Data from: Thermal performance curves reveal shifts in optima, limits, and breadth in early life

Understanding thermal performance at life stages that
limit persistence is necessary to predict responses to climate
change, especially for ectotherms whose fitness (survival and
reproduction) depends on environmental temperature. Ectotherms
often undergo stage-specific changes in size, complexity and
duration that are predicted to modify thermal
performance. Yet performance is mostly explored for adults, while
performance at earlier stages that typically limit persistence
remains poorly understood. Here, we experimentally isolate
thermal performance curves at fertilization, embryo development
and larval development stages in an aquatic ectotherm whose early
planktonic stages (gametes, embryos and larvae) govern adult
abundances and dynamics. Unlike previous studies based on
short-term exposures, responses with unclear links to fitness or proxies
in lieu of explicit curve descriptors (thermal optima, limits and
breadth), we measured performance as successful completion of
each stage after exposure throughout, and at temperatures that
explicitly capture curve descriptors at all stages. Formal
comparisons of descriptors using a combination of generalized
linear mixed modelling and parametric bootstrapping reveal
important differences among life stages. Thermal
performance differs significantly from fertilization to embryo
development (with thermal optimum declining by ∼2°C, thermal
limits shifting inwards by ∼8–10°C and thermal breadth narrowing
by ∼10°C), while performance declines independently of
temperature thereafter. Our comparisons show that thermal
performance at one life stage can misrepresent performance at
others, and point to gains in complexity during embryogenesis,
rather than subsequent gains in size or duration of exposure, as
a key driver of thermal sensitivity in early life.