Autopodial skeletal diversity in hystricognath rodents: Functional and phylogenetic aspects

Metapodials and phalanges of the second to fourth digital ray were measured for the hands and feet of 214 specimens belonging to 45 extant species of hystricognath rodents, encompassing members of all major clades of the radiation. Principal components analysis (PCA), the phalangeal index of the third digital ray in the hands and feet, and the relationship between second and fourth digital ray were used to investigate intrinsic autopodial proportions as well as to provide a base for comparisons between hands and feet. PCA separated cursorial Hystricognathi from arboreal ones, but lead to little distinction in other locomotory modes. Cursors have longer metapodials and shorter phalanges, particularly in their hind limb, while arboreal species have relatively longer manual and pedal phalanges. Terrestrial, scansorial, fossorial, and semi-aquatic species were not clearly distinguished, but there is a tendency towards elongated manual digits and relatively short feet in most fossorial species. Closely related species with similar locomotory habits tend to group together in PCA morphospace, and also have similar phalangeal indices. The results are in agreement with current hypotheses on locomotory adaptations of the hand and foot, and concur with many previous findings on autopodial proportions in arboreal, cursorial, and fossorial species. They also highlight the limited use of autopodial proportions for inferring systematic affinities. The lack of distinction in the majority of species is likely related to the lack of highly specialized locomotory types in Hystricognathi.     

Haematological correlates of burrowing in Ctenomys

Haematological parameters related to O2 transport and regulation of acid-base equilibrium were determined for two species of Ctenomys. The oxygen capacity values of Ctenomys blood are similar to those of other fossorial mammals. Ctenomys blood has almost half the number of red blood cells of Rattus blood but the amount of Hb in each blood cell is 2-2.5 times higher. Blood pH is within typical mammalian values. Concentration of inorganic phosphate is higher in Ctenomys than in rats while bicarbonate and protein values are within typical mammalian range.     

Foot structure and phylogeny in the Viverridae (Carnivora)

The structure of feet is widely used as a diagnostic feature in mammalian taxonomy. The relationship between the lengths of the metacarpals and foot pads are described with regard to plantigrade and digitigrade feet in the Viverridae. Although species in the Herpestinae, Paradoxurinae and Galidiinae vary considerably in size (from 450 g to 10 kg), the increase in length of the metapodial is isometric. Feet in which the metacarpals are less than 15 % of total limb length are plantigrade (Paradoxurinae and Cryptoproctinae) while those larger than 15% are digitigrade (Herpestinae and Galidiinae). The Viverrinae are composed of two natural groups, one in which the species have plantigrade forefeet and digitigrade hind feet and one in which both fore- and hind feet are digitigrade. The Hemigalinae does not appear to be a natural grouping, because the banded palm civet has plantigrade fore- and hind feet while other members of the subfamily have digitigrade feet; it may be better to reclassify the subfamily into three (Hemigalinae, Fossinae and Euplerinae).     

An investigation of rugby scrimmaging posture and individual maximum pushing force

Although rugby is a popular contact sport and the isokinetic muscle torque assessment has recently found widespread application in the field of sports medicine, little research has examined the factors associated with the performance of game-specific skills directly by using the isokinetic-type rugby scrimmaging machine. This study is designed to (a) measure and observe the differences in the maximum individual pushing forward force produced by scrimmaging in different body postures (3 body heights x 2 foot positions) with a self-developed rugby scrimmaging machine and (b) observe the variations in hip, knee, and ankle angles at different body postures and explore the relationship between these angle values and the individual maximum pushing force. Ten national rugby players were invited to participate in the examination. The experimental equipment included a self-developed rugby scrimmaging machine and a 3-dimensional motion analysis system. Our results showed that the foot positions (parallel and nonparallel foot positions) do not affect the maximum pushing force; however, the maximum pushing force was significantly lower in posture I (36% body height) than in posture II (38%) and posture III (40%). The maximum forward force in posture III (40% body height) was also slightly greater than for the scrum in posture II (38% body height). In addition, it was determined that hip, knee, and ankle angles under parallel feet positioning are factors that are closely negatively related in terms of affecting maximum pushing force in scrimmaging. In cross-feet postures, there was a positive correlation between individual forward force and hip angle of the rear leg. From our results, we can conclude that if the player stands in an appropriate starting position at the early stage of scrimmaging, it will benefit the forward force production.     

Burrow structure and foraging costs in the fossorial rodent,Thomomys bottae

Summary A model for calculating the energy cost of burrowing by fossorial rodents is presented and used to examine the energetics of foraging by burrowing. The pocket gopher Thomomys bottae (Rodentia: Geomyidae) digs burrows for access to food. Feeding tunnels of Thomomys are broken into segments by laterals to the surface that are used to dispose of excavated soil. Energy cost of burrowing depends on both soil type and on burrow structure, defined by the length of burrow segments, angle of ascent of laterals, depth of feeding tunnels, and burrow diameter. In a desert scrub habitat, Thomomys adjust burrow segment length to minimize cost of burrowing. Observed segment lengths (mean=1.33 m) closely approximate the minimum-cost segment length of 1.22 m. Minimizing energy expended per meter of tunnel constructed maximizes efficiency of foraging by burrowing in the desert scrub. Burrow diameter and cost of burrowing increase with body size, while benefits do not, so foraging by burrowing becomes less enconomical as body size increases. Maximum possible body size of fossorial mammals depends on habitat productivity and energy cost of burrowing in local soils.     

Lateralisation in birds of prey: adaptive and phylogenetic considerations

Lateralisation, the different use of one or other side or appendix of the body, is basically determined by brain asymmetry which, in turn, is likely to be due to adaptive reasons. Several studies have been carried out on birds in general. However, birds of prey in particular, although they are very good candidates, have not been investigated from the sensory lateralisation point of view. In fact, many species scan for prey while perched and capture terrestrial prey with the feet, having at the same time the obvious necessity to keep their balance. This paper, therefore, investigates the existence of some sort of lateralisation in several species of both Falconiformes and Strigiformes temporarily in captivity. Attention is given to: (a) the direction of body rotation when perceiving a sound stimulus from behind the body and (b) the use of the feet when grasping a terrestrial prey. Lateralisation was found to be clearly present in both types of tests, although with some difference in its expression. In fact, almost every species tested rotated its body anti-clockwise, i.e. to the left, both in the first test and in repeated tests, with no noticeable difference between Falconiformes and Strigiformes. Also prey grasping showed a preferential use of one foot. Falconiformes preferred clearly to grasp the prey with one foot only in both the first test and in subsequent ones. Strigiformes, on the other hand, preferred using both feet, although a not insignificant proportion of individuals used one foot. Only the little owl seemed to have the tendency to prefer to use the right foot only, in a similar manner to Falconiformes. In fact, this bird is the most "diurnal" owl species among those tested, suggesting that lateralisation in footedness might be affected by adaptive constraints more than by phylogenetic similarities. Lateralisation, therefore, seems to be very widespread among birds of prey. Preferential use of the right foot also appears to be a general habit, and this is probably connected to the use of left hemisphere when manipulating food items.     

Three-dimensional in vivo motion of adult hind foot bones

Knowledge of hind foot bone motion is important for understanding gait as well as various foot pathologies, but the three-dimensional (3D) motion of these bones remains incompletely understood. The purpose of this study was to quantify the motion of the talus, calcaneus, navicular, and cuboid in normal adult feet during open chain quasi-static uniplanar plantar flexion motion. Magnetic resonance images of the right feet of six normal young adult males were taken from which 3D virtual models were made of each hind foot bone. The 3D motion of these models was analyzed. Each hind foot bone rotated in the same plane about half as much as the foot (mean 0.54 degrees of bone rotation per degree of foot motion, range 0.40-0.73 degrees per degree of foot motion as measured relative to the fixed tibia). Talar motion was primarily uniaxial, but the calcaneus, navicular, and cuboid bones exhibited biplanar (sometimes triplanar) translation in addition to biaxial rotation. Net translational motions of these bones averaged 0.39 mm of bone translation per degree of foot motion (range 0.06-0.62 mm per degree of foot motion). These data reflect the functional anatomy of the foot, extend the findings of prior studies, provide a standard for comparison to patients with congenital or acquired foot deformities, and establish an objective reference for quantitatively assessing the efficacy of various hind foot therapies.     

Skeletal indicators of locomotor adaptations in living and extinct rodents

Living rodents show great diversity in their locomotor habits, including semiaquatic, arboreal, fossorial, ricochetal, and gliding species from multiple families. To assess the association between limb morphology and locomotor habits, the appendicular skeletons of 65 rodent genera from 16 families were measured. Ecomorphological analyses of various locomotor types revealed consistent differences in postcranial skeletal morphology that relate to functionally important traits. Behaviorally similar taxa showed convergent morphological characters, despite distinct evolutionary histories. Semiaquatic rodents displayed relatively robust bones, enlarged muscular attachments, short femora, and elongate hind feet. Arboreal rodents had relatively elongate humeri and digits, short olecranon processes of the ulnae, and equally proportioned fore and hind limbs. Fossorial rodents showed relatively robust bones, enlarged muscular attachments, short antebrachii and digits, elongate manual claws, and reduced hind limb elements. Ricochetal rodents displayed relatively proximal insertion of muscles, disproportionate limbs, elongate tibiae, and elongate hind feet. Gliding rodents had relatively elongate and gracile bones, short olecranon processes of the ulnae, and equally proportioned fore and hind limbs. The morphological differences observed here can readily be used to discriminate extant rodents with different locomotor strategies. This suggests that the method could be applied to extinct rodents, regardless of ancestry, to accurately infer their locomotor ecologies. When applied to an extinct group of rodents, we found two distinct ecomorphs represented in the beaver family (Castoridae), semiaquatic and semifossorial. There was also a progressive trend toward increased body size and increased aquatic specialization in the giant beaver lineage (Castoroidinae). J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

Climbing of Leaf Trichomes by Eriophyid Mites Impedes Their Location by Predators

Eriophyid mites are plant parasites that are well adapted to hide away from predators. Tiny and wormlike, they can invade very narrow spaces in plants or form galls that, apart from other functions, serve as a shelter from predation. Previous observations showed that some free-living eriophyids as well as tetranychid mites spend their quiescence on the top of leaf trichomes. Here, I investigated climbing leaf trichomes by the eriophyid, Rhinophytoptus concinnus, and tested whether it enables the herbivores to avoid phytoseiid mites. Climbing behavior took place just prior to the quiescent period of juveniles. Larvae and nymphs raised the hind part of their stiffening bodies and walked, turning around on their axis. Having found a hair, juveniles attached their anal suckers to its tip, and, pushing back from a leaf surface or the base of the hair, they lifted their bodies up to become motionless. As revealed by the playback experiments with the phytoseiid mite, Typhloctonus tiliarum, predatory females needed much more time to find quiescent nymphs perching on hairs than those placed on a leaf surface. The time of nymph handling was similar in both situations. Also, a similar number of predators gave up feeding on nymphs in both locations. I conclude that climbing leaf trichomes enables the herbivorous mite to hide from predators. After detection, however, placement on trichomes does not give the quiescent juveniles any advantage over those placed on a leaf blade.     

Biochemical polymorphisms and phenetic relationships in rodents of the genusCtenomys from Southern Brazil

Protein variation at 20 loci was analyzed by starch gel electrophoresis in population samples of Ctenomys flamarioni, C. torquatus, C. sp., and C. minutus collected in 25 localities of Southern Brazil. Results show that these four species exhibit higher levels of genetic variability (He = 0.11-0.17) than those reported for most other fossorial rodents. Estimates of similarity coefficients indicate that C. minutus and C. sp. (S = 0.91) are the closest species, while C. flamarioni (S = 0.77) is the most distant from the others. The data presented here support the hypothesis of a relatively recent disjunction of C. minutus from C. sp. Within-species similarity indices are of the same order of magnitude as those found between species. The relatively high levels of heterozygosity observed are not in accordance with the view that subterranean taxa should be less variable than aboveground species due to the uniformity of their environment.     

两种穿山甲外形量衡度的测定及比较

There are 7 species of pangolin in the world. This paper deah with the measurement of some morphology indices in Manis petadactyla and Mania javanica. Measured variables included the body weight, the total body length, the length of head and body, the length of tail,the length of protruding rim of external ear, the length of hind feet, the length of middle claws of fore feet, the length of middle claws of hind feet, the number of rows of scales round mid-body, the number of single flank scales of edge tail. All variables measured were compared respectively between this 2 species. The results indicated that: ( 1 ) there were no signifieant differences in body weight and length of hind feet between this 2 species, but differences in the other variables were extremely significant. (21 The ratio of the length of middle claws of hind feet and fore feet in Mania pentadactyla was less than 1/2 ( n = 48 ), while Mania jaw, nica was more than 1/2 ( n = 15 ) ; the length of protruding rim of external ear in Mania pentadactyla was over 10 mm { n = 38 ), whereas Manis javanica was under 10 mm { n = 13 ) ; the number of single flank scales of edge tail in Mania pentadactyla was not beyond 21 (n = 65), and Mania javanica exeeeded 21 (n = 14) . So the ratio of the length of middle claws of hind feet and fore feet, the length of protruding rim of external ear, arid the ntunber of single flank scales of edge tail should be regard as distinctive features and taxonomic indices between this 2 species. (3) The relationships between body weight ( Y) and the total body length, the length of head and body, the length of tail {X) were positive correlation, and satisfied relation equation Y= aX^b.     

Structure of the plantar sweat glands of the Bank vole Clethrionomys glareolus

The plantar pads of the hind feet of 15 male and female, young and old Clethrionomys glareolus (Rodentia–family Muridae) were examined for the presence of tubular glands. Groups of eight or nine coiled glands were found in all of the 11 plantar pads. The secretory portion of the gland lies deep in the fatty hypodermis and communicates with the plantar surface by a coiled duct whose lining cells merge with those of the stratum basale of the undersurface of the foot. Groups of shallow depressions mark the site of the duct openings. They are not associated with any hairs.
Although light microscopy shows only one cell type, electron microscopy reveals two morphologically different cell types. Neither conform directly to the light and dark secretory cells of the human sweat glands although similarities exist. Myoepithelial cells surround the secretory cells, but do not appear to be present around the duct cells.     

Breeding biology of the fossorial rodent Ctenomys talarum (Rodentia: Octodontidae)

The paper describes the breeding biology of the South American herbivorous fossorial rodent Ctenomys talarum (tuco-tuco), covering the following aspects: length of breeding season, prenatal mortality, mean litter size and its correlates, sex ratio and its density-dependence, and late sexual maturity of both sexes. These parameters are compared and contrasted with those of other conspecifics and other subterranean rodents.     

Évaluation lymphoscintigraphique d’éventuelles anomalies du système lymphatique au niveau des membres inférieurs de joueurs de football : à propos de six observations

In order to demonstrate possible abnormalities of the lymphatic system as consequence of soccer practice, lymphoscintigraphic investigations of the lower limbs have been performed (1) in five young male volunteers with at least ten years of soccer practice (kicking with one foot in the five cases; previous osteoarticular events involving the ankles in four: no clinical edema observed) and (2) in one professional female soccer player (also kicking with one foot) who presented with one bilateral distal edema of the lower limbs. After the subcutaneous injection of ^99mTc-labeled HSA nanosized colloids in the first interdigital space of the feet and the limbs being at rest during 30 min, the tracer did reach normally the first inguinal nodes in only three subjects (their kicking limbs), suggesting thus one functional insufficiency of the lymphatic system at the level of nine of the twelve limbs. With exercise (tip-toeing during 5 min), one (abnormal) functional asymmetry (activity reaching the inguinal nodes greater at the level of the kicking limb than at the level of the not-kicking one) was also observed. Finally, the female player with distal limb edemas showed at the end of the investigation the lowest values (within the group) of tracer disappearance at the level of the injection sites. Morphological abnormalities on the lymphatic system of the lower limbs (as dermal backflow, lymphostasis, …) were observed in none of the subjects at the end of the investigation, suggesting lesions at the level of the tissues injected and/or of the initial lymphatics of the feet rather than lesions at the level of the great lymphatic vessels of the limbs. To conclude and although based on a limited series of subjects, the results suggest the development of functional lymphatic abnormalities at the level of the feet in soccer players, abnormalities mostly without clinical manifestations but that can lead to clinically obvious edemas. These abnormalities would have to be confirmed on a larger series.     

Elastic properties of the hind foot of the Donkey, Equus asinus

The elastic properties of the hind feet of Donkeys, and of tendons removed from the feet, have been investigated by methods similar to those used in a previous study of the forefoot. The elastic strain energy stored in the foot, during a trotting step, is calculated to be approximately the optimum which would minimize the work required of the muscles in this gait.     

Hindlimb suspension and hind foot reversal in Varecia variegata and other arboreal mammals

The foot, perhaps more than any other region of the primate body, reflects the interaction of positional behaviors with the geometric properties of available supports. The ability to reverse the hind foot during hindlimb suspension while hanging from a horizontal support or descending a large diameter vertical trunk has been noted in many arboreal mammals, including primates. Observations of Varecia variegata in the wild and under seminatural conditions document hindlimb suspension in this lemurid primate. The kinematics and skeletal correlates of this behavior are examined. Analogy is made with the form and function exhibited by nonprimate mammalian taxa employing this behavior. Examples of carnivores and rodents display very similar adaptations of the tarsals while other mammals, such as the xenarthrans, accomplish a similar end by means of different morphologies. However, a suite of features is identified that is shared by mammals capable of hind foot reversal. Hindlimb suspension effectively increases the potential feeding space available to a foraging mammal and represents a significant, and often unrecognized, alternative adaptive strategy to forelimb suspension and prehensile-tail suspension in primates. Am J Phys Anthropol 103:85–102, 1997. © 1997 Wiley-Liss, Inc.     

Hind foot drumming: Morphofunctional analysis of the hind limb osteology in three species of African mole-rats (Bathyergidae)

Hind foot drumming is a form of seismic signaling that plays a vital role in the communication of several Bathyergidae species. Hind foot drumming is initiated by the rapid movement of the whole hind limb by flexion and extension of the hip and knee. This study aimed to determine if morphological adaptations of the hind limb osteology were measurable using established morphometric analyses in two drumming (Bathyergus suillus and Georychus capensis) and one non-drumming (Cryptomys hottentotus natalensis) African mole-rat species. Forty-three linear measurements of the hind limb were taken in 48 limbs (n = 16 limbs per species) and 32 indices were calculated. Mixed model analysis of variance was used to compare the three species and sexes within a species. Thirteen indices had significant differences between species. Eleven indices had significant differences between sexes within a species. Significant differences between the drumming (B. suillus and G. capensis) and the non-drumming species were observed in three indices. The femoral greater trochanter was relatively shorter in the drumming species compared to the non-drumming species, which is proposed to allow for increased hip joint mobility, thereby permitting drummers to move their limbs at the rapid speed required to generate seismic signals. Furthermore, the small in-lever (shorter greater trochanter) may increase the velocity of limb motion. The robust tibias in the drumming species, as indicated by the tibial robustness index, are likely to counter the additional biomechanical load caused by the muscles involved in hind foot drumming. The relatively small hind feet seen in the drumming species allows for reduced limb weight needed for the rapid extension and flexion motion required during hind foot drumming. The significant differences reflected in the hind limb osteological indices between B. suillus and G. capensis and the non-drumming species are indicative of adaptations for hind foot drumming.     

Incipient morphological specializations associated with fossorial life in the skull of ground squirrels (Sciuridae,Rodentia)

Anatomical and biological specializations have been studied extensively in fossorial rodents, especially in subterranean species, such as mole-rats or pocket-gophers. Sciurids (i.e., squirrels) are mostly known for their diverse locomotory behaviors, and encompass many arboreal species. They also include less specialized fossorial species, such as ground squirrels that are mainly scratch diggers. The skull of ground squirrels remains poorly investigated in a fossorial context, while it may reflect incipient morphological specializations associated with fossorial life, especially due to the putative use of incisors for digging in some taxa. Here, we present the results of a comparative analysis of the skull of five fossorial sciurid species, and compare those to four arboreal sciurids, one arboreal/fossorial sciurid and one specialized fossorial aplodontiid. The quantification of both cranial and mandibular shapes, using three dimensional geometric morphometrics, reveals that fossorial species clearly depart from arboreal species. Fossorial species from the Marmotini tribe, and also Xerini to a lesser extent, show widened zygomatic arches and occipital plate on the cranium, and a wide mandible with reduced condyles. These shared characteristics, which are present in the aplodontiid species, likely represent fossorial specializations rather than relaxed selection on traits related to the ancestral arboreal condition of sciurids. Such cranial and mandibular configurations combined with proodont incisors might also be related to the frequent use of incisors for digging (added to forelimbs), especially in Marmotini evolving in soft to hard soil conditions. This study provides some clues to understand the evolutionary mechanisms shaping the skull of fossorial rodents, in relation to the time spent underground and to the nature of the soil.     

How does environmental variation influence body mass,body size,and body condition? Roe deer as a case study

We tested the influence of population density and of drought intensity (measured as the Gaussen Index in spring and summer of the year of birth) on winter body mass, hind foot length, and body condition of roe deer fawns. Body mass decreased with increasing density and increased with increasing Gaussen Index in summer, in a similar way for both males and females. Hind foot length of males showed the same response. On the other hand, hind foot length of females decreased with increasing density only after dry summers, hence when environmental conditions were very harsh. Body condition was affected neither by density nor by drought intensity. Our results indicate that body mass and size are much better indicators of phenotypic quality than body condition in roe deer. The sex-specific responses of body size to environmental conditions could correspond to a differential allocation in favour of daughters by heavier than average roe deer mothers.     

The influence of snow on lynx and coyote movements: does morphology affect behavior?

Summary We studied sympatric lynx (Lynx canadensis) and coyotes (Canis latrans) to assess how morphological disadvantages to locomotion over snow affected movement patterns. Both species are of similar size and mass, but the feet of lynx are much larger, and coyotes were found to have 4.1–8.8 times the foot-load (ratio of body mass to foot area) of lynx. This resulted in greater mean sinking depths of coyote limbs, although the magnitude of the difference was less than that in foot-load. Coyotes exhibited stronger use of behavioral patterns that reduced negative effects of snow on movements. Coyotes were most abundant at low elevations where snow was shallow, whereas lynx were mostly at higher elevations. Coyotes also used areas at both elevations where snow was shallower than average, while lynx used areas where snow was deeper. further, both species used travel routes where snow was shallower than it was near the track. Coyotes traveled on harder snow and used trails more frequently, thereby tending to reduce sinking depths to those similar to lynx. The behavioral repertoire of coyotes reduced the morphological advantage of large feet possessed by lynx; however, overall sinking depths were still greater in coyotes. Snowshoe hares (Lepus americanus) were the main prey of both species, and their foot-load was less than that of either predator. Hare kills by coyotes occurred after fewer bounds than did those by lynx, and the large difference between foot-loads of both species of predators may have forced coyotes to ambush rather than chase hares, as did lynx.