ASEXUAL REPRODUCTION IN THE PLANKTIC FORAMINIFER NEOGLOBOQUADRINA PACHYDERMA AND MORPHOLOGICAL AND TRACE ELEMENT VARIABILITY IN THE RESULTING OFFSPRING

The morphology and geochemistry of the shells of planktic foraminifera leave behind an invaluable fossil record that can be used to reconstruct the long-term history of Earth’s oceans and climate. However, an incomplete understanding of their reproductive behavior, life history, and heritability of paleontologically significant traits have left important knowledge gaps. Here, we present observations from laboratory culture of asexual reproduction and ontogeny in the planktic foraminifer Neogloboquadrina pachyderma, the offspring of which released gametes. Our results contribute to a growing body of observations demonstrating that planktic foraminifera can reproduce both sexually and asexually. A mixed reproductive strategy can explain the observed rapid spatial and temporal response of imperceptibly low populations to optimal conditions. We find that asexually produced offspring display extensive phenotypic plasticity in response to non-heritable factors, despite little macroenvironmental variability in culture conditions. Shell morphologies encompassed much of the diversity observed in natural populations, including left and right coiling. Analyses of trace elements frequently used as environmental proxies (Ca, Mg, Sr, Mn, Ba & Zn) were carried out on the ocean-grown parent shell and five offspring, one of which was cultured in 24-hour darkness and the other four in alternating 12-hour light/dark conditions. Substantial interindividual variability in Mn/Ca, Ba/Ca, Mn/Ca, and Zn/Ca ratios among offspring demonstrate the importance of microenvironment and individual physiology as drivers of geochemistry as well as morphology.