Unravelling macroecological patterns in extant planktonic Foraminifera

• Main Author: Costa Rillo, Marina
• Format: Thesis
• Language: English
• Published: University of Southampton 2019
• Subjects: Planktonic foraminifera
• Online Access: https://eprints.soton.ac.uk/435406/; https://eprints.soton.ac.uk/435406/1/Rillo_e_thesis.pdf

Present-day ecological communities and the deep-time fossil record both inform us about the processes that give rise to, and maintain, diversity of life on Earth. However, these two domains differ in temporal, spatial and taxonomic scales. Integrating these scales remains a major challenge in biodiversity research, mainly because the fossil record gives us an incomplete picture of the extinct communities. Planktonic Foraminifera provide an excellent model system to integrate present and past changes in biodiversity. They are single-celled marine zooplankton that produce calcite shells, yielding a remarkably complete fossil record across millions of years, and are alive today enabling genetic and ecological studies. Their fossil record has been widely used in the fields of stratigraphy and palaeoclimate. However, we have limited knowledge about their ecology, preventing us from fully understanding the evolutionary processes that shaped their diversity through time. The primary objective of this thesis is to improve our understanding of community ecology of extant planktonic Foraminifera species, to enable us to more comprehensively study their fossil record. I created a large image dataset of over 16,000 individuals from a historical museum collection (Chapter 2) and assessed its potential biases (Chapter 3). Using the data gathered from the collection, I investigated the extent to which individuals of the same species vary in shell size (Chapter 4). Size relates to many physiological and ecological characteristics of an organism, thus understanding how it varies within species and across space gives us insights about the function of the species in the ecosystem. Planktonic Foraminifera species greatly differ in how much size variation is explained by environmental (temperature and productivity) and/or ecological (local relative abundance) conditions, suggesting that the known pattern of large size at favourable conditions is not widespread in the group. Next, I explored how planktonic Foraminifera species ...