PT - JOURNAL ARTICLE AU - Tobler, Michael AU - Culumber, Zachary TI - Ecology drives diversification of reproductive strategies in viviparous fishes AID - 10.1101/442830 DP - 2019 Jan 01 TA - bioRxiv PG - 442830 4099 - 4100 - AB - Major shifts in life history evolution often coincide with other evolutionary phenomena, such as changes in sexual selection, parent-offspring conflict, and speciation. However, we rarely understand the causative links between correlated patterns of diversification or the tipping points that initiate changes with cascading effects. We investigated livebearing fishes with repeated transitions from pre- to post-fertilization maternal provisioning and correlated mating system evolution to identify the order of evolutionary shifts and the ultimate drivers of initial evolutionary transitions. Comparative analyses of temporal dynamics across 94 species revealed that repeated shifts from lecithotrophy (pre-fertilization provisioning) to matrotrophy (post-fertilization provisioning) preceded concomitant changes in sexual selection, establishing a previously missing causal link in the correlated evolution of these traits. In addition, we show that bi-directional evolution along the lecithotrophy-matrotrophy continuum is correlated with ecology, supporting adaptive hypotheses of life history diversification. Consistent with theoretical models, matrotrophy was associated with high resource availability and low competition. Our results indicate that geographic variation in ecological conditions is the underlying force that promotes an evolutionary cascade in life history, sexual selection, and potentially speciation.