EFFECT OF MAJOR CENOZOIC PALAEOCEANOGRAPHIC EVENTS ON COCCOLITHOPHORE MORPHOTYPES: CLIMATICALLY INDUCED CHANGES IN C. PELAGICUS S.L. CLIMORPH.

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Effect of major Cenozoic palaeoceanographic events on coccolithophore morphotypes : climatically induced changes in C. pelagicus s.l. (CliMorph)

Publication . Prista, Gonçalo; Cachão, Mário; Narciso, Áurea

The Cenozoic (past 65 Ma) is characterized by an overall cooling climatic trend punctuated by warming events. The biosphere underwent progressive adaptations towards a cooler world while also being affected by periods of global warming. Thus, the Cenozoic emerges as a fundamental time interval to study how species respond to opposite trends of climate change. Coccolithophores constitute a major component of planktonic communities throughout the world's oceans, being among the main primary producers, and playing a distinct role in the oceans' ecosystems. They're a good proxy on palaeotemperature estimation, have a significant role on the global carbon and sulphur cycles, which arises from the fact that they're among the most important pelagic calcifying organisms in the modern ocean, accounting up to 20% of total carbon fixation. Biological populations evolve with respect to the distribution of organism size and other phenotypic traits by differential fitness. How a phenotypic character like body size evolves over time and what environmental factors influence phenotypic change are fundamental questions of biology and palaeontology. Coccoliths are produced intracellularly, so that their final proportions are attained prior to being extruded to the coccosphere. The size of coccoliths, preserved in the fossil record, is therefore an intrinsic property of a particular (morpho)species or ecophenotype. Coccolith morphometry has great potential in palaeoceanographic studies addressing questions such as taxonomy, biostratigraphy and palaeoecology of calcareous nannoplankton. In this work a new tool – IMMA – was developed to study microevolution on coccolithophores, having C. pelagicus s.l. as targeted species. With more than 60 Ma of evolution and a wide geographic distribution, this coccolithophore species is ideal for studies of microevolution on coccolithophores. Its morphotypes can be related to a variety of palaeoceanographic conditions. IMMA allowed for the observation of C. pelagicus s.l. morphological plasticity in high-resolution Quaternary samples, and provided interesting resulting in older Cenozoic periods, opening new important discussions on coccolithophores morphometry.

2019-04Tese de doutoramento

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Fundação para a Ciência e a Tecnologia

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OE

Número da atribuição

SFRH/BD/95593/2013