Ellen Barrowclift

Conflicts of Interest The authors declare no conflicts of interest. Data Availability Statement The datasets supporting this article are available at FigShare (DOI: https://doi.org/10.6084/m9.figshare.20182109). The R code to reproduce these analyses will be available at Github (https://github.com/EBarrowclift/batoid-rmax-offspring-scaling).

1 Introduction Life history strategies of animals and plants reflect trade-offs at the species level. For example, the fast-slow continuum represents the trade-off between reproduction versus survival (Stearns 1983), often irrespective of body size or phylogenetic relatedness (Williams 1966; Gadgil et al. 1970; Reznick 1983; Gaillard et al. 2016). Yet, trade-offs also operate within individuals, such as trading off growth versus reproduction in the energy budget (Gadgil et al.

Abstract Life history strategies are shaped by phylogeny, environmental conditions and individual energy budgets, and have implications for conservation biology. We summarised life history traits of 151 elasmobranch species into life history strategies for two contrasting feeding levels in a principal components analysis. Two axes, reproductive output and generation turnover, structure elasmobranch life history strategies, contrasting with results from similar studies.