Coexistence of metabolically co-operating replicators in a cellular automaton: the importance of space without mesoscopic structure TAMÁS CZÁRÁN 1,2 AND EÖRS SZATHMÁRY 1,2 1 Ecological Modelling Research Group, Dept of Plant Taxonomy and Ecology, Eötvös University, Ludovika tér 2, H-1083 Budapest, Hungary. 2 Collegium Budapest (Institute for Advanced Study), Szentháromság u. 2, H- 1014 Budapest, Hungary Fax: +36 1 457 7610, E-mail: szathmary@colbud.hu Word count: Page heading: Spatial dynamical molecular coexistence Key words: molecular coexistence, cellular automata, mesoscopic structure, hypercycle, origin of life, metabolic systems