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PubMed2004

John Bowlby and Margaret s. Mahler: their lives and theories.

Traumatic aspects of the lives of John Bowlby and Margaret Mahler can be seen to inform their intellectual careers, a perspective that suggests that attachment theory and separation-individuation theory are far more consonant with one another than otherwise. Articulating the domains of convergence between the two theories reveals the essential complementarity of the special strengths of each. Both theories were attempts to understand the role of experience in the development of mental representations. Mahler paid close clinical attention to inner mental states and their evolution, while Bowlby searched for behavioral correlates that could lend themselves to empirical observation and inferences about internal representations.

Child↗

PubMed2005

An empirical assessment of long-branch attraction artefacts in deep eukaryotic phylogenomics.

In the context of exponential growing molecular databases, it becomes increasingly easy to assemble large multigene data sets for phylogenomic studies. The expected increase of resolution due to the reduction of the sampling (stochastic) error is becoming a reality. However, the impact of systematic biases will also become more apparent or even dominant. We have chosen to study the case of the long-branch attraction artefact (LBA) using real instead of simulated sequences. Two fast-evolving eukaryotic lineages, whose evolutionary positions are well established, microsporidia and the nucleomorph of cryptophytes, were chosen as model species. A large data set was assembled (44 species, 133 genes, and 24,294 amino acid positions) and the resulting rooted eukaryotic phylogeny (using a distant archaeal outgroup) is positively misled by an LBA artefact despite the use of a maximum likelihood-based tree reconstruction method with a complex model of sequence evolution. When the fastest evolving proteins from the fast lineages are progressively removed (up to 90%), the bootstrap support for the apparently artefactual basal placement decreases to virtually 0%, and conversely only the expected placement, among all the possible locations of the fast-evolving species, receives increasing support that eventually converges to 100%. The percentage of removal of the fastest evolving proteins constitutes a reliable estimate of the sensitivity of phylogenetic inference to LBA. This protocol confirms that both a rich species sampling (especially the presence of a species that is closely related to the fast-evolving lineage) and a probabilistic method with a complex model are important to overcome the LBA artefact. Finally, we observed that phylogenetic inference methods perform strikingly better with simulated as opposed to real data, and suggest that testing the reliability of phylogenetic inference methods with simulated data leads to overconfidence in their performance. Although phylogenomic studies can be affected by systematic biases, the possibility of discarding a large amount of data containing most of the nonphylogenetic signal allows recovering a phylogeny that is less affected by systematic biases, while maintaining a high statistical support.

Animals↗

PubMed1984

Evolution of multigene families under interchromosomal gene conversion.

A model for the evolution of the probabilities of genetic identity within and between loci of a multigene family in a finite population is formulated and investigated. Unbiased interchromosomal gene conversion, equal crossing-over between tandemly repeated genes, random genetic drift, and mutation to new alleles are incorporated. Generations are discrete and nonoverlapping; the diploid, monoecious population mates at random. Formulae for the equilibrium values of the probabilities of identity and for the rate of convergence are deduced. At equilibrium, the amount of intralocus homology, f, always exceeds the amount of interlocus homology, ĝ. The equilibrium homologies f and ĝ and the characteristic convergence time T are independent of the crossover rate. As the population size and the number of repeats increase, f and ĝ decrease and T increases; as the rate of gene conversion increases, f and T decrease whereas ĝ increases. The time T can be sufficiently short to imply that interchromosomal gene conversion may be an important mechanism for maintaining sequence homogeneity among repeated genes.

Biological Evolution↗

PubMed1987

Evolution of the primary and secondary structures of the E1a mRNAs of the adenovirus.

In this paper we investigate and compare (evolutionary) patterns in the primary and secondary structure of four homologous E1a mRNAs of the adenovirus. Our main results are as follows: (1) The similarity of the coding regions of the mRNA sequences reflects both similarity in function (i.e., oncogenicity) and evolutionary divergence. (2) The similarity of the leader and the trailer regions reflects host specificity (i.e., human or simian) and must therefore arise from convergence. (3) Minimal energy foldings of the mRNAs show similar secondary structures (in particular around the splice sites). The conservation of pre-mRNA secondary structure shows that mRNAs are subject to selection constraints in addition to those associated with proteins. (4) The conserved secondary (helical) structures consist of nonhomologous subsequences, i.e., shifts have occurred. The observed shifts near the splice sites seem to be the simplest way of dealing with the dual constraints.

Adenoviridae↗

PubMed2002

Reconstructing the evolution of complex bird song in the oropendolas.

The elaborate songs of songbirds are frequent models for investigating the evolution of animal signals. However, few previous studies have attempted to reconstruct historical changes in song evolution using a phylogenetic comparative approach. In particular, no comparative studies of bird song have used a large number of vocal characters and a well-supported, independently derived phylogeny. We identified 32 features in the complex vocal displays of male oropendolas (genera Psarocolius, Gymnostinops, and Ocyalus) that are relatively invariant within taxa and mapped these characters onto a robust molecular phylogeny of the group. Our analysis revealed that many aspects of oropendola song are surprisingly evolutionarily conservative and thus are potentially useful characters for reconstructing historical patterns. Of the characters that varied among taxa, nearly two thirds (19 of 29) showed no evidence of evolutionary convergence or reversal when mapped onto the tree, which was reflected in a high overall consistency index (CI = 0.78) and retention index (RI = 0.88). Some reconstructed patterns provided evidence of selection on these signals. For example, rapid divergence of the songs of the Montezuma oropendola, Gymnostinops montezuma, from those of closely related taxa suggests the recent influence of strong sexual selection. In general, our results provide insights into the mode of vocal evolution in songbirds and suggest that complex vocalizations can provide information about phylogeny. Based on this evidence, we use song characters to estimate the phylogenetic affinities of three oropendola taxa for which molecular data are not yet available.

Animals↗

PubMed2005

The evolution of prefrontal inputs to the cortico-pontine system: diffusion imaging evidence from Macaque monkeys and humans.

The cortico-ponto-cerebellar system is one of the largest projection systems in the primate brain, but in the human brain the nature of the information processing in this system remains elusive. Determining the areas of the cerebral cortex which contribute projections to this system will allow us to better understand information processing within it. Information from the cerebral cortex is conveyed to the cerebellum by topographically arranged fibres in the cerebral peduncle - an important fibre system in which all cortical outputs spatially converge on their way to the cerebellum via the pontine nuclei. Little is known of their anatomical organization in the human brain. New in vivo diffusion imaging and probabilistic tractography methods now offer a way in which input tracts in the cerebral peduncle can be characterized in detail. Here we use these methods to contrast their organization in humans and macaque monkeys. We confirm the dominant contribution of the cortical motor areas to the macaque monkey cerebral peduncle. However, we also present novel anatomical evidence for a relatively large prefrontal contribution to the human cortico-ponto-cerebellar system in the cerebral peduncle. These findings suggest the selective evolution of prefrontal inputs to the human cortico-ponto-cerebellar system.

Adult↗

PubMed2006

The emergence of overweight as a disease entity: measuring up normality.

As Charles Rosenberg [(2002). The tyranny of diagnosis. The Milbank Quarterly, 80, 237-260] has recently written, clinical diagnosis contributes to imposing structure on cultural reality in a manner which is not unproblematic. A social power resides in the process of naming diseases-one, which legitimises concerns, explains reality, naturalises deviance and imposes status. But clinical entities are not static, as both the concerns of society, and the technological ability of practitioners change (what Rosenberg refers to as the "iatrogenesis of nosology"), so too do the range of labels available for identifying disease. In this paper, I argue that being "overweight," once predominantly an adjectival descriptor of corpulence, a physical sign or a symptom, and even, in some cultures, a sign of wealth and status, is undergoing the transformation to disease entity. I suggest that evidence of this is present in both the frequency and the way in which the term is being used by the media, the medical establishment and the laity. I argue that this change stems from the convergence of two particular phenomena. The first is the belief in the neutrality of quantification, and the objectivity that measurement brings to qualitative description. The second is the importance attributed to normative appearance in health. I discuss some of the implications of this evolution and its impact on health practices, including the exploitation of this purported disease state for commercial benefit.

Disease↗

PubMed2005

Dynamic professional boundaries in the healthcare workforce.

The healthcare professions have never been static in terms of their own disciplinary boundaries, nor in their role or status in society. Healthcare provision has been defined by changing societal expectations and beliefs, new ways of perceiving health and illness, the introduction of a range of technologies and, more recently, the formal recognition of particular groups through the introduction of education and regulation. It has also been shaped by both inter-professional and profession-state relationships forged over time. A number of factors have converged that place new pressures on workforce boundaries, including an unmet demand for some healthcare services; neo-liberal management philosophies and a greater emphasis on consumer preferences than professional-led services. To date, however, there has been little analysis of the evolution of the workforce as a whole. The discussion of workforce change that has taken place has largely been from the perspective of individual disciplines. Yet the dynamic boundaries of each discipline mean that there is an interrelationship between the components of the workforce that cannot be ignored. The purpose of this paper is to describe four directions in which the existing workforce can change: diversification; specialisation and vertical and horizontal substitution, and to discuss the implications of these changes for the workforce.

Health Care Sector↗

PubMed2005

[The best of interventional cardiology in 2004].

During 2004 the evolution of interventional cardiology has been largely dominated by the expansion of activated endoprostheses, whose advantages have been continuously shown in several studies and surveys. The extension of new indications and the evaluation of new drugs have been witnessed. A new field of converging interest has appeared with the very promising treatment for valvulopathies, in particular mitral insufficiency and calcified aortic stenosis.

Heart Diseases↗

PubMed1991

[Reactions of neurons of the preoptic area in the presence of serial cortical stimuli].

Evoked potentials (EPs) and neuronal responses of the medial (MPO) and lateral (LPO) preoptic region (RPO) and adjacent areas of the anterior hypothalamus to serial (6-300 s) stimulation of the prefrontal (area 8), cingulum (area 24), periamygdaloideus (RPA) cortex and hippocampus (field CA3) were studied on experimental cats anesthetized by ketamine. Cortical areas were selected according to their evolutionary status. Responses of preoptic neurons to serial stimulation were grouped into four main types: excitatory, inhibitory, excitatory on-off-effect and inhibitory on-off-effect. No pronounced changes in the patterns of response reactions were found when frequency of the stimuli increased, only intensity of the reactions changed. Neurons responding to serial cortical stimulation were located mainly in the central part of the MPO and in the basal part of the LPO. These areas of the RPO contained neurons with the most pronounced convergence of different cortical stimuli to the same cell. In serial cortical stimulation inhibitory reactions developed more frequently than excitatory ones (ratio 3.4:1). A gradient of inhibitory reactions to stimulation of different cortical areas was observed while comparing them in terms of evolution from new to old structures. Prevalence of inhibitory responses over excitatory ones was minimal (ratio 1.7:1), when the neocortex (area 8) was stimulated and it was more pronounced (ratio 1.9:1) during stimulation of the evolutionary intermediate cortex (area 24). That prevalence was still more significant (ratio 4.5:1) in case of paleocortical (RPA) stimulation and it was the most pronounced (ratio 10.2:1) during stimulation of the archicortex (hippocampus).

Animals↗

PubMed2000

Masticatory stress, orbital orientation and the evolution of the primate postorbital bar.

A postorbital bar is one of a suite of derived features which distinguishes basal primates from their putative sister taxon, plesiadapiforms. Two hypotheses have been put forward to explain postorbital bar development and variation in circumorbital form: the facial torsion model and visual predation hypothesis. To test the facial torsion model, we employ strain data on circumorbital and mandibular loading patterns in representative primates with a postorbital bar and masticatory apparatus similar to basal primates. To examine the visual predation hypothesis, we employ metric data on orbit orientation in Paleocene and Eocene primates, as well as several clades of visual predators and foragers that vary interspecifically in postorbital bar formation.A comparison of galago circumorbital and mandibular peak strains during powerful mastication demonstrates that circumorbital strains are quite low. This indicates that, as in anthropoids, the strepsirhine circumorbital region is excessively overbuilt for countering routine masticatory loads. The fact that circumorbital peak-strain levels are uniformly low in both primate suborders undermines any model which posits that masticatory stresses are determinants of circumorbital form, function and evolution. This is interpreted to mean that sufficient cortical bone must exist to prevent structural failure due to non-masticatory traumatic forces. Preliminary data also indicate that the difference between circumorbital and mandibular strains is greater in larger taxa.Comparative analyses of several extant analogs suggest that the postorbital bar apparently provides rigidity to the lateral orbital margins to ensure a high level of visual acuity during chewing and biting. The origin of the primate postorbital bar is linked to changes in orbital convergence and frontation at smaller sizes due to nocturnal visual predation and increased encephalization. By incorporating in vivo and fossil data, we reformulate the visual predation hypothesis of primate origins and thus offer new insights into major adaptive transformations in the primate skull.

Animals↗

PubMed1996

Crossroads, milestones and landmarks in insect development and evolution: implications for systematics.

Our understanding of insect development and evolution has increased greatly due to recent advances in the comparative developmental approach. Modern developmental biology techniques such as in situ hybridization and molecular analysis of developmentally important genes and gene families have greatly facilitated these advances. The role of the comparative developmental approach in insect systematics is explored in this paper and we suggest two important applications of the approach to insect systematics--character dissection and morphological landmarking. Existing morphological characters can be dissected into their genetic and molecular components in some cases and this will lead to more and richer character information in systematic studies. Character landmarking will he essential to systematic studies for clarifying structures such as shapes or convergences, which are previously hard to analyze anatomical regions. Both approaches will aid greatly in expanding our understanding of homology in particular, and insect development in general.

Animals↗

PubMed1989

Gross morphology and evolution of the mechanoreceptive lateral-line system in teleost fishes.

The morphology and development of the mechanoreceptive lateral-line system in teleost fishes is reviewed, and the systematic distribution of defined types of lateral-line systems is summarized. The importance of an understanding of ontogeny is stressed and the roles of phylogenetic and developmental constraints in the evolution of the lateral-line system are discussed. Four types of head canal systems are identified on the basis of the relative development of the canals and the orientation of the neuromast receptors contained within them. The distribution of these patterns in the four major teleost clades is analyzed. It is suggested that a branched tubule system associated with the head canals is a primitive teleost character, while widened and reduced head canal patterns are convergent functional specializations in many taxa. The trunk canals are contained in a continuous series of lateral-line scales, and eight trunk canal patterns are described in teleosts. Given the correlation of the systematic distribution of the different trunk canal patterns, ecological habit and body shape, it appears that the trunk canals may function as a hydrodynamic monitor in swimming fishes.

Animals↗

PubMedDate not supplied

Phylogeny of Old and New World vultures (Aves: Accipitridae and Cathartidae) inferred from nucleotide sequences of the mitochondrial cytochrome b gene.

The molecular phylogeny of 11 Old World and 5 New World vultures was inferred from nucleotide sequences of the mitochondrial cytochrome b (cyt b) gene. According to this analysis carrion-feeding has evolved independently at least three times during evolution: 1.) In the New World vultures, which are clearly separated from vultures of the family Accipitridae; 2.) in the Neophron-Gypaetus clade which is positioned at the base of the Accipitrid tree and 3.) in the Gyps-Aegypius-complex which encloses the largest group of Old World vultures. Thus the genetic data clearly show that the carrion-feeding lifestyles and associated morphologies shared by New and Old World vultures are rather based on convergence than on close genetic relatedness. Employing the cyt b sequences of 12 other members of the Falconiformes and 10 members of the Ciconiiformes (sensu Sibley and Monroe, 1990) the phylogenetic relationship between the three clades of vultures and these other taxa was assessed. New World Vultures appear to share distant ancestry with storks but a close relationship is unlikely.

Animals↗

PubMed2003

Converging on nursing home quality.

This paper looks at nursing home quality initiatives, built around public reporting of quality data, that have been inaugurated by the Centers for Medicare and Medicaid Services and the California Health Care Foundation. How the projects were developed is explored, along with preliminary indicators of their impact on consumers and providers and likely next steps in their evolution.

California↗

PubMed2005

Measure dynamics on a one-dimensional continuous trait space: theoretical foundations for adaptive dynamics.

The measure dynamics approach to modelling single-species coevolution with a one-dimensional trait space is developed and compared to more traditional methods of adaptive dynamics and the Maximum Principle. It is assumed that individual fitness results from pairwise interactions together with a background fitness that depends only on total population size. When fitness functions are quadratic in the real variables parameterizing the one-dimensional traits of interacting individuals, the following results are derived. It is shown that among monomorphisms (i.e. measures supported on a single trait value), the continuously stable strategy (CSS) characterize those that are Lyapunov stable and attract all initial measures supported in an interval containing this trait value. In the cases where adaptive dynamics predicts evolutionary branching, convergence to a dimorphism is established. Extensions of these results to general fitness functions and/or multi-dimensional trait space are discussed.

Adaptation, Physiological↗

PubMed1999

Convergence of specialised behaviour, eye movements and visual optics in the sandlance (Teleostei) and the chameleon (Reptilia)

Chameleons have a number of unusual, highly specialised visual features, including telescopic visual optics with a reduced lens power, wide separation of the eye's nodal point from the axis of rotation, a deep-pit fovea, rapid pre-calculated strikes for prey based on monocular depth judgements (including focus), and a complex pattern of partially independent alternating eye movements. The same set of features has been acquired independently by a teleost, the sandlance Limnichthyes fasciatus. Despite its underwater lifestyle, this fish displays visual behaviour and rapid strikes for prey that are remarkably similar to those of the chameleon [1]. In a direct comparison of the two species, we have revealed other, previously unsuspected, similarities, such as corneal accommodation, which was unknown in teleosts, as well as bringing together, for the first time, data collected from both species. The sandlance is the only teleost, among thousands studied, that has corneal refraction, corneal accommodation and reduced lens power, as well as sharing the other specialised optical features seen in chameleons. The independent eye movement pattern in the sandlance is also unusual and similar to that of the chameleon. The selection pressures that have produced this remarkable example of convergence may relate to common visual constraints in the life styles of these two phylogenetically disparate species.

Animals↗

PubMed1997

Genetics of a pheromonal difference affecting sexual isolation between Drosophila mauritiana and D. sechellia.

Females of the sibling species Drosophila sechellia and D. mauritiana differ in their cuticular hydrocarbons: the predominant compound in D. sechellia is 7,11-heptacosadiene (7,11-HD), while that in D. mauritiana is 7-tricosene (7-T). We investigate the genetic basis of this difference and its involvement in reproductive isolation between the species. Behavioral studies involving hydrocarbon transfer suggest that these compounds play a large role in the sexual isolation between D. mauritiana males and D. sechellia females, while sexual isolation in the reciprocal hybridization results more from differences in female behavior than hydrocarbons. This interspecific difference in hydrocarbon profile is due to evolutionary change at a minimum of six loci, all on the third chromosome. The localization of evolutionary change to the third chromosome has been seen in very other genetic analysis of female hydrocarbon differences in the D. melanogaster group. We suggest that the high 7,11-HD phenotype seen in two species evolved twice independently from ancestors having the high 7-T phenotype and the recurrent third-chromosome effects are evolutionary convergences that may be due to a concentration of "hydrocarbon genes" on that chromosome.

Alkadienes↗