Beyond the Fast-Slow Continuum of Life Histories

Cost-effective use of limited conservation resources requires understanding which data can most contribute to alleviating biodiversity declines. Interventions might reasonably prioritise life-cycle transitions with the greatest influence on population dynamics, yet some contributing vital rates are particularly challenging to document; such pragmatic decision-making risks suboptimal management if less is known about influential rates. We aimed to explore whether study effort aligns with demographic impact on population growth rate, λ. We parameterised a matrix population model using meta-analysis of vital rates for the common eider (Somateria mollissima), an increasingly threatened yet comparatively data-rich species of seaduck. Female common eiders exhibit intermittent breeding, with some established breeders skipping one or more years between breeding attempts. We accounted for this behaviour by building breeding propensity (= 0.72) into our model with a discrete and reversible ‘non-breeder’ stage (to which surviving adults transition with a probability of 0.28). The transitions between breeding and non-breeding states had twice the influence on λ than fertility (summed matrix-element elasticities of 24% and 11%, respectively), whereas almost 15 times as many studies document components of fertility than breeding propensity (n = 103 and n = 7, respectively). Through comparative re-analyses, we find similar results for two amphibian species, further supporting our finding that study effort does not always occur in proportion to relative influence on λ. Our workflow could form part of the toolkit informing future investment of finite resources, to avoid repeated disconnects between data needs and availability thwarting evidence-driven conservation.

Rational: Organisms that grow a hard carbonate shell or skeleton, such as foraminifera, corals or molluscs, incorporate trace elements into their shell during growth that absorbs the environmental change and biological activity they experienced. These geochemical signals locked within the carbonate are archives used in proxy reconstructions to study past environments and climates, to decipher taxonomy of cryptic species and to resolve evolutionary responses to climatic changes. Methods: Here we use a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a time resolved acquisition to quantify the elemental composition of carbonate shells. We present the LABLASTER (Laser Ablation BLASt Through Endpoint in R) package, which imports a single time resolved LA-ICP-MS analysis, then detects when the laser has ablated through the carbonate as a function of change in signal over time, and outputs key summary statistics. We provide two worked examples within the package: a planktic foraminifera and a tropical coral. Results: We present the first R package that improves signal: noise ratios in data reduction workflows by automating the detection of when the laser has ablated through a sample using a smoothed time-series and subsequent removal of off-target data points. The functions are flexible and adjust dynamically to enhance the signal: noise ratio of the desired geochemical target. Visualisation tools for manual validation are also included. Conclusions: LABLASTER increases transparency and repeatability by algorithmically identifying when the laser has either ablated fully through a sample or across a mineral boundary and is thus no longer documenting a geochemical signal associated with the desired sample. LABLASTER’s focus on better data targeting means more accurate extraction of biological and geochemical signals.