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Movement behavior is a critical process that interacts with landscape structure to affect population connectivity and persistence in fragmented or altered landscapes. The purpose of our study was to test whether different substrates (forest litter, soil, grass, gravel, and asphalt) found in fragmented forested landscapes affected the movement behavior of the Southern Graycheek Salamander (Plethodon metcalfi Brimley, 1912). Latency period of the salamanders was highest on grass substrate and significantly lower only on soil substrate. Sinuosity of the movement path of salamanders was lowest and contained more turns in grass and was significantly higher than only gravel and asphalt substrates. Velocity of the salamanders was highest on asphalt substrate but was not different from gravel substrate. Velocity was higher on asphalt than on grass, forest, or soil, and velocity was higher on gravel than on grass substrate. The results indicated that P. metcalfi reacted differently to natural and anthropogenic substrates, and we suggest that these behavioral differences could have both positive and negative implications for movement success and habitat resistance in forested landscapes fragmented by roads and development. Key words: amphibian, connectivity, habitat resistance, movement behavior, roads, sinuosity, Southern Graycheek Salamander (Plethodon metcalfi), substrate, velocity. Le comportement de deplacement est un processus cle dont les interactions avec la structure du paysage ont une incidence sur la connectivite et la persistance des populations dans les paysages fragmentes ou modifies. L'etude avait pour but d'evaluer si differents substrats (litiere, terre, herbe, gravier et asphalte) presents dans des paysages forestiers fragmentes avaient une incidence sur le comportement de deplacement de la salamandre Plethodon metcalfi Brimley, 1912. La periode de latence des salamandres etait la plus longue sur l'herbe, mais ce parametre n'etait significativement plus faible que sur le substrat terreux. La sinuosite de la trajectoire des deplacements des salamandres etait la plus faible et comptait le plus grand nombre de virages sur l'herbe, ce nombre n'etant toutefois significativement plus eleve que le nombre de virages sur substrats de gravier et d'asphalte. La vitesse des salamandres etait la plus grande sur le substrat d'asphalte, bien que cette vitesse ne soit pas differente de la vitesse sur gravier. La vitesse etait plus grande sur l'asphalte que sur l'herbe, la litiere et la terre, et la vitesse sur gravier etait plus grande que sur l'herbe. Ces resultats indiquent que les P. metcalfi ont reagi differemment selon que le substrat etait naturel ou artificiel. Nous postulons que ces differences de comportement pourraient avoir des consequences aussi bien positives que negatives sur le succes des deplacements et la resistance de l'habitat dans des paysages forestiers fragmentes par des routes et amenagements. Mots-cles : amphibien, connectivite, resistance de l'habitat, comportement de deplacement, routes, sinuosite, salamandre Plethodon metcalfi, substrat, vitesse. [Traduit par la Redaction], Introduction The movement of individuals is a critical ecological process that maintains populations through dispersal and connectivity. Successful movement is especially important in fragmented and altered landscapes for rescue of [...]

To better place the form and motion of the human foot in an evolutionary context, understanding how foot motions change when quadrupeds walk bipedally can be informative. For this purpose, we compared the pressures beneath the foot during bipedal and quadrupedal walking in Japanese macaques (Macaca fuscata). The pressure at nine plantar regions was recorded using a pressure mat (120 Hz), while the animals walked on a level walkway at their preferred speeds. The results revealed substantial differences in foot use between the two modes of locomotion, and some features observed during bipedal walking resembled human gait, such as the medial transfer of the center of pressure (COP), abrupt declines in forefoot pressures, and the increased pressure beneath the hallux, all occurring during the late-stance phase. In particular, the medial transfer of the COP, which is also observed in bonobos (Vereecke et al.: Am J Phys Anthropol 120 (2003) 373-383), was due to a biomechanical requirement for a hind limb dominant gait, such as bipedal walking. Features shared by bipedal and quadrupedal locomotion that were quite different from human locomotion were also observed: the heel never contacted the ground, a foot longitudinal arch was absent, the hallux was widely abducted, and the functional axis was on the third digit, not the second. DOI 10.1002/ajpa.21240 KEY WORDS foot function; bipedal walking; quadrupedal walking; kinetics

Didelphid marsupials specialized in arboreal locomotion have morphological features convergent with primates, and hence are an ideal group to test hypotheses about the evolution of arboreality. We analyzed the relative contributions of allometric, phylogenetic, and adaptive aspects to the climbing performance of 7 species of didelphid marsupials of the Atlantic Forest of Brazil. These species encompass a diversity of body sizes, use of the vertical strata, and lineages within didelphid marsupials. Climbing performance was evaluated by measuring the velocity in climbing 3 nylon ropes of 0.6, 0.9, and 1.25 cm diameter. The cycle of maximum velocity was chosen to measure relative stride length, frequency, and relative velocity. As expected, arboreal species (Gracilinanus microtarsus, Marmosops incanus, Micoureus paraguayanus, and Caluromys philander) had higher relative climbing velocities than more terrestrial species (Didelphis aurita, Philander frenatus, and Metachirus nudicaudatus). Stride frequency was mostly associated with phylogeny and vertical use of the forest, but relative velocities generally were determined by a combination of stride length and frequency. Differences in climbing performance originated early in the diversification of the group, but continued to evolve because significant differences also were detected at the subfamily, tribe, and genus levels, which seems to parallel the evolution of grasping abilities in primates. Key words: Didelphimorphia, locomotion, neotropical forest, performance, velocity, vertical stratification

Movement is important to all organisms, and accordingly it is addressed in a huge number of papers in the literature. Of nearly 26,000 papers referring to movement, an estimated 34% focused on movement by measuring it or testing hypotheses about it. This enormous amount of information is difficult to review and highlights the need to assess the collective completeness of movement studies and identify gaps. We surveyed 1,000 randomly selected papers from 496 journals and compared the facets of movement studied with a suggested framework for movement ecology, consisting of internal state (motivation, physiology), motion and navigation capacities, and external factors (both the physical environment and living organisms), and links among these components. Most studies simply measured and described the movement of organisms without reference to ecological or internal factors, and the most frequently studied part of the framework was the link between external factors and motion capacity. Few studies looked at the effects on movement of navigation capacity, or internal state, and those were mainly from vertebrates. For invertebrates and plants most studies were at the population level, whereas more vertebrate studies were conducted at the individual level. Consideration of only population-level averages promulgates neglect of between-individual variation in movement, potentially hindering the study of factors controlling movement. Terminology was found to be inconsistent among taxa and sub-disciplines. The gaps identified in coverage of movement studies highlight research areas that should be addressed to fully understand the ecology of movement. dispersal | foraging | migration | navigation | physiology

Organisms spanning a 107-fold range in length of the body engage in aquatic propulsion--swimming; they do so with several kinds of propulsors and take advantage of several different fluid mechanical mechanisms. A hierarchical classification of swimming modes can impose some order on this complexity. More difficult are the issues surrounding the different kinds of propulsive devices used by different organisms. These issues can be in part exposed by an examination of how speeds and accelerations scale with changes in body length, both for different lineages of swimmers and for all swimmers collectively. Clearly, fluid mechanical factors impose general rules and constraints; just as clearly, these only roughly anticipate actual scaling. Indeed, collections of data on scaling can serve as useful correctives for assumptions about functional mechanisms. They can also reveal size-dependent constraints on biological designs.

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. KEY WORDS laterality; posture; locomotion; chimpanzees

Angelman syndrome is a neurological disorder whose symptoms include severe mental retardation, loss of motor coordination, and sleep disturbances. The disease is caused by a loss of function of UBE3A, which encodes a HECT-domain ubiquitin ligase. Here, we generate a Drosophila model for the disease. The results of several experiments show that the functions of human UBE3A and its fly counterpart, dube3a, are similar. First, expression of Dube3a is enriched in the Drosophila nervous system, including mushroom bodies, the seat of learning and memory. Second, we have generated dube3a null mutants, and they appear normal externally, but display abnormal locomotive behavior and circadian rhythms, and defective long-term memory. Third, flies that overexpress Dube3a in the nervous system also display locomotion defects, dependent on the ubiquitin ligase activity. Finally, missense mutations in UBE3A alleles of Angelman syndrome patients alter amino acid residues conserved in the fly protein, and when introduced into dube3a, behave as loss-of-function mutations. The simplest model for Angelman syndrome is that in the absence of UBE3A, particular substrates fail to be ubiquitinated and proteasomally degraded, accumulate in the brain, and interfere with brain function. We have generated flies useful for genetic screens to identify Dube3a substrates. These flies overexpress Dube3a in the eye or wing and display morphological abnormalities, dependent on the critical catalytic cysteine. We conclude that dube3a mutants are a valid model for Angelman syndrome, with great potential for identifying the elusive UBE3A substrates relevant to the disease. E6-AP | UBE3A | ubiquitin ligase | mental retardation

For squirrels, physical size varies with ancestry, locomotion, and sex. Body length has little variation associated with subfamilies or tribes but varies significantly among genera within tribes. Thus, patterns in body size among genera represent more recent evolutionary pressures. Flying squirrels weigh less than similarly sized tree or ground squirrels but ecological profile and ancestry are confounded for flying squirrels. Tail length has clear relationships with ecological profile in squirrels. Tail length is shorter in ground squirrels, longer in tree squirrels, and longest in flying squirrels. In addition, in arboreal squirrels, females have longer tails, relative to body length, than those of males. This latter result suggests that reproductive constraints can influence external features of morphology. Key words: allometry, body size, flying squirrels, gliding locomotion, ground squirrels, tail length, tree squirrels

This article examines the curvature of the manual proximal and middle phalanges of species belonging to Pan, Gorilla, Ateles, Macaca, Pongo, Hylobates, and Cebus to determine whether middle phalangeal curvature, when considered in conjunction with proximal phalangeal curvature, yields a locomotor signal. Prior studies have demonstrated the discriminatory power of proximal phalanges for separating suspensory species (including knuckle walkers) from pronograde quadrupedal species, but less emphasis has been placed on the distinguishing phalangeal characteristics of taxa within the suspensory category. This study demonstrates, first, that middle phalanges discriminate suspensory from nonsuspensory species, although not as cleanly as proximal phalanges. Finer discrimination of locomotor signals, including subtle differences among animals employing different modes of suspension, is possible through a comparison of the curvatures of the proximal phalanges and corresponding middle phalanges. Their relative curvature differs in quadrupeds, brachiators, and knuckle walkers. Knuckle walkers (Pan and Gorilla) have relatively little curvature of the middle phalanges coupled with marked curvature of the proximal phalanges, whereas brachiators (Ateles and Hylobates) display marked curvature of both proximal and middle phalanges, and pronograde quadrupeds (Cebus and Macaca) have relatively straight proximal and moderately curved middle phalanges. Quadrumanous climbers (Pongo) have a unique combination of traits, whereby curvature is high in both proximal and middle phalanges, but less so in the latter than the former. These differences, predictable on the basis of the biomechanical forces to which digits are subjected, may open a new venue for future research on the locomotor repertoire of prebipedal ancestors of hominins. 2008. KEY WORDS phalangeal curvature; locomotion; African apes; Pongo; Macaca; Cebus; Ateles

Specific sites on the palmar diaphysis of the manual middle phalanges provide attachment for the flexor digitorum superficialis (FDS) tendon. It has been assumed in the literature that lateral palmar fossae on these bones reflect locations for these attachments and offer evidence for relative size of the flexor tendon. This assumption has led to predictions about relative FDS muscle force potential from sizes of fossae on fossil hominin middle phalanges. Inferences about locomotor capabilities of fossil hominins in turn have been drawn from the predicted force potential of the flexor muscle. The study reported here provides a critical first step in evaluating hypotheses about behavioral implications of middle phalangeal morphology in fossil hominins, by testing the hypothesis that the lateral fossae reflect the size of the FDS tendon and the location of the terminal FDS tendon attachments on the middle phalanx. The middle phalangeal region was dissected in 43 individuals from 16 primate genera, including humans. Qualitative observations were made of tendon attachment locations relative to the lateral fossae. Length measurements of the fossae were tested as predictors of FDS tendon cross-sectional area and of FDS attachment tendon lengths. Our results lead to the conclusion that the hypothesis must be rejected, and that future attention should focus on functional implications of the palmar median bar associated with the lateral fossae. Am J Phys Anthropol 134:141-151, 2007. KEY WORDS primate hand; fossil hominins; flexor tendon attachments

Bipedal walking is evident in the earliest hominins [Zollikofer CPE, Ponce de Leon MS, Lieberman DE, Guy F, Pilbeam D, et al. (2005) Nature 434:755-759], but why our unique two-legged gait evolved remains unknown. Here, we analyze walking energetics and biomechanics for adult chimpanzees and humans to investigate the long-standing hypothesis that bipedalism reduced the energy cost of walking compared with our ape-like ancestors [Rodman PS, McHenry HM (1980) Am J Phys Anthropol 52:103-106]. Consistent with previous work on juvenile chimpanzees [Taylor CR, Rowntree VJ (1973) Science 179:186-187], we find that bipedal and quadrupedal walking costs are not significantly different in our sample of adult chimpanzees. However, a more detailed analysis reveals significant differences in bipedal and quadrupedal cost in most individuals, which are masked when subjects are examined as a group. Furthermore, human walking is [approximately equal to] 75% less costly than both quadrupedal and bipedal walking in chimpanzees. Variation in cost between bipedal and quadrupedal walking, as well as between chimpanzees and humans, is well explained by biomechanical differences in anatomy and gait, with the decreased cost of human walking attributable to our more extended hip and a longer hindlimb. Analyses of these features in early fossil hominins, coupled with analyses of bipedal walking in chimpanzees, indicate that bipedalism in early, ape-like hominins could indeed have been less costly than quadrupedal knucklewalking. biomechanics | human evolution | locomotion | limb length | inverse dynamics

The semicircular canal system of vertebrates helps coordinate body movements, including stabilization of gaze during locomotion. Quantitative phylogenetically informed analysis of the radius of curvature of the three semicircular canals in 91 extant and recently extinct primate species and 119 other mammalian taxa provide support for the hypothesis that canal size varies in relation to the jerkiness of head motion during locomotion. Primate and other mammalian species studied here that are agile and have fast, jerky locomotion have significantly larger canals relative to body mass than those that move more cautiously. generalized least-squares analysis | mammals | vestibular system

We investigated the effects of [beta]-estradiol on the locomotor behavior of female mice in a radial maze. Data comprising the total distance traveled during each arm entry were obtained from video records of six consecutive daily recording sessions. Distributions of these data were bimodal for both ovariectomized control and [beta]-estradiol-treated ovariectomized subjects. Data were fit with the sum of two gamma probability distributions. Three parameters of the analytic fits were useful for quantifying the effect of [beta]-estradiol on locomotor behavior: (i) the sampling distance (median of the total distance traveled during each arm entry in the short-distance peak of a bimodal distribution), (ii) the committed distance (median of the total per-arm-entry distance traveled in the long-distance peak), and (iii) the partition distance (distance represented by the minimum between the two peaks). Analysis showed that for sampling-distance arm entries [beta]-estradiol typically had little if any significant effect on female locomotor behavior, whereas it significantly increased the total distance traveled during committed-distance arm entries on the first 2 days of exposure to the empty maze. [beta]-Estradiol also increased the ability of females to discriminate between empty maze arms and arms that contained intact or castrated male mice and partially prevented loss of this capacity after removal of the males. analytic fit | bimodal distribution estrogen | gamma distribution | exploratory behavior

Investigations of cross-sectional geometry in nonhuman primate limb bones typically attribute shape ratios to qualitative behavioral characterizations, e.g., leaper, slow climber, brachiator, or terrestrial vs. arboreal quadruped. Quantitative positional behavioral data, however, have yet to be used in a rigorous evaluation of such shape-behavior connections. African apes represent an ideal population for such an investigation because their relatedness minimizes phylogenetic inertia, they exhibit diverse behavioral repertoires, and their locomotor behaviors are known from multiple studies. Cross-sectional data from femoral and humeral diaphyses were collected for 222 wild-shot specimens, encompassing Pan paniscus and all commonly recognized African ape subspecies. Digital representations of diaphyseal cross sections were acquired via computed tomography at three locations per diaphysis. Locomotor behaviors were pooled broadly into arboreal and terrestrial categories, then partitioned into quadrupedal walking, quadrumanous climbing, scrambling, and suspensory categories. Sex-specific taxonomic differences in ratios of principal moments of area (PMA) were statistically significant more often in the femoral diaphysis than the humeral diaphysis. While it appears difficult to relate a measure of shape (e.g., PMA ratiot to individual locomotor modes, general locomotor differences (e.g., percentage arboreal vs. terrestrial locomotion) are discerned more easily. As percentage of arboreal locomotion for a group increases, average cross sections appear more circular. Associations between PMA ratio and specific locomotor behaviors are less straightforward. Individual behaviors that integrate eccentric limb positions (e.g., arboreal scrambling) may not engender more circular cross sections than behaviors that incorporate repetitive sagittal movements (e.g., quadrupedal walking) in a straightforward manner. KEY WORDS cross-sectional geometry; principal moment of area; locomoter behavior; Pan; Gorilla

Ctenomys talarum is a solitary subterranean rodent that maintains exclusive territories by constant movement through a sealed tunnel system. In this study we evaluate the distance traveled in an artificial burrow and maximum natural locomotor speed reached in a 24-h period. Distance moved per day was 179.99 m [+ or -] 69.62 SD, and ratio of distance moved to total burrow length was 12.4:1. Maximum locomotor speed was 0.75 m/s or -] 0.01 SD. No relationships were found between either distance moved or speed and photoperiod or ambient temperature, and between body mass and distance moved or locomotor speed. Distance moved by C. talarum is related to maintenance of burrow and territorial defense, and locomotor speed, probably, responds to aboveground predation. Key words: Ctenomys, daily movements, maximum speed, subterranean rodent

Flapping flight and swimming in many organisms is accompanied by significant bending of flexible wings and fins. The instantaneous shape of wings and fins has, in turn, a profound effect on the fluid dynamic forces they can generate, with non-monotonic relationships between the pattern of deformation waves passing along the wing and the thrust developed. Many of these deformations arise, in part, from the passive mechanics of oscillating a flexible air- or hydrofoil. At the same time, however, their instantaneous shape may well emerge from details of the fluid loading. This issue--the extent to which there is feedback between the instantaneous wing shape and the fluid dynamic loading--is core to understanding flight control. We ask to what extent surface shape of wings and fins is controlled by structural mechanics versus fluid dynamic loading. To address this issue, we use a combination of computational and analytic methods to explore how bending stresses arising from inertial-elastic mechanisms compare to those stresses that arise from fluid pressure forces. Our analyses suggest that for certain combinations of wing stiffness, wing motions, and fluid density, fluid pressure stresses play a relatively minor role in determining wing shape. Nearly all of these combinations correspond to wings moving in air. The exciting feature provided by this analysis is that, for high Reynolds number motions where linear potential flow equations provide reasonable estimates of lift and thrust, we can finally examine how wing structure affects flight performance. Armed with this approach, we then show how modest levels of passive elasticity can affect thrust for a given level of energy input in the form of an inertial oscillation of a compliant foil.

In animals, muscles are the most common effectors that translate neuronal activity into behavior. Nowhere is behavior more restricted by the limits of muscle performance than at the upper range of high-frequency movements. Here, we see new and multiple designs to cope with the demands for speed. Extremely rapid oscillations in force are required to power cyclic activities such as flight in insects or to produce vibrations for sound. Such behaviors are seen in a variety of invertebrates and vertebrates, and are powered by both synchronous and asynchronous muscles. In synchronous muscles, each contraction/relaxation cycle is accompanied by membrane depolarization and subsequent repolarization, release of activator calcium, attachment of cross-bridges and muscle shortening, then removal of activator calcium and cross-bridge detachment. To enable all of these to occur at extremely high frequencies a suite of modifications are required, including precise neural control, hypertrophy of the calcium handling machinery, innovative mechanisms to bind calcium, and molecular modification of the cross-bridges and regulatory proteins. Side effects are low force and power output and low efficiency, but the benefit of direct, neural control is maintained. Asynchronous muscles, in which there is not a 1:1 correspondence between neural activation and contraction, are a radically different design. Rather than rapid calcium cycling, they rely on delayed activation and deactivation, and the resonant characteristics of the wings and exoskeleton to guide their extremely high-frequency contractions. They thus avoid many of the modifications and attendant trade-offs mentioned above, are more powerful and more efficient than high-frequency synchronous muscles, but are considerably more restricted in their application.

Byline: Yu. P. Gerasimenko (1), A. N. Makarovskii (2), O. A. Nikitin (1) Keywords: spinal cord; stepping movement generator; epidural stimulation; propriospinal system Abstract: Electrical epidural stimulation of the dorsal surface of the spinal cord at the level of the second lumbar segment induced step-like movements accompanied by the corresponding electromyographic activity in the leg muscles in patients lacking supraspinal influences as a result of vertebral trauma. Triggering of stepping movements was shown to occur with particular stimulation parameters. The results provide evidence that in humans, as in other mammals, the spinal cord contains a network of interneurons acting as generators of stepping movements and producing coordinated patterns of movement activity. Experiments on chronic spinal cats demonstrated the leading role of the propriospinal system of the spinal cord in activating the spinal generators of stepping in response to epidural stimuli. Author Affiliation: (1) Laboratory for Movement Physiology, I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034, St. Petersburg, Russia (2) Department of Vertebral Surgery, Institute of Phthysiopulmonology, Ministry of Health of the Russian Federation, 32 Politekhnicheskaya Street, 194064, St. Petersburg, Russia Article History: Registration Date: 10/10/2004

Initiation of a particular behavior requires not only activation of the neural center directly involved in its control but also inhibition of the neural networks controlling competing behaviors. In the pteropod mollusc, Clione limacina, many identified serotonergic neurons activate or modulate different elements of the swimming system resulting in the initiation or acceleration of the swimming behavior. Cerebral serotonergic neurons are described here, which produce excitatory inputs to the swimming system as well as inhibitory inputs to the neural centers that control competing behaviors. Whole-body withdrawal behavior is incompatible with swimming activity in Clione. The main characteristic of whole-body withdrawal is complete inhibition of swimming. Cerebral serotonergic neurons were found to produce a prominent inhibition of the pleural neurons that control whole-body withdrawal behavior. By inhibiting pleurai withdrawal cells, serotonergic neurons eliminate its inhibitory influence on the swimming system and thus favor increased swimming speed. Serotonergic neurons also produce a prominent inhibition of the Pleural White Cell, which is presumably involved in reproductive or egg-laying behavior. Thus the serotonergic system directly activates swimming system and, at the same time, alters a variety of other neural systems preventing simultaneous initiation of incompatible behaviors.

This paper supplies quantitative data on the hind- and forelimb musculature of common chimpanzees (Pan troglodytes) and calculates maximum joint moments of force as a contribution to a better understanding of the differences between chimpanzee and human locomotion. We dissected three chimpanzees, and recorded muscle mass, fascicle length, and physiological cross-section area (PCSA). We also obtained flexion/extension moment arms of the major muscles about the limb joints. We find that in the hindlimb, chimpanzees possess longer fascicles in most muscles but smaller PCSAs than are predicted for humans of equal body mass, suggesting that the adaptive emphasis in chimpanzees is on joint mobility at the expense of tension production. In common chimpanzee bipedalism, both hips and knees are significantly more flexed than in humans, necessitating muscles capable of exerting larger moments at the joints for the same ground force. However, we find that when subject to the same stresses, chimpanzee hindlimb muscles provide far smaller moments at the joints than humans, particularly the quadriceps and plantar flexors. In contrast, all forelimb muscle masses, fascicle lengths, and PCSAs are smaller in humans than in chimpanzees, reflecting the use of the forelimbs in chimpanzee, but not human, locomotion. When subject to the same stresses, chimpanzee forelimb muscles provide larger moments at the joints than humans, presumably because of the demands of the forelimbs during locomotion. These differences in muscle architecture and function help to explain why chimpanzees are restricted in their ability to walk, and particularly to run bipedally. Am J Phys Anthropol 110:179-199, 1999.

Three pursuit-diving seabird species, the shag, the black guillemot and the common guillemot, showed a peak in the relationship between the ratio of dive duration to the duration of the subsequent period on the surface and dive duration. The dive to surface ratio peaked at short dive durations with the depletion of oxygen stores upon surfacing, supporting the predictions of two marginal value diving models where the oxygen uptake curve has been incorporated.

In vivo bone strain experiments were performed on the ulnae of three female rhesus macaques to test how the bone deforms during locomotion. The null hypothesis was that, in an animal moving its limbs predominantly in sagittal planes, the ulna experiences anteroposterior bending. Three rosette strain gauges were attached around the circumference of the bone slightly distal to midshaft. They permit a complete characterization of the ulna's loading environment. Strains were recorded during walking and galloping activities. Principal strains and strain directions relative to the long axis of the bone were calculated for each gauge site. In all three animals, the lateral cortex experienced higher tensile than compressive principal strains during the stance phase of walking. Compressive strains predominated at the medial cortex of two animals (the gauge on this cortex of the third animal did not function). The posterior cortex was subject to lower strains; the nature of the strain was highly dependent on precise gauge position. The greater principal strains were aligned closely with the long axis of the bone in two animals, whereas they deviated up to 45 [degrees] from the long axis in the third animal. A gait change from walk to gallop was recorded for one animal. It was not accompanied by an incremental change in strain magnitudes. Strains are at the low end of the range of strain magnitudes recorded for walking gaits of nonprimate mammals. The measured distribution of strains in the rhesus monkey ulna indicates that mediolateral bending, rather than anteroposterior bending, is the predominant loading regime, with the neutral axis of bending running from anterior and slightly medial to posterior and slightly lateral. A variable degree of torsion was superimposed over this bending regime. Ulnar mediolateral bending is apparently caused by a ground reaction force vector that passes medial to the forearm. The macaque ulna is not reinforced in the plane of bending. The lack of buttressing in the loaded plane and the somewhat counterintuitive bending direction recommend caution with regard to conventional interpretations of long bone cross-sectional geometry. KEY WORDS in vivo bone strain; macaque ulna; functional morphology

Seven measurements in the cerebellar complex were completed on 45 individuals, including 26 species of anthropoids from Stephan's collection. These included 12 species of New World monkeys, 10 species of Old World monkeys, and Hylobates, Gorilla, Pan, and humans. The measurements were the volume of medial (fastigial) (CM), interpositus (globose and emboliform) (CI), and lateral (dentate) (CL) cerebellar nuclei, ventral pons (VPo), inferior olivary principal (OLIPr), and accessory (OLIAc) nuclei and vestibular nuclear complex (VES). The relative size of each nucleus was expressed in size indices based upon the allometric line obtained by the reduced major axis analysis. The indices of three cerebellar nuclei reflect the relative size of three longitudinal zones of the cerebellum. The cerebellar hemisphere-lateralis zone is represented by the CL indices, the vermis-medialis zone by the CM indices, and the pars intermedius-interpositus zone by the CI indices. The results show that the VPo and OLIPr indices are closely related to the CL indices. This lateral zone group of nuclei is the most progressively developed in humans, whereas the CM, CI, OLIAc, and VES are independent of the developmental trend manifest by the lateral zone group of nuclei. The indices are discussed in relation to the predominant locomotor pattern exhibited by a species. The size indices of arboreal quadrupeds show a development of all nuclei in the cerebellar complex. This is interpreted as indicating that arboreal monkeys live in complicated, discontinuous, three-dimensional space and need exceptional cerebellar capacity for each pattern of locomotion and positional behavior. Progressive development of the lateral zone group of nuclei only compared to other nuclei was recognizable in humans. This development is considered to be related not to bipedalism, but to versatile and coordinated finger movement, resulting after bipedalism was established. This cerebellar reorganization is also a prerequisite (Leiner et al. [1993] TINS 16: 444-447) for the evolution of human language. The differences between size indices of the nuclei of Macaca (=pronograde primate) and Ateles (=antipronograde one) are compared in relation to their vertical climbing kinesiological data. KEY WORDS cerebellar complex; morphometry; locomotor types; anthropoids; Stephan's collection

Interlimb coordination is directly relevant to the understanding of the neural control of locomotion, but few studies addressing this topic for nonhuman primates are available, and no data exist for any hominoid other than humans. As a follow-up to Jungers and Anapol's ([1985] Am. J. Phys. Anthropol. 67:89-97) analysis on a lemur and talapoin monkey, we describe here the patterns of interlimb coordination in two chimpanzees as revealed by electromyography. Like the lemur and talapoin monkey, ipsilateral limb coupling in chimpanzees is characterized by variability about preferred modes within individual gaits. During symmetrical gaits, limb coupling patterns in the chimpanzee are also influenced by kinematic differences in hindlimb placement ('overstriding'). These observations reflect the neurological constraints placed on locomotion but also emphasize the overall flexibility of locomotor neural mechanisms. Interlimb coordination patterns are also species-specific, exhibiting significant differences among primate taxa and between primates and cats. Interspecific differences may be suggestive of phylogenetic divergence in the basic mechanisms for neural control of locomotion, but do not preclude morphological explanations for observed differences in interlimb coordination across species. KEY WORDS locomotion; CPG; electromyography; Pan; Miopithecus; Lemur; phase intervals

Analysis of the fluctuations in optimal body temperature during shuttling between two sites in desert antelope ground squirrels shows that the body temperature of squirrels leaving a burrow varies inversely with travel time and higher heating or cooling rates. The temperature also decreases with diminished body temperature while returning to the burrow and with increased rates of net energy gain.

The evolution of locomotor energetics in North American hylid frogs was investigated. The aimwas to examine the validity of the aerobic capacity hypothesis, which assumes that the evolution of metabolic rate and the origin of endothermy were related to functional and evolutionary links between physiological traits such as resting and maximum rates of metabolism and locomotor traits such as locomotor endurance. Phylogenetic analysis showed positive correlation between resting and maximal rates of metabolism, thus supporting the aerobic capacity hypothesis.

In 1979 Bliss predicted that, "land crabs are and will undoubtedly continue to be promising objects of scientific research." Studies of rapid running ghost crabs support her contention and have resulted in several general findings relating to locomotion and activity. 1) Energy exchange mechanisms during walking are general and not restricted to quadrupedal and bipedal morphologies. 2) "Equivalent gaits," such as trots and gallops, may exist in 4-, 6- and 8-legged animals that differ greatly in leg and skeletal (i. e., exo- vs. endoskeletal) design. These findings support the hypothesis that terrestrial locomotion in many species can be modeled by an inverted pendulum or spring-mass system. 3) An open circulatory system and chitin-covered gills do not necessarily limit the rate at which oxygen consumption can be increased or the factorial increase in oxygen consumption over resting rates. 4) Interspecific and intraspecific (i.e., ontogenetic) scaling of sub-maximal oxygen consumption and maximal aerobic speed can differ significantly. 5) Locomotion at speeds above the maximal aerobic speed requiring non-aerobic contributions may be far more costly than can be predicted from aerobic costs alone. The cost of transport may attain a minimum at less than maximum speed. 6) The speed which elicits maximal oxygen consumption during continuous exercise is attained at moderate walking speeds in crabs and probably other ectotherms. Speeds 15- to 20-fold faster are possible, but cannot be sustained. 7) The low endurance associated with the low maximal oxygen consumption and maximal aerobic speed of ectotherms moving continuously can be increased or decreased by altering locomotor behavior and moving intermittently. Ectotherms can locomote at high speeds and travel for considerable distances or remain active for long periods by including rest pauses. Alternatively, intense activity with extended exercise periods or with short pause periods may actually reduce behavioral capacity or work accomplished relative to continuous activity during which the behavior is carried out at a lower intensity level without pauses.

SYNOPSIS. The identification and demonstration of an evolutionary constraint is suggested to be a four step process: 1) recognition of a possible mechanism of constraint, 2) formation of an historical scenario of the consequences of the constraint, 3) elucidation of the causal mechanism in the modern analog or model, and 4) phylogenetic correlation of the constraint with the proposed effect in extant lineages. Steps 1 and 2 represent the formation of two interdependent hypotheses, and steps 3 and 4 are tests of those hypotheses. This approach is illustrated with an example from the musculo-skeletal system of tetrapod vertebrates. Consideration of the anatomy and mode of locomotion of lizards led to the hypothesis that they may not be able to run and breathe at the same time. Analysis of the pattern of ventilatory airflow of lizards supports this hypothesis. Tidal and minute volume increase above resting levels during slow walking (i.e., speeds below 10% of maximum running speed), but decline rapidly at higher speeds. Furthermore, electromyographic monitoring of the hypaxial muscles indicates a clear conflict between locomotor and ventilatory functions. Key anatomical characters, suggested to be responsible for the conflict, can be traced back to the earliest tetrapods. The organization of the two extant lineages that do breathe while running (i.e., birds and mammals) suggests that the evolution of an ability to breathe during locomotion required modifications of the ancestral configuration that separate locomotor and ventilatory function.

Three forms of forward locomotion have been described in the pteropod mollusk Clione limacina, including slow, fast, and escape swimming. The neuromuscular organization of the swimming system suggests that a two-geared system operates for slow and fast swimming, while the escape response is superimposed on fast swimming. In addition to escape, changes in locomotory speed can occur through a dramatic "change-of-gears," or through a more subtle change of speed within gears. The former involves reconfiguration of the central pattern generator and recruitment of previously inactive motor units. The latter can be due to: changes in tonic inputs to the central neurons, central modulation that is not sufficient to "change gears," endogenous properties of muscle cells, and peripheral modulation of muscle contractility. The initial ballistic phase of escape swimming is believed to be triggered by activity in a newly identified pair of swim motor neurons that neither receive information from, nor provide input to, the central pattern generator. These neurons appear to produce a startle response. Evidence presented suggests that most, if not all, of these variables help produce locomotory plasticity in Clione.

The statocyst in cephalopods is the main organ of balance and operates in a manner similar to the vestibular system of vertebrates. This paper reviews the principal factors affecting the sensitivity and frequency response of the statocyst. These include morphological features, such as the size and shape of the statocyst, its canal structure, and the size of the cupulae and maculae, as well as physiological features, such as the electronic coupling of sensory cells, the impact of the efferents, and the motility of some cells. The use of statocyst characteristics in predicting the locomotory performance of different cephalopod species is discussed.

Selection on locomotor performance was determined for a series of marked and recaptured individuals from a population of garter snakes (Thamnophis sirtalis fitchi) in Northern California. We measured snake length and mass, burst speed, endurance on a treadmill, and the distance crawled around a stationary circular track. Size-corrected values (residuals) of mass and locomotor performance were generated from the scaling equations of S-V length (SVL). Randomization tests and regressions were used to determine the probability that a trait was a significant predictor of survivorship, and a nonparametric, cubic spline estimate of the fitness function was used to facilitate detection of the patterns of selection. From 275 ('cohort') snakes measured and tested within 8 days of birth in 1985, 79 were recaptured in the spring-summer of 1986 and subsequent years. Birth SVL was the only significant (randomization P = 0.022) predictor of neonatal survival from 1985 to 1986 with directional selection favoring larger individuals. In addition to the lab-born cohort, 382 field-born snakes from all ages in the population were captured, tested, and released during spring-summer 1986. Similar to the 1985 cohort, the survivorship of 37 of 86 neonates from 1986 to 1987 showed no significant relationship with any residual value using any statistical test. Survivorship from 1986 to 1987 for 127 of 250 yearlings (including 32 lab-born cohort snakes) analyzed with the randomization test showed that greater values of both speed (P = 0.007) and distance residual (P = 0.008) significantly favored survival, whereas intermediate values of mass residual (P = 0.006) were significantly more likely to survive. Univariate randomization test, but in a multiple regression with yearling burst speed residual, distance capacity residual, and a quadratic term of mass residual, distance capacity residual was the least important predictor variable. For the survivorship of 37 of the 113 older snakes, greater burst speed residual significantly favored survival (randomization P = 0.001).

I tested biomechanical predictions that morphological proportions (snout-vent length, forelimb length, hindlimb length, tail length, and mass) and maximal springting and jumping ability have evolved concordantly among 15 species of Anolis lizards from Jamaica and Puerto Rico. Based on a phylogenetic hypothesis for these species, the ancestor reconstruction and contrast approaches were useed to test hypotheses that variables coevolved. Evolutionary change in all morphological and performance variables scales positively with evolution of body size (represented by snout-vent length); size evolution accounts for greater than 50% of the variance in sprinting and jumping evolution. With the effect of the evolution of body size removed, increases in hindlimb length are associated with increases in sprinting and jumping capability. When further variables are removed, evolution in forelimb and tail length exhibits a negative relationship with evolution of both performance measures. The success of the biomechanical predictions indicates that the assumption that evolution in other variables (e.g., muscle mass and composition) did not affect performance evolution is probably correct; evolution of the morphological variables accounts for approximately 80% of the evolutionary change in performance ability. In this case, however, such assumptions are clade-specific; extrapolation to taxa outside the clade is thus unwarranted. The results have implications concerning ecomorphological evolution. The observed relationship between forelimb and tail length and ecology probably is a spurious result of the correlation between these variables and hindlimb length. Further, because the evolution of jumping and sprinting ability are closely linked, the ability to adapt to certain microhabitats may be limited.

A study of the activity levels in the wild of the Nautilus is reported. The aim was to understand why nautiloids survived relatively unchanged from the Ordovician, while ammonites and all other ectocochleate cephalopods became extinct. The study involved obtaining high-resolution tracks of animal position and depth and telemetered jet pressures to examine animal lifestyle and economics. The results showed that Nautilus is more active in the wild than in captivity, but expend less energy. The animal reduces transport energy costs by taking advantage of vertical movement. Also, it moves to deeper, cooler waters after feeding to allow a single feeding to last longer.