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Supplementary Information for Vyssotski, 2013 Supplementary Information for Vyssotski, 2013 www.evolocus.com/evolocus/v1/evolocus-01-013-s.pdf Evolocus Supplementary Information for Transgenerational epigenetic compensation and sex u al d imorph ism 1,2,3 Dmitri L. Vyssotski Published 17 May 2013, Evolocus 1, 13-18 (2013): http://www.evolocus.com/evolocus/v1/evolocus-01-013.pdf In natu ral popu lation transgenerational epigenetic compensation is by unknown mechanisms, the mechanisms those were difficult to generated in h omoz y gou s mu tants, mainly in males. It d oes not imagine, and this possibility was abandoned for over 47 years. immed iately affect th e ph enoty pe of h omoz y gou s mu tants, w h ere The higher variability in males can be a result of a not so good it w as generated . Transgenerational epigenetic compensation is canalization of their ontogenesis, and the canalization of localiz ed not in th e same locu s as original mu tation and it is ontogenesis is modulated by sex hormones. Thus, we can d ominant, b ecau se it affects th e ph enoty pe ev en if it is receiv ed imagine that the canalization of ontogenesis in males is from one parent. In fu rth er generations, starting from F 2, it is more artificially decreased in comparison with females by means of ex pressed in females th an in males: it increases fitness of hormonal differences. h omozy gou s mu tant females, d ecreases fitness of w ild ty pe The shift of the female distribution to the right was not females and h as w eak effect on h eterozy gou s females. If th e possible to explain from the positions of classic genetics. popu lation remains a rand om b reed ing one, th e transgenerational However this shift is a direct result of the transgenerational epigenetic compensation increases th e selection coefficient of epigenetic compensation, more deeply pronounced in females. mu tant allele and accelerates th e replacement of w ild ty pe allele b y mu tant one, b u t th e total loss of animals in popu lation can b e h igh . If h omoz y gou s mu tant females can ch oose h omoz y gou s mu tant males as potential mates and w ild ty pe females can ch oose w ild ty pe males as potential mates, th en th e popu lation w ill not b e panmictic any more and it w ill b e d iv id ed into mu tant and w ild ty pe su b popu lations. Th e most of animals w ill su rv iv e and a new v ariety on th e b asis of h omozy gou s mu tants w ill b e formed . In 1965-1966, when the role of sexual dimorphism in evolution was first described by Vigen A. Geodakian, he considered two theoretical possibilities concerning differences between males and females: “There are two main possibilities for drawing the females’ curve. The latter can either shift to the right (Fig. 9.117), or it can have a smaller dispersion than the males’ curve (Fig. 9.217)” (Supplementary Fig. 1). At the intuitive level Geodakian had a feeling that both possibilities could be good for evolution: “If we include all the males in the population in one team and include all the females in the other and arrange competitions between the two teams, then the champions in all personal competitions will be the males, whereas in a whole-team competition (where the results of all participants count) the 17 Supplementary Fig. 1 Transgenerational epigenetic compensation in females will be the winners” (p. 8 ). microevolution. The hereditary basis of transgenerational compensation The greater variability in males could be easily achieved with develops mainly in males. Epigenetic changes are transmitted to the next a help of hormonal mechanisms, whereas the shift of the generation through both males and females. Above-mentioned epigenetic distribution of the females to the right could be explained only changes have more deep impact upon female phenotype. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 1Evolocus LLC, Tarrytown, New York, USA. 2Institute of Anatomy, University of Zurich, Zurich, Switzerland. 3P.K. Anokhin Institute of Normal Physiology, Russian Academy of Medical Sciences, Moscow, Russia. Correspondence should be addressed to D.L.V. ([email protected]). 1 Supplementary Information for Vyssotski, 2013 www.evolocus.com/evolocus/v1/evolocus-01-013-s.pdf a b 1) Schmalhausen was trying to be as different from Trofim D. Drug- Morphine- Drug- Thyroxine- Lysenko as possible, and it is not a good motivation is science naive × treated naive × treated (Lysenko was looking at biological phenomena, first, from the physiological position and, second, from the position of genetics; F1 F1 F1 × F1 Schmalhausen with his “stabilizing selection” was using New “correct”, reversed order); 2) Waddington was using the term naive × F1 Drug- Morphine- “canalization of ontogenesis” as a description of a final result of naive × treated a given process and as a description of a set of mechanisms that F2 × F2 F2 × F2 leads to this final result. The “stabilizing selection” is only one F1 × F1 – Not part of the one of such mechanisms, because the natural selection tested F3 F3 F3 F3 in evolution is only one part of evolutionary process, and sometimes it is not the most important part. F2 F2 “Incross” “Outcross” The transgenerational epigenetic compensation, being more phenotypically expressed in females than in males, brilliantly Supplementary Fig. 2 a Breeding paradigms. ( ) Wistar rats, morphine explains the sexual dimorphism in a lifespan in the experiment study. (b) DBA/2J mice, thyroxine study. Solid arrows indicate the with mutant Per2Brdm1 mice under semi-natural outdoor appearance of progeny, dashed arrows – transition of the same animals. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 15 conditions, conducted by Serge Daan and co-authors (2011) . In our experiment with thyroxine we use the term “outcross” In some individuals, probably due to some stochastic to describe breeding with new drug-naïve animals developmental deviations, transgenerational epigenetic (Supplementary Fig. 2). In the classic genetics the cross with an compensation can be unmasked in males and dormant in original stock, in our case with wild-type untreated animals, can females. These individuals have increased probability to be be described as a “backcross”. However, the backcross in a homosexual males and lesbian females, respectively. transgenerational epigenetic experiment as well can be seen as a 17 The term “canalization” was not used by Geodakian in 1966 ; cross of F1 animals to their drug-treated parents (generation P or 31 this term was introduced by Conrad H. Waddington in 1942 or F0). To avoid this confusion, we do not use the term “backcross”, may be even earlier. Geodakian in 196516 was using but any cross with new untreated animals is described by us as terminology, developed by Soviet biologist Ivan I. an “outcross”. The term “incross” does not have similar Schmalhausen, namely “stabilizing selection” (p. 25732). The problems – it is always a cross between animals of the same terminology of Schmalhausen is unacceptable due to 2 reasons: group (experimental or control). F2 ♀ , P105, Incross F2 ♀ , P105, Outcross F3 ♀ , P105, Incross F3 ♀ , P105, Outcross a b * c d * 80 80 * 80 80 * 70 70 70 70 60 ** 60 60 60 50 50 50 50 40 40 * 40 40 30 30 30 30 20 20 ** 20 20 Correct responses T (n = 39) Correct responses T (n = 46) Correct responses T (n = 28) Correct responses T (n = 28) 10 10 10 10 C (n = 33) C (n = 49) C (n = 20) C (n = 24) 0 0 0 0 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 Training days Training days Training days Training days F ♂ , P90, Incross F ♂ , P90, Outcross F ♂ , P90, Incross F ♂ , P90, Outcross e 2 f 2 g 3 h 3 80 80 80 80 ** * 70 70 70 70 * 60 60 60 60 50 50 50 50 40 40 40 40 30 30 30 30 20 * 20 20 20 Correct responses T (n = 43) Correct responses T (n = 46) Correct responses T (n = 23) Correct responses T (n = 26) 10 10 10 10 C (n = 37) C (n = 46) C (n = 20) C (n = 28) 0 0 0 0 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 Training days Training days Training days Training days Supplementary Fig. 3 Two-way avoidance in the Incross and Outcross subgroups. F1 males, obtained from thyroxine-treated males and drug-naive females, were bred with F1 females and with new drug-naive females to produce F2 Incross and Outcross, respectively. F2 Incross and Outcross were bred as independent lines to produce F3 (see Supplementary Fig. 2b). In the F2 generation we can see identical changes in the Incross and Outcross, but only in females (a-b). In the F3-outcross, but not in the F3-incross, the difference has appeared in males during the last 2 training days (h). Similar shapes of learning curves of experimental F3-incross and F3-outcross, together with their relative vertical shift (g-h), indicate that both Incross and Outcross males have some impairment of performance during the last 2 days, but this impairment is compensated somehow in the Incross during the whole 5-day training period. T – experimental group, C – control one. Asterisk, P < 0.05;
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