Planktonic foraminiferal species identification is central to many paleoceanographic studies, from selecting species for geochemical research to elucidating the biotic dynamics of microfossil communities relevant to physical oceanographic processes and interconnected phenomena such as climate change. However, few resources exist to train students in the difficult task of discerning amongst closely related species, resulting in diverging taxonomic schools that differ in species concepts and boundaries. This problem is exacerbated by the limited number of taxonomic experts. Here we document our initial progress toward removing these confounding and/or rate-limiting factors by generating the first extensive image library of modern planktonic foraminifera, providing digital taxonomic training tools and resources, and automating species-level taxonomic identification of planktonic foraminifera via machine learning using convolution neural networks. Experts identified 34,640 images of modern (extant) planktonic foraminifera to the species level. These images are served as species exemplars through the online portal Endless Forams (endlessforams.org) and a taxonomic training portal hosted on the citizen science platform Zooniverse (zooniverse.org/projects/ahsiang/ endless-forams/). A supervised machine learning classifier was then trained with~27,000 images of these identified planktonic foraminifera. The best-performing model provided the correct species name for an image in the validation set 87.4% of the time and included the correct name in its top three guesses 97.7% of the time. Together, these resources provide a rigorous set of training tools in modern planktonic foraminiferal taxonomy and a means of rapidly generating assemblage data via machine learning in future studies for applications such as paleotemperature reconstruction.

15The influence of within-species variation and covariation on evolutionary patterns is 16 well established for generational and macroevolutionary processes, most prominently 17 through genetic lines of least resistance. However, it is not known whether intraspecific 18 phenotypic variation also directs microevolutionary trajectories into the long term 19 when a species is subject to varying environmental conditions. Here we present a 20 continuous, high-resolution bivariate record of size and shape changes among 12,633 21 individual planktonic foraminifera of a surviving and an extinct-going species over 500 22 thousand years. This time interval spans the late Pliocene to earliest Pleistocene 23 intensification of Northern Hemisphere glaciation, an interval of profound climate 24 upheaval that can be divided into three phases of increasing glacial intensity. We found 25 that within each of these three Plio-Pleistocene climate phases the within-population 26 allometries predict evolutionary change from one time-step to the next, and that the 27 2 within-phase among-population (i.e. evolutionary) allometries match their 28 corresponding static (within-population) allometries. However, the evolutionary 29 allometry across the three climate phases deviates significantly from the static and 30 phase-specific evolutionary allometries in the extinct-going species. Although 31 intraspecific variation leaves a clear signature on mean evolutionary change from one 32 time-step to the next, our study suggests that the link between intraspecific variation 33 and longer-term micro-and macroevolutionary phenomena is prone to environmental 34 perturbation that can overcome constraints induced by within-species trait covariation. 35 36 3 Introduction 37

Abstract. Barium (Ba) incorporated in the calcite of many foraminiferal species is proportional to the concentration of Ba in seawater. Since the open ocean concentration of Ba closely follows seawater alkalinity, foraminiferal Ba / Ca can be used to reconstruct the latter. Alternatively, Ba / Ca from foraminiferal shells can also be used to reconstruct salinity in coastal settings in which seawater Ba concentration corresponds to salinity as rivers contain much more Ba than seawater. Incorporation of a number of minor and trace elements is known to vary (greatly) between foraminiferal species, and application of element / Ca ratios thus requires the use of species-specific calibrations. Here we show that calcite Ba / Ca correlates positively and linearly with seawater Ba / Ca in cultured specimens of two species of benthic foraminifera: Heterostegina depressa and Amphistegina lessonii. The slopes of the regression, however, vary two-to threefold between these two species (0.33 and 0.78, respectively). This difference in Ba partitioning resembles the difference in partitioning of other elements (Mg, Sr, B, Li and Na) in these foraminiferal taxa. A general trend across element partitioning for different species is described, which may help develop new applications of trace elements in foraminiferal calcite in reconstructing past seawater chemistry.