Evolution of Phytoplankton in Relation to Their Physiological Traits

Abstract

Defining the physiological traits that characterise phytoplankton involves comparison with related organisms in benthic habitats. Comparison of survival time in darkness under natural conditions requires more information. Gas vesicles and flagella as mechanisms of upward movement relative to surrounding water, allowing periodic vertical migration, are not confined to plankton, although buoyancy changes related to compositional changes of a large central vacuole may be restricted to plankton. Benthic microalgae have the same range of photosynthetic pigments as phytoplankton; it is not clear if there are differences in the rate of regulation and acclimation of photosynthetic machinery to variations in irradiance for phytoplankton and for microphytobenthos. There are inadequate data to determine if responses to variations in frequency or magnitude of changes in the supply of inorganic carbon, nitrogen or phosphorus differ between phytoplankton and benthic microalgae. Phagophotomixotrophy and osmophotomixotrophy occur in both phytoplankton and benthic microalgae. Further progress in identifying physiological traits specific to phytoplankton requires more experimentation on benthic microalgae that are closely related to planktonic microalgae, with attention to whether the benthic algae examined have, as far as can be determined, never been planktonic during their evolution or are derived from planktonic ancestors.

The tonoplast localized protein PtNPF1 participates in the regulation of nitrogen response in diatoms

“…2g), suggesting that the nutrient is reallocated through the efflux in the cytosol and assimilated. Since morphology is not affected, one possibility is that the changes in intracellular NO 3 À content, mainly vacuolar, lead to a different texture or biochemical composition of the vacuole (McCarthy et al, 2017;Raven & Beardall, 2022), not detectable with confocal microscopy. In fact, the vacuole represents approximately half of the cell volume, and it also plays a critical role in osmotic regulation, predator defence and buoyancy control (Behrenfeld et al, 2021).…”

“…In fact, the vacuole represents approximately half of the cell volume, and it also plays a critical role in osmotic regulation, predator defence and buoyancy control (Behrenfeld et al ., 2021). Therefore, a chemical modification rather than changes in vacuole size and number can be the consequence of a self‐regulatory programme aimed to respond efficiently to sudden variation of nutritional demands (Raven & Beardall, 2022).…”

Abrupt and acclimation responses to changing temperature elicit divergent physiological effects in the diatom Phaeodactylum tricornutum

“…We cultivated the model species Phaeodactylum tricornutum Bohlin, which is known to have different morphotypes that are associated to different habitats and divergent evolutionary adaptation potential (Sabir et al ., 2018). Pelagic and benthic strains, however, show very few differences in physiological traits (Raven & Beardall, 2022). The here used triradiate morphotype of P. tricornutum (CCAP 1052/1A) was grown at 6°C and 15°C in 0.2 μm sterile‐filtered North Sea seawater (Salinity 33), enriched with vitamins and trace metals according to f/2 media (Guillard & Ryther, 1962).…”

Eco-evolutionary emergence of macroecological scaling in plankton communities

“…However, how these losses vary with size is not well quantified. Particulate sinking speeds of phytoplankton increase with size ( 42 ), but owing to, for example, buoyancy regulation, motility, and turbulence, it is not clear to what extent sinking speeds determine sinking losses ( 43 ). Background losses in phytoplankton can be substantial ( 44 ), but what processes dominate remains unclear.…”