Adaptive evolution
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[1st ed.] ix, 270 s., grafy
Speciation mechanisms remain controversial. Two speciation models occur in Israeli subterranean mole rats, genus Spalax: a regional speciation cline southward of four peripatric climatic chromosomal species and a local, geologic-edaphic, genic, and sympatric speciation. Here we highlight their genome evolution. The five species were separated into five genetic clusters by single nucleotide polymorphisms, copy number variations (CNVs), repeatome, and methylome in sympatry. The regional interspecific divergence correspond to Pleistocene climatic cycles. Climate warmings caused chromosomal speciation. Triple effective population size, Ne , declines match glacial cold cycles. Adaptive genes evolved under positive selection to underground stresses and to divergent climates, involving interspecies reproductive isolation. Genomic islands evolved mainly due to adaptive evolution involving ancient polymorphisms. Repeatome, including both CNV and LINE1 repetitive elements, separated the five species. Methylation in sympatry identified geologically chalk-basalt species that differentially affect thermoregulation, hypoxia, DNA repair, P53, and other pathways. Genome adaptive evolution highlights climatic and geologic-edaphic stress evolution and the two speciation models, peripatric and sympatric.
- MeSH
- biologická adaptace MeSH
- biologická evoluce * MeSH
- epigeneze genetická MeSH
- genetická variace MeSH
- genom MeSH
- jednonukleotidový polymorfismus MeSH
- molekulární evoluce MeSH
- populační genetika MeSH
- reprodukční izolace MeSH
- Spalax genetika fyziologie MeSH
- sympatrie * MeSH
- tok genů MeSH
- variabilita počtu kopií segmentů DNA MeSH
- vazebná nerovnováha MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Izrael MeSH
1st ed. iv, 360 s.
Punctuational theories of evolution suggest that adaptive evolution proceeds mostly, or even entirely, in the distinct periods of existence of a particular species. The mechanisms of this punctuated nature of evolution suggested by the various theories differ. Therefore the predictions of particular theories concerning various evolutionary phenomena also differ.Punctuational theories can be subdivided into five classes, which differ in their mechanism and their evolutionary and ecological implications. For example, the transilience model of Templeton (class III), genetic revolution model of Mayr (class IV) or the frozen plasticity theory of Flegr (class V), suggests that adaptive evolution in sexual species is operative shortly after the emergence of a species by peripatric speciation--while it is evolutionary plastic. To a major degree, i.e. throughout 98-99% of their existence, sexual species are evolutionarily frozen (class III) or elastic (class IV and V) on a microevolutionary time scale and evolutionarily frozen on a macroevolutionary time scale and can only wait for extinction, or the highly improbable return of a population segment to the plastic state due to peripatric speciation.The punctuational theories have many evolutionary and ecological implications. Most of these predictions could be tested empirically, and should be analyzed in greater depth theoretically. The punctuational theories offer many new predictions that need to be tested, but also provide explanations for a much broader spectrum of known biological phenomena than classical gradualistic evolutionary theories.
[1st ed.] 387 s., obr.
BACKGROUND: Darwin's evolutionary theory could easily explain the evolution of adaptive traits (organs and behavioral patterns) in asexual but not in sexual organisms. Two models, the selfish gene theory and frozen plasticity theory were suggested to explain evolution of adaptive traits in sexual organisms in past 30 years. RESULTS: The frozen plasticity theory suggests that sexual species can evolve new adaptations only when their members are genetically uniform, i.e. only after a portion of the population of the original species had split off, balanced on the edge of extinction for several generations, and then undergone rapid expansion. After a short period of time, estimated on the basis of paleontological data to correspond to 1-2% of the duration of the species, polymorphism accumulates in the gene pool due to frequency-dependent selection; and thus, in each generation, new mutations occur in the presence of different alleles and therefore change their selection coefficients from generation to generation. The species ceases to behave in an evolutionarily plastic manner and becomes evolutionarily elastic on a microevolutionary time-scale and evolutionarily frozen on a macroevolutionary time-scale. It then exists in this state until such changes accumulate in the environment that the species becomes extinct. CONCLUSION: Frozen plasticity theory, which includes the Darwinian model of evolution as a special case--the evolution of species in a plastic state, not only offers plenty of new predictions to be tested, but also provides explanations for a much broader spectrum of known biological phenomena than classic evolutionary theories. REVIEWERS: This article was reviewed by Rob Knight, Fyodor Kondrashov and Massimo Di Giulio (nominated by David H. Ardell).
Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424 vol. 104, suppl. 1, May 15, 2007
iii, 8563-8676 s. : il., tab. ; 28 cm
- MeSH
- biogeneze organel MeSH
- biologická adaptace MeSH
- biologická evoluce MeSH
- biologické jevy MeSH
- fenotyp MeSH
- fyziologická adaptace MeSH
- selekce (genetika) MeSH
- umělé chromozomy MeSH
- vývojová biologie MeSH
- Publikační typ
- souborné dílo MeSH
- Konspekt
- Biologické vědy
- NLK Obory
- biologie
Legionellaceae are intracellular bacteria known as important human pathogens. In the environment, they are mainly found in biofilms associated with amoebas. In contrast to the gammaproteobacterial family Enterobacteriaceae, which established a broad spectrum of symbioses with many insect taxa, the only instance of legionella-like symbiont has been reported from lice of the genus Polyplax. Here, we sequenced the complete genome of this symbiont and compared its main characteristics to other Legionella species and insect symbionts. Based on rigorous multigene phylogenetic analyses, we confirm this bacterium as a member of the genus Legionella and propose the name Candidatus Legionella polyplacis, sp.n. We show that the genome of Ca. Legionella polyplacis underwent massive degeneration, including considerable size reduction (529.746 bp, 484 protein coding genes) and a severe decrease in GC content (23%). We identify several possible constraints underlying the evolution of this bacterium. On one hand, Ca. Legionella polyplacis and the louse symbionts Riesia and Puchtella experienced convergent evolution, perhaps due to adaptation to similar hosts. On the other hand, some metabolic differences are likely to reflect different phylogenetic positions of the symbionts and hence availability of particular metabolic function in the ancestor. This is exemplified by different arrangements of thiamine metabolism in Ca. Legionella polyplacis and Riesia. Finally, horizontal gene transfer is shown to play a significant role in the adaptive and diversification process. Particularly, we show that Ca. L. polyplacis horizontally acquired a complete biotin operon (bioADCHFB) that likely assisted this bacterium when becoming an obligate mutualist.
- MeSH
- Anoplura genetika mikrobiologie MeSH
- fyziologická adaptace MeSH
- genom bakteriální genetika MeSH
- koevoluce MeSH
- Legionella klasifikace genetika fyziologie MeSH
- molekulární evoluce * MeSH
- přenos genů horizontální MeSH
- sekvenční analýza DNA MeSH
- symbióza MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Cellular metabolism, the interconversion of small molecules by chemical reactions, is a tightly coordinated process that requires integration of diverse environmental and intracellular cues. While for many organisms the topology of the network of metabolic reactions is increasingly known, the regulatory principles that shape the network's adaptation to diverse and changing environments remain largely elusive. To investigate the principles of metabolic adaptation and regulation in metabolic pathways, we propose a computational approach based on in-silico evolution. Rather than analyzing existing regulatory schemes, we let a population of minimal, prototypical metabolic cells evolve rate constants and appropriate regulatory schemes that allow for optimal growth in static and fluctuating environments. Applying our approach to a small, but already sufficiently complex, minimal system reveals intricate transitions between metabolic modes. These results have implications for trade-offs in resource allocation. Going from static to varying environments, we show that for fluctuating nutrient availability, active metabolic regulation results in a significantly increased overall rate of metabolism.
- MeSH
- algoritmy MeSH
- analýza metabolického toku metody MeSH
- biologické hodiny genetika MeSH
- fyziologická adaptace genetika MeSH
- lidé MeSH
- metabolom genetika MeSH
- modely genetické * MeSH
- molekulární evoluce * MeSH
- počítačová simulace MeSH
- signální transdukce genetika MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Hominidé byli donedávna zkoumáni jen paleoantropologickými prostředky. V současnosti se s rostoucím významem uplatňuje populační genetika a molekulární biologie. Anatomická evoluce mozku popisuje desetinásobné zvětšení počtu korových oblastí v průběhu vývoje savců – z 20 na 200. Molekulární evoluce mozku popisuje selekci mutací řady genů. Významnější je však regulace jejich exprese. Hlavním selekčním tlakem zvětšujícím objem mozku vývojové linie směřující k současnému člověku byla podle hypotézy sociálního mozku rostoucí složitost vztahů ve skupinách sociálních primátů.
Until recently hominids could only be studied by means of paleoanthropology. Population genetics and molecular biology play an ever larger role today. The anatomical evolution of the brain describes a tenfold enlargment of the number of cortical brain areas during the evolution of mammals – from about 20 to 200. The molecular evolution of the brain records selection of adaptive mutations of a number of genes. Regulation of their expression is more significant however. According the social brain hypothesis, the complexity of social relationships was the fundamental selection pressure that lead to enlargment of brain volume in evolutionary ancestry in early man.
