Sexual size dimorphism in the lizard Oplurus cuvieri cuvieri (Squamata,Opluridae) from Madagascar

Sexual size dimorphism in the medium-sized lizard Oplurus cuvieri cuvieri, which is endemic to the dry deciduous forest of Madagascar, is presented. Adults are sexually dimorphic in body size, head size, and tail length. Males have a greater snout–vent length (SVL), head depth, head width, jaw length, tail length and body mass than females. Juvenile males have greater annual SVL growth rates than juvenile females, contributing to adult sexual size dimorphism. Moreover, the rates of increase in head depth and width differ significantly between the sexes after reaching maturity so that adult males have larger heads for a given body size than adult females. I suggest three proximate mechanisms that may cause sex-related differences in adult head size of O. c. cuvieri based on natural selection; to reduce intersexual food competition, sexual selection involving mate acquisition in males, and ontogenetic change of allometry to improve reproductive output in females.     

新疆塔里木盆地叶城沙蜥的两性异形

叶城沙蜥是一种主要分布于中国新疆南部地区的蜥蜴,通过测量和比较采自新疆塔里木盆地且末县叶城沙蜥的个体大小以及口宽等8个形态特征,研究了叶城沙蜥的两性异形。研究共采集叶城沙蜥62只,其中成年雌性个体27只,雄性个体35只。结果显示:(1)叶城沙蜥雌雄性成体的体长有显著差异,雄性大于雌性,表明叶城沙蜥具有雄性偏大的两性异形模式;(2)叶城沙蜥其他身体形态特征中尾长、腹长和头长3个特征有显著差异,其中雄性的尾长和头长大于雌性,而雌性的腹长大于雄性;(3)叶城沙蜥雌雄性个体间的口宽、眼间距等其他形态特征则没有显著差异。叶城沙蜥的两性异形表现为雄性大于雌性,并且雄性具有更大的头部和更长的尾部,雌性具有更长有腹部,这可能是雄性个体面临的性选择压力与雌性个体面临的繁殖压力共同作用的结果。     

Sexual dimorphism in the African legless skink subfamily Acontiinae (Reptilia: Scincidae)

The extent to which sexual dimorphism in snout–vent length, tail length and head shape (length, width and height) manifests itself in the legless fossorial skink subfamily Acontiinae was investigated in representatives of all four of its genera, Acontias, Microacontias, Acontophiops and Typhlosaurus. Where data were available fecundity selection and diet partitioning (ecological causation) were tested as possible proximate causes for dimorphisms found. The possibility of a relationship between head shape and microhabitat density was also investigated. The data showed that significant sexual dimorphism in snout–vent length and head shape was present in only a minority of taxa and that it was absent with respect to tail length. There are indications of a relationship between head shape and microhabitat density, and head shape seems to become increasingly more pointed as SVL increases. A serious impediment to placing the findings of this study into a firm evolutionary context is the general lack of information about the ecology, social organization and behaviour of the taxa.     

Narrow versus broad: sexual dimorphism in the wing form of western European species of the subgenus Avaritia (Culicoides,Ceratopogonidae)

While wing form is known to differ between males and females of the genus Culicoides, detailed studies of sexual dimorphism are lacking. In this study, we analyze sex-specific differences in the wing form of 5 species of the subgenus Avaritia, using geometric morphometrics and comparative phylogenetic methods. Our results confirm the existence of marked sexual dimorphism in the wing form of the studied species and reveal for the first time that while there is a shared general pattern of sexual shape dimorphism within the subgenus, sexual size dimorphism, and particular features of sexual shape dimorphism differ among species. Sexual shape dimorphism was found to be poorly associated to size and the evolutionary history of the species. The tight association of sexual shape dimorphism with aspect ratio suggests that the shape of the wing is optimized for the type of flight of each sex, that is, dispersal flight in females versus aerobatic flight in males. Moreover, the fact that interspecific shape differences are greater and more strongly associated to aspect ratio in males than in females might be indicating that in males the selective pressures affecting flight performance characteristics are more heterogeneous and/or stronger than in females among the studied species.     

A Livestock Guardian Dog by Any Other Name: Similar Response to Wolves Across Livestock Guardian Dog Breeds

Nonlethal tools for reducing livestock depredations, such as livestock guardian dogs (LGDs; Canis familiaris), reduce lethal management of livestock predators and have been widely adopted by domestic sheep (Ovis aries) producers in the United States. However, compared with their success in reducing coyote (Canis latrans) depredations, commonly used LGD breeds appear less effective against wolves (Canis lupus). With more than 30 distinct LGD breeds found throughout the world, certain breeds may be more effective at deterring specific threats. We compared LGD breeds commonly used in the United States, collectively called whitedogs, with three European breeds selected for boldness toward carnivores, history of use in areas with wolves, lack of aggression toward humans, and size. We collected data on LGD behavior with sheep herds in Idaho, Montana, Oregon, Washington, and Wyoming in 2015 and 2016. We also developed a test to examine LGDs’ response to a simulated encounter with a wolf while on summer grazing range. Results from generalized linear mixed models of proportion of time spent in a given behavior indicate that few significant behavioral differences exist among tested breeds. Kangals tended to be more investigative when engaging a decoy, karakachans more vigilant, and transmontanos more able to decipher a threatening from unthreatening stimulus. Transmontanos also spent less time scanning than whitedogs, and there was a marginally significant effect of karakachans moving more than whitedogs. While these subtle behavioral differences may help livestock producers make tailored decisions in choosing the appropriate LGD for their needs and circumstance, our results suggest that behavioral differences among breeds may be less common than often suggested.     

Multivariate characterisation of the phenotypic traits of Djallonke and Sahel sheep in Northern Ghana

The characterisation of the small ruminant populations in developing countries will play a major role in the maintenance of the genetic resources as the basis for future improvement in livestock production. The present study aimed at morphological characterisation of the two main breeds of sheep in Ghana by assessing variation within and between breed populations using principal component and discriminant analyses. The two breeds were the Sahel and the Djallonke sheep of both sexes and of two groups namely, young (1 year old, consisting of 74 animals) and mature sheep (≥2 years old, comprising 219 animals). The analysis of variance revealed significant (P?<?0.05) differences in the morphological traits of the Sahel and the Djallonke sheep breeds with higher values recorded for the former. Sexual dimorphism was in favour of male animals in all the morphological traits examined. Mature animals also had comparative advantage over the young. Two principal components were extracted to discern the structure of the two genetic groups. The most discriminating traits between the two sheep breeds were rump height, height at withers, neck girth and pin-bone width. Mahalanobis distance between the two genetic groups was 5.723 (P?<?0.0001). The developed discriminant functions clearly discriminated and classified the Sahel and the Djallonke sheep into their breeds of origin, thus yielding 100, 93.4 and 90.4 % accurate classification for the rams, ewes and the overall sheep population, respectively. The present approach would greatly help in establishing management and conservation policies for the sustainable production of the two Ghanaian sheep breeds.     

Identification of genomic regions that exhibit sexual dimorphism for size and muscularity in cattle

Sexual dimorphism, the phenomenon whereby males and females of the same species are distinctive in some aspect of appearance or size, has previously been documented in cattle for traits such as growth rate and carcass merit using a quantitative genetics approach. No previous study in cattle has attempted to document sexual dimorphism at a genome level; therefore, the objective of the present study was to determine whether genomic regions associated with size and muscularity in cattle exhibited signs of sexual dimorphism. Analyses were undertaken on 10 linear-type traits that describe the muscular and skeletal characteristics of both males and females of five beef cattle breeds: 1,444 Angus (AA), 6,433 Charolais (CH), 1,129 Hereford, 8,745 Limousin (LM), and 1,698 Simmental. Genome-wide association analyses were undertaken using imputed whole-genome sequence data for each sex separately by breed. For each single-nucleotide polymorphism (SNP) that was segregating in both sexes, the difference between the allele substitution effect sizes for each sex, in each breed separately, was calculated. Suggestively (P ≤ 1 × 10⁻⁵) sexually dimorphic SNPs that were segregating in both males and females were detected for all traits in all breeds, although the location of these SNPs differed by both trait and breed. Significantly (P ≤ 1 × 10⁻⁸) dimorphic SNPs were detected in just three traits in the AA, seven traits in the CH, and three traits in the LM. The vast majority of all segregating autosomal SNPs (86% in AA to 94% in LM) had the same minor allele in both males and females. Differences (P ≤ 0.05) in allele frequencies between the sexes were observed for between 36% (LM) and 66% (AA) of the total autosomal SNPs that were segregating in both sexes. Dimorphic SNPs were located within a number of genes related to muscularity and/or size including the NAB1, COL5A2, and IWS1 genes on BTA2 that are located close to, and thought to be co-inherited with, the MSTN gene. Overall, sexual dimorphism exists in cattle at the genome level, but it is not consistent by either trait or breed.     

Sexual dimorphism in two girdled lizard species,Cordylus niger and Cordylus cordylus

The extent of sexual selection in two girdled lizard species was evaluated by measuring sexual dimorphism in those characters normally affected by sexual selection. Neither Cordylus niger, a cool-adapted species, nor C. cordylus, a warm-adapted species, displayed any notable sexual differences in asymptotic body sizes, but both species displayed slight dimorphism in head size measurements. The C. niger sample contained more large males than large females, which may be attributed to a lower growth rate in females. In the cool Saldanha area, females of both species lack generation glands. In the warmer Gansbaai area, these glands are present in females of C. cordylus, but in lower numbers than in males. Sex ratios favouring females, have been recorded for both species. The observed sexual dimorphism in the two species seems to be mainly the result of differential energy allocation by females, and not of sexual selection perse.     

Sexual Dimorphism of Endocranial,Facial and Limb Measurements in the Yellow Baboon (Papio cynocephalus)

The present study focused on the sexual dimorphism of yellow baboon (Papio cynocephalus) to clarify its relationship with social behaviour. The degree of sexual dimorphism in the endocranial volume is the lowest among the investigated measurements. Among the facial measurements, the degree value of sexual dimorphism was the maximum (38.4%) for palate length and the minimum for palate breadth at the upper second molar (M2) (16.8%). Reduced major axis (RMA) regression analysis indicated that most positive allometry in relation to body mass was barely shown in the endocranial volume, palate length, palate breadth at M2 and mandibular ramal width. On the other hand, most negative allometry in relation to body mass was barely indicated in the bizygomatic breadth, skull length, humeral length and femoral length. The plate breadth at M2 in males was smaller than that in females in equivalent to body mass. The results of the present study suggest that more males have longer pointed muzzles than females, which is considered to create an impressive view of large canine teeth. This contributes to display among males and agonistic encounters rather than to necessity of increased facial size due to larger body size or dietary influences.     

Evaluating Domestic Sheep Survival with Different Breeds of Livestock Guardian Dogs

Livestock guard dogs (LGDs; Canis familiaris) have been widely adopted by domestic sheep (Ovis aries) producers because they reduce predation by wild carnivores. LGDs were originally used in the United States to reduce coyote (Canis latrans) depredations, but their efficacy against a suite of large carnivores, including wolves (Canis lupus), brown bears (Ursus arctos), black bears (Ursus americanus), and cougars (Puma concolor), and whether specific breeds perform better than others remains unclear. To assess breed-specific effectiveness at reducing depredations from a suite of livestock predators, we compared survival rates of sheep protected by different breeds of LGDs, including three breeds from Europe (Turkish kangal, Bulgarian karakachan, and Portuguese cão de gado transmontano) and mixed-breed LGDs, “whitedog,” common in the United States. With the help of participating sheep producers, we collected cause-specific mortality data from domestic sheep in Idaho, Montana, Oregon, and Wyoming between 2013 and 2016. All three of the novel breeds of LGD tested were associated with overall reductions in sheep depredation relative to whitedogs, ranging from 61% to 95% (P < 0.05). In terms of predator-specific effectiveness, the Turkish kangal was associated with decreases in depredation from cougars (e^β = 0.31, 95% CI = 0.10–0.94, P = 0.04), black bears (e^β = 0.33, 95% CI = 0.28–0.37, P < 0.01), and coyotes (e^β = 0.56, 95% CI = 0.35–0.90, P = 0.02). The Bulgarian karakachan was associated with a decrease in coyote depredations (e^β = 0.07, 95% CI = 0.01–0.49, P < 0.01). The Portuguese transmontano was not associated with significant reductions in depredation hazard for any specific predator. Although variations in breed-specific effectiveness were subtle and nuanced, these findings will help livestock producers and wildlife managers make tailored decisions about how best to incorporate different breeds of LGD into sheep grazing regimes.     

Ecology of Wahlberg’s velvet gecko,Homopholis wahlbergii,in southern Africa

We examined 170 museum specimens of the southern African gekkonid lizard Homopholis wahlbergii, to quantify sexual dimorphism, male and female reproductive cycles and diet. The largest male and female we recorded were 116 and 119 mm snout–vent length (SVL) respectively. We compared SVL, tail length, head length, head width and eye diameter and found no evidence of sexual dimorphism in any of these characters. The smallest female with thickened muscular oviducts and follicles, indicating sexual maturity, was 59 mm SVL, but the smallest female we found with fully developed eggs was 85mmSVL. Virtually all females larger than 59 mm appeared to be in some stage of reproduction, suggesting that females reproduce every year once they reach sexual maturity. Egg size ranged from 17–19mm long. Egg size was not correlated with maternal SVL. We found adult females with ready-to-lay eggs during the warmer months of the year, but not during winter and spring. The smallest sexually mature male was 72 mm SVL. Virtually all males larger than this size displayed at least semi-turgid testes and most adult male testes were at least semi-turgid for much of the year. The only significant decrease in testicular activity was in mid-winter (June–August), thus, spermatogenesis is closely tied to female follicular development and ovulation. Velvet geckos are largely insectivorous (92%) and feed on a broad spectrum of prey. Their diet was dominated both numerically (34%) and volumetrically (22%) by beetles. Lepidoptera were the next most important prey category, suggesting that they exploit both terrestrial and flying invertebrates. They are unusual among lizards because they feed on millipedes. Males and females had very similar diets which may be explained by their lack of sexual dimorphism, although females tended to eat a greater volume of prey. Interestingly, less than half (37%) of the lizards examined contained prey items, suggesting that most individuals were not in positive energy balance. We also found evidence of prey size selection as a function of gape size, such that larger geckos took advantage of larger prey items.     

On the weight-bearing function of the medial coronoid process in dogs

The shape of and proportions between the surface areas of the medial coronoid process (MCP) and the fovea of the radial head were determined in 88 juvenile dogs and 146 adult dogs grouped as giant, large, mid-sized, chondrodystrophic, or small dogs. Thereby, the longitudinal (length) and transverse (width) extension of the MCP and fovea of the radial head have been measured. Original values were used to describe changes of the parameters attributed to growth. Normalized values (i.e. values expected in case of a width of the fovea of the radial head of 20 mm) were used to determine potential differences between constitutional types. All original values increased during growth (P < 0.05) except for the width and length of the MCP in chondrodystrophic and small breeds. Normalized values revealed a proportional decrease in width and length of the MCP during growth (P < 0.05) compared with the radial head. In adults, the normalized MCP was widest in giant dogs followed by large, mid-sized, small, and chondrodystrophic breeds. The MCP was also longest in giant dogs but shortest in large and chondrodystrophic dogs with those of large dogs being significantly (P < 0.05) shorter than those in giant, mid-sized and small dogs. Present results suggest that a deficiency in length-growth of the MCP--which has been present especially in large dogs--results in smaller humeral contact areas and decreased weight-bearing capacity of the MCP. Because loading forces acting on the MCP increase with body weight, the condition noted in large dogs might increase the risk of fragmentation of the MCP in these.     

The Os Coxae of a Digging Form of the Northern Water Vole, Arvicola terrestris (Rodentia, Arvicolidae)

Data on the morphology, relative growth and sexual dimorphism of the os coxae of a digging form of the northern water vole Arvicola terrestris (A.t. monticola) are given. Two hundred ninety-nine specimens (146 males and 153 females) caught in the Aran Valley (Spanish Pyrenees) were analyzed. The specimens were distributed into six classes of relative age, according to the skull morphology, kind of coat, moulting state, weight and sexual state. The morphological features of the os coxae in these specimens are similar to those described in other species of Arvicolidae. The hormonal effect upon the pelvis in adult females during pregnancy and parturition leads to the appearance of marked intersexual differences in the obturator foramen length, the pubis length, the pelvis length and, specially, in the pelvis height and the pubis width. By means of Becker's and Dunmire's procedures both sexes can be correctly discriminated in a 78.87 and a 76.4% respectively. Conjugating the variation patterns obtained with Becker's index and the pelvis height, we have obtained a more effective method of sexual differentiation (an 85.51% of correct discrimination).     

Motor laterality in 4 breeds of dog

The aim of the current study was designed to explore possible breed differences in a basic behavioral phenotype in dogs. It measured paw use during food-retrieval from a cylindrical, hollow, rubber toy to assess motor laterality (pawedness) in 4 breeds of dogs selected for their morphological differences: 45 greyhounds (males n = 23/females n = 22), 47 whippets (15/32), 46 pugs (15/31), and 45 boxers (17/28). A laterality index was calculated from the use of individual paws to restrain the toy during feeding. An association was found between sex and the laterality index (P = 0.035), reflecting a significant bias for left-paw use by entire male dogs and right-paw use by entire female dogs but no sex difference was found in the mean strength of laterality. No significant association was found between age and the laterality index. No breed difference was found in the laterality index (P = 0.423) or the absolute strength of laterality (i.e., the laterality index without direction, P = 0.259). However, important breed differences in the use of the test device emerged. The frequency of simultaneous use of both paws was lowest in pugs (P < 0.0001). In addition, both brachycephalic breeds (pugs and boxers) took less time than the dolichocephalic breeds (the whippets and greyhounds) to complete the criteria of 100 paw-use scores that was set for the laterality test. The absence of breed differences in the laterality index for paw use suggests that the task is a reliable measure of motor laterality in dogs during a food-retrieval task.     

Domestic dog skull diversity across breeds,breed groupings,and genetic clusters

Domestic dogs have become a model organism for studying the extent and consequences of morphological diversity, especially in the skull. It has been demonstrated that Cephalic Index (CI, skull width/skull length) correlates with central concentration of ganglion cells in the retina and with ventral rotation of the cerebral hemispheres. These changes may be reflected in the behavior of breeds with different skulls shapes. This study explored skull variation in the breed groups (n = 7) described by the Australian National Kennel Club to determine if CI differed significantly among the breed groups; groups were expected to differ not least in behavior. The CI of 12 representative dogs (females, n = 6; males, n = 6) of the most popular breeds (n = 80; total n = 960 dogs) were measured. Multivariate analysis of variance was performed to determine CI variance among the breed groups and between previously reported clusters of breeds with similar DNA, which identifies common ancestry. Although CI differed significantly among some breed groups, neither the breed groupings nor the DNA clusters satisfactorily explained all the variance in CI. The results show that breed groupings and genetic clusters only partially explain CI differences. They also suggest that CI is on a continuum and that the definition of three categories of canine skull as dolichocephalic, mesocephalic, and brachycephalic may be overly arbitrary.     

Evaluation of the sexual dimorphism in Mangalarga Marchador horses using discriminant analysis

This study used discriminant analysis to evaluate body measures and sexual dimorphism in Mangalarga Marchador horses. Discriminant analysis is a multivariate method that generates functions to classify animals using a prior criterion. In this study a prior criterion is male or female. The study analyzed 25 linear and 11 angular measures obtained from 25 stallions and 56 mares registered with the Mangalarga Marchador Brazilian Breeders Association. Knee girth, cannon girth, chest width, chest girth, back-loin length, hip width, distance from elbow to knee, hind limb hoof length, head width, shoulder length, and body length were found to be linear measures that provided evidence of sexual dimorphism. Angular measures with evidence of sexual dimorphism were shoulder–humerus, metacarpal–phalanx, coxae–femur, and femur–tibial angles. Stallions were larger than mares for almost all linear measures, except for back-loin length, hip width, and distance from elbow to knee. Shoulder–humerus and coxal–femur angles were larger in mares, while metacarpal–phalanx and femur–tibial angles were larger in stallions. Using linear measures, two mares were classified as stallions and three stallions were classified as mares. For angular measures, two other mares were classified as stallions and three other stallions were classified as mares. The discriminant functions can be useful for the selection of horses and to avoid registration of animals not meeting the phenotypic standards of the breed association.     

Effects of breed and ejaculate volume on sperm morphology and semen parameters of boars

The aim of the study was to determine the relation between the semen quality, frequency of sperm defects, sperm dimensions and shape, and the ejaculate volume of Large White and Landrace boars. A total of 648 ejaculates collected from 31 Large White and 30 Landrace boars were divided into three groups according to the criterion of the ejaculate volume. In this study Landrace boars produced ejaculates with higher volume, sperm concentration, and total numbers of spermatozoa than Large White boars. Landrace boars also showed a lower frequency of sperm with morphological abnormalities (P < 0.05). Landrace boars sperm had larger heads, which were by 0.15 μm longer, and by a larger perimeter and area (P < 0.05). Landrace boar spermatozoa also had a longer flagellum and were generally larger and by 2.07 μm longer than Large White boar sperm (P < 0.05). Significant differences were also found in the shape of sperm of the two breeds (P < 0.05). Landrace boars sperm had more elongated heads, and the ratio of head size to flagellum length was lower than in Large White boars sperm (P < 0.05). Sperm from ejaculates with low volume had a shorter flagellum and a greater head length/flagellum length ratio than sperm from medium- and high-volume ejaculates (P < 0.05).     

Morphological responses of three persistent native anuran species after forest conversion into monoculture pine plantations: tolerance or prosperity?

Species loss by habitat replacement operating as an ecological filter is a well‐known consequence of modern human activities. In contrast, the ecological and evolutionary response of species overcoming those filters in converted habitats has not been thoroughly explored. Species that persist are subject to novel and potentially stressful conditions that may induce certain morphological changes. We evaluated changes in the functional morphology of three anuran species persisting after the conversion of areas of the Atlantic Forest into pine plantations. We specifically evaluated differences in body size and body condition indices, head width, and hind legs’ length between adult individuals from both habitats and sexes. Habitat conversion and sexual dimorphism affected the morphology of the three anurans, with varying effects upon species and traits. Regarding the effect of habitat conversion, Elachistocleis bicolor increased body condition in plantations with no changes in the other traits, Physalaemus cuvieri showed only a marginal increment in residual body mass in plantations, and Odontophrynus americanus exhibited a substantial increment in body size while maintaining its body condition in plantations. Remarkably, none of the results suggested these persistent anurans were stressed by forest conversion. This study shows that habitat conversion may induce intraspecific morphological changes in ecologically relevant traits of persistent species, and that disturbed areas do not necessarily imply stressful, low quality habitats affecting all persistent native species negatively.     

Sexual dimorphism in jaw muscles of the Japanese sparrowhawk (Accipiter gularis)

Materials suitable for anatomical research of raptorial birds are rare. Bird‐eating raptors show distinct inter‐sexual differences in body size and parental roles. The large females catch larger prey and prepare small morsels to feed their young using their hooked beaks. Here, we investigated the architectural properties of different jaw muscles of the Japanese sparrowhawk (Accipiter gularis) and examined whether there is sexual dimorphism in their architectural design. The results showed that musculus depressor mandibulae, the opener of the lower jaw, was characterized by relatively long fascicle length, whereas musculus pterygoideus was characterized by its larger mass and physiological cross‐sectional area (PCSA) in both sexes. Females have the potential capacity to produce rapid and strong bites by their significantly longer fascicle length of M. depressor mandibulae and larger mass and PCSA of M. pterygoideus. For body size‐matched gender, jaw muscles of males had fibres of relatively longer length than females, enabling greater velocity and excursion. Architectural characteristics of jaw muscles, together with the absolute dimorphism (the fascicle length of M. depressor mandibulae, the muscle mass and PCSA of M. pterygoideus) and relative dimorphism in the muscle mass of M. pterygoideus, reflect dietary difference and asymmetric parental roles between the sexes.     

Body measurements of newborn calves and relationship of calf shape to sire breeding values for birth weight and calving ease

Body measurements on Angus- (n = 374) and Polled Hereford-sired (n = 438) calves were used to quantify calf shape via multivariate factor analysis, and measurements on Polled Hereford-sired calves were further used to investigate relationships between calf shape and sire expected progeny differences (EPD) for birth weight and first-calf calving ease. Calf birth weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded at 24 h postpartum. Sire birth weight EPD was positively associated (P less than .05) with all calf measures but only with head and cannon circumference after adjustment for phenotypic birth weight and gestation length. Thus, at constant birth weight, calves from higher birth weight EPD bulls tended to have larger cannon and head circumferences. Calving ease EPD was negatively related (P less than .05) to all calf measures except shoulder width. After adjustment for birth weight, only cannon circumference was associated with calving ease EPD, and this effect was removed by additional adjustment for birth weight EPD. Thus, at constant birth weight, bulls with higher EPD for calving ease sired calves with smaller cannon circumference, but at constant birth weight EPD, body measures were not associated with calving ease EPD. Factor analysis defined underlying skeletal width and frame components of shape (independent of birth weight) for both sire breeds. Calf shape differed among sires and was in part explained by birth weight EPD. No additional variation in shape was explained by calving ease EPD. Calf shape seemed to add no information for prediction of dystocia to that provided by birth weight EPD.