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Yoh Iwasa Last modified date:2016.06.05

Professor / dynamic biology
Department of Biology
Faculty of Sciences

Graduate School
Undergraduate School
Administration Post

Home page for Yoh Iwasa
What is mathematical biology?
CV, list of publications .
Academic Degree
Ph.D (Dr. Sc.)
Field of Specialization
Mathematical Biology
Outline Activities
(1) Population dynamics of animals and plants including spatial components.
(2) Extinction of wild populations and conservation policy
(3) Genomic imprinting and genomic conflict -- mathematical modelling
(4) Mate choice evolution.
(5) Morphogenesis in developmental processes
(6) Immune system
(7) Cancer as an evolutionary process
(8) Incorporating social sciences in ecosystem management
Research Interests
  • Novel mathematical modeling for allopatric speciation and developing of novel theory for biodiversity.
    keyword : allopatric specieation, biodiversity, neutral model. stochastic process
  • Mathematical and computational analysis of animal groups.
    keyword : march, circle, interaction between individuals
  • Evolution of masting in trees
    keyword : forest, masting, evolution
  • Mathematical modeling of coupled ecological and socio-economical dynamics.
    keyword : deforestation, lake water pollution, socio-economic choice, catastrophic-regime shift
    2004.04~2018.03Coupled ecological and socio-economical dynamics have been studied mathematically. I chose two systems -- one for terrestrial system focusing on the condition for deforestatiobn. The second system is for the lake water pollution problem where the issue is on the cooperation among local players. .
  • Stochastic processes related to cancer
    keyword : cancer, Moran process, Chronic Myeloid Leukemia, escape
    2002.09~2018.03We study the carcinogenetic processes as stochastic model in which mutations and replacement of cells by mutants repeated. We evaluate the effect of chromosomal instability and the tissue structure. We also analyze CML data for imanitib resistance..
  • Evolution of cooperation by indirect reciprocity
    keyword : indirect reciprocity, leading eight, evolutionary game
    2003.02~2018.03A high level of cooperation can be maintained at the evolutionarily stable strategy when the players have reputation based on their past actions and the players cooperate depending on the reputation of the opponent..
  • mathematical and computational modeling of morphogenesis in development
    keyword : self-organization, Turing system, lattice model, Cellular Potts model, adhesion, leaf vein system
    1992.03~2012.03Mathematical modeling of pattern formation in development of organisms..
Current and Past Project
  • The whole project is to identify and quantify the biodiversity in East Asia and South-East Asia. It covers forest, fresh water and marine ecosystems as well as genetic diversity study. This particular group are to promote modeling. The whole project is called S9 which is the largest research grant supported by the Environment Ministry of Japan. Iwasa is in charge of developing coupled social-ecological dynamics.
Academic Activities
1. Sachi Yamaguchi, Jens Hoeg, Yoh Iwasa, Evolution of sex determination and sexually dimorphic larval sizes in parasitic barnacles., Journal of Theoretical Biology , 347, 2014.03.
2. Tadasu Matsuo, Marko Jusup, Yoh Iwasa, The conflict of social norms may cause the collapse of cooperation: indirect reciprocity with opposing attitudes towards in-group favoritism., Journal of Theoretical Biology , 346, 2014.03.
3. LEE JOUNGHUN, Yoh Iwasa, Modeling socio-economic aspects of ecosystem management and biodiversity conservation, POPULATION ECOLOGY, 56, 27-40, 2014.01.
4. Ryosuke Iritani, Yoh Iwasa, Parasite infection drives the evolution of state-dependent dispersal of the host, Theoretical Population Biology , 92, 2014.01.
5. Yuuya Tachiki, Yoh Iwasa, Coevolution of mast seeding in trees and extended diapause of seed predators, Interface Focus 2013, 339, 2013.12.
6. Ryo Yamaguchi, Yoh Iwasa, First passage time to allopatric speciation, Interface Focus 2013, 3, 6, 2013.12.
7. Sam Tazzyman, Yoh Iwasa, Andrew Pomiankowski, Signalling efficacy drives the evolution of larger sexual ornaments by sexual selection, Evolution, 68, 2013.11.
8. Uchinomiya, Kouki, Yoh Iwasa, Evolution of stalk/spore ratio in a social amoeba: Cell-to-cell interaction via a signaling chemical shaped by cheating risk, Journal of Theoretical Biology , 336, 110-118, 2013.11.
9. Liao, Jinbao, Li, Zhenqing, David E., Yoh Iwasa, Bogaert, Jan, Nijs, Ivan, Species persistence in landscapes with spatial variation in habitat quality: A pair approximation model, Journal of Theoretical Biology , 335, 22-30, 2013.10.
10. Sachi Yamaguchi, Kota Sawada, Yoichi Yusa, Yoh Iwasa, Dwarf males and hermaphrodites can coexist in marine sedentary species if the opportunity to become a dwarf male is limited., Journal of Theoretical Biology , 334, 2013.04.
11. Yoh Iwasa, LEE JOUNGHUN, Graduated punishment is efficient in resource management if people are heterogeneous. , Journal of Theoretical Biology , 333, 2013.06.
12. Hiroshi Haeno, Y.E. Maruvka, Yoh Iwasa, Franziska Michor, Stochastic tunneling of two mutations in a population of a constant number of cells., PLoS ONE , 8:e15724., 2013.05.
13. Ryo Yamaguchi, Yoh Iwasa, Reproductive character displacement by the evolution of female mate choice. , Evolutionary Ecology Research , 15, 2013.04.
14. Fukano, T., Yuuya Tachiki, Tetsukazu Yahara, Yoh Iwasa, Soil disturbances can suppress the invasion of alien plants under plant-soil-feedback. , Ecological Modelling , 85, 2013.04.
15. Sachi Yamaguchi, Kota Sawada, Yoichi Yusa, Yoh Iwasa, Dwarf males, large hermaphrodites, and females in marine species: a dynamic optimization model of sex allocation and growth. , Theoretical Population Biology , 85, 2013.04.
16. Mayumi Seto, Noriko Takamura, Yoh Iwasa, Individual and combined suppressive effects of submerged and floating-leaved macrophytes on algal blooms, JOURNAL OF THEORETICAL BIOLOGY, 319, 122-133, 2013.02.
17. John M. Halley, Despina Vokou, Yoh Iwasa, Comment on "Extinction Debt and Windows of Conservation Opportunity in the Brazilian Amazon", SCIENCE, 339, 6117, 271-+, 2013.01.
18. Joe Y. Wakano, Yoh Iwasa, Evolutionary Branching in a Finite Population: Deterministic Branching vs. Stochastic Branching, GENETICS, 193, 1, 229-241, 2013.01.
19. Yoshiki Koizumi, Yoh Iwasa, Mathematical Study of the Role of Delta/Notch Lateral Inhibition during Primary Branching of Drosophila Trachea Development, BIOPHYSICAL JOURNAL, 103, 12, 2549-2559, 2012.12.
20. Cinthia M. Tanaka, Yoh Iwasa, Cultural evolution of a belief controlling human mate choice: Dynamic modeling of the hinoeuma superstition in Japan, Journal of Theoretical Biology, 309, 20-28, 2012.09.
21. Joung Hun Lee, Yoh Iwasa, Optimal investment in enhancing social concern on biodiversity conservation: a dynamic approach, Theoretical Population Biology, 82, 2012.08.
22. John Halleuy, Yoh Iwasa, Neutrality without incoherence: a response to Clark, Trends in Ecology and Evolution, 27, 7, 363-363, 27:363, 2012.07.
23. Nao Takashina, Akihiko Mougi, Yoh Iwasa, Paradox of marine protected areas: suppression of fishing may cause species loss, Population Ecology, 54, 3, 475-485, 54:475-485, 2012.07.
24. Kazuhiro Bessho, Yoh Iwasa, Variability in the evolutionarily stable seasonal timing of germination and maturation and the mode of competition. , Journal of Theoretical Biology , 304, 2012.03.
25. Tachiki, Y. and Y. Iwasa, , Evolutionary jumping and breakthrough in the trees' masting evolution. , Theoretical Population Biology , 81:20-31., 2012.02.
26. Akiko Satake, Yoh Iwasa, A stochastic model of chromatin modification: cell population coding of winter memory in plants. , Journal of Theoretical Biology , 302:6-17., 2012.03.
27. Hironaka, K., Y. Iwasa, and Y. Morishita. , Multiple feedback loops achieve robust localization of wingless expression in Drosophila notum development. , Journal of Theoretical Biology , 292:18-29., 2012.01.
28. Morishita, Y. and Y. Iwasa. , Coding design of positional information for robust morphogenesis. , Biophysical Journal , 101:2324-2335., 2011.11.
29. Lee, Joung-Hun and Y. Iwasa. , Tourists and traditional divers in a common fishing ground. , Ecological Economics , 70:2350-2360., 2011.10.
30. Muko, S., and Y. Iwasa. 2011. , Long-term effect of coral transplantation: Restoration-goals and the choice of species. , Journal of Theoretical Biology , 280:127-138., 2011.08.
31. Mougi, A., and Y. Iwasa. , Green world maintained by adaptation. , Theoretical Ecology , 4: 201-210., 2011.07.
32. Mougi, A., O. Kishida, and Y. Iwasa. , Coevolution of phenotypic plasticity in predator and prey: why inducible offense is rarer than inducible defense?, Evolution , 65: 1079-1081., 2011.06.
33. Iwasa, Y. and F. Michor, Evolutionary dynamics of tumor diversity., PLoS ONE , 6: e17866., 2011.05.
34. Mougi, A. and Y. Iwasa, Unique coevolutionary dynamics in a predator-prey system., Journal of Theoretical Biology, 277:83-89., 2011.04.
35. Saeki, K. and Y. Iwas, T cell anergy as a strategy to reduce the risk of autoimmunity. , Journal of Theoretical Biology, 277:74-82., 2011.04.
36. Halley, J.M., and Y. Iwasa, Neutral theory as a predictor of avifaunal extinctions following habitat loss. , Proc. Nat. Acad. Sci. USA , 108:2316-2321., 2011.03.
37. Muko, S., and Y. Iwasa, Optimal choice of species and size classes for transplantation of coral community., Journal of Theoretical Biology, 273:130-137., 2011.02.
38. Seto, M., and Y. Iwasa, Regime shift and robustness of organism-created environment: a model for microbial ecosystem. , Journal of Theoretical Biology, 269:297-306., 2011.01.
39. Bessho, K. and Y. Iwasa. , Optimal seasonal schedule of heteromorphic and isomorphic life-cycles in macroalgae, and their relative dominance. , Journal of Theoretical Biology, 267:201-212. , 2010.10.
40. Tachiki, Y., Y. Iwasa, and A. Satake, Pollinator coupling can induce synchronized flowering among different plant species. , Journal of Theoretical Biology, 267:153-163. , 2010.10.
41. Tachiki, Y. and Y. Iwasa. , Both seedling banks and specific seed predators promote the evolution of synchronized and intermittent reproduction (masting) in trees. , Journal of Ecology , 98:1398-1408. , 2010.08.
42. Brooks, M., and Y. Iwasa., Size-dependent sex change is the ESS without size-advantage of reproduction. , Theoretical Population Biology , 78:183-191. , 2010.06.
43. Mougi, A. and Y. Iwasa, Evolution towards oscillation or stability in a predator-prey system. , Proceeding of Royal Sciety London ser. B , 277: 3163-3171. , 2010.04.
44. Uriu, K., Y. Morishita, and Y. Iwasa., Synchronized oscillation of the segmentation clock gene in vertebrate development. , Journal of Mathematical Biology , 61:217-229., 2010.04.
45. Uriu, K., Y. Morishita, and Y. Iwasa., Synchronization of segmentation clock is promoted by random cell movement. , Proc. Nat. Acad. Sci. USA , 107:4979-4984. , 2010.03.
46. Tazzyman, S.J., and Y. Iwasa., Sexual selection can increase the effect of random genetic drift -- A quantitative genetic model of polymorphism in O. Pumilio, the Strawberry poison-dart frog. , Evolution , 64:1719-1728., 2010.03.
47. Iwasa, Y., Y. Suzuki-Ohno, and H. Yokomizo, Paradox of nutrient removal in coupled socio-economic and ecological dynamics for lake water pollution , Theoretical Ecology , 3:113-122. , 2010.02.
48. Saeki, K., and Y. Iwasa., Optimal number of regulatory T cells., Journal of Theoretical Biology , 263:210-218. , 2010.02.
49. Uehara, T. and Y. Iwasa., Global mutations and local mutations have very different effects on evolution, illustrated by mixed strategies of asymmetric binary games. , Journal of Theoretical Biology , 262: 223-231., 2010.01.
50. Hirashima, T., Y. Iwasa, and Y. Morishita. , Mechanisms for split localization of Fgf10 observed in early lung development., Developmental Dynamics , 238:2813–2822., 2009.11.
51. Saeki, K., and Y. Iwasa., Advantage of having regulatory T cells requires localized suppression of immune reactions. , Journal of Theoretical Biology , 260: 392-401., 2009.10.
52. Bessho, K., and Y. Iwasa., Heteromorphic and isomorphic alternations of generations in macroalgae, as adaptations to a seasonal environment. E, volutionary Ecology Research , 111: 691-771. , 2009.09.
53. Morishita, Y. and Y. Iwasa, , Accuracy of positional information provided by multiple chemical gradients with correlated noises. , Physical Review E, 79: art. no. 061905., 2009.07.
54. Gokhale, C., Y. Iwasa, M.A. Nowak, and A. Traulsen. , The pace of evolution across fitness valleys. , Journal of Theoretical Biology , 259: 613-620. , 2009.07.
55. Hirashima, T., Y. Iwasa, and Y. Morishita, Dynamic modeling of ureteric tube branching in the early kidney development. , Journal of Theoretical Biology , 259: 58-66., 2009.07.
56. Suzuki, Y., and Y. Iwasa, , The coupled dynamics of human socio-economic choice and lake water system: the interaction of two sources of nonlinearity. , Ecological Research , 24: 479-489. , 2009.06.
57. Uriu, K., Y. Morishita and Yoh Iwasa. , Traveling wave formation in vertebrate segmentation. , Journal of Theoretical Biology , 257: 385-396. , 2009.06.
58. Suzuki, Y., and Y. Iwasa, , Conflict between groups of players in coupled socio-economic and ecological dynamics. , Ecological Economics , 68,1106-1115., 2009.05.
59. Ohtsuki, H., Y.Iwasa, and M.A. Nowak. , Indirect reciprocity provides only a narrow margin of efficiency for the costly punishment. , Nature, 457:179-182. , 2009.01.
60. Tachiki, Y. and Y. Iwasa. , Role of gap dynamics in the evolution of masting of trees. , Evolutionary Ecology Research. , 10: 893-905., 2008.11.
61. Morishita, Y. and Y. Iwasa, Growth based morphogenesis in vertebrate limb bud. , Bulletin of Mathematical Biology , 70, 1957-1978., 2008.09.
62. Morishita, Y. and Y. Iwasa., Optimal placement of multiple morphogen sources., Physical Review E, E 77, art. no. 041909, 2008.10.
63. Iwasa, Y., T. Uchida, and H. Yokomizo. , Nonlinear behavior of the socio-economic dynamics for lake water pollution control., Ecological Economics, 63: 219-229., 2007.01.
64. Iwasa, Y., F. Michor, and M.A. Nowak., Evolution of resistance in clonal expansion, Genetics, 172: 2557-2566., 2006.01.
65. Ohtsuki, H. and Y. Iwasa., How should we define goodness? -- reputation dynamics in indirect reciprocity., Journal of Theoretical Biology, 231, 1, 231, 107-120., 2004.01.
66. Nowak, M.A., F. Michor, N.L. Komarova and Y. Iwasa., Evolutionary dynamics of tumor suppressor gene inactivation., Proc. Natl. Acad. Sci. USA, 101, 29, 101, 10635-10638., 2004.01.
67. Michor, F., Y. Iwasa, H. Rajagopalan, C. Lengauer, M. A. Nowak. 2004., A linear model of colon cancer initiation., Cell Cycle, 3:358-362., 2004.01.
68. Michor, F., Y. Iwasa, and M.A. Nowak., Dynamics of cancer progression., Nature Review Cancer, 4, 3, 4:197-205. ., 2004.01.
69. Nowak, M.A., F. Michor, and Y. Iwasa, The linear process of somatic evolution., Proc. Nat. Acad. Sci. USA, 100, 25, 100:14966-14969., 2003.12.
70. Yokomizo, H., J. Yamashita, and Y. Iwasa., Optimal conservation effort for a population in a stochastic environment., Journal of Theoretical Biology, 220, 2, 220:215-231., 2003.01.
71. Kurosawa, G., and Y. Iwasa., Saturation of enzyme kinetics in circadian clock models., Journal of Biological Rhythms, 17, 6, 17:568-588., 2002.01.
72. Iwasa, Y., Dynamic optimization of plant growth., Evolutionary Ecology Research, 2, 4, 2: 437-455., 2000.01.
73. Nakamaru, M., H. Nogami and Y. Iwasa., Score-dependent fertility model for the evolution of cooperation in a lattice., Journal of Theoretical Biology, 194, 1, 194:101-124, 1998.01.
74. Tohya, S., A. Mochizuki, S. Imayama and Y. Iwasa,, On rugged shape of skin tumor (Basal cell carcinoma)., Journal of Theoretical Biology, 194, 1, 194:65-78., 1998.01.
75. Pomiankowski, A. and Y. Iwasa., Runaway ornament diversity caused by Fisherian sexual selection., Proc. Nat. Acad. Sci. USA, 95, 9, 95(9):5106-5111., 1998.01.
  • The foreign hononary member of The American Academy of Arts and Sciences
  • Third Motoo-Kimura Prize, Society for the Evolutionary Studies, Japan
  • First Ecological Society of Japan Prize