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At least 19 recordsLinked to original sources
PubMed1992

Evolutionary biology: a basic science for psychiatry?

Evolutionary biology has much to offer psychiatry. It distinguishes between ultimate and proximate explanations of behavior and addresses the functional significance of behavior. Subtheories, frequently voiced misconceptions, specific applications, testable hypotheses and limitations of evolutionary theory are reviewed. An evolutionary perspective is likely to improve understanding of psychopathology, refocus some clinical research, influence treatment and help integrate seemingly unrelated findings and theoretical explanations.

Behavior↗
PubMed1992

Evolving views of viral evolution: towards an evolutionary biology of viruses.

Despite considerable interest in viral evolution, at least among virologists, viruses are rarely considered from the same evolutionary vantage point as other organisms. Early work of necessity emphasized phenotype and phenotypic variation (and therefore arguably was more oriented towards the broader biological and ecological perspectives). More recent work (essentially since the development of molecular evolution in the 1960's but beginning earlier) has concentrated on genotypic variation, with less clarity about the significance of such variations. Other aspects of evolutionary theory, especially considerations of natural selection and of evolutionary constraints, have not widely been applied to viruses, and an evolutionary framework for virology has long been lacking. This becomes apparent in considering 'emerging' viruses, which have often been treated on an ad hoc basis. It was often felt that, because previously unrecognized viruses are involved, mechanisms of viral emergence must mirror the unpredictability of mutations in the viral genome. However, most examples of viral emergence are independent of mutation, at least initially, and are often pre-existing viruses in changed circumstances ('viral traffic'). This conclusion also readily follows from ordinary Darwinian premises, which would require that, like other living species, 'new' organisms are descended only from existing species. In this respect, from a Darwinian perspective, viruses would appear to resemble other organisms.

Biological Evolution↗
PubMed1975

The comparative evolutionary biology of the sibling species, Drosophila melanogaster and D. simulans.

1. D. melanogaster and D. simulans are sibling species; they are morphologically almost identical and genetically very similar. Whereas their sexual behavior patterns are qualitatively similar, hybrids are rarely produced and when they are, they are sterile. 2. Although not all data are in agreement, D. melanogaster generally exhibits more chromosomal, enzyme, and protein polymorphism than does D. simulans. Utilizing this relationship, as well as arguments presented in the literature, one can argue for an association between genetic variability and level of ecological heterogeneity. This association is found for two major environmental variables, temperature and light dependence. 3. On a seasonal basis, D. melanogaster achieves large population numbers early in the summer, as D. simulans does in the autumn...

Animals↗
PubMed1992

Contributions to the history of psychology: XC. Evolutionary biology and heritable traits (with reference to oriental-white-black differences): the 1989 AAAS paper.

Genetic distance estimates calculated from DNA sequencing indicate that in years since emergence from the ancestral hominid line, Mongoloids = 41,000, Caucasoids = 110,000, and Negroids = 200,000. Data also show that this succession is matched by numerous other differences such that Mongoloids > Caucasoids > Negroids in brain size and intelligence (cranial capacity = 1448, 1408, 1334 cm3; brain weight = 1351, 1336, 1286 gm.; millions of excess neurons = 8900, 8650, 8550; IQ = 107, 100, 85); maturational delay (age to walk alone, age of first intercourse, age of death); sexual restraint (ovulation rate, intercourse frequencies, sexually transmitted diseases including AIDS); quiescent temperament (aggressiveness, anxiety, sociability); and social organization (law abidingness, marital stability, mental health). This pattern is ordered by a theory of r/K reproductive strategies in which Mongoloids are posited to be more K-selected than Caucasoids and especially more than Negroids. (K-selected reproductive strategies emphasize parental care and are to be contrasted with r-selected strategies which emphasize fecundity, the bioenergetic trade-off between which is postulated to underlie cross-species differences in brain size, speed of maturation, reproductive effort, and longevity.) It is suggested that this pattern came about because the ice ages exerted greater selection pressures on the later emerging populations to produce larger brains, longer lives, and more K-like behavior. One theoretical possibility is that evolution is progressive and that some populations are more "advanced" than others. Predictions are made concerning economic projections and the spread of AIDS.

Asian People↗
PubMed1992

Evolutionary biology and pathology of vitamin D.

There is mounting evidence that essentially all fungi, plants and animals living on earth produce provitamin D. It is likely that once exposed to sunlight, these provitamins are converted to previtamin D. It is unclear why fungi, phytoplankton, zooplankton and plants have the capacity to produce such large quantities of provitamin D. It is likely, however, that provitamin D and possibly vitamin D play an important biologic role in these organisms. Buchala and Schmid found, for example, that vitamin D3 promoted adventitious root development. It may be that provitamin D has a more fundamental function in lower life forms. Provitamin D and its photoproducts have UV absorption spectra that overlap with the ultraviolet absorption spectra from ultraviolet radiation-sensitive macromolecules including DNA, RNA and proteins. Thus, provitamin D and photoisomers could serve as a photon sink, and therefore, act as a natural sunscreen to protect lower life forms from the damaging effects of the high energy ultraviolet radiation that they are exposed to. It is more clear, however, that amphibians, reptiles, birds, mammals and humans all require vitamin D and that the vitamin D must be metabolized to 1,25(OH)2D3 before it can carry-out its physiologic functions on calcium and bone metabolism. The intense research activities during the past decade on the antiproliferative and differentiation activities of 1,25(OH)2D3 has opened a new chapter for this vitamin/hormone. 1,25(OH)2D3 and its analogs are being developed for the treatment of psoriasis, breast cancer, and leukemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2025

Admixture Mapping Reveals Evidence for Multiple Mitonuclear Incompatibilities in Swordtail Fish Hybrids.

How barriers to gene flow arise between closely related species is one of the oldest questions in evolutionary biology. Classic models in evolutionary biology predict that negative epistatic interactions between variants in the genomes of diverged lineages, known as hybrid incompatibilities, will reduce viability or fertility in hybrids. The genetic architecture of these interactions and the evolutionary paths through which they arise have profound implications for the efficacy of hybrid incompatibilities as barriers to gene flow between species. While these questions have been studied using theoretical approaches for several decades, only recently has it become possible to genetically map larger numbers of hybrid incompatibilities. Here, we use admixture mapping in natural hybrid populations of swordtail fish (Xiphophorus) to identify hybrid incompatibilities involving genetic interactions between the mitochondrial and nuclear genomes. We find that at least nine regions of the genome are involved in mitonuclear incompatibilities. These incompatibilities involve interactions between the nuclear genome and the X. malinche mitochondria, the X. birchmanni mitochondria, or both. Moreover, they vary in the strength of selection they experience and the degree to which they limit gene flow in natural hybrid populations. Our results build a deeper understanding of the complex architecture of selection against incompatibilities in naturally hybridising species and highlight an important role of mitonuclear interactions in the evolution of reproductive barriers between closely related species.

Animals↗
PubMed1992

The population biology and evolutionary significance of Ty elements in Saccharomyces cerevisiae.

The basic structure and properties of Ty elements are considered with special reference to their role as agents of evolutionary change. Ty elements may generate genetic variation for fitness by their action as mutagens, as well as by providing regions of portable homology for recombination. The mutational spectra generated by Ty1 transposition events may, due to their target specificity and gene regulatory capabilities, possess a higher frequency of adaptively favorable mutations than spectra resulting from other types of mutational processes. Laboratory strains contain between 25-35 elements, and in both these and industrial strains the insertions appear quite stable. In contrast, a wide variation in Ty number is seen in wild isolates, with a lower average number/genome. Factors which may determine Ty copy number in populations include transposition rates (dependent on Ty copy number and mating type), and stabilization of Ty elements in the genome as well as selection for and against Ty insertions in the genome. Although the average effect of Ty transpositions are deleterious, populations initiated with a single clone containing a single Ty element steadily accumulated Ty elements over 1,000 generations. Direct evidence that Ty transposition events can be selectively favored is provided by experiments in which populations containing large amounts of variability for Ty1 copy number were maintained for approximately 100 generations in a homogeneous environment. At their termination, the frequency of clones containing 0 Ty elements had decreased to approximately 0.0, and the populations had became dominated by a small number of clones containing > 0 Ty elements. No such reduction in variability was observed in populations maintained in a structured environment, though changes in Ty number were observed. The implications of genetic (mating type and ploidy) changes and environmental fluctuations for the long-term persistence of Ty elements within the S. cerevisiae species group are discussed.

Biological Evolution↗
PubMedDate not supplied

[Biological and evolutionary significance of the major histocompatibility complex].

The recent advances in the understanding of the Major Histocompatibility Complex, particularly of human HLA and murine H2, are critically reviewed. Special emphasis has been given to the new hypotheses regarding MHC a "rejection" system for recognizing and eliminating cells that have been altered in the expression of their so called transplantation antigens by viral infection or oncogenic transformation. Because Ir genes are certainly involved in controlling the immune response against modified autologous MHC antigens, the author forwards an original hypothesis for explaining the linkage disequilibrium between different alleles at the HLA: A, B, C loci: the Ir gene (genes) in a given haplotype is particularly efficient for recognizing some particular altered antigens of different serie (say A1 and B8; A3 and B7). If these is the case the Ir gene (genes) would be the Keystone for maintaining the preferential associations of some pseudoalleles in some haplotypes.

Alleles↗
PubMed2026

IQ-NET: fast and accurate quartet phylogenetic inference using deep learning trained on empirical DNA alignments.

Phylogenetic inference is fundamental to modern biology, with many applications including evolutionary biology, epidemiology, and comparative genomics. While maximum likelihood and Bayesian methods remain the gold standard for phylogenetic analysis, they rely on simplifying assumptions and are computationally intensive. Recent machine learning approaches for phylogenetics offer speed advantages, but have several limitations: exclusive reliance on simulated data for training, inadequate handling of gaps, and sensitivity to input sequence order. Here, we introduce IQ-NET (Intelligent Quartet NETwork), a deep learning framework that solves these limitations to infer four-taxon trees. IQ-NET estimates both tree topology and branch lengths directly from gapped alignments. IQ-NET outperforms existing machine learning methods in terms of accuracy, and obtained a 24-fold speedup compared with the widely used maximum likelihood software, IQ-TREE. We finally introduce a pipeline using IQ-NET and the ASTRAL software to reconstruct a larger species tree, i.e., with more than four taxa.

Empirical data training↗