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PubMed2002

Quantifying temporal bone morphology of great apes and humans: an approach using geometric morphometrics.

The hominid temporal bone offers a complex array of morphology that is linked to several different functional systems. Its frequent preservation in the fossil record gives the temporal bone added significance in the study of human evolution, but its morphology has proven difficult to quantify. In this study we use techniques of 3D geometric morphometrics to quantify differences among humans and great apes and discuss the results in a phylogenetic context. Twenty-three landmarks on the ectocranial surface of the temporal bone provide a high level of anatomical detail. Generalized Procrustes analysis (GPA) is used to register (adjust for position, orientation and scale) landmark data from 405 adults representing Homo, Pan, Gorilla and Pongo. Principal components analysis of residuals from the GPA shows that the major source of variation is between humans and apes. Human characteristics such as a coronally orientated petrous axis, a deep mandibular fossa, a projecting mastoid process, and reduced lateral extension of the tympanic element strongly impact the analysis. In phenetic cluster analyses, gorillas and orangutans group together with respect to chimpanzees, and all apes group together with respect to humans. Thus, the analysis contradicts depictions of African apes as a single morphotype. Gorillas and orangutans lack the extensive preglenoid surface of chimpanzees, and their mastoid processes are less medially inflected. These and other characters shared by gorillas and orangutans are probably primitive for the African hominid clade.

Adult↗
PubMedDate not supplied

Major regulatory factors in the evolution of development: the roles of goosecoid and Msx in the evolution of the direct-developing sea urchin Heliocidaris erythrogramma.

The transcription factors Gsc and Msx are expressed in the oral ectoderm of the indirect-developing sea urchin Heliocidaris tuberculata. Their patterns of expression are highly modified in the direct developer Heliocidaris erythrogramma, which lacks an oral ectoderm. We here test the hypothesis that they are large effect genes responsible for the loss of the oral ectoderm module in the direct-developing larva of H. erythrogramma as well as for the restoration of an overt oral ectoderm in H.e. xH.t. hybrids. We undertook misexpression/overexpression and knockdown assays in the two species and in hybrids by mRNA injection. The results indicate that dramatic changes of function of these transcription factors has occurred. One of these genes, Gsc, has the ability when misexpressed to partially restore oral ectoderm in H. erythrogramma. On the other hand, Msx has lost any oral function and instead has a role in mesoderm proliferation and patterning. In addition, we found that the H. tuberculataGsc is up regulated in H.e. xH.t. hybrids, showing a preferential use of the indirect developing parental gene in the development of the hybrid. We suggest that Gsc qualifies as a gene of large evolutionary effect and is partially responsible for the evolution of direct development of H. erythrogramma. We discuss these results in light of modularity and genetic networks in development, as well as in their implications for the rapid evolution of large morphological changes in development.

Animals↗
PubMedDate not supplied

Phylogenetic analyses of small subunit ribosomal RNA coding regions reveal a monophyletic lineage of euglyphid testate amoebae (Order Euglyphida).

The Testaceafilosia includes amoebae with filopodia and with a proteinaceous, agglutinated or siliceous test. To explore the deeper phylogeny of this group, we sequenced the small subunit ribosomal RNA coding region of 13 species, including the first sequence of an amoeba with an agglutinated test, Pseudodifflugia sp. Phylogenetic analyses using maximum parsimony and maximum likelihood methods as well as neighbor joining method yielded the following results: the order Euglyphida forms a monophyletic lineage with the sarcomonads as sister group. The next related taxa are the Chlorarachnea and the unidentified filose strain N-Por. In agreement with the previous studies the Phytomyxea branch off at the base of this lineage. The Monadofilosa (Testaceafilosia and Sarcomonadea) appear monophyletic. The Testaceafilosia are polyphyletic, because Pseudodifflugia sp. is positioned as the sister taxon to the sarcomonads. Within the order Euglyphida Paulinella branches off first, together with Cyphoderia followed by Tracheleuglypha. In maximum likelihood and neighbor joining analyses, the genus Euglypha is monophyletic. The branching pattern within the order Euglyphida reflects the evolution of shell morphology from simple to complex built test.

Amoeba↗
PubMed2001

Altered timing of the extracellular-matrix-mediated epithelial-mesenchymal interaction that initiates mandibular skeletogenesis in three inbred strains of mice: development, heterochrony, and evolutionary change in morphology.

Subtle changes in embryonic development are a source of significant morphological alterations during evolution. The mammalian mandibular skeleton, which originates from the cranial neural crest, is a complex structure comprising several components that interact late in embryogenesis to produce a single functional unit. It provides a model system in which individual developmental events at the basis of population-level evolutionary change can be investigated experimentally. Inbred mouse strains exhibit obvious morphological differences despite the relatively short time since their divergence from one another. Some of these differences can be traced to small changes in the timing of early developmental events such as the formation of the cellular condensations that initiate skeletogenesis. This paper examines an even earlier event for changes in timing, the epithelial-mesenchymal interaction(s) required to initiate chondrogenesis of Meckel's cartilage and osteogenesis of the dentary bone. Using three inbred strains of mice (CBA, C3H and C57) we found that, within each strain, cartilage and bone are induced at the same time and by the same (mandibular) epithelium, that chondrogenesis and osteogenesis are initiated by a matrix-mediated epithelial-mesenchymal interaction, and that timing of the interactions differs among the three inbred strains. These results are discussed with respect to the possible molecular basis of such temporal shifts in inductive interactions and how such studies can be used to shed light on heterochrony as a mechanism of evolutionary change in morphology.

Animals↗
PubMed1987

Chromosome phylogenies of man, great apes, and Old World monkeys.

The karyotypes of man and of the closely related Pongidae--chimpanzee, gorilla, and orangutan--differ by a small number of well known rearrangements, mainly pericentric inversions and one fusion which reduced the chromosome number from 48 in the Pongidae to 46 in man. Dutrillaux et al. (1973, 1975, 1979) reconstructed the chromosomal phylogeny of the entire primate order. More and more distantly related species were compared thus moving backward in evolution to the common ancestors of the Pongidae, of the Cercopithecoidae, the Catarrhini, the Platyrrhini, the Prosimians, and finally the common ancestor of all primates. Descending the pyramid it becomes possible to assign the rearrangements that occurred in each phylum, and the one that led to man in particular. The main conclusions are that this phylogeny is compatible with the occurrence during evolution of simple chromosome rearrangements--inversions, fusions, reciprocal translocation, acquisition or loss of heterochromatin--and that it is entirely consistent with the known primate phylogeny based on physical morphology and molecular evolution. If heterochromatin is not taken into account, man has in common with the other primates practically all of his chromosomal material as determined by chromosome banding. However, it is arranged differently, according to species, on account of chromosome rearrangements. This interpretation has been confirmed by comparative gene mapping, which established that the same chromosome segments, identified by banding, carry the same genes (Finaz et al., 1973; Human Gene Mapping 8, 1985). A remarkable observation made by Dutrillaux is that different primate phyla seem to have adopted different chromosome rearrangements in the course of evolution: inversions for the Pongidae, Robertsonian fusions for the lemurs, etc. This observation may raise many questions, among which is that of an organized evolution. Also, the breakpoints of chromosomal rearrangements observed during evolution, in human chromosomal diseases, and after ionizing irradiation do not seem to be distributed at random. Chromosomal rearrangements observed in evolution are known to be harmful in humans, leading to complete or partial sterility through abnormal offspring in the heterozygous state but not in the homozygous state. They then become a robust reproductive barrier capable of creating new species, far more powerful than gene mutations advocated by neo-Darwinism. The homozygous state may be achieved especially through inbreeding, which must have played a major role during primate evolution.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2001

Kinetics and morphologies of viscoelastic phase separation.

In this paper, the effects of relaxational bulk modulus and the average composition of polymers on the viscoelastic phase separation are investigated in detail. It is found that there are two typical morphologies, i.e., moving droplet phase and phase inversion, and the relaxation of the dynamical asymmetry and the amplification of the concentration fluctuation are responsible for the appearance and evolution of different morphologies of viscoelastic phase separation. It is found that, for the viscoelastic phase separation, the scattering function has two peaks. The growth exponents of the main and the secondary peaks in the late stage are almost the same and approximately 0.6, which also agrees with the experimental observations. On the other hand, the growth exponent of the secondary peak increased from approximately 0.42 to approximately 0.66 with increase of straight phi(0) from 0.275 to 0.4, in the intermediate stage.

Journal Article↗
PubMed1998

Morphological diversity of anatomical strepsirrhinism and the evolution of the lemuriform toothcomb.

The hypothesis that the vomeronasal organ has an important functional relationship with, and led to the evolution of, the prosimian toothcomb has not been well tested. This paper examines the diversity of anatomical strepsirrhinism across several mammalian taxa to determine if fossil and living strepsirrhine primates exhibit any derived characters that may highlight the functional link between the vomeronasal organ and the toothcomb, and to examine the potential importance of anatomical strepsirrhinism to toothcomb origins. Results indicate that extant gregarious lemuriforms are derived in having a relatively wide interincisal gap, providing an unobstructed line of communication between the vomeronasal organ and anterior rostral structures such as the toothcomb. This finding is consistent with the proposal that anatomical strepsirrhinism is functionally related to use of the toothcomb in grooming. However, the importance of the vomeronasal organ to toothcomb origins is less clear. If the morphology of adapiforms and non-gregarious lemuriforms is representative of the morphology of basal lemuriforms, then it can be inferred that early lemuriforms did not possess the wide-gap autapomorphy; hence, anatomical evidence discussed here cannot be used to rule out non-social hypotheses of toothcomb origins.

Animals↗
PubMed1995

Clinical and lesion morphologic determinants of coronary angioplasty success and complications: current experience.

OBJECTIVES: This study evaluated the validity of the American College of Cardiology/American Heart Association ABC lesion classification scheme and its modifications. BACKGROUND: With the continued refinement in angioplasty technique and equipment evolution, the lesion morphologic determinants of immediate angioplasty outcome have changed significantly. Hence, the validity of the classification scheme has been questioned. METHODS: We assessed the lesion morphologic determinants of immediate angioplasty outcome in 729 consecutive patients who underwent coronary angioplasty of 994 vessels and 1,248 lesions. RESULTS: Angioplasty success was achieved in 91% of lesions, and abrupt closure occurred in 3%. Success was achieved in 96%, 93% and 80% of type A, B and C lesions, respectively (A vs. B, p = NS; B vs. C, p < 0.001; A vs. C, p < 0.001; A vs. B1, p = NS; A vs. B2, p = 0.03; B1 vs. B2, p = 0.02; B2 vs. C, p < 0.001; C1 vs. C2, p = NS). Abrupt closure occurred in 2.1%, 2.6% and 5% of type A, B and C lesions, respectively (A vs. B, B vs. C, A vs. C and A vs. B1, all p = NS; B1 vs. B2, p = 0.01; B2 vs. C1, p = NS; C1 vs. C2, p = 0.04). Type B characteristics had a success rate ranging from 74% to 95% and an abrupt closure rate ranging from 2.2% to 14%. Type C characteristics had a success rate ranging from 57% to 88% and an abrupt closure rate ranging from 0% to 16%. Longer lesions, calcified lesions, diameter stenosis of 80% to 99% and presence of thrombus were predictive of a lower success rate. Longer lesions, angulated lesions, diameter stenosis of 80% to 99% and calcified lesions were predictive of an abrupt closure. CONCLUSIONS: The previously proposed classification schemes are outdated and need to be changed for application in current angioplasty practice. Analyzing specific lesion morphologic characteristics rather than applying a simple lesion classification score when evaluating angioplasty outcome may be more useful because it provides a more precise profile of the lesion and allows better patient stratification and selection.

Adult↗
PubMed2005

Ancient hunters and their modern representatives: William Sollas's (1849-1936) Anthropology from disappointed bridge to trunkless tree and the instrumentalisation of racial conflict.

During the first decades of the 20th century, many anthropologists who had previously adhered to a linear view of human evolution, from an ape via Pithecanthropus erectus (today Homo erectus) and Neanderthal to modern humans, began to change their outlook. A shift towards a branching model of human evolution began to take hold. Among the scientific factors motivating this trend was the insight that mammalian evolution in general was best represented by a branching tree, rather than by a straight line, and that several new fossil hominids were discovered that differed significantly in their morphology but seemed to date from about the same period. The ideological and practical implications of imperialism and WWI have also been identified as formative of the new evolutionary scenarios in which racial conflict played a crucial role. The paper will illustrate this general shift in anthropological theory for one particular scientist, William Sollas (1849-1936). Sollas achieved a synthesis of human morphological and cultural evolution in what I will refer to as an imperialist model. In this theoretical framework, migration, conflict, and replacement became the main mechanisms for progress spurred by 'nature's tyrant,' natural selection.

Animals↗
PubMed2005

Synthesis and evolution of novel hollow ZnO urchins by a simple thermal evaporation process.

Delicate hollow ZnO urchins have been fabricated by thermal evaporation of metallic zinc powders in a tube furnace without the use of additive, high temperature, or low pressure. The phase transformation, morphologies, and photoluminescence evolution of the ZnO products were carefully studied and investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra. These studies indicated that the growth of hollow ZnO urchins involves the vaporization of Zn powder, solidification of liquid droplets, surface oxidation, sublimation, and self-catalytic growth of one-dimensional nanowires.

Chemistry, Physical↗
PubMed2002

Sexual selection: an evolutionary force in plants?

Sexual selection has traditionally been used to explain exaggerated sexual traits in male animals. Today the concept has been developed and various other sexually related traits have been suggested to evolve in the same manner. In nearly all new areas where the theory of sexual selection has been applied, there has been an intense debate as to whether the application is justified. Is it the case that some scientists are all too ready to employ fashionable ideas? Or are there too many dogmatic researchers refusing to accept that science develops and old ideas are transformed? Maybe the controversies are simply a reflection of the difficulty of defining a theory under constant re-evaluation. Thus, we begin by summarizing the theory of sexual selection in order to assess the influence of sexual selection on the evolution of plant morphology. We discuss empirical findings concerning potentially affected traits. Although we have tried to address criticisms fairly, we still conclude that sexual selection can be a useful tool when studying the evolution of reproductive traits in plants. Furthermore, by including the evidence from an additional kingdom, a fuller understanding of the processes involved in sexual selection can be gained.

Biological Evolution↗
PubMedDate not supplied

Evolution and development of gastropod larval shell morphology: experimental evidence for mechanical defense and repair.

The structural diversity of gastropod veliger larvae offers an instructive counterpoint to the view of larval forms as conservative archetypes. Larval structure, function, and development are fine-tuned for survival in the plankton. Accordingly, the study of larval adaptation provides an important perspective for evolutionary-developmental biology as an integrated science. Patterns of breakage and repair in the field, as well as patterns of breakage in arranged encounters with zooplankton under laboratory conditions, are two powerful sources of data on the adaptive significance of morphological and microsculptural features of the gastropod larval shell. Shells of the planktonic veliger larvae of the caenogastropod Nassarius paupertus [GOULD] preserve multiple repaired breaks, attributed to unsuccessful zooplankton predators. In culture, larvae isolated from concentrated zooplankton samples rapidly repaired broken apertural margins and restored the "ideal" apertural form, in which an elaborate projection or "beak" covers the head of the swimming veliger. When individuals with repaired apertures were reintroduced to a concentrated mixture of potential zooplankton predators, the repaired margins were rapidly chipped and broken back. The projecting beak of the larval shell is the first line of mechanical defense, covering the larval head and mouth and potentially the most vulnerable part of the shell to breakage. Patterns of mechanical failure show that spiral ridges do reinforce the beak and retard breakage. The capacity for rapid shell repair and regeneration, and the evolution of features that resist or retard mechanical damage, may play a more prominent role than previously thought in enhancing the ability of larvae to survive in the plankton.

Animals↗
PubMed1990

Primate evolution at the DNA level and a classification of hominoids.

The genetic distances among primate lineages estimated from orthologous noncoding nucleotide sequences of beta-type globin loci and their flanking and intergenic DNA agree closely with the distances (delta T50H values) estimated by cross hybridization of total genomic single-copy DNAs. These DNA distances and the maximum parsimony tree constructed for the nucleotide sequence orthologues depict a branching pattern of primate lineages that is essentially congruent with the picture from phylogenetic analyses of morphological characters. The molecular evidence, however, resolves ambiguities in the morphological picture and provides an objective view of the cladistic position of humans among the primates. The molecular data group humans with chimpanzees in subtribe Hominina, with gorillas in tribe Hominini, orangutans in subfamily Homininae, gibbons in family Hominidae, Old World monkeys in infraorder Catarrhini, New World monkeys in semisuborder Anthropoidea, tarsiers in suborder Haplorhini, and strepsirhines (lemuriforms and lorisiforms) in order Primates. A seeming incongruency between organismal and molecular levels of evolution, namely that morphological evolution appears to have speeded up in higher primates, especially in the lineage to humans, while molecular evolution has slowed down, may have the trivial explanation that relatively small genetic changes may sometimes result in marked phenotypic changes.

Animals↗
PubMed2005

Ploidy, geographical distribution and morphological differentiation of Parasenecio auriculata (Senecioneae; Asteraceae) in Japan.

Parasenecio auriculata is a woodland perennial herb widely distributed in Northeastern Asia, constituted by a poorly understood polyploidy with a diploid (2n = 2x = 60) and a tetraploid (2n = 4x = 120). In this study, for a better understanding of the polyploidal evolution, cytogeography and morphological variation were analyzed in Japanese P. auriculata, including two varieties; var. bulbifera endemic to central Hokkaido and var. kamtschatica widely distributed in northern Honshu and Hokkaido. The occurrence of two polyploidal levels was reconfirmed. While var. bulbifera is predominantly tetraploid, var. kamtschatica is comprised of diploid and tetraploid. Morphological variation among 22 quantitative characteristics is continuous and not distinctive among cytotypes or varieties, but plant size tended to be larger in the order, diploid of var. kamtschatica, var. bulbifera, and tetraploid of var. kamtschatica. The cytotype distribution showed a conspicuous geographical pattern. Besides var. bulbifera endemic to the central Hokkaido, the diploid of var. kamtschatica is mainly found in Southern Hokkaido, and the tetraploid has a disjunct distribution in eastern and northern Hokkaido and northern Honshu. Such a geographical pattern is possibly attributable to the differentiation of climatic preference among cytotypes and varieties, and may have been established in association with the climatic cline along the Japanese archipelago.

Analysis of Variance↗
PubMed2002

mtDNA from fossils reveals a radiation of Hawaiian geese recently derived from the Canada goose (Brantacanadensis).

Phylogenetic analysis of 1.35 kb of mtDNA sequence from fossils revealed a previously unknown radiation of Hawaiian geese, of which only one representative remains alive (the endangered Hawaiian goose or nene, Branta sandvicensis). This radiation is nested phylogenetically within a living species, the Canada goose (Branta canadensis) and is related most closely to the large-bodied lineage within that species. The barnacle goose (Branta leucopsis) is also nested within the Canada goose species and is related most closely to the small-bodied lineage of Canada geese. The peripheral isolation of the barnacle goose in the Palearctic apparently allowed the evolution of its distinctive plumage pattern, whereas the two Nearctic lineages of Canada geese share a primitive plumage pattern. The Hawaiian lineage of Canada geese diverged more dramatically, splitting into at least three species that differ in body size, body proportions, and flight ability. One fossil species, limited to the island of Hawaii, was related closely to the nene but was over four times larger, flightless, heavy-bodied and had a much more robust cranium. Application of a rate calibration to levels of DNA divergence suggests that this species evolved on the island of Hawaii in less than 500,000 years. This date is consistent with the potassium/argon-based age of the island of Hawaii of 430,000-500,000 years. The giant Hawaii goose resembles the moa-nalos, a group of massive, extinct, flightless ducks that lived on older Hawaiian Islands and thus is an example of convergent evolution of similar morphologies in island ecosystems.

Animals↗
PubMed2003

Hypertension superimposed on type II diabetes in Goto Kakizaki rats induces progressive nephropathy.

BACKGROUND: Type II diabetes in the Goto Kakizaki (GK) rats (derived from Wistar rats) is not associated with the development of obesity, hyperlipidemia, hypertension, or pronounced renal functional changes. The aim of this study was to investigate the effect of superimposed hypertension on renal function and morphology under conditions of hyper- and normoglycemia. METHODS: The evolution of biochemical and morphologic renal changes was examined in GK and Wistar rats treated with deoxycorticosterone acetate (DOCA) salt over 24 weeks. RESULTS: Blood pressure was increased from 6 weeks on in GK and Wistar rats with no difference in blood pressure levels between both groups (week 24, 183 +/- 14 mm Hg vs. 191 +/- 13 mm Hg, P = NS, vs. 144 +/- 6 mm Hg in normal controls, P < 0.01). A progressive increase in proteinuria was observed in hypertensive GK rats from 12 weeks on (week 24, 168 +/- 62 mg/day vs. 41 +/- 30 mg/day in hypertensive Wistar rats, P = 0.002). Histologic analysis at weeks 15 and 24 showed progressive glomerulosclerosis in hypertensive GK and Wistar rats (week 24, 13 +/- 4% vs. 8 +/- 1%, P = NS) but not in nonhypertensive GK controls. This was associated with evidence of podocyte damage (de novo desmin expression) in hypertensive as compared to nonhypertensive GK rats (week 24, score 1.4 +/- 0.1 vs. 0.8 +/- 0.1, P < 0.001) while no significant increase was observed in hypertensive vs. nonhypertensive Wistar rats. Tubulointerstitial damage was increased in hypertensive GK as compared to hypertensive Wistar rats (week 24, score 1.5 +/- 0.6 vs. 0.6 +/- 0.3, P = 0.01). By immunohistochemistry, this was associated with an up-regulation of tubulointerstitial type IV collagen as well as alpha-smooth muscle actin (alpha-SMA) expression, macrophage infiltration and cell proliferation in hypertensive GK rats. CONCLUSION: Our data demonstrate that long-standing type II diabetes alone is not sufficient to induce progressive nephropathy unless secondary injurious mechanisms such as hypertension are present. The hypertensive GK rat provides a novel model to investigate the mechanisms involved in diabetic nephropathy.

Animals↗