represents usually small, random deviations from symmetry in bilateral morphological characters. The ontogeny of asymmetry in morphological characters may reveal information about developmental processes in a general sense. I studied the development of fluctuating asymmetry in feather characters of the barn swallow Hirundo rustica, that are developed repeatedly during the single annual moult, with the following results. First, the side developing a larger feather was found to be partially biased, as demonstrated by one side consistently developing a larger feather under natural and experimentally induced growth episode events. Second, asymmetric feathers were found to consist of asymmetric daily growth increments, and the size of the increments developing under different environmental conditions were positively correlated. Third, fluctuating asymmetries of feathers developing under different environmental conditions were positively correlated, although the level of asymmetry was larger under adverse environmental conditions. Fourth, individual asymmetries in tail length and growth bar length were unrelated to the duration of the developmental period, although late growth increments were smaller and more symmetric than early increments. These observations suggest that fluctuating asymmetry partially arises as a consequence of a random bias in the feather follicles and differences in environmental conditions during ontogeny of feathers.     

Do Exotic Vertebrates Structure the Biota of Australia? An Experimental Test in New South Wales

From 1993 to 2001, we conducted a series of experiments in a mixed grassland–woodland system in central New South Wales (NSW) to quantify the interactions between red foxes and their prey and competitors. Foxes were removed from two areas around the perimeter of Lake Burrendong, and data were collected from these areas and a nearby untreated area before, during, and after the period of fox control. The arrival of rabbit hemorrhagic disease (RHD) in 1996 provided an opportunity to examine the interactive effects of controlling foxes and rabbits. In this landscape, typical of central NSW, (a) the fox population was not affected by a large reduction in the abundance of rabbits, or vice versa; (b) the cat population declined in areas where foxes were removed after the large RHD-induced reduction in rabbit numbers, but there was no consistent response to the removal of foxes; (c) the abundance of some macropod species increased in response only to the combined removal of rabbits and foxes; (d) there were no consistent changes in the abundances of bird species in response to the removal of either foxes or rabbits, but there were clear habitat differences in bird species richness; and (e) there was likely to be an increase in woody plant species after the large reduction in rabbit populations by RHD. We conclude that (a) long-term field experiments (more than 3 years) are required to quantify the indirect consequences of controlling foxes and rabbits, and (b) single manipulations, such as fox control or rabbit control, are not necessarily sufficient for the conservation of remnant woodland communities in southeastern Australia.     

Spatial use and interaction of the invasive raccoon dog and the native red fox in Central Europe: competition or coexistence?

The main objective was to discover extent of interference and/or exploitative competition between the native red fox (Vulpes vulpes) and the introduced, invasive raccoon dog (Nyctereues proconoides) in the intensively used, agricultural landscape of northeast Germany (Mecklenburg-Western Pomerania) using very high frequency (VHF) radio telemetry. We recorded location data for 12 foxes and 16 raccoon dogs between July 2004 and December 2006. Species had similar average home range sizes estimated in each season (K95). Home ranges of adjacent raccoon dogs and foxes overlapped from 0.5 to 74.5 % with a mean of 26.4 %. We found a significantly different home range overlap index between the species showing that raccoon dog ranges shifted between seasons to a greater extent than red fox ranges. The raccoon dog differed significantly from the red fox in its use of habitat types, preferring dense vegetation cover and avoiding open areas. The red fox displayed less preference for or avoidance of specific habitat types. Moreover, an almost neutral inter-specific interaction index ranging from ?0.12 to 0.12 indicates that raccoon dogs and red foxes ignored each other. It is concluded that widespread and available resources and differences in spatial use patterns prevent competition between red foxes and raccoon dogs in the agricultural landscape of northeast Germany.     

Patterns of fluctuating asymmetry in developing primary feathers: a test of the compensational growth hypothesis

The study of asymmetry ontogeny may reveal the mechanisms controlling the development of bilaterally symmetrical characters and the causes of asymmetry. In birds, flight feather asymmetries appear to increase at the beginning of growth and decrease at the end of their development. It has been proposed that such a pattern could be proximately caused by a developmental mechanism of compensational growth between the left and right wings, which should act to restore trait symmetry at the end of growth. In this study, I tested the hypothesis of the existence of a mechanism of compensational growth by performing an experiment, which consisted of provoking small asymmetries in the seventh primary feathers of house sparrows (Passer domesticus) by inducing the two feathers (one each side) to moult two days apart. On each side, the feathers grew in a similar way, independently of the growth of the other side. Feather length asymmetries were shortened with the advance of growth. However, the differences in time of growth persisted throughout development. These results do not support the existence of a mechanism of compensational growth. Primary feathers'' asymmetries could decrease at the end of growth because the growth of the two feathers follows a programmed trajectory, which tends towards a certain maximum potential size.     

A marker set for construction of a genetic map of the silver fox (Vulpes vulpes)

The silver fox, a variant of the red fox (Vulpes vulpes), is a close relative of the dog (Canis familiaris). Cytogenetic differences and similarities between these species are well understood, but their genomic organizations have not been compared at higher resolution. Differences in their behavior also remain unexplained. Two silver fox strains demonstrating markedly different behavior have been generated at the Institute of Cytology and Genetics of the Russian Academy of Sciences. Foxes selected for tameness are friendly, like domestic dogs, while foxes selected for aggression resist human contact. To refine our understanding of the comparative genomic organization of dogs and foxes, and enable a study of the genetic basis of behavior in these fox strains, we need a meiotic linkage map of the fox. Towards this goal we generated a primary set of fox microsatellite markers. Four hundred canine microsatellites, evenly distributed throughout the canine genome, have been identified that amplify robustly from fox DNA. Polymorphism information content (PIC) values were calculated for a representative subset of these markers and population inbreeding coefficients were determined for tame and aggressive foxes. To begin to identify fox-specific single nucleotide polymorphisms (SNPs) in genes involved in the neurobiology of behavior, fox and dog orthologs of serotonin 5-HT1A and 5-HT1B receptor genes have been cloned. Sequence comparison of these genes from tame and aggressive foxes reveal several SNPs. The close relationship of the fox and dog enables canine genomic tools to be utilized in developing a fox meiotic map and mapping behavioral traits in the fox.     

Genetic polymorphism of plasma α1B-glycoprotein and transferrin in arctic and silver foxes

Plasma samples of 235 foxes from 38 complete families (14 of arctic foxes, 21 of silver foxes and 3 with arctic x silver fox hybrid offspring) were analysed by one-dimensional horizontal polyacrylamide gel electrophoresis (PAGE) pH 9.0 followed by general-protein staining of gels. A major postalbumin of fox plasma was identified as alpha 1B-glycoprotein (alpha 1B) by using immunoblotting with antiser m specific to human or pig plasma alpha 1B. Four codominant, autosomal alleles of alpha 1B were found in arctic foxes. Two transferrin (TF) alleles (TfF, TfS) were observed in arctic foxes and two (TfD, Tff) in silver foxes; the TF F type of both of the fox species showed identical electrophoretic mobilities. The arctic foxes showed a high degree of polymorphism for both TF and alpha 1B. The silver foxes showed a scarce polymorphism of TF and were monomorphic for alpha 1B. The arctic fox, silver fox and their hybrids could be clearly differentiated from one another by their plasma protein patterns obtained by the PAGE method.     

Does culling reduce fox (Vulpes vulpes) density in commercial forests in Wales, UK?

Forests within agricultural landscapes can act as safe harbourages for species that conflict with neighbouring landowners’ interests, including mammalian predators. The agency responsible for the management of forests in upland Wales, UK, has permitted the killing of foxes (Vulpes vulpes) on their land as a “good neighbour policy” with the aim of reducing fox numbers. The principal method used was the use of dogs to drive foxes to a line of waiting shooters; a small number of foxes were also killed by shooting at night with a rifle. However, it has been postulated that recent restrictions on the use of dogs to kill foxes in Britain could lead to an increase in fox numbers in plantations. The aim of this study was to determine whether over-winter culling (i.e. driving foxes to guns using dogs and rifle shooting) in these forests acted to reduce fox density. Fox faecal density counts were conducted in commercial forests in Wales in autumn 2003 and spring 2004. Data were analysed from 29 sites (21 individual forests and 8 forest blocks, the latter consisting of pooled data from 20 individual forests). The over-winter change in faecal density was negatively related to the proportion of felled land and the proportion of land more than 400 m altitude, these associations probably reflecting reduced food availability. Over-winter change was positively associated with culling pressure (i.e. more foxes were killed where more foxes were present, or vice versa), but this was not significant. The number of foxes killed was large relative to the estimated resident population, but losses appeared to be negated (most likely) by immigration. Pre-breeding (spring) faecal density counts were significantly positively related to culling pressure, i.e. more foxes were killed with increased fox density or vice versa. Overall, there was no evidence to suggest that culling reduced fox numbers. Consequently, restrictions on the use of dogs to control foxes are unlikely to result in an increase in fox numbers in commercial forests.     

The effects of sex,age, season and habitat on diet of the red fox <Emphasis Type="Italic">Vulpes vulpes</Emphasis> in northeastern Poland

The diet of the red fox Vulpes vulpes was investigated in five regions of northeastern Poland by stomach content analysis of 224 foxes collected from hunters. The red fox is expected to show the opportunistic feeding habits. Our study showed that foxes preyed mainly on wild prey, with strong domination of Microtus rodents, regardless of sex, age, month and habitat. Voles Microtus spp. were found in 73% of stomachs and constituted 47% of food volume consumed. Other food items were ungulate carrion (27% of volume), other mammals (11%), birds (9%), and plant material (4%). Sex- and age-specific differences in dietary diversity were found. Adult males and juvenile foxes had larger food niche breadths than adult females and their diets highly overlapped. Proportion of Microtus voles increased from autumn to late winter. Significant habitat differences between studied regions were found. There was a tendency among foxes to decrease consumption of voles with increasing percentage of forest cover. Based on our findings, red foxes in northeastern Poland can be recognized as a generalist predators, consuming easily accessible and abundant prey. However, high percentage of voles consumed regardless of age, sex, month, or habitats may indicate red fox specialization in preying on Microtus rodents.     

Farmed arctic foxes on the Fennoscandian mountain tundra: implications for conservation

Hybridization between wild and captive-bred individuals is a serious conservation issue that requires measures to prevent negative effects. Such measures are, however, often considered controversial by the public, especially when concerning charismatic species. One of the threats to the critically endangered Fennoscandian arctic fox Alopex lagopus is hybridization with escaped farm foxes, conveying a risk of outbreeding depression through loss of local adaptations to the lemming cycle. In this study, we investigate the existence of escaped farm foxes among wild arctic foxes and whether hybridization has occurred in the wild. We analysed mitochondrial control region sequences and 10 microsatellite loci in samples from free-ranging foxes and compared them with reference samples of known farm foxes and true Fennoscandian arctic foxes. We identified the farm fox specific mitochondrial haplotype H9 in 25 out of 182 samples, 21 of which had been collected within or nearby the wild subpopulation on Hardangervidda in south-western Norway. Genetic analyses of museum specimens collected on Hardangervidda (1897–1975) suggested that farm fox genotypes have recently been introduced to the area. Principal component analysis as well as both model- and frequency-based analyses of microsatellite data imply that the free-ranging H9s were farm foxes rather than wild arctic foxes and that the entire Hardangervidda population consisted of farm foxes or putative hybrids. We strongly recommend removal of farm foxes and hybrids in the wild to prevent genetic pollution of the remaining wild subpopulations of threatened arctic foxes.     

Natal den selection by sympatric arctic and red foxes on Herschel Island,Yukon, Canada

In the twentieth century, red fox (Vulpes vulpes) expanded into the Canadian Arctic, where it competes with arctic fox (Vulpes lagopus) for food and shelter. Red fox dominates in physical interactions with the smaller arctic fox, but little is known about competition between them on the tundra. On Hershel Island, north Yukon, where these foxes are sympatric, we focused on natal den choice, a critical aspect of habitat selection. We tested the hypothesis that red fox displaces arctic fox from dens in prey-rich habitats. We applied an approach based on model comparisons to analyse a 10-year data set and identify factors important to den selection. Red fox selected dens in habitats that were more prey-rich in spring. When red foxes reproduced, arctic fox selected dens with good springtime access, notably many burrows unblocked by ice and snow. These provided the best refuge early in the reproductive season. In the absence of red foxes, arctic foxes selected dens offering good shelter (i.e. large isolated dens). Proximity to prey-rich habitats was consistently less important than the physical aspects of dens for arctic fox. Our study shows for the first time that red foxes in the tundra select dens associated primarily with prey-rich areas, while sympatric arctic foxes do not. These results fit a model of red fox competitively interfering with arctic fox, the first detailed study of such competition in a true arctic setting.     

Comparative nutrient digestibility of arctic foxes (Alopex lagopus) on Svalbard and farm-raised blue foxes (Alopex lagopus)

Arctic foxes from Svalbard (n=4) and farmed blue foxes (n=4) was used in a digestibility experiment with a high-carbohydrate feed to add more information to the nutritional physiology of the arctic fox, and to compare its digestive capacity with that of the farmed blue fox. The arctic fox has a diet containing mainly protein and fat from mammals and birds, while farmed blue foxes have been exposed to an omnivorous dietary regime for more than 80 generations. The experiment showed in general no difference in digestive capacity for protein and fat between the foxes (P>0.05), but for carbohydrates, including starch and glucose, the blue fox revealed higher digestibility values. The superior digestive capacity for carbohydrates in blue fox might be a result of a long-term selection of animals digesting dietary carbohydrates more efficiently, or that an early age exposition to dietary carbohydrates has given permanent improvement of the carbohydrate digestion in the gut.     

THE ONTOGENY OF ASYMMETRY IN EARWIG FORCEPS

Fluctuating asymmetry may play an important role in the evolution of naturally selected and secondary sexual traits. However, very little is known about how asymmetries arise or how organisms maintain symmetry during development. Here I propose three mutually exclusive patterns for the development of asymmetries through consecutive growth stages: (1) compensatory growth, in which growth of the shorter side is greatest at the following growth stage; (2) persistent growth, in which growth of the longer side is greatest at the following growth stage; and (3) uncorrelated growth in which growth of the following stage is unrelated to the asymmetry at the previous one. I followed the growth in the forceps of male earwigs through four successive instars. Dyar's rule was used as a null model of insect growth. In the molt from the second to third instar, asymmetries increased through uncorrelated growth and with the magnitude but not the sign expected from Dyar's rule. However, following this, at the molts between instars 3–4 and 4–5, compensatory growth maintained asymmetries at a lower level than expected from Dyar's rule. Although there was no reduction in the absolute magnitude of asymmetry, relative asymmetry did decline. The net growth of forceps length did not follow Dyar's rule. The interpretation of patterns of growth were more sensitive and informative than the interpretation of the relations between asymmetries at consecutive instars.