(327) 26Adult body sizes in Austrolebias annual killifish vary a lot between species. The current 27 hypothesis is that large sizes and specialized piscivory have evolved in successive vicariance 28 speciation events with gradual evolution. We revisit this hypothesis using size measures 29 combined with range data and new phylogenetic trees based on mitochondrial and nuclear 30 molecular markers. Our analysis repeats biogeographic and Ornstein-Uehlenbeck trait evolution 31 modeling across the posterior distributions of phylogenetic trees. We identify three events where 32 large evolved from small. Our mtDNA phylogenetic trees reject the null hypothesis that all 33 speciations were allopatric, but we note that some sympatric speciations might mark The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/121806 doi: bioRxiv preprint first posted online Mar. 29, 2017; 3 species, we can reject the giant-dwarf hypothesis. The absence of substantial and rapid jaw 49 length evolution suggests that they evolved due to other selective processes.

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