Non-senescent species are not immortal: Stress and decline in two planaria species

Potential immortality is observed in several species (e.g., prickly pear cactus, hydra, flatworms) and is indicative of their negligible or even negative senescence rates. Unlike in senescent species, which experience reduced individual performance with age due to physiological degradation, species with negligible or negative senescence display mortality rates that remain constant or decline with age, respectively. These rates vary across taxa and are correlated with life history traits. Yet, the extent to which variable resource availability, a key driver of variation in life history traits, impacts species that show negligible or negative senescence is currently unknown. Here, we examine whether and how variation in the quantity, quality, and feeding interval of resources impact population structure, population performance, and life history trait trade-offs in two long-lived planaria that do not senesce: Schmidtea mediterranea and Dugesia tahitiensis. In a full factorial design, diffe..., , , # Data from: Non-senescent species are not immortal: stress and decline in two planaria species

[https://doi.org/10.5061/dryad.v15dv425h](https://doi.org/10.5061/dryad.v15dv425h)

## Description of the data and file structure

To test our hypotheses regarding how variability in resource availability impacts populations of *S. mediterranea* and *D. tahitiensis*, we randomly assigned populations to a full-factorial design for each of the two species. This design included three resource factors: quality, quantity, and feeding interval. Quality of resource had two levels, differing in energy content and relative protein-to-carbohydrate ratio: high quality (high carbohydrate level, *HQ* hereafter) *vs.* low quality (low carbohydrate level, *LQ* hereafter). The high quality diet was organic calf’s liver and the low quality diet bloodworm. The protein-to-carbohydrate ratio indicates resource quality, with low carbohydrate-to-protein content corresponding to poorer quality (Lee et al. 2008). T...