Boreskov

OP‐26OPTIMIZATION OF STRESS RESPONSE AS A MECHANISMOF RAPID ADAPTATIONSuslov V.V.Institute of Cytology and Genetics SB RAS, Novosibirsk State University, Novosibirsk, RussiaFull‐genome projects have revealed the amount of genetic variability: within‐ andbetween‐species comparisons claim from 3 million to 10 million SNPs per genomedepending on the species. Any genome contains a large number of degenerate regulatorysites, which a few substitutions can turn active [1]. On the other hand, Haldane's Dilemmaprevents an adaptive evolution of too many genes simultaneously (in eukaryotes, thisnumber is ~10‐15 genes). Consequently, the evolution of a small population (especially if itlives peripherally close to tolerance limits, which requires rapid adaptability) by way offlashes of increased mutability 1 [2] appears extremely demanding, and so does the genecopyingof modifications [3], which is the selection of mutations that raise the probability ofadaptive modifications (whether they are adaptive or not will be tested by selection) duringontogenesis.If the realized niche is not larger than the fundamental niche [5], the econiche cannot beescaped but only divided according to Gause’s rule. Invasion beyond the econiche absolutelyrequires preadaptation. Noteworthy, if the preadaptation is something that is not anaromorphosis, the invader at once or in a long term 2 will be in a less advantageous situationthan any aborigine polished by evolution 3 . Aromorphoses are rare and take a long time toemerge [3, 5], while invasion from original niches is a common (but not mass) occurrence,which takes place even if there is no strong competition in the original econiches [6, 7]).Abundance of polymorphisms in the genomes requires that the organisms address on anon‐trivial evolutionary problem: reduce the cost of natural selection by letting only thosemutations go that hold most promise for fitness. As a non‐specific adaptation‐relatedsyndrome (after H. Selye [8]), stress provides resistance to adverse factors (cross‐resistance ‐СR) in a short term; however, it depletes and kills in a long term. Thus, it appears as though a1 Admittedly, this genesis of rapid adaptation will work in larger populations [2] or if an increase in mutability is due to asingle gene [4].2 Because invaders are few (unless “waves of life” are concerned), they will eventually become vulnerable, because thegenetic diversity in their population is lower than that in the aboriginal population.3 Zherikhin [5] explained a particular case: invasion is successful if the comers‐in disrupt early stages of succession bygradually ousting the aborigines from their niche but not competing with them directly.73