Evolution of ontogeny in the hippopotamus skull: using allometry to dissect developmental change

Allometry describes the effect of size change on aspects of an organism's form and can be used to summarize the developmental history of growing parts of an animal. By comparing how allometric growth differs between species, it is possible to reveal differences in their pathways of development. The ability to compare and categorize developmental change between species is demonstrated here using morphometric methods. This involves the interspecific statistical comparison of a large number of bivariate relationships that summarize ontogenetic trajectories. These linear ontogenetic trajectories can be modified as they evolve in any of three ways: ontogenetic scaling indicative of change in the duration of growth, lateral shifts indicative of changes in prenatal development, and directional change indicative of novel modes of postnatal growth. I apply this analysis to skulls of the common hippopotamus ( Hippopotamus amphibius ) and the pygmy hippopotamus ( Hexaprotodon liberiensis ). The number of allometric changes falling into each category was statistically determined and Jolicoeur's multivariate generalization of simple allometry was used to provide an overview of cranial variation. For these skulls, directional change was not found to be statistically significant, but ontogenetic scaling and lateral shifts were both common. This indicates that conserved patterns of growth covariance (ontogenetic scaling) can be separated from novel or derived patterns (directional change and/or lateral shifts). This study demonstrates that He. liberiensis is not simply an ontogenetically scaled version of its larger relative. The evolutionary implications of allometric growth variation are discussed in the light of these findings and those of other studies.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 625–638.     

Redescription of Mastacembelus liberiensis Boulenger, 1898 and description of a new West African spiny‐eel (Synbranchiformes: Mastacembelidae) from the Konkoure River basin, Guinea

Mastacembelus liberiensis Boulenger, 1898 of West Africa is discussed with reference to its distribution within the Konkoure River basin (Guinea). The synonymies of M. reticulatus Boulenger, 1911 and M. laticauda Ahl, 1937 with M. liberiensis are both confirmed. Further, intraspecific meristic, morphometric and colour pattern variation within M. liberiensis is documented and discussed. Finally, a new species, M. kakrimensis sp. nov., endemic to the Konkoure River basin is identified and described.     

湘鄂与闽粤猕猴颅骨的多变量分析

本文是中国猕猴湖南－湖北和广东－福建种群颅骨的多变量分析,结果表明,二者的面宽和颅肌的形态结构除有明显的性二型外,还存在较大的差异。湖南－湖北种群的颅骨结构相对大于福建广东种群。它们与云南南部和海南岛猕猴颅骨的判别分别结果表明,由于地理和生态隔离,四者雌雄两性颅骨的形态结构均有较大的差异,达到种群间的显著差异水平,分别应属不同的亚种。     

Cranial variation and taxonomic content of the marbled polecat Vormela peregusna (Mustelidae,Carnivora)

Morphometric variation in 26 characters of 245 skulls of the marbled polecat (Vormela peregusna) was studied across the distribution range. Morphological diversity was low with respect to both the size and the shape of the skull. The sexual size dimorphism of cranial characters in V. peregusna was low compared with other similar-sized mustelids. This finding may be a result of more specialized behaviour, resulting in less intra-specific competition with respect to habitat and food selection. Analysis of the geographic variation of skulls revealed two morphological groups – western and eastern. These groups were treated as distinct subspecies in this study. Nominotypical V. p. peregusna (Güldenstädt, 1770) (syn. sarmatica, euxina) is found in southern and eastern Europe, Asia Minor and Caucasus. The eastern subspecies V. p. koshewnikowi Satunin, 1910 (syn. alpherakii, chinensis, negans, obscura, ornata, pallidior, syriaca, and tedshenika) is found south and east of the Middle East, in Middle and Central Asia and eastward to China. Our data revealed a gradual decrease in the morphological diversity in Vormela skulls from west to east in the distribution range. This phenomenon may be explained by the later origin of the eastern subclusters of the marbled polecat. The pattern of geographic variation revealed in this study may reflect the Pleistocene history of the species range formation, rather than a relationship to climate conditions throughout the modern species range.     

A re-examination of the subspecies of Red deer (Cervus elaphus) with particular reference to the stocks in Britain

In 1906, Lönnberg identified a native subspecies of Red deer Cervus elaphus scoticus L., in Britain after examining a sample of stags' skulls from Glenquoich (Inverness-shire, Scotland). In north-west England, it is commonly believed that "Red deer of indigenous stock have persisted in this area (Furness Fells, Lancashire, England) from time immemorial…" (Chard, 1966). Arrangements were made to introduce animals into a park within this area in 1970, which, in view of this local opinion, would have been the only Red deer within the district not of native origin. Therefore, it was thought desirable to examine all the stocks of wild or feral Red deer in Britain and to determine which, if any, of them could be considered native and thus deserving of special measures to ensure their survival.
After examining samples of skulls, using multivariate analysis, it appeared that, within the limits of the material representing the various subspecies of the world, there was little support for the concept of subspeciation in Red deer. In Great Britain, however, there appeared to be two distinct forms of Red deer leading a free existence, one presumed to be native and the other to be of park derivation. Visually, the differences were indetectable and could be demonstrated only by discriminant analyses.     

Morphometric variations of the skull in the Gray Wolf (<Emphasis Type="Italic">Canis lupus</Emphasis>) in Iran

The Gray Wolf is a wide ranging carnivore in Iran, absent only in the central deserts and Dasht-e Lut. This study was carried out to verify whether, despite their high mobility, individual wolves belonging to different populations show morphological variations in the skull. We collected 48 skulls from various regions of Iran and measured 24 variables on the cranium. These primary variables were then used to generate six indices to examine any variations in the shape of the skulls collected in different regions of the country. Although the largest skulls collected for this study originated in the mountainous regions of the northwest, northeast, and west, principle component analysis (PCA) did not result in a meaningful difference in the size and shape of wolf skulls in different regions of Iran. Our results confirm that the minor morphological variations of the skull in wolves of Iran are not an evidence for the separation of wolf populations in different regions or the existence of various subspecies in the country. This uniformity can be explained by the strong gene flow among populations as well as high mobility of the wolf that facilitates movement of individuals between populations.     

Morphometric studies in the taxonomy of the orang-utan (Pongo pygmaeus. L. 1760

The purpose of this study is to verify the subspecific level of the two recent refugial groups of Orang-utan on Borneo and Sumatra. A total of 47 skulls from both regions were studied by means of 32 craniometric characters. Univariate analysis showed highly significant differences only in males, whereas multivariate statistical analysis led to complete discrimination in both sexes. These results support the assumption that the geographically isolated Orang groups are subspecies.     

Morphological variation of the Japanese raccoon dog: implications for geographical isolation and environmental adaptation

To test the effect of geographical isolation by 'Blakiston's Line' and the possibility of Bergmann's rule being valid, we comparatively examined the morphology of the crania, mandible and teeth of two subspecies of raccoon dog allopatrically distributed in Japan: Nyctereutes procyonoides albus and Nyctereutes procyonoides viverrinus . The Blakiston's Line is a biogeographic border separating mammalian and avian fauna in Japan, including N. p. albus and N. p. viverrinus . Most skull measurements of N. p. albus were larger than those of N. p . viverrinus , suggesting that the body size of N. p. albus could also be larger than that of N. p . viverrinus . Both subspecies were clearly isolated by Blakiston's Line and followed Bergmann's rule, with skulls of the northern subspecies, N. p. albus , larger than N. p. viverrinus . Premolars and molars of N. p. viverrinus were larger than those of N. p. albus , suggesting that N. p. viverrinus may be more frugivorous. The narrow postorbital constriction associated with development of temporal muscles in N. p. albus suggests this subspecies is more carnivorous.     

中华菊头蝠头骨形态特征地理差异的研究

中华菊头蝠是由鲁氏菊头蝠华东亚种提升的一个种.本文测量了海南、广东以及川渝地区中华菊头蝠的23项头骨形态测量指标,应用主成分分析、判别分析和单变量分析方法对中华菊头蝠头骨测量值进行数据处理和分析.主成分分析结果表明,3个地域种群的头骨在总体形态上存在显著的差异;判别分析和单变量分析的结果亦与上述结论相符;沿海种群头骨形态的绝大部分指标比川渝种群大.     

Cranometric Variability in Brown Bears of the Russian Far East

Morphometric analysis of 282 skulls of the brown bear Ursus arctos from the Far Eastern part of the range was carried out. The presence of two morphological clusters for both males and females is shown. Samples from two clusters were compared with their geographical location and subspecies. It was found that one cluster or another had no specific reference to the particular region or subspecies of a particular cluster, only the superiority of one over the other in a cluster of different subspecies and regions was changed. A comparison with the spread of brown bear genetic lines in the Far East of Russia is made. It was noted that the precise distribution of a particular cluster to a specific genetic line of haplotypes was not found.     

The Laptev Sea walrus Odobenus rosmarus laptevi: an enigma revisited

The walrus ( Odobenus rosmarus ) is in some current systematic schemes divided into three subspecies: O. r. rosmarus in the North Atlantic, O.   r. divergens in the North Pacific and O.   r. laptevi in the Laptev Sea. These three subspecies have been described as differing in body size, but the taxonomic status of O.   r. laptevi is disputed. The current study applies molecular and morphometric methods to assess the taxonomic status of O.   r. laptevi and to analyse the systematic and phylogeographic relationships between the three purported walrus subspecies. Tusk length and tusk circumference were measured from the few skulls available of O.   r. laptevi , and the obtained values were within the ranges reported for Pacific walruses. Thus, morphologically, subspecies status for O.   r. laptevi is not supported according to the Amadon–Mayr '75% rule'. Phylogenetic analyses and haplotype networks based on mitochondrial nucleotide sequence data of NADH dehydrogenase 1, 16S rRNA, cytochrome oxidase I and the d -loop of the control region of the historic O.   r. laptevi bone material and contemporary O.   r. rosmarus and O.   r. divergens showed that the Laptev Sea walrus groups with individuals from the North Pacific. Thus, the mitochondrial sequence data do not support the recognition of three walrus subspecies as reciprocally monophyletic evolutionary units with independent evolutionary histories. Only O.   r. rosmarus and O.   r. divergens meet this criterion with the present sampling. Accordingly, we recommend that Odobenus r. laptevi be abandoned and the Laptev walrus instead be recognized as the westernmost population of the Pacific walrus, Odobenus r. divergens. However, further research is recommended to assess whether the Laptev walrus could be considered as a significant unit in terms of conservation and management, since it is unique in several ecological parameters.     

猕猴牙齿的变异性研究

本文是猕猴（Ｍａｃａｃａｍｕｌａｔｔａ）７个亚种１３０个头骨的牙齿比较研究结果。在２２项变量中,有１２项表现出明显的性二型,对另外１０项不等于２２项的单因子方差分析表明,除Ｍ＿２近中远侧距离（ＬＭ＿２ＭＤＬ）外,其余变量在７个亚种之间具有显著性差异。判别分析结果说明,其中６项变量虽对亚种的划分具有显著性贡献,但各亚种间的总判别率仅为３２．５６％,亦即牙齿结构在猕猴各亚种间的变异较小。６项变量组成的星状图表明,印度指名亚种与中国各亚种的牙齿形态有较大差异。在中国猕猴各亚种间,指名亚种ｍｕｌａｔｔａ（Ｃｈｉｎａ）与福建亚种ｌｉｔｔｏｒａｌｉｓ和西藏亚种ｖｅｓｔｉｔａ与川西亚种ｌａｓｉｏｔｉｓ表现出较大的相似性。猕猴的牙齿结构随纬度不同呈现出梯度性变化。各亚种间的牙齿差异主要表现在大小或形状方面,这与不同亚种的个体大小相关。     

The reproductive cycle, condition and feeding in Barbus liberiensis, a tropical stream-dwelling cyprinid

This investigation examines the biology of Barbus liberiensis , a small cyprinid living in the forest streams of Sierra Leone and Liberia, in relation to seasonal changes in the environment. The population studied showed a single discrete breeding season coinciding with the early part of the rains. Maturing fish previously marked moved upstream at this time. The pattern of gonad development is analysed and the relationship of fecundity to body size is defined numerically. The total and somatic (i.e. excluding gonad weights) condition of the fishes, relative to the length/weight data in September-November when the gonads are resting, reach a peak at spawning time for both mature males and females and for immature fish. The pattern of condition during a year differs in the two sexes.
B. liberiensis consumes a wide variety of foods but relies largely on insects and higher plant fragments. Debris from the forest canopy is an important source of nutriment. The fish feed, during the daytime and possibly at night, throughout the year. Experiments to determine the rate at which food passes through the gut are described and show that food passage is rapid.
The seasonal cycles in condition and reproduction are discussed in relation to cycles in some other tropical and temperate riverine fishes.     

Cranial capacity estimations of the FrankfurtPan troglodytes verus collection

Cranial capacity measurements of 18 individuals (9 ♂, 9 ♀) of a total collection of 277Pan troglodytes verus skulls were taken using four different methods:- two conventional filling methods and two mathematical methods. The two mathematical analyses normally used in hominids, were for the first time specifically modified forPan. The results probably present a more accurate estimation of total cranial capacity inPan and specifically inPan troglodytes verus (352 cm³) than previously available. Sexual differences related to this trait were also measured. Regardles of the methods used,Pan troglodytes verus seems to manifest the smallest cranial capacity of all subspecies ofPan.     

Asymmetry in the skull.

Various linear and angular measurements were taken in 118 normal skulls of adult humans. The two halves of the skulls were found to be symmetrical. The phenomenon of asymmetry of various parts of the body, in relation to cerebral dominance and specific skills has been discussed in view of the findings of the study and in the light of the available literature.     

浙江余姚河姆渡新石器时代人类头骨

本文对距今约七千年前的河姆渡新石器时代早期的两具人头骨进行了观察和测量,认为这两具头骨在蒙古人种形态的发育上比旧石器时代晚期的柳江人更明显,同时具有某些类似澳大利亚-尼格罗人种的性状。