Data from: Environmental influence on growth history in marine benthic foraminifera
Keating-Bitonti, Caitlin R., Stanford University
Payne, Jonathan L., Stanford University
Published May 02, 2018 on Dryad.
Cite this dataset
Keating-Bitonti, Caitlin R.; Payne, Jonathan L. (2018). Data from: Environmental influence on growth history in marine benthic foraminifera [Dataset]. Dryad. https://doi.org/10.5061/dryad.d5p86fp
Energy availability influences natural selection on the ontogenetic histories of organisms. However, it remains unclear if physiological controls on size remain constant throughout ontogeny or instead shift as organisms grow larger. Benthic foraminifera provide an opportunity to quantify and interpret the physicochemical controls on both initial (proloculus) and adult volumes across broad environmental gradients using first principles of cell physiology. Here, we measured proloculus and adult test dimensions of 129 modern rotaliid species from published images of holotype specimens using holotype size to represent the maximum size of all species’ occurrences across the North American continental margin. We merged size data with mean annual temperature, dissolved oxygen concentration, particulate organic carbon flux, and seawater calcite saturation for 718 unique localities to quantify the relationship between physicochemical variables and among-species adult/proloculus size ratios. We find that correlation of community mean adult/proloculus size ratios with environmental parameters reflects co-variation of adult test volume with environmental conditions. Among-species proloculus sizes do not co-vary identifiably with environmental conditions, consistent with the expectation that environmental constraints on organism size impose stronger selective pressures on adult forms due to lower surface area-to-volume ratios at larger sizes. Among-species adult/proloculus size ratios of foraminifera occurring in resource-limited environments are constrained by the limiting resource in addition to temperature. Identified limiting resources are food in oligotrophic waters and oxygen in oxygen minimum zones. Because among-species variations in adult/proloculus size ratios from the North American continental margin are primarily driven by the local environment’s influence on adult sizes, the evolution of foraminiferal sizes over the Phanerozoic may have been strongly influenced by changing oceanographic conditions. Furthermore, lack of correspondence between among-species proloculus sizes and environmental conditions suggests that offspring size in foraminifera are rarely limited by physiological constraints and are more susceptible to selection related to other aspects of fitness.
Figure S1. (A) Results of L1-regularized regression analysis assessing the correlations between environmental predictors and log adult/proloculus size ratios for Atlantic endemic species. Plots B-E show the relationship between Atlantic endemic species’ log adult/proloculus size ratios to local temperature, oxygen, calcite saturation, and oxygen, respectively, with solid black lines representing the linear regression of these data. The L1-regularized regression analysis identified that temperature alone best predicts the log adult/proloculus size ratios of Atlantic endemics and the plot B supports this result with the largest R2 value compared to the other environmental variables (see Table S1).