Biology subjects

Sikder, A.

Publications and source records attributed to Sikder, A..

4 recordsLinked to original sources

bioRxiv2026

Acclimation response type shapes temporal stability of cyanobacterial communities under thermal fluctuations

Thermal fluctuations increasingly take the form of recurring heatwaves, yet how the acclimation responses of community members shape collective temporal stability remains untested. Using communities of the marine pico-cyanobacterium Synechococcus sp. assembled in microcosms to span a broad range of mean response and response diversity, we tracked total cell density and per-cell chlorophyll a through a 16-day warming-cooling fluctuation regime. Temporal stability of total density was predicted by community mean response and response diversity, but only when computed from acute acclimation responses, not when computed from chronic responses at sustained conditions. Higher acute response diversity increased stability, while a higher mean acute response reduced it, independently of intraspecific richness. Community growth was sub-additive at warming transitions but matched the additive prediction at cooling, indicating that inter-strain interactions suppress community growth specifically as the community enters the warm state. Acclimation response is thus a determinant of both the predictability and the realized dynamics of microbial communities under recurring thermal stress.

ecology↗

bioRxiv2026

Functional and biological diversity jointly shape growth and recovery of Synechococcus communities under stressors.

Biodiversity is expected to enhance the stability of ecological communities under environmental stress, but the relative roles of functional, interspecific, and intraspecific diversity remain poorly resolved, particularly under multiple concurrent stressors. We tested how these diversity dimensions shaped the growth and recovery of marine Synechococcus communities in a microcosm experiment manipulating strain composition across four strain-richness levels and two interspecific diversity levels under control, atrazine, warming, and combined atrazine-plus-warming treatments. Functional diversity was quantified from flow-cytometric trait data and analyzed as initial functional diversity during the stress phase and assembled functional diversity during recovery. Contrary to our expectations, higher initial functional diversity was associated with lower community growth during stress, while higher assembled functional diversity was generally associated with weaker recovery. However, these relationships depended on stressor identity and interspecific diversity: in two-species communities, the negative effects of functional diversity were reduced, and under combined stress, higher assembled functional diversity was associated with improved recovery. In contrast, intraspecific diversity consistently enhanced community growth and recovery, while interspecific diversity primarily promoted functional recovery. Together, our results show that functional, interspecific, and intraspecific diversity can influence stress responses through distinct pathways.

ecology↗

bioRxiv2025

Trait and Growth Responses to Sequential Environmental Change linked to Sensitivity in Synechococcus populations

O_LIEnvironmental change often occurs as a sequence of stressors rather than as isolated events. While the individual and combined effects of multiple stressors are well studied, the ecological consequences of sequential environmental change remain poorly understood. Such sequences, for example, a marine heatwave followed by seasonal herbicide runoff, are increasingly common under global change. C_LIO_LIWe investigated how legacy effects (the imprint of past environmental conditions) influence subsequent population performance and functional traits, and how these effects are mediated by strain-specific sensitivities. C_LIO_LIUsing a fully factorial design, we exposed six strains of the globally abundant pico-phytoplankton Synechococcus sp. to three environmental conditions: warming, herbicide exposure, and a control, under both chronic (same condition across time) and sequential (different conditions across time) regimes. We measured population performance (per-capita growth rate, maximum density) and key functional traits (cell size, chlorophyll content). C_LIO_LIPopulation responses diverged significantly between chronic and sequential exposures, revealing a strong legacy effect. Trait changes were often decoupled from growth metrics, suggesting independent response axes. Strain identity and its interaction with past conditions explained substantial variation in both growth and trait responses. C_LIO_LIWe identify and conceptualise four distinct mechanisms of legacy effects during sequential change: overcompensation, amplification, constraint and depression, each linked to strain-specific responses. Consequently, incorporating legacy effects into predictions of biodiversity dynamics and ecosystem function under global change is therefore both feasible and essential. C_LI

ecology↗

bioRxiv2022

Polymer nanoparticles pass the plant interface

As agriculture strives to feed an ever-increasing number of people, it must adapt to cope with climate change. It is also clear that our biosphere is suffering from an increasing burden of anthropogenic waste which includes minute plastic particles. It is not yet known whether plants will accumulate such micro- and nanoplastic materials, nor how their surface properties might influence uptake. Therefore, we prepared well-defined block copolymer nanoparticles with a range of different sizes (Dh = 20 - 100 nm) and surface chemistries by aqueous dispersion polymerisation using different functional macro chain transfer agents. A BODIPY fluorophore was then incorporated via hydrazone formation and uptake of these fluorescent nanoparticles into intact roots and protoplasts of Arabidopsis thaliana was investigated using confocal microscopy. Where uptake was seen, it was inversely proportional to nanoparticle size. Positively charged particles accumulated around root surfaces and were not taken up by roots or protoplasts, whereas negatively charged nanoparticles accumulated slowly in protoplasts and roots, becoming prominent over time in the xylem of intact roots. Neutral nanoparticles exhibited early, rapid penetration into plant roots and protoplasts, but lower xylem loads relative to the negative nanoparticles. These behaviours differ from those recorded in animal cells and our results show that, despite robust cell walls, plants are vulnerable to nanoplastic particles in the water and soil. The data form both a platform for understanding plastic waste in the farmed environment, and may also be used constructively for the design of precision delivery systems for crop protection products. Significance StatementSustainable food production must keep pace with the growing global population, as well as adapt to climate change and other anthropogenic insults. It has become clear that micro-and nanoscale plastics are accumulating in all parts of the biosphere and we have set out to study how vulnerable plants are to such waste. We show that the size and surface properties of the designed plastics significantly affect both their speed of uptake and distribution within intact roots. Crucially, it is clear that rigid cell walls around plant cells are no barrier to the smallest particles and these pass into the plants vasculature. Our results relate to plastic waste but can also be used to develop precision vehicles for crop protection.

plant biology↗