Patterns Of Morphometric Variation Research Articles

Morphometric variability of Praomys misonnei (Rodentia: Muridae) in west central African forests reveals complex relationships between populations

This study addresses the morphological biometrics of Praomys misonnei and the signatures of its population history through a survey of external morphological characters measured on 133 individuals from eight West Central African (Gabon and Cameroon) localities. Four standard external characters were measured: head + body length, tail length, hindfoot length, and ear length. Using univariate and multivariate statistics, we inferred inter-population relationships from these morphometric characteristics and tested hypotheses of historical patterns of local adaptation (phylogenetic relationships) or of association with ecological gradients. We also tested the influence of sex on morphometric parameters. Our results support the existence of two morphometrically distinct groups of P. misonnei. The first one includes individuals from northern, central, and southern Gabon, while the second one includes individuals from southern Cameroon and one locality in southern Gabon (Mbaya). This result could be explained by the fact that the first group inhabits an area mainly covered by dense rainforest (about 90% of Gabon), while the second group is found in degraded forest or mosaics of forest-savanna habitats (Cameroon and southeastern Gabon). Another reason could be seasonal reversal, which has been postulated right at border between Gabon and Cameroon. The pattern of morphometric variation was correlated with local environmental factors. No sexual dimorphism was recorded.

Skull Variation in Asian Moles of the Genus Euroscaptor (Eulipotyphla: Talpidae) in Vietnam

The patterns of morphometric variation in skulls among different species and among intraspecies geographic populations, of five taxa (four species and one subspecies) of the mole genus Euroscaptor from Vietnam were investigated. Univariate and multivariate analyses were conducted based on 16 measurements of 140 specimens. Four groups based on skull size and shape were identified: 1. E. kuznetsovi + E. orlovi, 2. E. subanura, 3. E. parvidens ngoclinhensis, and 4. E. p. parvidens. Euroscaptor p. parvidens and E. p. ngoclinhensis clearly differed in overall size, proportions, and allometry trends. Therefore, E. p. parvidens and E. p. ngoclinhensis likely represent distinct species. Our analysis also revealed remarkable interspecies and geographic variations in 18 Vietnamese populations of studied taxa. Based on morphological divergence patterns, previous molecular evidence, and data on geographic distribution, we discuss the importance of geographical isolation caused by rivers, mountains, and altitudinal distribution.

Human Carpal Evolution and its Implications for Hominin Locomotor Ancestry

The ancestral locomotor repertoire from which hominin bipedalism emerged remains a subject of frequent debate, with multiple competing hypotheses maintaining support among active researchers. This study contributes to this ongoing debate by reconstructing the morphological and locomotor evolution of hominoids based on patterns of morphometric variation in the capitate, hamate, lunate, and triquetrum among extant and fossil anthropoids, including humans and fossil hominins. Aspects of carpal morphology found to consistently covary with locomotor behavior are used to reconstruct adaptive transitions within the anthropoid clade associated with locomotor behavior. The prevalence of different locomotor behaviors at the origin of nested clades within Hominoidea, including the one we share with Pan, are also estimated.While there is some inconsistency of morphological covariation with function and phylogeny among carpal elements, results are consistent in supporting frequent parallelism during hominoid locomotor evolution. This support is strongest as it applies to suspensory behaviors, with the last common ancestors of both apes and great apes predicted to have remained quite generalized relative to the clades’ extant representatives. The last common ancestor of humans and chimpanzees/bonobos is also estimated to have lacked adaptations in association with knuckle‐walking, providing further support for the hominin clade having descended from a relatively generalized ancestral morphotype that is not well modeled by any of the surviving hominoid lineages.

Morphometric Variation in thePericrocotusMinivets of Northeast Asia

Abstract The status of the two taxa of Pericrocotus minivets recorded in northeast Asia (divaricatus and tegimae) is controversial, with some authorities considering them subspecies but most considering them full species. Therefore, in order to further understand the status of these taxa and to elucidate geographic patterns of morphometric variation in their populations, I examined 85 museum specimens collected from Japan and neighbouring territories. The results confirm that morphometric differences exist between the two taxa, the northern migratory divaricatus and the southern sedentary tegimae, and that these differences are statistically significant. However, the results also reveal that there is considerable geographic variation, in terms of wing length, between populations within each taxon. In particular, the population of tegimae resident in Kyushu, Japan, has significantly longer wings than populations further south in the Nansei Shoto; and populations of divaricatus from the Korean Peninsula and...

Body shape evolution of Chromis and Azurina species (Percifomes, Pomacentridae) of the eastern Pacific

Chromis is a circumglobal tropical and temperate genus with over 84 species of damselfishes. Studies based in osteological and molecular data have cited the relationship between Azurina and Chromis in the eastern Pacific. The main objectives of the study are: (1) to characterize size and shape in all Chromis and Azurina species of the eastern Pacific, (2) explore the phylogenetic signal of external morphology, and (3) present a hypothesis of the diversification process of this group. According to the results, there is no significant relationship between size and shape. The variation in body shape among all species is related to the height of the trunk, position of the snout and eye, and length of the caudal peduncle. The main morphologic variation between Azurina and Chromis is the degree of elongation of the body. Both Azurina species are closely related to C. punctipinnis and C. atrilobata. The morphological pattern of Azurina integrated it into Chromis. The phylogenetic pattern found by geometric morphometric analyses presented a high similarity with previous results based on molecular data. Phylogeny recovered two main clades, slender-bodied and deep-bodied species. This pattern of morphometric variation is closely related to exploitation of two different reef environments.

Morphometric and Karyological Differentiation Among Populations of <I>Discoglossus Pictus</I> (Discoglossidae: Anura) in Eastern North Africa

Abstract. To assess karyological and morphometric diversity within Discoglossus pictus Otth 1837, morphometric and cytogenetic analyses were carried out on five populations from the northern Tunisia and Algeria. A total of eight morphometric adult traits were evaluated, tadpole oral disc structure was described and chromosome patterns were assessed by means of conventional staining and banding methods (C-, Ag-NOR and CMA3 banding). Karyological data indicated the same chromosome and chromatin characters among the five populations. We observed also the same oral disk structure (LTRF: ⅔) in all studied Discoglossus tadpoles. However, we found significant differences in morphometric parameters of the specimens from these localities. Discriminant Function Analysis (DFA) of morphometric variables correctly classified 88% of individuals to their original localities. The pattern of morphometric variation does not match the genetic observation, which suggests that body shape differences result from the phenotypic...

Morphometric variation in the Tunisian green frog, Rana saharica Anura: Ranidae)

Rana saharica is the most widely distributed anuran in Tunisia. We examined morphological variation in 124 specimens as a function of their geographical origin, using univariate and multivariate statistics with traditional morphometrics. Our results supported the existence of three morphotypes of this species, correctly classified 84.7% of specimens, and indicated significant degrees of variation in morphometric characteristics between regions. No significant differences were found between sexes among populations. We observed an increase in body size and a decrease in body mass as a function of latitude. Specimens from the southernmost region had the smallest bodysize and the greatest morphometric divergence. The pattern of morphometric variation probably results from phenotypic plasticity correlated with local environmental factors.

Morphometric Variation in the Tunisian Green Frog,Rana saharica(Anura: Ranidae)

Rana saharica is the most widely distributed anuran in Tunisia. We examined morphological variation in 124 specimens as a function of their geographical origin, using univariate and multivariate statistics with traditional morphometrics. Our results supported the existence of three morphotypes of this species, correctly classified 84.7% of specimens, and indicated significant degrees of variation in morphometric characteristics between regions. No significant differences were found between sexes among populations. We observed an increase in body size and a decrease in body mass as a function of latitude. Specimens from the southernmost region had the smallest body size and the greatest morphometric divergence. The pattern of morphometric variation probably results from phenotypic plasticity correlated with local environmental factors.

Patterns of morphometric variation among species of the genus Cicada (Hemiptera: Cicadidae) in the Mediterranean area

Selected populations of five closely related species of the genus Cicada L. were collected mainly on the Portuguese, Greek and Turkish mainland, as well as on several Aegean islands. Ten morphometric traits of external structures and seven of male genitalia were analysed and the results revealed patterns in morphometric variation for each species. Only C. lodosi was always completely discriminated by both character sets and C. barbara by the male genitalia analysis. For the remaining species there was great overlap between the clusters. Body length, of the external morphological structures, and measurements of the pygophore, of the male genitalia, were the best variables for identifying C. lodosi and C. barbara. The present morphometric analyses revealed that divergence in morphology is much less pronounced than the divergence in acoustic signals and DNA. Thus, the congruence between morphological divergence, namely at the level of the external structures, and both behavioural (acoustic) and genetic divergence is quite low.

Patterns of morphometric variation in the alpine newt (Mesotriton alpestris) at the southern limit of its distribution: environmental correlates

We applied multivariate analyses to an array of body measures of alpine newt specimens derived from 11 local populations in Greece to describe, analyse and detect patterns and putative causes of within-population and among-population morphometric variation. The observed morphometric variation was partitioned into several independently varying aspects of the external phenotype, frequently following variation patterns in different environmental factors. The size and features of the aquatic habitat were found to affect body size, while altitude was found to affect head-shape variation in both sexes. At the intra-population level, variation in generalized body size and shape was found to be significantly lower when competitive newt species were present in the habitat, indicating stabilizing selection towards a decrease in inter-specific competition. No clear discrimination on body size and shape proportions was detected between the two genetic lineages examined, implying ecogenetic or environmentally induced variation rather than phylogeny.

Patterns of morphometric variation in the smooth newt (Lissotriton vulgaris) from Greece: environmental correlates

Multivariate analyses were applied to an array of body measures of smooth newt specimens derived from 14 local populations of two subspecies in Greece, in order to describe, analyse and detect patterns and putative causes of among‐population morphometric variation. The two subspecies do not differ morphometrically, in spite of their considerable genetic differentiation. Paedomorphosis explains a significant portion of the observed morphometric differentiation of populations. Differences between the two morphs refer mostly to characters and structures relevant to feeding and locomotion, which might lead to niche segregation and subsequent reduction of intra‐population competition. Body size varies in relation to altitude probably as a result of differential developmental processes or as an environmentally induced response to varying predation pressures. Variation of different aspects of the external morphology is correlated both to climatic factors and habitat characteristics.

Geographic phenetic variation of two eastern-Mediterranean non-commensal mouse species, Mus macedonicus and M. cypriacus (Rodentia: Muridae) based on traditional and geometric approaches to morphometrics

We tested the hypothesis that skull shape within the genus Mus may vary with geographic location by assessing the extent and spatial distribution of phenotypic skull variation within and among two wild mouse species, M. macedonicus and M. cypriacus, using traditional and geometric morphometrics including a rather novel application of sliding semilandmarks. Shape was shown to be significantly correlated both with longitude and latitude in M. macedonicus, yet the correlation between morphometric and geographic distances was not significant, and morphometric differences between Asian and European populations were not higher than those within the particular continents. The phylogenetic signal was found to be stronger in dental characters than in cranial ones, however, overall concordance between the pattern of morphometric variation and the presumed history of M. macedonicus was rather weak. In both species, the dorsal and ventral sides of the skull were shown to covary in many aspects though there were also some differences between them, making the functional interpretation of these differences difficult. Discrimination between M. cypriacus and M. macedonicus as well as discrimination between two M. macedonicus subspecies was highly reliable using both traditional and geometric morphometric tools to analyze skull measurements.

Patterns of morphometric variation and a new supraspecific classification of apomictic taxa of Hieracium (Asteraceae) from Denmark and southern Sweden

Patterns of variation among all micro-species of Hieracium sect. Hieracium and H. sect. Vulgata known from Denmark and southern Sweden are investigated. Forty-three, possibly independent morphological characters are used. Significant correlations were revealed among the majority of the characters. Multivariate analyses did not reveal any discontinuities in the variation or any discrete groups of species. However, there were obvious correlations between previous taxonomic classifications and the result of the multivariate analyses. Based on the statistical analyses, three sections and 38 informal species aggregates are recognized. H. sect. Bifidum T. Tyler is described anew. The characters that turned out to be most influential in the multivariate analyses, and thus most important for the classification, were the distribution of stellate tomentum on the phyllaries, the amount of glandular hairs and the amount and pigmentation of simple hairs on the phyllaries, the shape of the leaf-base and the regularity of the leaf dentation. The evolution of the group and the taxonomic treatment is thoroughly discussed in the light of the results.

Morphometric differentiation of the moor frog (Rana arvalis Nilss.) in Central Europe

Morphometric variation of 11 characters was studied in 14 samples of Rana arvalis from allopatric population groups in Central Europe, representing two subspecies formerly recognised: R. a. arvalis and R. a. wolterstorffi. All samples from Poland (nine) were collected from the area, which is believed to be populated by the nominal form. In addition, the isolated population of R. arvalis from the Eastern Carpathians of Romania was classified to that form. All the Hungarian samples fall into the range of R. a. wolterstorffi. No significant differences in body size between sexes and among the populations from the three geographic regions (Poland, Hungary and Romanian Eastern Carpathians) were found. Multivariate analysis of the differences in body shape among groups showed that the populations from Hungary differed from the nominal form mainly in the relative hindlimb length. However, substantial overlap in overall shape differences resulted in a relatively low percentage of correct classifications to the respective geographic groups in the Discriminant Analysis. Large intrapopulation variation in the values of the two ratios (SVL/TL and TL/IMT) formerly used for differentiate the two European subspecies of R. arvalis makes them unreliable characters for distinguishing the two forms. The pattern of morphometric variation does not match the overall genetic divergence of the R. arvalis populations, which suggests that the body shape differences in this species result from the phenotypic plasticity correlated with local climatic factors.

Patterns of morphometric variation in birds' tails: length, shape and variability

Abstract In Palaearctic birds, tail length was more variable than wing and tarsus, but not bill lengths. Tails of the ornamental shapes pin, lyre and graduated varied more in length than did non-ornamental shapes. Log coefficient of variation (CV) tail length showed an overall U-shaped relationship with longtailedness, but although the CV for most tail shapes increased in short-tailed species, only in ornamental shapes was CV also high in long-tailed species. CV of fork depth was lowest at a fork depth of 2, and considerably higher in shallow forked tails. CV streamer lengths were similar to CV deep fork depths. The more deeply forked tails thus seem ornamental. Phylogenetically independent contrasts confirmed in males, but not females, that long-tailed species had greater CV than medium-tailed species, and the greater CV of graduated than square tails, but the CV of short- and medium-tailed species did not differ. These comparisons, however, did not control for tail shape. The greater elongation and CV of tails with ornamental shapes are consistent with an influence of sexual/signal selection on these tails, and the increase in CV with longtailedness suggests that Weber's law applies to the perceptual threshold for tail length. Sexual selection may have a widespread, but moderate, influence on tail traits in birds.

Patterns of morphometric variation in birds' tails: length, shape and variability

Abstract In Palaearctic birds, tail length was more variable than wing and tarsus, but not bill lengths. Tails of the ornamental shapes pin, lyre and graduated varied more in length than did non-ornamental shapes. Log coefficient of variation (CV) tail length showed an overall U-shaped relationship with longtailedness, but although the CV for most tail shapes increased in short-tailed species, only in ornamental shapes was CV also high in long-tailed species. CV of fork depth was lowest at a fork depth of 2, and considerably higher in shallow forked tails. CV streamer lengths were similar to CV deep fork depths. The more deeply forked tails thus seem ornamental. Phylogenetically independent contrasts confirmed in males, but not females, that long-tailed species had greater CV than medium-tailed species, and the greater CV of graduated than square tails, but the CV of short- and medium-tailed species did not differ. These comparisons, however, did not control for tail shape. The greater elongation and CV of tails with ornamental shapes are consistent with an influence of sexual/signal selection on these tails, and the increase in CV with longtailedness suggests that Weber's law applies to the perceptual threshold for tail length. Sexual selection may have a widespread, but moderate, influence on tail traits in birds.

Patterns of Morphometric Variation in the Channel and Headwater Catfishes

Abstract The purpose of this study was to compare external morphological variation between the headwater catfish Ictalurus lupus and the channel catfish Ictalurus punctatus, and to determine if external characters could be used to improve our ability to identify these highly similar species, as most individuals cannot be identified in the field using available methods. Morphological differences were found between species but were obscured by geographic variation and allometric growth. Overall, headwater catfish tended to be broader, have shorter spines, and have a shorter anal fin base than channel catfish when measurements were adjusted for body size. Fish of both species were broader in New Mexico than their counterparts in Texas; headwater catfish from Mexico tended to be intermediate. A south-to-north cline of decreasing anal ray counts was observed for both species. Each species exhibited similar patterns of allometric growth, with snout and mouth widths and interorbital distances increasing, and len...

Morphometric Variation in Kangaroo Rats (Genus Dipodomys) and Its Relationship to Selected Abiotic Variables

Geographic patterns of morphometric variation, as represented by projections of samples on the first principal component, were obtained for 14 species of kangaroo rats (genus Dipodomys ) by using principal components analysis. The amount of variation accounted for by the first principal component ranged in males from 37.5 ( D. nelsoni ) to 87.1% ( D. californicns ) with a mean of 61.2%. These values for females were from 51.1 ( D. phillipsii ) to 83.9% ( D. californicus ) with a mean of 65.3%. Characters that consistently accounted for the most variation for this component were total length of skull, basal length, greatest width of skull, and width of mastoid bullae. Values for the projections of the samples on principal component I (frequently considered a body-size index) were compared to values of latitude, and annual values and seasonal ranges of temperature, precipitation, and actual evapotranspiration by using Pearson's product-moment correlation analyses. Of these abiotic variables, annual temperature was considered a slightly more-appropriate predictor of size variation. Beyond a tendency for size to increase with decreasing annual temperature (in accordance with Bergmann's Rule), there was little general pattern of correlation between morphometric variation and these abiotic features. Had fewer species of kangaroo rats been examined, conclusions would have depended on the taxa analyzed. It appears that abiotic parameters may effect morphometric variation in some portions of the distribution of a species, but may be superseded by different factors in other parts of that taxon's range.

Genetic Compatibility of Peromyscus maniculatus and Peromyscus melanotis, as Indicated by Breeding Studies and Morphometrics

Reproductive compatibility, skull morphometrics, color of pelage, and size and structure of bacula and sperm were compared in nine populations of Peromyscus maniculatus and P. melanotis from the southwestern United States and Mexico. Breeding data indicated that there is no conspicuous reduction of fertility between populations of P. maniculatus , or of P. melanotis. However, no P. maniculatus × P. melanotis hybrids were produced. In most instances, patterns of morphometric variation corroborated genetic affinities revealed by breeding, chromosomal, and electrophoretic studies; however, it is unlikely that the same conclusions would have been drawn without the supporting breeding, chromosomal, and electrophoretic data—it is possible that the two species would have been considered conspecific if only morphometric data were used. Pelage color, and size and structure of bacula and sperm proved of little value in separating P. melanotis and P. maniculatus . Based on cranial morphology, certain individuals of P. maniculatus rufinus from Otero County, New Mexico, and P. melanotis from near El Salto, Durango, are difficult to distinguish to species. This similarity in morphology is probably due to convergent evolution resulting from adaptations to similar habitats. That P. maniculatus and P. melanotis are sibling species is substantiated by the fact that certain populations of the latter from southern Arizona previously were referred to as P. maniculatus rufinus. Breeding, electrophoretic, and chromosomal data clearly reveal that these populations are P. melanotis; however, when these populations are compared with others of P. melanotis , no basis for subspecies distinction can be found. Therefore, P. melanotis remains a monotypic species.