Functional and cellular adaptation to weightlessness in primates

Considerable data has been collected on the response of hindlimb muscles to unloading due to both spaceflight and hindlimb suspension. One generalized response to a reduction in load is muscle fiber atrophy, although not all muscles respond the same. For example, predominantly slow extensor muscles like the Sol exhibit a large reduction in fiber size to unloading, while fast extensors like the plantaris and fast flexors like the tibialis anterior show little, if any, atrophy. Our understanding of how muscles respond to microgravity, however, has come primarily from the examination of hindlimb muscles in the unrestrained rat in space. The non-human primate spaceflight paradigm differs considerably from the rodent paradigm in that the monkeys are restrained, usually in a sitting position, while in space. Recently, we examined the effects of microgravity on muscles of the Rhesus monkey by taking biopsies of selected hindlimb muscles prior to and following spaceflights of 14 and 12 day durations (Cosmos 2044 and 2229). Our results revealed that the monkey's response to microgravity differs from that of the rat. The apparent differences in the atrophic response of the hindlimb muscles of the monkey and rat to spaceflight may be attributed to 1) a species difference, 2) a difference in the manner in which the animals were maintained during the flight (i.e., chair restraint or "free-floating"), and/or 3) an ability of the monkeys to counteract the effects of spaceflight with resistive exercise.     

Advances in insectivore and rodent systematics due to geometric morphometrics

• 1 Morphometrics, the study of the variation and change in form amongst organisms, serves as a basic methodological tool in various fields of biological research, including systematics. Because it includes information about spatial relationships amongst anatomical landmarks, geometric morphometrics is more suitable for analyzing morphometric variation than methods based on distance measurements.
• 2 Geometric morphometrics allows us to answer general ecological and evolutionary questions about shape.
• 3 In this paper, landmark‐based methods are described and illustrated, based on a dataset of measurements from 295 Apodemus mandibles, and the applications of such methods in the systematics of insectivores (Eulipotyphla) and rodents (Rodentia) are summarized.

     

基于几何形态测量学的黄蜻翅的雌雄二态性研究

【目的】本研究运用几何形态测量学方法对黄蜻Pantala flavescens Fabricius前翅和后翅的雌雄二态性进行分析,探讨黄蜻雌雄性在翅上的形态差异。【方法】通过对黄蜻的前翅和后翅做数字化标点,获得翅的形态信息。经主成分分析(PCA)和薄片样条法(TPS)获得雌雄性在翅型和翅脉上的差异性。【结果】PCA结果表明,黄蜻雌雄性的前翅和后翅在翅型、翅脉结构上存在着明显差异,而且后翅间的差异更大。经TPS分析可知,雌雄性黄蜻前翅上的差异部位主要发生在亚翅结和三角室,后翅的差异部位主要发生在亚翅结、肘脉域和臀角区域。对黄蜻前后翅的大小分析(CS)可知,雌性黄蜻前后翅较大,雄性黄蜻前后翅较小。【结论】黄蜻雌雄性间的翅型结构差异性表明雌雄性在其各自生活史中履行不同的职责,特定的飞行模式逐渐形成特定的翅型、翅脉结构。     

Bias and error in estimates of mean shape in geometric morphometrics

Sampling experiments were performed to investigate mean square error and bias in estimates of mean shape produced by different geometric morphometric methods. The experiments use the isotropic error model, which assumes equal and independent variation at each landmark. The case of three landmarks in the plane (i.e., triangles) was emphasized because it could be investigated systematically and the results displayed on the printed page. The amount of error in the estimates was displayed as RMSE surfaces over the space of all possible configurations of three landmarks. Patterns of bias were shown as vector fields over this same space. Experiments were also performed using particular combinations of four or more landmarks in both two and three dimensions.It was found that the generalized Procrustes analysis method produced estimates with the least error and no pattern of bias. Averages of Bookstein shape coordinates performed well if the longest edge was used as the baseline. The method of moments (Stoyan, 1990, Model. Biomet. J. 32, 843) used in EDMA (Lele, 1993, Math. Geol. 25, 573) exhibits larger errors. When variation is not small, it also shows a pattern of bias for isosceles triangles with one side much shorter than the other two and for triangles whose vertices are approximately collinear causing them to resemble their own reflections. Similar problems were found for the log-distance method of Rao and Suryawanshi (1996, Proc. Nat. Acad. Sci. 95, 4121). These results and their implications for the application of different geometric morphometric methods are discussed.     

Interspecific comparison of growth and shape within Diapterus (Gerreidae: Perciformes) using geometric morphometrics

Morphometric analyses can generate useful information to solve taxonomic problems by direct comparison of each species representative’s shape or by analyzing its growth patterns. In this study, growth patterns and shape variation of the four fish species belonging to the genus Diapterus (Gerreidae) were analyzed using geometric morphometrics. We examined 287 specimens, D. auratus (n = 65), D. aureolus (n = 76), D. brevirostris (n = 87) and D. rhombeus (n = 59). For the exploration of growth trajectories of each species, the standard length was used as a size measurement, and the Procrustes distance as a morphological variation measurement. We also compared averages of the morphological change direction within each species through a pairwise comparison between vector angles. These analyses were also used to select those fishes whose increase in size did not lead to a significant change in Procrustes distance. Once this subsample was selected, the body shapes of the four species were compared using Canonical variate Analysis and Multivariate Analysis of Variance. Diapterus aureolus showed the most different morphological trajectory and the most divergent vector within the genus. An average of 93% of correct classification was estimated from Mahalanobis distances. The Canonical Variate Analysis generated three statistically significant canonical variates (p < 0.001) and indicated that D. auratus, D. brevirostris, and D. rhombeus presented a more related shape between them than D. aureolus, as indicated in previous studies. In this context, we considered the shape and growth of D. aureolus with regard to its congeners can be an important element for suggesting a taxonomic rearrangement. However, our interpretation should be supported by phylogenetic analysis. Based in our study, we suggest that trajectories analyses can be directly used in morphometric comparisons to detect those specimens affected by allometry.     

Functional morphology and anatomy of cervical vertebrae in Nacholapithecus kerioi, a middle Miocene hominoid from Kenya

This paper describes the morphology of cervical vertebrae in Nacholapithecus kerioi, a middle Miocene primate species excavated from Nachola, Kenya in 1999-2002. The cervical vertebrae in Nacholapithecus are larger than those of Papio cynocephalus. They are more robust relative to more caudal vertebral bones. Since Nacholapithecus had large forelimbs, it is assumed that strong cervical vertebrae would have been required to resist muscle reaction forces during locomotion. On the other hand, the vertebral foramen of the lower cervical vertebrae in Nacholapithecus is almost the same size as or smaller than that of P. cynocephalus. Atlas specimens of Nacholapithecus resemble those of extant great apes with regard to the superior articular facet, and they have an anterior tubercle trait intermediate between that of extant apes and other primate species. Nacholapithecus has a relatively short and thick dens on the axis, similar to those of extant great apes and the axis body shape is intermediate between that of extant apes and other primates. Moreover, an intermediate trait between extant great apes and other primate species has been indicated with regard to the angle between the prezygapophyseal articular facets of the axis in Nacholapithecus. Although the atlas of Nacholapithecus is inferred as having a primitive morphology (i.e., possessing a lateral bridge), the shape of the atlas and axis leads to speculation that locomotion or posture in Nacholapithecus involved more orthograde behavior similar to that of extant apes, and, in so far as cervical vertebral morphology is concerned, it is thought that Nacholapithecus was incipiently specialized toward the characteristics of extant hominoids.     

Application of molecular genetics and geometric morphometrics to taxonomy and conservation of cave beetles in central Italy

Integration of molecular genetic techniques and geometric morphometrics represent a valuable tool in the resolution of taxonomic uncertainty and the identification of significant units for conservation. We combined mitochondrial DNA cytochrome c oxidase subunit II gene sequence data and geometric morphometric analysis to examine taxonomic status and identify units for conservation in four species of the hypogean beetle Duvalius (Coleoptera, Trechinae) using mainly museum specimens collected in central Italy. Previous taxonomic studies based on morphological traits described several subspecies often inhabiting geographically distinct caves. Phylogenetic analysis identified two well supported monophyletic lineages and a number of different clades with relatively small genetic differences, suggesting a short divergence time in line with known geological history of the study area. Geometric morphometrics, on the other hand, recovered a high level of distinctiveness among specimens. Both genetic and morphometric analyses did not entirely corroborate former taxonomic nomenclature, suggesting possible rearrangements and the definition of evolutionary significant units. Beetles of the genus Duvalius are protected by regional laws and the majority of taxa considered in this study inhabit caves located outside protected areas. Our study advocates the importance of devoting protection efforts to networks of cave ecosystems rather than single locations or species.     

Correction to: Methods for studying allometry in geometric morphometrics: a comparison of performance

Evolutionary Ecology -     

Pathology of degenerative osteoarthrosis of the thoracic vertebrae in rats

Degenerative osteoarthrosis was observed in the thoracic vertebrae in specific pathogen-free Sprague-Dawley rats at the ages of eight and 19 weeks. Histological changes seen in the lesions were degenerated matrix intermixed with collagen fibers, erosion or ulceration, and formation of cysts in the articular cartilage, and degeneration and necrosis in the subchondral bone.     

Tracking the history of grapevine cultivation in Georgia by combining geometric morphometrics and ancient DNA

Vegetation History and Archaeobotany - The Near East and the Caucasus are commonly regarded as the original domestication centres of Vitis vinifera (grapevine), and the region continues to be home...     

Evolution of activity patterns and chromatic vision in primates: morphometrics, genetics and cladistics

Hypotheses for the adaptive origin of primates have reconstructed nocturnality as the primitive activity pattern for the entire order based on functional/adaptive interpretations of the relative size and orientation of the orbits, body size and dietary reconstruction. Based on comparative data from extant taxa this reconstruction implies that basal primates were also solitary, faunivorous, and arboreal. Recently, primates have been hypothesized to be primitively diurnal, based in part on the distribution of color-sensitive photoreceptor opsin genes and active trichromatic color vision in several extant strepsirrhines, as well as anthropoid primates (Tan & Li, 1999 Nature402, 36; Li, 2000 Am. J. phys. Anthrop. Supple.30, 318). If diurnality is primitive for all primates then the functional and adaptive significance of aspects of strepsirrhine retinal morphology and other adaptations of the primate visual system such as high acuity stereopsis, have been misinterpreted for decades. This hypothesis also implies that nocturnality evolved numerous times in primates. However, the hypothesis that primates are primitively diurnal has not been analyzed in a phylogenetic context, nor have the activity patterns of several fossil primates been considered.This study investigated the evolution of activity patterns and trichromacy in primates using a new method for reconstructing activity patterns in fragmentary fossils and by reconstructing visual system character evolution at key ancestral nodes of primate higher taxa. Results support previous studies that reconstruct omomyiform primates as nocturnal. The larger body sizes of adapiform primates confound inferences regarding activity pattern evolution in this group. The hypothesis of diurnality and trichromacy as primitive for primates is not supported by the phylogenetic data. On the contrary, nocturnality and dichromatic vision are not only primitive for all primates, but also for extant strepsirrhines. Diurnality, and possibly X-linked polymorphic trichromacy, evolved at least in the stem lineage of Anthropoidea, or the stem lineage of all haplorhines.     

Comparative anatomy and histology of the cervix uteri in non-human primates

The uterine cervix of rhesus macaque, crab-eating macaque, stump-tailed macaque, pig-tailed macaque, marmoset, baboon, patas, and squirrel monkeys was studied macroscopically and microscopically. Distribution of spermatozoa and leukocytes in the lumen and within the crypts and clefts was studied in rhesus and marmoset uterine cervix. The cervical canal of baboon, patas, marmoset, and stump-tailed monkeys is straight or slightly bent. The presence of variably developed ventral and dorsal colliculi in rhesus, crab-eating, and pig-tailed macaques causes the dorsoventral sinuosity of the cervical canal. The cervix of all investigated specimens is fundamentally fibrous tissue and the amount of muscle fibers increases toward the uterine corpus. The cervical mucosa of baboon, marmoset, and patas monkeys contains a large amount of clefts and tubular tunnels of variable structure, length, width, direction, and degree of branching. The cervical mucosa of macaques contains a large number of crypts of complex structure, length, width and degree of branching. The cervical crypts in macaques are usually longer in the ectocervix; whereas, in the midcervix, mucosa contains small crypts, clefts and long tunnels. Squamo-columnar junction is located near the external os in baboon, patas, marmoset, rhesus, crab-eating, and pig-tailed monkeys. In squirrel monkey, squamous epithelium is continuous through the external os, covers the vestibule and external surface of the cervical colliculi. In stump-tailed macaque, squamo columnar junction is located in the vagina, 1–3 cm from the external os of the cervix. The vaginal wall between the squamo-columnar junction and the external os of the cervix is covered with heavily branched mucosa lined with columnar epithelium. Ciliated cells of cervical epithelium occur in 9 to 19%. A large number of spermatozoa and a relatively low number of leucocytes have been found within crypts and clefts of cervical mucosa. The results are discussed in relation to the function of the cervix in different stages of the cycle, during pregnancy and parturition.This investigation was supported in part by Ford Foundation Grant No. 710-0287.     

Principal components analysis of distal humeral shape in Pliocene to recent African hominids: the contribution of geometric morphometrics

The shape of the distal humerus in Homo, Pan (P. paniscus and P. troglodytes), Gorilla, and six australopithecines is compared using a geometric approach (Procrustes superimposition of landmarks). Fourteen landmarks are defined on the humerus in a two-dimensional space. Principal components analysis (PCA) is performed on all superimposed coordinates. I have chosen to discuss the precise place of KNM-KP 271 variously assigned to Australopithecus anamensis, Homo sp., or Praeanthropus africanus, in comparison with a sample of australopithecines. AL 288-1, AL 137-48 (Hadar), STW 431 (Sterkfontein), and TM 1517 (Kromdraai) are commonly attributed to Australopithecus afarensis (the two former), Australopithecus africanus, and Paranthropus robustus, respectively, while the taxonomic place of KNM-ER 739 (Homo or Paranthropus?) is not yet clearly defined. The analysis does not emphasize a particular affinity between KNM-KP 271 and modern Homo, nor with A. afarensis, as previously demonstrated (Lague and Jungers [1996]     

The evolution of cranial form and function in theropod dinosaurs: insights from geometric morphometrics

Theropod dinosaurs, an iconic clade of fossil species including Tyrannosaurus and Velociraptor, developed a great diversity of body size, skull form and feeding habits over their 160+ million year evolutionary history. Here, we utilize geometric morphometrics to study broad patterns in theropod skull shape variation and compare the distribution of taxa in cranial morphospace (form) to both phylogeny and quantitative metrics of biting behaviour (function). We find that theropod skulls primarily differ in relative anteroposterior length and snout depth and to a lesser extent in orbit size and depth of the cheek region, and oviraptorosaurs deviate most strongly from the "typical" and ancestral theropod morphologies. Noncarnivorous taxa generally fall out in distinct regions of morphospace and exhibit greater overall disparity than carnivorous taxa, whereas large-bodied carnivores independently converge on the same region of morphospace. The distribution of taxa in morphospace is strongly correlated with phylogeny but only weakly correlated with functional biting behaviour. These results imply that phylogeny, not biting function, was the major determinant of theropod skull shape.