Morphometry and allometry of the primate humerus

The primate distal humerus has been used both in phylogenetic reconstruction and in assessing locomotor and postural adaptations. This study uses an allometric approach to predict locomotor patterns of extant primates regardless of phylogenetic position. By showing the relationship between form and function in living primate taxa it will be possible to use this data set to predict locomotor behavior of extinct primates. Several linear measurements were taken from the distal humerus of 71 extant primate species (anthropoids and prosimians). Allometric regressions of each measurement were performed with mandibular M₂ area as a surrogate for body size. These measurements were used to determine if significant differences in distal humerus morphology exist among locomotor groups. The results were then used to test several hypotheses about the relationship between humeral form and function. For example, the hypothesis that suspensory primates have a large medial epicondyle is confirmed; the hypothesis that terrestrial quadrupeds have a deep olecranon fossa could not be confirmed with quantitative data. In addition to this hypothesis testing, the residuals from the allometric regressions of the humeral measurements were used in a discriminant functions analysis to estimate locomotor behavior from distal humerus morphology. The discriminant functions analysis correctly reclassified 64/71 (90%) species.     

Evolutionary morphology of the Tenrecoidea (Mammalia) carpal complex

The mammalian carpus can be difficult to interpret both phylogenetically and functionally. It is evolutionarily constrained in terms of functional morphology, yet there is considerable variation among many eutherian and metatherian lower and higher level taxa. The ecologically diverse Tenrecoidea (Mammalia) is a useful model for morphological interpretation of the interplay between function and phylogenetic constraint. Elements from the wrist and hand of 13 tenrecoid species, and one species each from Macroscelididae, Solenodontidae, and Erinaceidae, were compared to test form–function hypotheses of specific carpal, metacarpal, and phalangeal characters. Qualitative comparisons illustrate that several aspects of the tenrecoid carpus can be correlated with positional behaviour. Convergences within Tenrecoidea, and between tenrecoids and nontenrecoids with similar locomotor regimes, confirm a small number of carpal characters and a larger number of distal forearm, metacarpal, and phalangeal characters that reliably correspond with functional expectations. In addition, several features of the carpus appear to be phylogenetically constrained and indicate specific affinities within Tenrecoidea. Finally, there are a significant number of carpal features that vary among the studied taxa and remain ambiguous in terms of phylogenetic and/or functional significance.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 267–288.     

A stochastic locomotor control model for the nurse shark,ginglymostoma cirratum

Summary The locomotor behavior of the nurse shark (Ginglymostoma cirratum) is characterized by 17 variables (frequency and ratios of left, right, and total turns; their radians; straight paths (steps); distance travelled; and velocity) Within each of these variables there is an internal time dependency the structure of which was elaborated together with an improved statistical model predicting their behavior within 90% confidence limits. The model allows for the sensitive detection of subtle locomotor response to sensory stimulation as values of variables may exceed the established confidence limits within minutes after onset of the stimulus. The locomotor activity is well described by an autoregression time series model and can be predicted by only seven variables. Six of these form two independently operating clusters. The first one consists of: the number of right turns, the distance travelled, and the mean velocity; the second one of: the mean size of right turns, of left turns, and of all turns. The same clustering is obtained independently by a cluster analysis of cross-sections of the seven time series. It is apparent that, among a total of 17 locomotor variables, seven behave as individually independent agents, presumably controlled by seven separate and independent centers. The output of each center can only be predicted by its own behavior. In spite of the individual behavior of the seven variables, their internal structure is similar in important aspects which may result from control by a common command center. The shark locomotor model differs in important aspects from that previously constructed for the goldfish. The interdependence of the locomotor variables in both species may be related to the control mechanisms postulated by von Holst for the coordination of rhythmic fin movements in fishes. A locomotor control model for the nurse shark is proposed.     

SYMMETRY,LOCOMOTION, AND THE EVOLUTION OF AN ANTERIOR END: A LESSON FROM SEA URCHINS

Bilaterally symmetrical, “regular” sea urchins in the Family Echinometridae (Class Echinoidea; Phylum Echinodermata) were found to lack a locomotor anterior. Heterocentrotus mammillatus and Echinometra mathaei were observed while locomoting. Members of both ellipsoidal species were found to proceed with their short or long axis foremost with statistically equivalent frequencies. This finding demonstrates that the evolution of bilateral symmetry is not always accompanied by the evolution of a locomotor “anterior” end. The elliptical echinometrid sea urchins provide a particularly appropriate study group for investigating the relationship between the evolution of body form and locomotor behavior. Although the radially symmetrical regular sea urchins, from which the echinometrids sprang, lack a locomotor anterior, all “irregular” echinoids, which are also derived from a regular ancestor but are bilaterally symmetrical, possess an “obligate” locomotor anterior. The symmetry and behavior exhibited by the elliptical echinometrid sea urchins therefore demonstrates that the first irregular echinoids (which exhibit bilateral symmetry by definition) need not have possessed a locomotor anterior as they do today.     

Testing phylogenetic implications of eggshell characters in side-necked turtles (Testudines: Pleurodira)

Amniote egg and eggshell morphology is a rich source of characters to link aspects of reproductive biology with systematics. Extensive work concerning both anatomy and phylogenetic assignability has been done on fossil bird and dinosaur eggs, but little is known for extant sauropsids. The utility of eggshell characters for phylogenetic analyses is tested and discussed for extant side-necked turtles (Pleurodira), and the diversity of egg ultrastructure is examined in several species. Egg gross morphology and eggshell ultrastructure of 12 species of extant side-necked turtles was documented using scanning electron microscopy. Thirteen eggshell characters were scored and mapped on a composite phylogeny and ancestral character states were reconstructed. Many of the characters do not show a phylogenetic signal according to a test comparing the number of steps on the chosen phylogeny with that on randomly generated trees. The presence of conservative, clade-supporting features could be demonstrated, and the following clades are supported by several characters: the Elseya-Emydura entity, short-necked Australasian chelids, is backed by two characters, and two additional characters could potentially support this group. Three characters support the monophyly of South American chelids, whereas two characters argue for the exclusion of Hydromedusa, a long-necked form resembling Australian chelids rather than South American forms, from this clade.     

Polymorphism of spawners of the resident form of European river lamprey <Emphasis Type="Italic">Lampetra fluviatilis</Emphasis> (Petromyzontidae)

Data on polymorphism (plastic and meristic characters) are obtained for spawners of resident nonparasitic form of European river lamprey Lampetra fluviatilis from the Serebristaya River. The new data verify the diagnosis of this species and contribute to the formulation of a hypothesis on the presence of several phenotypic groups: dwarf, small-sized, and common. Analysis of plastic characters and of the number of trunk myomeres demonstrated that the values of these characters reliably depend on position of lampreys in a certain discerned group. Some aspects of biology of this species are discussed: spawning and interaction between resident nonparasitic river and migrating parasitic lampreys.     

Fiber‐type composition in the perivertebral musculature of lizards: Implications for the evolution of the diapsid trunk muscles

The perivertebral musculature of lizards is critical for the stabilization and the mobilization of the trunk during locomotion. Some trunk muscles are also involved in ventilation. This dual function of trunk muscles in locomotion and ventilation leads to a biomechanical conflict in many lizards and constrains their ability to breathe while running (“axial constraint”) which likely is reflected by their high anaerobic scope. Furthermore, different foraging and predator‐escape strategies were shown to correlate with the metabolic profile of locomotor muscles in lizards. Because knowledge of muscle's fiber‐type composition may help to reveal a muscle's functional properties, we investigated the distribution pattern of muscle fiber types in the perivertebral musculature in two small lizard species with a generalized body shape and subjected to the axial constraint (Dipsosaurus dorsalis, Acanthodactylus maculatus) and one species that circumvents the axial constraint by means of gular pumping (Varanus exanthematicus). Additionally, these species differ in their predator‐escape and foraging behaviors. Using refined enzyme‐histochemical protocols, muscle fiber types were differentiated in serial cross‐sections through the trunk, maintaining the anatomical relationships between the skeleton and the musculature. The fiber composition in Dipsosaurus and Acanthodactylus showed a highly glycolytic profile, consistent with their intermittent locomotor style and reliance on anaerobic metabolism during activity. Because early representatives of diapsids resemble these two species in several postcranial characters, we suggest that this glycolytic profile represents the plesiomorphic condition for diapsids. In Varanus, we found a high proportion of oxidative fibers in all muscles, which is in accordance with its high aerobic scope and capability of sustained locomotion. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.     

The semicircular canal system and locomotion: The case of extinct lemuroids and lorisoids

Paleontologists reconstruct the locomotor and postural behavior of extinct species by analogy with living forms and biomechanical analyses. In rare cases, behavioral evidence such as footprints can be used to confirm fossil‐based reconstructions for predominantly terrestrial orders of mammals. For instance, the chalicothere prints from Laetoli show that these perissodactyls supported their body weight on the metacarpals, as previously reconstructed. 1 Unfortunately, primates are mostly arboreal and rarely leave footprints. The cercopithecid and hominin prints at Laetoli are a rare exception. We have recently shown that the semicircular canal system can be used to test and augment locomotor reconstructions based on postcranial material or to provide first estimations of locomotor behavior for taxa not known from the postcranium. Using a sample of modern primates, we have been able to demonstrate that the radii of curvature of the semicircular canals are significantly correlated with both body mass and agility of locomotion. 2 This paper reviews those results and examines the relationship between semicircular canal morphology and other evidence in efforts to reconstruct locomotor behavior in subfossil lemurs from the Holocene of Madagascar and fossil lorisoids from the Miocene of Africa.     

Effects of training and testosterone on muscle fiber types and locomotor performance in male six-lined racerunners (Aspidoscelis sexlineata)

Testosterone (T) is thought to affect a variety of traits important for fitness, including coloration, the size of sexual ornaments, aggression, and locomotor performance. Here, we investigated the effects of experimentally elevated T and locomotor training on muscle physiology and running performance in a nonterritorial male lizard species (Aspidoscelis sexlineata). Additionally, several morphological attributes were quantified to examine other characters that are likely affected by T and/or a training regimen. Neither training alone nor training with T supplementation resulted in increased locomotor performance. Instead, we found that T and training resulted in a decrease in each of three locomotor performance variables as well as in hematocrit, ventral coloration, and testis size. Strikingly, neither the size nor the fiber composition of the iliofibularis or gastrocnemius muscles was different among the two treatments or a group of untrained control animals. Hence, the relationships among T, training, and associated characters are not clear. Our results offer important insights for those hoping to conduct laboratory manipulations on nonmodel organisms and highlight the challenges of studying both training effects and the effects of steroid hormones on locomotor performance.     

Development and morphological variation of the axial and appendicular skeleton in hylidae (Lissamphibia,Anura)

The axial and appendicular skeleton, the associated musculature and tendons form a functional system related to specific modes of locomotion in anurans. Many transformations in the structures linked with the locomotor function of the adult occur during larval stages and metamorphosis. In this study, we present the larval ontogeny and adult morphology of the axial and appendicular skeletons of 14 species of frogs in the family Hylidae with different locomotor modes and habitat uses. Among Hylidae, a diversity of shapes, locomotory types occurs (e.g., walker, swimmer, jumper, hopper) and different habitat types occupied (shrubby, terrestrial, aquatic, arboreal). Many elements complete differentiation at the end of metamorphosis; others, such as sesamoids, still show an incomplete development at that stage. Sixty seven characters were scored and optimized in an available phylogeny. Nine characters of developmental timing and adult osteology are optimized as synapomorphies of specific groups. Some characters appear to be related to the locomotor type (e.g., the sacro‐urostyle region configuration is highly linked with the jumping mode; nonexpanded diapophyses would related to aquatic habitat use). Nevertheless, the functional interpretations are quite particular to this family. Monophyletic clades are also groups with shared locomotory modes or habitat uses. Hence, the hypothesis of common ancestry or adaptation can be evaluated, taking into account the analysis level of the phylogenetic context, so that, when a character is inherited via common ancestry, it necessarily means that functional constraints could also be inherited. Here, we outline the basis for further work on: postmetamorphic development as a fundamental period for the complete differentiation of structures related to a full locomotor functionality; the biomechanical performance in relationship to the variation in ligaments and sesamoids; the importance of analyzing these topics within the frame of heterochrony. J. Morphol. 277:786–813, 2016. © 2016 Wiley Periodicals, Inc.     

The relationship between locomotor behavior and limb morphology in brown (Cebus apella) and weeper (Cebus olivaceus) capuchins

This study is a comparison of locomotor behavior and postcranial form in two species of capuchin monkey, the brown capuchin (Cebus apella), and the weeper capuchin (Cebus olivaceus). Behavioral data from groups of wild C. apella and C. olivaceus in Guyana were collected during the period of December 1999 through November 2000. Postcranial variables including 40 measurements and three indices were taken from 43 adult and subadult specimens of C. apella and 14 adult and subadult specimens of C. olivaceus housed in American museums, as well as two wild-caught adult specimens of C. olivaceus from the Georgetown Zoo in Guyana. The results of this study indicate that these two capuchins exhibit similar patterns of locomotor behavior, but that there are important differences in how they move through their homerange, particularly with respect to quadrupedalism. These differences in behavior are reflected in their postcranial morphology and can be related to differences in foraging strategies. This study provides an example of the importance of using more exclusive categories of quadrupedal behaviors when comparing closely related arboreal quadrupeds, as well as an alternative explanation for some of the postcranial features of C. apella that may relate to foraging postures and foraging strategy rather than traditionally categorized patterns of locomotor behavior.     

The correspondence between proximal phalanx morphology and locomotion: implications for inferring the locomotor behavior of fossil catarrhines

Phalanges are considered to be highly informative in the reconstruction of extinct primate locomotor behavior since these skeletal elements directly interact with the substrate during locomotion. Variation in shaft curvature and relative phalangeal length has been linked to differences in the degree of suspension and overall arboreal locomotor activities. Building on previous work, this study investigated these two skeletal characters in a comparative context to analyze function, while taking evolutionary relationships into account. This study examined the correspondence between proportions of suspension and overall substrate usage observed in 17 extant taxa and included angle of curvature and relative phalangeal length. Predictive models based on these traits are reported. Published proportions of different locomotor behaviors were regressed against each phalangeal measurement and a size proxy. The relationship between each behavior and skeletal trait was investigated using ordinary least-squares, phylogenetic generalized least-squares (pGLS), and two pGLS transformation methods to determine the model of best-fit. Phalangeal curvature and relative length had significant positive relationships with both suspension and overall arboreal locomotion. Cross-validation analyses demonstrated that relative length and curvature provide accurate predictions of relative suspensory behavior and substrate usage in a range of extant species when used together in predictive models. These regression equations provide a refined method to assess the amount of suspensory and overall arboreal locomotion characterizing species in the catarrhine fossil record.     

The behavioral repertoire of the black-and-white ruffed lemur, Varecia variegata variegata (Primates: Lemuridae)

A stable social group of 7 semifree-ranging black-and-white ruffed lemurs (Varecia variegata variegata) was studied for 4 months to catalog the behavioral repertoire of this species. Observations focussed on particular aspects of behavior were conducted before and after this 4-month period to supplement information gathered. Behavior in 11 major categories is detailed: postures, terrestrial locomotion, arboreal locomotion, feeding behavior, vocalizations, scent-marking, affinitive social behavior, agonistic social behavior, play behavior, sexual behavior, and parental behavior. Ruffed lemurs frequently used body positions and locomotor patterns unusual among lemurids, including bipedal hanging and long-descent leaps. These behaviors reinforce dental evidence that Varecia are among the most frugivorous of the Malagasy lemurs. Low intragroup cohesion, infrequent social interaction, and antiphonal use of several long-distance vocalizations suggest that ruffed lemurs naturally exhibit fission-fusion sociality. Social structure based on interindividual familiarity probably extends across foraging parties for several of the diurnally active lemurs; however, thus far only Varecia seems likely to exhibit fission-fusion sociality analogous to that seen in spider monkeys and chimpanzees.     

Morphology of the female reproductive system of three dorippid crabs (Crustacea: Decapoda: Brachyura: Dorippidae) and the role of accessory cuticle structures associated with seminal receptacles

The reproductive systems of crabs reveal characters of considerable importance for the understanding of brachyuran phylogeny and evolution. The Dorippoidea show several plesiomorphic characters within Eubrachyura and similarities to podotreme crabs. Hence, they are often considered as an early diverging lineage, sometimes even as the sister group to all remaining eubrachyurans. Due to their role as prime candidates for putative plesiomorphic characters of the reproductive system of the Eubrachyura, we compared the morphology of the vaginae, seminal receptacles, and ovaries of three dorippid species using histological methods, micro‐computed tomography, and 3‐D reconstructions. Despite the putative phylogenetic position of dorippids, the female reproductive system shows features that are regarded as derived characters in eubrachyurans, including a concave vagina and a ventral‐type seminal receptacle. In contrast to other eubrachyurans, the oviduct does not enter the seminal receptacle directly but through specific cuticular valves. The female reproductive systems of Dorippe sinica and Dorippe quadridens are remarkable in further aspects. The seminal receptacles of both species are completely cuticle‐lined and have accessory sperm storage structures, the bursae. Our findings on the morphology of the female reproductive system of dorippids with its unique combination of basal, derived, and new characters challenges the prevailing hypothesis on the evolution of sperm storage organs in Eubrachyura.     

Analysis of the locomotor activity of a nocturnal desert lizard (Reptilia: Gekkonidae: Teratoscincus scincus) under varying moonlight

1. This project seeks to identify determinants of the variation observed in the foraging behavior of predatory animals, especially in moonlight, using a lizard as a model. 2. Moonlight generally enhances the foraging efficiency of nocturnal visual predators and often depresses the locomotor activity of prey animals. Previous evidence has indicated for three different nocturnal species of smallish gecko lizards that they respond to moonlight by increasing their activity. 3. In this study some aspects of the foraging activity of the somewhat larger nocturnal psammophilous Teratoscincus scincus, observed near Repetek and Ashgabat, Turkmenistan, were significantly depressed by moonlight, while several confounding factors (sex, maturity, size, sand temperature, hour, prior handling and observer effect) were taken into account. 4. This behavioral difference may relate to the eye size of the various species. 5. Additionally, a novel method of analyzing foraging behavior shows that in this species the duration of moves increases the duration of subsequent stationary pauses. Measurement of locomotor speed, yielding an average speed of 220% of the maximum aerobic speed, indicates a need for these pauses. Secondarily, pause duration decreases the duration of subsequent moves, precluding escalation of move duration. 6. The results of this and related projects advocate the taking into account of physiological and environmental factors that may affect an animal's foraging behavior.     

A functional multivariate analysis of Mesopithecus (Primates: Colobinae) humeri from the Turolian of Greece

The genus Mesopithecus is well represented in the late Miocene of Greece by several recognized species. The present paper investigates functional aspects of the humeri of Mesopithecus delsoni/pentelicus, M. pentelicus and M. aff. pentelicus of several Turolian sites from central and northern Greece, using multivariate approaches. For these purposes, we selected significant humeral functional features, which were represented by 23 linear dimensions and three angles on 14 fossil humeri and 104 humeri from 10 genera and 22 species of extant African and Asian Colobines. All size-adjusted measurements were examined through a principal components analysis, followed by a discriminant function analysis, and a canonical variates analysis. All analyses revealed that the selected characters were able to discriminate between extant colobine genera. Functional groups, such as arboreal walking/climbing, arboreal walking/suspensory and semi-terrestrial walking, were set apart from a central cluster formed by the arboreal walking and arboreal walking/terrestrial groups. This cluster also grouped the three studied Mesopithecus species, which were mainly classified as arboreal walkers with significant terrestrial activities. These observations match with paleoenvironmental reconstructions and the suggested opportunistic feeding habits. Moreover, the overall arboreal/terrestrial locomotor tendencies of these fossil forms are discussed in relation to their earlier migration from Africa and later dispersal to eastern and southern Asia.     

The effects of locomotion on the structural characteristics of avian limb bones

Despite the wide range of locomotor adaptations in birds, little detailed attention has been given to the relationships between the quantitative structural characteristics of avian limb bones and bird behaviour. Possible differences in forelimb relative to hindlimb strength across species have been especially neglected. We generated cross‐sectional, geometric data from peripheral quantitative computed tomography scans of the humerus and femur of 127 avian skeletons, representing 15 species of extant birds in 13 families. The sample includes terrestrial runners, arboreal perchers, hindlimb‐propelled divers, forelimb‐propelled divers and dynamic soarers. The hindlimb‐propelled diving class includes a recently flightless island form. Our results demonstrate that locomotor dynamics can be differentiated in most cases based on cross‐sectional properties, and that structural proportions are often more informative than bone length proportions for determining behaviour and locomotion. Recently flightless forms, for example, are more easily distinguished using structural ratios than using length ratios. A proper phylogenetic context is important for correctly interpreting structural characteristics, especially for recently flightless forms. Some of the most extreme adaptations to mechanical loading are seen in aquatic forms. Penguins have forelimbs adapted to very high loads. Aquatic species differ from non‐aquatic species on the basis of relative cortical thickness. The combination of bone structural strength and relative cortical area of the humerus successfully differentiates all of our locomotor groups. The methods used in this study are highly applicable to fossil taxa, for which morphology is known but behaviour is not. The use of bone structural characteristics is particularly useful in palaeontology not only because it generates strong signals for many locomotor guilds, but also because analysing such traits does not require knowledge of body mass, which can be difficult to estimate reliably for fossil taxa. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 153 , 601–624.     

Tail Autotomy Plays No Important Role in Influencing Locomotor Performance and Anti‐Predator Behavior in a Cursorial Gecko

We used the frog‐eyed sand gecko (Teratoscincus scincus) as a model system to evaluate the locomotor costs of tail loss, and to examine whether tailless geckos use alternative anti‐predator behavior to compensate for the costs of tail loss. Of the 16 field‐captured geckos, eight were used as experimental animals and the remaining ones as controls. Locomotor performance, activity level and anti‐predator behavior were measured for experimental geckos before and after the tail‐removing treatment. Control geckos never undergoing the tail‐removing manipulation were measured to serve as controls for the measurements taken at the same time for experimental geckos. Experimental geckos did not differ from controls in activity level before they underwent the tail‐removing manipulation, but became less active thereafter. The mean locomotor stamina of tailless geckos was reduced by about 30% of the mean value for tailed ones. However, as the maximum stamina predicted from the laboratory trials is seldom required in nature, we expect that the costs associated with the reduced locomotor stamina may be relatively minor in T. scincus. All other examined locomotor (overall speed, maximal speed and stride length) and behavioral (distance to refuge, approach distance and flight distance) traits were not affected by the tail‐removing manipulation. Overall, our results suggest that tail autotomy plays no important role in influencing locomotor performance and anti‐predator behavior in lizards where the tail has no direct role in locomotion but is used to direct predatory strikes away from the torso.     

Entrainment to Light of Circadian Activity Rhythms in Tench (Tinca tinca)

The present article analyzes locomotor activity rhythms in Tinca tinca. To that end, three different experiments were conducted on 24 animals (20 g body weight) kept in pairs in 60‐liter aquaria fitted with infrared sensors connected to a computer to continuously record fish movements. The first experiment was designed to study the endogenous circadian clock under free‐running conditions [ultradian 40:40 min LD pulses and constant dark (DD)] and after shifting the LD cycle. Our results demonstrate that tench has a strictly nocturnal activity pattern, an endogenous rhythm being evident in 45.8% of the fish analyzed. The second experiment was conducted to test the influence of different photoperiods (LD 6:18, 12:12, 18:6, and 22:2) on locomotor activity, the results showing that even under an extremely long photoperiod, tench activity is restricted to dark hours. The third experiment examined the effect of light intensity on locomotor activity rhythms. When fish were exposed to decreasing light intensities (from 300:0 lux to 30:0, 3:0, and 0.3:0 lux) while maintaining a constant photoperiod (LD 12:12), the highest percentage of locomotor activity was in all cases associated with the hours of complete darkness (0 lux). In short, our results clearly show that (a) tench is a species with a strictly nocturnal behavior, and (b) daily activity rhythms gradually entrain after shifting the LD cycle and persist under free‐running conditions, pointing to their circadian nature. However, light strongly influences activity rhythms, since (c) the length of the active phase is directly controlled by the photophase, and (d) strictly nocturnal behavior persists even under very dim light conditions (0.3 lux). The above findings deepen our knowledge of tench behavior, which may help to optimize the aquacultural management of this species, for example, by adjusting feeding strategies to their nocturnal behavior.