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PubMed2005

Phylogeny of eagles, Old World vultures, and other Accipitridae based on nuclear and mitochondrial DNA.

We assessed phylogenetic relationships for birds of prey in the family Accipitridae using molecular sequence from two mitochondrial genes (1047 bases ND2 and 1041 bases cyt-b) and one nuclear intron (1074 bases beta-fibrinogen intron 7). We sampled representatives of all 14 Accipitridae subfamilies, focusing on four subfamilies of eagles (booted eagles, sea eagles, harpy eagles, and snake eagles) and two subfamilies of Old World vultures (Gypaetinae and Aegypiinae) with nearly all known species represented. Multiple well-supported relationships among accipitrids identified with DNA differ from those traditionally recognized based on morphology or life history traits. Monophyly of sea eagles (Haliaeetinae) and booted eagles (Aquilinae) was supported; however, harpy eagles (Harpiinae), snake eagles (Circaetinae), and Old World vultures were found to be non-monophyletic. The Gymnogene (Polyboroides typus) and the Crane Hawk (Geranospiza caerulescens) were not found to be close relatives, presenting an example of convergent evolution for specialized limb morphology enabling predation on cavity nesting species. Investigation of named subspecies within Hieraaetus fasciatus and H. morphnoides revealed significant genetic differentiation or non-monophyly supporting recognition of H. spilogaster and H. weiskei as distinctive species.

Animals↗
PubMed2006

Distinct population structure in a phenotypically homogeneous rock-dwelling cichlid fish from Lake Tanganyika.

Several lineages of cichlid fishes in the East African Great Lakes display stunning levels of morphological diversification. The rapid evolution of rock-dwelling polygynous mouthbrooders in Lake Malawi, for example, was in part ascribed to their allopatric distribution on disjunct stretches of rocky coast, where even short habitat discontinuities reduce gene flow effectively. However, as seen in other cichlids, ecological barriers do not always prevent gene flow, whereas genetic structure can develop along continuous habitat, and morphological diversification does not necessarily accompany genetic differentiation. The present study investigates the population structure of Variabilichromis moorii, a monogamous substrate-brooding lamprologine of rocky coasts in Lake Tanganyika, which occurs over about 1000 km of shoreline almost without phenotypic variation. Phylogeographic analyses of mitochondrial DNA sequences indicated that dispersal is infrequent and generally occurs between adjacent locations only. Exceptions to this pattern are closely related haplotypes from certain locations on opposite lakeshores, a phenomenon which has been observed in other species and is thought to reflect lake crossing along an underwater ridge in times of low water level. Genetic population differentiation, estimated from mitochondrial DNA and microsatellite data in six adjacent populations, was equally high across localities separated by sandy shores and along uninterrupted stretches of rocky shore. Our results suggest that ecological barriers are not required to induce philopatric behavior in Variabilichromis, and that morphological stasis persists in the face of high levels of neutral genetic differentiation.

Alleles↗
PubMed1988

Positional behavior of long-tailed macaques (Macaca fascicularis) in northern Sumatra.

Although the majority of extant primates are described as "quadrupedal," there is little information available from natural habitats on the locomotor and postural behavior of arboreal primate quadrupeds that are not specialized for leaping. To clarify varieties of quadrupedal movement, a quantitative field study of the positional behavior of a highly arboreal cercopithecine, Macaca fascicularis, was conducted in northern Sumatra. At least 70% of locomotion in travel, foraging, and feeding was movement along continuous substrates by quadrupedalism and vertical climbing. Another 14-25% of locomotion was across substrates by pronograde clambering and vertical clambering. The highest frequency of clambering occurred in foraging for insects, and on the average smaller substrates were used in clambering than during quadrupedal movement. All postural behavior during foraging and feeding was above-substrate, largely sitting. Locomotion across substrates requires grasping branches of diverse orientations, sometimes displaced away from the animal's body. The relatively low frequency of across-substrate locomotion appears consistent with published analyses of cercopithecoid postcranial morphology, indicating specialization for stability of limb joints and use of limbs in parasagittal movements, but confirmation of this association awaits interspecific comparisons that make the distinction between along- and across-substrate forms of locomotion. It is suggested that pronograde clambering as defined in this study was likely a positional mode of considerable importance in the repertoire of Proconsul africanus and is a plausible early stage in the evolution of later hominoid morphology and locomotor behavior.

Animals↗
PubMed2000

Sensitivity of indocyanine green angiography for the follow-up of active inflammatory choriocapillaropathies.

BACKGROUND: Inflammatory choriocapillaropathies (choriocapillaritis) correspond to the clinical spectrum of lesions of the fundus, including acute posterior multifocal placoid pigment epitheliopathy (APMPPE), multiple evanescent white dot syndrome (MEWDS), multifocal choroiditis (MC), and other rarer entities caused by inflammatory disturbances of choriocapillaris perfusion. The aim here was to study the sensitivity of indocyanine green (ICG) angiography in investigating and following inflammatory choriocapillaropathies. PATIENTS AND METHODS: Patients with inflammatory choriocapillaropthies were included who had had a dual fluorescein and ICG angiography as well as visual field testing (Goldman or computerized perimetry) at presentation and on follow-up visits. ICG angiography was performed according to a routine angiographic protocol used for inflammatory diseases and was correlated with fundus examination, fluorescein angiography, and visual field testing. RESULTS: Three patients with MEWDS, two with APMPPE, and two with MC were included. The visual field alterations in all seven patients were well correlated with the extent of the hypofluorescent areas seen on ICG angiography, whereas they were badly correlated with fluorescein angiographic signs and their evolution. The visual field in MEWDS was particularly well correlated with the importance of peripapillary hypofluorescence seen on ICG angiography. In MC, the evolution of new lesions was well demonstrated by ICG angiography and well correlated with visual symptoms and visual fields, but was barely detected on fundus examination and by fluorescein angiography. CONCLUSIONS: ICG angiographic signs were shown to be closely correlated with visual function (visual field testing). This was not the case for either fundus examination or fluorescein angiography. ICG angiography appears as a very sensitive follow-up parameter in inflammatory choriocapillaropathies, giving morphological information on the evolution of the disease and on the response to treatment when therapy is indicated.

Adult↗
PubMed1979

[Rule of homology and morbid anatomy (author's transl)].

1. According to J.W. Goethe, morphology is a theory of evolution, H. Braus defined it as a theory of historic incidents, and according to D. Starck morphology is the role of shapes of the organisms. 2. The term homology was coined by morphologic researchers. Of course, it is used nowadays also in mathematics, chemistry, and linguistics and other logic matters. 3. Homologies have a special position in Goethe's work on the theory of types. Goethe's morphologic research and Schiller's aesthetic speculations are considered to be the origin of a 'typologic point of view.' 4. Coherences of Platon's theory of ideas and Goethe's theory of types are scrutinized. The theory of shapes ('Gestalt theory') is inconceivable without Platon's theory, and scientic morphology is inconceivable without shapes, either, and according to C. v. Ehrenfels "Gestaltphilosophie" could not exist without the shapes of Platon's theory. 5. It is shown that without Gestalt philosophy one cannot comprehend the following coherences: Gestalt (shape) as an idea, idea as a type of Goethe's rule, type as an element of the theory of homologies and even of constitution. 6. Homology will be constituted using certain criterions: a) detection of an equal descent, b) equal position of organismic structures in individuals, c) evidence of interpositions, and d) certain qualities of parts which are compared with each other. Homologous structures may be dissimilar in their architecture. 7. The term homology is explained a) by giving an analysis of morphologic and teratologic lines, b) by scrutinizing froms of symmetry, and c) by presenting the histopathology of topographical diverse but according to the morphogenetic mode coinciding tumours which are resembling each other in their microscopic patterns. 8. The application of the rule of homology in the morphologic investigation of diseases proves to be a) valuable from a heuristic point of view, b) an instrument of communication to characterize comparable matters, c) a means of classification, and d) a basic requirement to uncover inconceivable correlations of morphologic patterns in the first instance and then a basis for the prognosis findings which may be expected in the future. So far the didactic value of proven homologies is inestimably great. 9. The application of the rules of homology in morbild anatomy requires controls by 'regulatives.' There are: a) all facts must be born in mind, b) the rules of the mathematical logic, those of demonstrative and plausible conclusions need to be taken into consideration, and c) the criterions of Ehrenfels should be applied accurately. 10. At the contact surface of two scientific fields special difficulties may emerge. As far as contemporary pathology is concerned, elements of the Arts should be assimilated. This challenge is by no means a novel one. Covered traces of it could be found in our archive 50 years ago. We should not forget but keep in mind these elements.

Biological Evolution↗
PubMed2001

Costs and the diversification of exaggerated animal structures.

Sexual selection can favor production of extravagant ornaments and weapons in the contest for access to the opposite sex. Existing explanations for the diversity of sexually selected structures focus on reproductive benefits conferred by particular ornament or weapon morphologies. Here, I show that costs of weapon production also may drive patterns of weapon evolution. In beetles, production of horns reduces the size of neighboring morphological structures (antennae, eyes, or wings, depending on the location of the horns), and these tradeoffs reveal unexpected functional associations between ecology and horn morphology. This study illustrates a critical but overlooked role of costs in sexual selection and has implications for understanding the evolution of animal morphology.

Animals↗
PubMed1993

A prey-type dependent hypoglossal feedback system in the frog Rana pipiens.

Nerve transection experiments combined with high-speed videography and electromyography were used to characterize a prey-type dependent hypoglossal feedback system which coordinates mouth opening and tongue protraction in the common leopard frog, Rana pipiens. When feeding on small prey, sensory feedback from the tongue through the hypoglossal nerve is necessary to trigger mouth opening. If sensory feedback is prevented from reaching the brain by transection of the hypoglossal nerve, then the mouth fails to open although the feeding behavior appears otherwise normal. However, when feeding on large prey, the mouth opens normally even after the hypoglossal nerve has been transected. Thus, peripheral feedback is not necessary to trigger mouth opening when feeding on large prey, and presumably a central coordination mechanism is used. In Rana pipiens, the evolution of a new tongue morphology and a new motor pattern for feeding on small prey has been accompanied by the evolution of a novel, peripheral mechanism for coordinating tongue protraction and mouth opening. However, the primitive motor pattern for feeding on large prey and the primitive coordinating mechanism have been retained. These results imply that the neural circuits producing the different motor patterns for large and small prey are anatomically distinct at some level in the central nervous system. If they are not anatomically distinct, then sensory feedback should be necessary to trigger mouth opening regardless of which motor pattern is being expressed. While the anatomy of these distinct pathways remains to be elucidated, these results suggest that novel neural circuits may in fact underlie different behaviors even when they seem, superficially, to be relatively similar.

Animals↗
PubMed1987

The evolution of sexes.

It is very likely that sexual differentiation into two morphologically indistinguishable mating types has preceded the evolution of anisogamy. Therefore, the study of the evolution of mating types in an isogamous population is more informative for understanding the forces responsible for the evolution of different sexes than the study of the evolution of anisogamy; the latter represents the secondary problem of how, after the establishment of two sexes, an increasing degree of gamete dimorphism may evolve. Mating type evolution has been analyzed theoretically in population genetic models. These explorations show that mating types may evolve as a consequence of selection for more efficient gamete recognition, and also as a result of intragenomic conflict between nuclear and cytoplasmic DNA. However, in both cases the selection forces have to be very strong, which makes these possible explanations less convincing. Nearly all theories proposed for the evolution of anisogamy assume two conflicting selection forces to be relevant: selection for greater gamete productivity, and selection for greater zygote size. Although the explanation is intuitively plausible, the comparative evidence is a bit disappointing. Alternatively, anisogamy can be explained as a side-effect of selection for a greater efficiency in finding a mating partner by using sexual pheromones. Firm empirical evidence is lacking, however. In both problem areas--mating type evolution and anisogamy evolution--experimental work is badly needed.

Animals↗
PubMed2004

Phylogenetic analysis of Phytophthora species based on mitochondrial and nuclear DNA sequences.

A molecular phylogenetic analysis of the genus Phytophthora was performed, 113 isolates from 48 Phytophthora species were included in this analysis. Phylogenetic analyses were performed on regions of mitochondrial (cytochrome c oxidase subunit 1; NADH dehydrogenase subunit 1) and nuclear gene sequences (translation elongation factor 1alpha; beta-tubulin) and comparisons made to test for incongruence between the mitochondrial and nuclear data sets. The genus Phytophthora was confirmed to be monophyletic. In addition, results confirm that the classical taxonomic grouping as described by [Waterhouse (1963)] does not reflect true phylogenetic relations. Phytophthora species were redistributed into 8 clades, providing a more accurate representation of phylogenetic relationships within the genus Phytophthora. The evolution and transition of morphological, pathogenic, and reproductive traits was inferred from the cladogram generated in this study. Mating system was inferred to be a homoplasious trait, with at least eight independent transitions from homothallism to heterothallism observed.

Biological Evolution↗
PubMed2004

Mitochondrial DNA phylogeny and rates of larval evolution in Macrophiothrix brittlestars.

Phylogenetic analysis has led to significant insights into the evolution of early life-history stages of marine invertebrates. Although echinoderms have been a major focus, developmental and phylogenetic information are relatively poor for ophiuroids, the most species-rich echinoderm class. We used DNA sequences from two mitochondrial genes to develop a phylogenetic hypothesis for 14 brittlestar species in the genus Macrophiothrix (Family Ophiotrichidae). Species are similar in adult form and ecology, but have diverse egg sizes and modes of larval development. In particular, two species have rare larval forms with characteristics that are intermediate between more common modes of feeding and non-feeding development. We use the phylogeny to address whether intermediate larval forms are rare because the evolution of a simplified morphology is rapid once food is no longer required for development. In support of this hypothesis, branch lengths for intermediate forms were short relative to those for species with highly derived non-feeding forms. The absolute rarity of such forms makes robust tests of the hypothesis difficult.

Animals↗
PubMed2006

Crystallization of poly(L-lactid acid) monitored by dielectric relaxation spectroscopy and atomic force microscopy.

An investigation was carried out on the crystallization process of poly(l-lactid acid) by dielectric relaxation spectroscopy and atomic force microscopy. Experimental results were generated by dielectric relaxation spectroscopy over a wide range of frequency and temperature in both the wholly amorphous state and during crystallization. The variation of the average relaxation time was studied during crystallization at 80 degrees C and the temperature dependence of this relaxation time for wholly amorphous and crystallized samples was analysed. This behaviour was modelled by Havriliak-Negami and Vogel-Fulcher equations. The sensitivity of the segmental dynamics to the degree of crystallinity was analysed, taking into account the relaxing segments and the thickness of the amorphous layer between lamellae. The morphologies obtained during crystallization processes at 80, 130 and 150 degrees C were monitored by atomic force microscopy at both the lamellar level and by analysing the multilayered superstructures formed. Hedrites, intermediate structures between single lamellar crystals and mature spherulites, were found to appear at the highest temperatures, whereas no evidence of hedrites was found at 80 degrees C, the spherulites seemed to be constructed from a framework of individual dominant lamellae that splay apart and branch. Complementary to the atomic force microscopy study, the evolution of the obtained morphologies was also followed by optical microscopy. Supporting evidence about the thermal behaviour of the polymers was obtained with differential scanning calorimetry.

Journal Article↗
PubMed2001

Analysis of secondary chromosomal alterations in 165 cases of follicular lymphoma with t(14;18).

Follicular lymphoma is characterized by the t(14;18) in up to 85% of cases. Almost all cases display evidence of secondary chromosomal alterations at initial diagnosis. The influence of recurrent secondary changes on disease progression has not been fully determined. The purpose of this study was to define the full spectrum of recurrent karyotypic events present at diagnosis in a large cohort of cases and to evaluate the sequence of cytogenetic evolution in relation to morphologic progression. A total of 165 cases of follicular lymphoma with t(14;18) were ascertained for which complete clinical information, histopathology, immunophenotype, and karyotype were available. One hundred sixty cases showed secondary alterations with an average of 7.9 additional changes per case. Recurrent alterations seen at the 10% or greater level included +X, +1q21-q44, +7, +12q, +18q, del(1)(p36), del(6q), del(10)(q22-q24), the development of polyploidy and sidelines, and the presence of extra marker chromosomes and chromosomal additions. Changes that correlated with morphologic progression included del(1)(p36), del(6q), del(10)(q22-q24), +7, the total number of abnormalities, the number of markers and additions, and the presence of polyploidy. The most frequent second event arising after the t(14;18) was duplication of the der(18)t(14;18). This study demonstrates that the number and type of secondary chromosomal alterations in follicular lymphoma is highly variable between cases, but that a relatively small number of changes are seen repeatedly in different combinations. A consistent pattern of cytogenetic evolution could not be identified. Potentially significant gene duplications or amplifications may be disguised within marker chromosomes and additions. Additional cytogenetic investigation is required to decipher the karyotypic complexity associated with the progression of follicular lymphoma.

Adult↗
PubMed1994

[Neonatal screening for congenital hip dislocation. Indication of ultrasonography from a systematic study correlating clinical findings and ultrasonography].

INTRODUCTION: The aim of our study was to verify the correlation between clinical and sonographic screening for CDH. MATERIALS AND METHODS: Clinical and sonographic screening was carried out in 1000 newborns (2000 hips) during the first week of life. Anamnestic risk factors were evaluated and clinical examination was performed using the BARLOW, Le DAMANY and ORTOLANI maneuvers. We also took into account a possible limitation of abduction due to adductor hypertonia and the presence of a hip crepitation. All hips were evaluated by ultrasound examination using Graf's morphologic method. We considered as clinically pathological the positive BARLOW, Le DAMANY and ORTOLANI hips and "doubtful" the stable hips having "crepitation" or "hypertonia of the adductors". The hips considered pathological with the ultrasound were the hips 2c, 3a and 3b according to GRAF. RESULTS: 1) Hips clinically pathological (BARLOW, Le DAMANY and ORTOLANI): 150 (7.5 per cent). 2) The clinically stable hips but "doubtful":--crepitation: 105 (5.25 per cent); adductor hypertonia: 86 (4.3 per cent), total 191 (9.55 per cent). 3) Hips clinically normal but with at least anamnestic risk factor: 198 (9.9 per cent); 4) Hips clinically normal but without anamnestic risk factor: 1461 (73.05 per cent). 5) Hips echographically pathological, that is 2c, 3a and 3b according to Graf: 124 (6.2%) and particularly 2c: 61 (3.05 per cent), 3a: 61 (3.05 per cent) and 3b: 2 (0.1 per cent). DISCUSSION: 1) In the clinically pathological hips (BARLOW positive) 36 were echographically pathological with a clinical-sonographic correlation of 28.3 per cent (36 out of 127); all the ORTOLANI positive hips, were echographically pathological (100 per cent (23 out of 23)). In doubtful hips, sonograms were pathological in 17 of 105 hips with "crepitation" (0.85 per cent) and in 13 of 86 hips with "adductor hypertonia" (0.65 per cent). 2) The clinically and echographically pathological hips at birth, that is 2c, 3a and 3b, must be followed for months. At follow up they showed in almost all the cases an evolution towards normality. It is, therefore, indicated to repeat the clinical and sonographic examination in the first month, before undertaking any kind of treatment. 3) Finally, 12 hips, 0.6 per cent, presenting pathological sonographic type 2c and 3a, were found clinically normal. Nevertheless, almost all of these hips evolved normally. From this study only 0.05 per cent of clinically normal hips presented, later, a dysplasia of the acetabulum. Analysis of the results clearly showed that ultrasound examination may be an excellent help to clinical examination which, if well performed, has top priority for early diagnosis of C.D.H. CONCLUSION: The clinical examination, carefully performed in the first days of life, has priority because it allows discovering a pathological hip or a hip at risk. The sonographic examination is a useful image complementing the clinical examination because it allows confirmation of the diagnosis and follow up of the morphologic evolution of the hip with an inoffensive method and it can give indications for possible treatment. From our study we may conclude that at birth a clinical screening is preferable and that the ultrasound study is to be reserved for pathological, doubtful or at risk hips.

Data Interpretation, Statistical↗
PubMed1982

Structural anomalies of the X chromosome: personal observation and review of non-mosaic cases.

We describe a new case of partial deletion of the long arm of the X chromosome, found in a 24-year-old female with secondary amenorrhea; the karyotype of the proposita is 46,X,del(X)(q22). We take this opportunity to review the previously published descriptions of non-mosaic structural anomalies of the X chromosome (X isochromosomes excepted) with the goal of "testing" the recent hypothesis formulated about: (a) the existence of an X inactivation center (Therman et al. 1974b); (b) the presence of a "b" segment remaining active on Xp (Therman et al. 1976); (c) the potential importance of a critical area on Xq linked to gonadal function (Sarto et al. 1973); and (d) the presence of normal gonadal function despite and Xp terminal deletion (Fraccaro et al. 1977). We conclude that the above-mentioned theories, as well as those concerning phylogenetic evolution of sex chromosome morphology presented by Lyon (1974) and Hoo (1975), receive support from practically all of the 149 cases we compared. Regarding the features of the Turner syndrome, we propose "mapping" of the X chromosome as follows: the genes involved in gonadal function seem to be located on the proximal part of Xp and on the distal part of Xq, whereas the genes whose absence is responsible for somatic features of the syndrome may be distributed along the length of Xp and the middle section of Xq(q21-q26). Furthermore, we note some interesting analogies between the evolutional model proposed by Hoo (1975) and the map we visualize.

Adult↗
PubMed1996

What can 18S rDNA do for bivalve phylogeny?

Molecular characteristics, especially 18S rDNA sequences, may be of great value for the study of bivalve evolution and its numerous morphological convergencies once the reliability of these data can be evaluated. The analysis of 11 published complete molluscan sequences and two new ones, Arca noae and Atrina pectinata, reveals considerable differences in relative substitution rates. The gastropod and eulamellibranch species have the fastest and Atrina species have the slowest rates. Two methods are used to assess the information contents of the dataset in addition to bootstrap analysis, spectral analysis, and the "pattern of resolved nodes" technique. Tree reconstructions by parsimony, neighbor-joining, and maximum-likelihood differ in regard to the position of the eulamellibranch family Mactridae and of Crassostrea. Although there is a signal for the monophyly of Bivalvia, Mactridae cluster with Gastropoda in most runs, rendering Bivalvia diphyletic. The position of Crassostrea was extremely variable, probably due to the high substitution rate of this species. Atrina roots deeper than Arca in all trees, although a corresponding signal in spectral analysis is absent. Phylogenetic signals among the three pectinid species are low but sufficient to resolve the branching pattern. The tree inferred from the 18S rDNA and from morphological data has Bivalvia monophyletic with a basal polytomy of Mactridae, Crassostrea, and the remaining Pteriomorphia, where Arca branches off before Atrina and the Pectinidae. Argopecten is sister group to the other two pectinids; 18S sequence data will have great impact on our understanding of bivalve phylogeny, but only when more sequences of similar substitution rates are available.

Animals↗
PubMed2004

Molecular phylogeny of Lysimachia (Myrsinaceae) based on chloroplast trnL-F and nuclear ribosomal ITS sequences.

Both nuclear ribosomal ITS and chloroplast trnL-F sequences were acquired for 57 species (accessions) of Lysimachia and its close relatives, and were analyzed together with sequences retrieved from databases. The results of phylogenetic analyses based on these data (separately or combined) show that Lysimachia is paraphyletic, with the monotypic genus Glaux nested deeply inside. Previous suggestions that Anagallis and Trientalis could be ingroups of Lysimachia were not corroborated by our results. The molecular phylogenies do not support the current infrageneric divisions of Lysimachia. Subgenus Lysimachia contains at least five independent lineages. The Hawaii endemic subgenus Lysimachiopsis was shown to group with subgenera Palladia and Heterostylandra, instead of subgenus Idiophyton as previously suggested. The two North American representatives of Lysimachia, subgenus Seleucia and section Verticillatae of subgenus Lysimachia are group together as the most basal clade of the genus. Parallel and independent evolutions were inferred for morphological characters that were previously used as diagnostic criteria. Molecular phylogenies do not offer clear inferences on the overall historical biogeography of Lysimachia, but Southeast Asia origins of several clades, including the Hawaiian endemic clade and the Iberian Lysimachia ephemerum are strongly supported.

Cell Nucleus↗
PubMed2005

Morphological dynamics of swelling-induced surface patterns in metal-capped polymer bilayer.

We report on the morphological dynamics of surface patterns induced by swelling of metal-capped polymer bilayer on a substrate. When the bilayer is subject to solvent vapor, the strain is generated in the polymer layer that is confined by the substrate and the metal capping layer. An increase in the strain induces the development of the stress in the bilayer to deform the lower polymer layer perpendicularly to the surface of the bilayer. Isotropic surface wave patterns results from the stress relaxation, the wave number of the patterns shows a characteristic temporal dependency on the swelling time, such that km(t) approximately t(-1/8). This temporal evolution accompanied by the morphological dynamics gives smaller value of the growth rate of the characteristic wavelength than that of the case of swelling of gel.

Journal Article↗
PubMed1991

Parallel evolution in mammalian and avian brains: comparative cytoarchitectonic and cytochemical analysis.

Comparative morphology, which is based on the selection theory of evolution, analyses the impact of function upon structure and, therefore, emphasizes the adaptive events and biological advantage during the evolution of organs. A comparison based on analogies is described here as an adequate method. The hypothesis is proposed that the evolution of the brain follows the same trends in birds as in mammals. This hypothesis is proved by (1) allometric studies of brain weight and brain structure volume in relation to body weight in mammals and birds; (2) architectonic studies using image analysis on cell and fibre stains as well as on histochemical preparations and receptor autoradiography; and (3) hodological studies with injections of [3H]leucin, HRP and WGA-HRP. The results reveal a vast amount of structural and functional similarities in avian and mammalian brain organization, especially an expansion of structures that permit multimodal integration capacity in the telencephalon. Thus, a parallel evolution occurred in these two groups of vertebrates. It is argued that this may be a general phenomenon in evolution. A cladistic approach, which is based on the concept of homologies (plesio-, apomorphies), pushes aside the existence of analogies. For this reason, cladism does not seem to be a method to answer questions of evolutionary morphology adequately.

Animals↗