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PubMed1999

The evolutionary genetics of ageing and longevity.

Evolutionary theories of ageing are based on the observation that the efficacy of natural selection decreases with age. This is because, even without ageing, individuals will die of environmental causes, such as predation, disease and accidents. Ageing is thought to have evolved as the result of optimising fitness early in life. A second process, namely the progressive accumulation of mutations with effects late in life, will reinforce this result. Longevity of a species is therefore determined by the amount of environmental mortality caused by the ecology of a species. The experimental data concerning the relative roles of both processes are reviewed here. Recent discoveries of the levelling of mortality curves, and of age specific mutations in mutation accumulation lines of Drosophila melanogaster, require adjustments to the original models of the evolution of ageing and species longevity. These adjustments do not invalidate the underlying rationale of evolutionary theories of ageing. With current developments in QTL mapping and genetic association studies, the unravelling of the ageing process has the potential to progress rapidly.

Aging↗
PubMed2000

Genetics of adaptive radiation in Hawaiian species of Tetramolopium (Asteraceae). III. Evolutionary genetics of sex expression.

Despite numerous studies of speciation on oceanic islands, few insights exist on the genetic changes involved in the origin and diversification of island taxa. Here we report a genetic analysis of the evolutionary change in sex expression in Hawaiian Tetramolopium. The most diverse clade in the genus is characterized by a monoecious breeding system. The breeding system resulted from a change in sex expression in disc florets from the ancestral hermaphroditic condition to the derived male state. Analysis of an F2 population from a cross between the two forms of sex expression indicates two regions of the Tetramolopium linkage map are associated with the loss of female function in disc florets. Quantitative trait locus mapping of the two linkage groups confirms that two loci control 56% of the phenotypic variation of the trait in the F2 population. Additive and dominance effects are apparent but no statistical evidence of epistasis was found. Several related reproductive traits also have few genetic associations on the linkage map, but are generally distinct from the control of sex expression. Although modifier loci are likely to be involved, the apparent simple genetic change underlying sex expression parallels a major evolutionary diversification in Hawaiian Tetramolopium and may have initiated the divergence of this novel clade.

Adaptation, Biological↗
PubMed2002

Arrangement and structural conservation of the mitochondrial control region of two species of Plecoptera: utility of tandem repeat-containing regions in studies of population genetics and evolutionary history.

Low levels of primary sequence similarity across insect taxa have led to the suggestion of conserved structural elements in the insect mitochondrial control region. Our aim was to determine whether previously described motifs and secondary structures exist in stoneflies (Plecoptera). Several motifs and structural elements previously described in Orthoptera and Diptera were found, including a conserved 'hairpin' structure that may play a role in the initiation of mtDNA replication. The repeat region had the highest percentage similarity, lowest A-T content and highest transition to transversion ratio, suggesting a unique evolutionary pattern for the repeats. Finally, we discuss the usefulness of the control region in population genetic and evolutionary studies.

Animals↗
PubMed2000

Evolutionary conservation of prion-forming abilities of the yeast Sup35 protein.

Saccharomyces cerevisiae prion [PSI ] is a self-propagating isoform of the eukaryotic release factor eRF3 (Sup35p). Sup35p consists of the evolutionary conserved release factor domain (Sup35C) and two evolutionary variable regions - Sup35N, which serves as a prion-forming domain in S. cerevisiae, and Sup35M. Here, we demonstrate that the prion form of Sup35p is not observed among industrial and natural strains of yeast. Moreover, the prion ([PSI + ]) state of the endogenous S. cerevisiae Sup35p cannot be transmitted to the next generations via heterologous Sup35p or Sup35NM, originating from the distantly related yeast species Pichia methanolica. This suggests the existence of a 'species barrier' in yeast prion conversion. However, the chimeric Sup35p, containing the Sup35NM region of Pichia, can be turned into a prion in S. cerevisiae by overproduction of the identical Pichia Sup35NM. Therefore, the prion-forming potential of Sup35NM is conserved in evolution. In the heterologous system, overproduction of Pichia Sup35p or Sup35NM induced formation of the prion form of S. cerevisiae Sup35p, albeit less efficiently than overproduction of the endogenous Sup35p. This implies that prion induction by protein overproduction does not require strict correspondence of the 'inducer' and 'inducee' sequences, and can overcome the 'species barrier'.

Amino Acid Sequence↗
PubMed2003

Evolutionary history of asexual hybrid loaches (Cobitis: Teleostei) inferred from phylogenetic analysis of mitochondrial DNA variation.

Reconstruction of the evolutionary history of asexual lineages undermines their suitability as models for the studies of evolutionary consequences of sexual reproduction. Using molecular tools we addressed the origin, age and maternal ancestry of diploid and triploid asexual lineages arisen through the hybridization between spiny loaches Cobitis elongatoides, C. taenia and C. tanaitica. Reconstructions of the phylogenetic relationships among mitochondrial DNA (mtDNA) haplotypes, revealed by sequence analyses, suggest that both hybrid complexes (C. elongatoides-taenia and C. elongatoides-tanaitica) contained several asexual lineages of independent origin. Cobitis elongatoides was the exclusive maternal ancestor of all the C. elongatoides-tanaitica hybrids, whereas within the C. elongatoides-taenia complex, hybridization was reciprocal. In both complexes the low haplotype divergences were consistent with a recent origin of asexual lineages. Combined mtDNA and allozyme data suggest that the triploids arose through the incorporation of a haploid sperm genome into unreduced ova produced by diploid hybrids.

Animals↗
PubMed2004

Cranial evolution in sakis (Pithecia, Platyrrhini). II: Evolutionary processes and morphological integration.

Patterns of interspecific differentiation in saki monkeys (Pithecia) are quantitatively described and possible evolutionary processes producing them are examined. The comparison of species correlation matrices to expected patterns of morphological integration reveal significant and similar patterns of development-based cranial integration among species. Aspects of the facial region are more heavily influenced by general size variation than features of the neural region. The comparison of pooled within- and between-groups V/CV matrices suggests that genetic drift might be a sufficient explanation for saki cranial evolution. Differential natural selection gradients are also reconstructed because selection may also have caused population differentiation through evolutionary time. These gradients illustrate the inherent multivariate nature of selection, being a consequence of the interaction between existing morphological integration (correlation) among traits and the action of natural selection. Yet, our attempt to interpret selection gradients in terms of their functional significance did not result in any clear association between selection and function. Perhaps this is also an indication that morphological evolution in sakis was mostly neutral.

Animals↗
PubMed2004

The life history legacy of evolutionary body size change in carnivores.

We estimate the body sizes of direct ancestors of extant carnivores, and examine selected aspects of life history as a function not only of species' current size, but also of recent changes in size. Carnivore species that have undergone marked recent evolutionary size change show life history characteristics typically associated with species closer to the ancestral body size. Thus, phyletic giants tend to mature earlier and have larger litters of smaller offspring at shorter intervals than do species of the same body size that are not phyletic giants. Phyletic dwarfs, by contrast, have slower life histories than nondwarf species of the same body size. We discuss two possible mechanisms for the legacy of recent size change: lag (in which life history variables cannot evolve as quickly as body size, leading to species having the 'wrong' life history for their body size) and body size optimization (in which life history and hence body size evolve in response to changes in energy availability); at present, we cannot distinguish between these alternatives. Our finding that recent body size changes help explain residual variation around life history allometries shows that a more dynamic view of character change enables comparative studies to make more precise predictions about species traits in the context of their evolutionary background.

Age Factors↗
PubMed2001

Evolutionary approaches to psychopathology: the role of natural defences.

OBJECTIVE: Psychoanalytic theories of the mind emerged in the immediate post-Darwinian era of the 1880s and 1890s. Since that time much has changed in both psychoanalytic and evolutionary theorizing. This paper explores recent evolutionary thinking on psychopathology. METHOD: Relevant literature was reviewed. RESULTS: This paper outlines some of the common behavioural defence mechanisms and then explores ways in which they are represented in various disorders, with a focus on depression. This paper suggests that 'symptoms' can be related to the activation of evolved defence mechanisms to respond to losses and threats. Such will involve, for example, anxious arousal and heightened vigilance and attention to the threat, with the type of defence (e.g. fight, flight, submit, help seeking) being mirrored in particular symptom presentations. CONCLUSION: Defences can become pathological when they are too easily aroused or prolonged, are arrested (aroused but not expressed) and/or ineffective.

Adaptation, Psychological↗
PubMed2001

Origin and evolution of the neural crest: a hypothetical reconstruction of its evolutionary history.

The neural crest has long been regarded as one of the key novelties in vertebrate evolutionary history. Indeed, the vertebrate characteristic of a finely patterned craniofacial structure is intimately related to the neural crest. It has been thought that protochordates lacked neural crest counterparts. However, recent identification and characterization of protochordate genes such as Pax3/7, Dlx and BMP family members challenge this idea, because their expression patterns suggest remarkable similarity between the vertebrate neural crest and the ascidian dorsal midline epidermis, which gives rise to both epidermal cells and sensory neurons. The present paper proposes that the neural crest is not a novel vertebrate cell population, but may have originated from the protochordate dorsal midline epidermis. Therefore, the evolution of the vertebrate neural crest should be reconsidered in terms of new cell properties such as pluripotency, delamination-migration and the carriage of an anteroposterior positional value, key innovations leading to development of the complex craniofacial structure in vertebrates. Molecular evolutionary events involved in the acquisitions of these new cell properties are also discussed. Genome duplications during early vertebrate evolution may have played an important role in allowing delamination of the neural crest cells. The new regulatory mechanism of Hox genes in the neural crest is postulated to have developed through the acquisition of new roles by coactivators involved in retinoic acid signaling.

Animals↗
PubMed2002

What is the evolutionary advantage of migraine?

Susceptibility to migraine is determined by genetic factors and is therefore subject to the forces of natural selection. Migraine is a common and ancient disorder whose prevalence may be increasing, suggesting that a migraine-prone nervous system may be associated with reproductive or survival advantages. Five evolutionary explanations are reviewed that might account for the persistence of migraine: (i). migraine as a defence mechanism; (ii). migraine as a result of conflict with other organisms; (iii). migraine as result of novel environmental factors; (iv). migraine as a trade-off between genetic harms and benefits; and (v). migraine as a design constraint. An evolutionary perspective on migraine allows the generation of important hypotheses about the disorder and suggests rewarding possibilities for further research.

Biological Evolution↗
PubMed2000

Investigating human evolutionary history.

We rely on fossils for the interpretation of more than 95% of our evolutionary history. Fieldwork resulting in the recovery of fresh fossil evidence is an important component of reconstructing human evolutionary history, but advances can also be made by extracting additional evidence for the existing fossil record, and by improving the methods used to interpret the fossil evidence. This review shows how information from imaging and dental microstructure has contributed to improving our understanding of the hominin fossil record. It also surveys recent advances in the use of the fossil record for phylogenetic inference.

Animals↗
PubMed1996

Identification of evolutionary conserved regulatory sequences in the 5' untranscribed region of the neural-specific ubiquitin C-terminal hydrolase (PGP9.5) gene.

The structure at the 5' end of the gene encoding neural-specific protein gene product 9.5 (PGP9.5) has been compared between two evolutionary distant species: the human and Monodelphis domestica. In contrast to the highly conserved coding sequences of the gene, only a 48% identity was found across a 1-kb stretch of 5' untranslated and untranscribed DNA. Promoter function studies performed on the human sequence identified a 233-bp CpG-rich minimal promoter. Truncation mutagenesis revealed the presence of essential positive cis-acting regulatory sequences within the region -182 to -123 relative to the transcription initiation site. Sequence alignment analysis of the human and Monodelphis promoter sequences showed 76% identity in this 59-bp region of the gene. A perfectly conserved 12-bp sequence (PSN) located within this region acts as a non-cell-specific activator of transcription in a heterologous reporter gene (pBLCAT2). PGP9.5 gene expression can be readily detected in human neuroblastoma cell lines but is absent in nonneuronal cell lines such as HeLa. Studies on the cell type specificity of the human PGP9.5 promoter demonstrated that in contrast to the endogenous gene, the promoter is active in HeLa cells. However, the promoter displays higher levels of activity in human neuroblastoma cell lines. A conserved 16-bp sequence located at -356 (motif 5) was able to reduce the activity of a heterologous minimal promoter specifically in HeLa cells. In conclusion, we have shown that expression of the PGP9.5 gene is regulated by evolutionary conserved positive and negative cis-acting sequences located in the untranscribed region of the gene.

Animals↗
PubMedDate not supplied

Developmental system drift and flexibility in evolutionary trajectories.

The comparative analysis of homologous characters is a staple of evolutionary developmental biology and often involves extrapolating from experimental data in model organisms to infer developmental events in non-model organisms. In order to determine the general importance of data obtained in model organisms, it is critical to know how often and to what degree similar phenotypes expressed in different taxa are formed by divergent developmental processes. Both comparative studies of distantly related species and genetic analysis of closely related species indicate that many characters known to be homologous between taxa have diverged in their morphogenetic or gene regulatory underpinnings. This process, which we call "developmental system drift" (DSD), is apparently ubiquitous and has significant implications for the flexibility of developmental evolution of both conserved and evolving characters. Current data on the population genetics and molecular mechanisms of DSD illustrate how the details of developmental processes are constantly changing within evolutionary lineages, indicating that developmental systems may possess a great deal of plasticity in their responses to natural selection.

Animals↗
PubMed2001

The relevance of evolutionary genetics for identification of Trichinella sp. and other pathogens at the strain, subspecies and species levels.

In the specific field of Trichinella research, the impact of evolutionary methods has been until now limited. This is all the more distressing, since this group of parasites is characterized by hard taxonomical problems. Moreover, for the epidemiological tracking of Trichinella populations, high-discriminating genetic typing, conveniently analyzed by population genetic methods, could be of considerable help. With no additional efforts, many molecular data are already available and could be used for retrospective analyses able to solve many taxonomical problems. It is desirable that coming studies are specifically designed according to evolutionary genetics principles and the question under study (sample size, selection of the appropriate marker).

Animals↗
PubMed2001

Evolutionary perspectives on stress and affective disorder.

Three general approaches to evolutionary perspectives in psychiatry include the following domains. (1) information from general medicine and physiology that involves defenses against infectious disease and predators, with obsessive compulsive disorder and posttraumatic stress disorder (PTSD) amongst the psychiatric results of this. (2) Sociophysiology assumes that normal brain functions mediate social interactions, including social rank hierarchy, in-out group formation, and family bonding. At times these function maladroitly resulting in psychiatric symptoms, for example, mania, persecutory delusions, and depression. (3) Evolutionary psychology explains self-sacrificing and generous behavior despite how genes act selfishly in natural selection theory, via the helping of relatives, reciprocal altruism, and manipulation of social contracts.

Adaptation, Psychological↗
PubMed1996

Statistical approach for evolutionary relationship of alpha-conotoxins and members of insulin-superfamily.

Similar conserved structures appear in apparently unrelated protein families. Thus, the superfamily of insulin shows an evolutionary relationship with the alpha-conotoxins of marine fish-hunting snails as indicated by methods of protein comparison. In order to reach statistical significance, the A-chains of different insulins, insulin-like growth factors, relaxins, insulin related peptides from invertebrates were drawn for comparison. These data were correlated with sequences from randomly chosen proteins. The alpha-conotoxins show identity scores up to 37.5% and similarity up to 56.2% toward the members of the insulin-superfamily. These scores conform to values achieved by comparing the relaxin and the insulin/IGF-sequences. The data show clearly that the identity and similarity values obtained in the comparison with the insulins are significantly higher than the scores of randomly chosen protein primary structures. According to our calculated data, this hormone system regulating metabolism and growth in vertebrates and the mentioned toxin-receptor system share the same evolutionary ancestor. However, this statistical approach has to be substantiated on gene level.

Amino Acid Sequence↗
PubMed2003

An evolutionary scenario for the transition to undifferentiated multicellularity.

The evolutionary transition from single cells toward multicellular forms of life represents one of the major transitions in the evolution of complex organisms. In this transition, single autonomously reproducing cells became parts of larger reproducing entities that eventually constituted a new unit of selection. The first step in the evolutionary transition to multicellularity likely was the evolution of simple, undifferentiated cell clusters. However, what the selective advantage of such cell clusters may have been remains unclear. Here, we argue that in populations of unicellular organisms with cooperative behavior, clustering may be beneficial by reducing interactions with noncooperative individuals. In support of this hypothesis, we present a set of computer simulations showing that clustering can evolve as a biological, heritable trait for cells that cooperate in the use of external energy resources. Following the evolution of simple cell clusters, further benefits could have arisen from the exchange of resources between cells of a cluster.

Adenosine Triphosphate↗
PubMed2004

Application of evolutionary algorithm methods to polypeptide folding: comparison with experimental results for unsolvated Ac-(Ala-Gly-Gly)5-LysH+.

We present an evolutionary method for finding the low-energy conformations of polypeptides. The application, called FOLDAWAY,is based on a generic framework and uses several evolutionary operators as well as local optimization to navigate the complex energy landscape of polypeptides. It maintains two complementary representations of the structures and uses the CHARMM force field for evaluating the energies. The method is applied to unsolvated Met-enkephalin and Ac-(Ala-Gly-Gly)(5)-Lys(+)H(+). Unsolvated Ac-(Ala-Gly-Gly)(5)-Lys(+)H(+) has been the object of recent experimental studies using ion mobility measurements. It has a flat energy landscape where helical and globular conformations have similar energies. FOLDAWAY locates several large groups of structures not found in previous molecular dynamics simulations for this peptide, including compact globular conformations, which are probably present in the experiments. However, the relative energies of the different conformations found by FOLDAWAY do not accurately match the relative energies expected from the experimental observations.

Algorithms↗