1 Farming, slaving and enslavement: histories of endosymbioses during 2 kinetoplastid evolution 3 4 JANE HARMER1*, VYACHESLAV YURCHENKO2,3, ANNA NENAROKOVA2,4, JULIUS LUKEŠ2,4, MICHAEL L. 5 GINGER1* 6 7 1Department of Biological Sciences, School of Applied Sciences, University of Huddersfield, 8 Huddersfield, HD1 3DH, UK. 9 2Biology Centre, Institute of Parasitology, Czech Academy of Sciences, 370 05 České Budějovice 10 (Budweis), Czechia. 11 3Life Science Research Centre, Faculty of Science, University of Ostrava, 710 00 Ostrava, Czechia. 12 4Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czechia. 13 14 *Corresponding authors: E-mail:
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[email protected] 15 16 Short running title: Endosymbiosis in kinetoplastids 17 18 1 19 SUMMARY 20 Parasitic trypanosomatids diverged from free-living kinetoplastid ancestors several hundred million 21 years ago. These parasites are relatively well known, due in part to several unusual cell biological and 22 molecular traits and in part to the significance of a few - pathogenic Leishmania and Trypanosoma 23 species – as etiological agents of serious neglected tropical diseases. However, the majority of 24 trypanosomatid biodiversity is represented by osmotrophic monoxenous parasites of insects. In two 25 lineages, novymonads and strigomonads, osmotrophic lifestyles are supported by cytoplasmic 26 endosymbionts, providing hosts with macromolecular precursors and vitamins. Here, we discuss the 27 two independent origins of endosymbiosis within trypanosomatids and subsequently different 28 evolutionary trajectories that see entrainment versus tolerance of symbiont cell divisions cycles within 29 those of the host. With potential to inform on the transition to obligate parasitism in the 30 trypanosomatids, interest in the biology and ecology of free-living, phagotrohpic kinetoplastids is 31 beginning to enjoy a renaissance.