Biology subjects

Stajic, D.

Publications and source records attributed to Stajic, D..

3 recordsLinked to original sources

bioRxiv2026

Persistent maternal memory, transient offspring effects: the temporal and sex-specific architecture of heritable heat-stress responses in zebrafish

Environmental experiences can influence subsequent generations, yet little is known about the dynamics of such molecular memories across time, reproduction events, and offspring development. Here we provide a temporal map of the transmission of environmental information through egg provisioning and its phenotypic consequences in zebrafish. Specifically, we follow the effects of a 2-week heat wave across successive matings and two unexposed generations along a complete adult-to-egg-to-adult experimental trajectory, assessing gonad responses, maternal RNA, embryo survival, larval behaviour, adult stress resistance and liver transcriptomes. We find that oocyte maternal RNA retained a pronounced heat-shock signature across several weeks and multiple spawning events, with selected functional components persisting into oocytes of the next generation. Somatic responses followed a fundamentally different trajectory: effects on liver transcription were sex- and timepoint-specific, with minor intergenerational signatures of energy metabolism and metabolic stress in males. Parental heat exposure also altered offspring survival, larval behaviour and thermal tolerance, with progressively weakened effects across successive reproductive events and across generations. Our results reveal distinct temporal dynamics of environmental memory in the germline vs the developing and adult soma, with persistent molecular information in maternal provisioning coexisting with progressively fading offspring phenotypes. Such selective retention and loss of parental information align with theoretical predictions about the progressively declining value of inherited information and may determine the dynamics of cross-generational population-level responses to extreme events.

evolutionary biology↗

bioRxiv2024

Adaptation to complex environments reveals pervasive trade-offs and genomic targets with large pleiotropic effects

Much of our knowledge on the dynamics of adaptation comes from experimental evolution studies that expose populations to a single selective pressure. However, populations in nature rarely adapt to a single stress at a time. Instead, various biotic and abiotic factors come together to produce complex selective environments. Here, we used experimental evolution to describe adaptive dynamics in the presence of simultaneous stressors, and to quantify the evolution of trade-offs between stressors in a complex environment. We adapted populations of the yeast Saccharomyces cerevisiae to a full-factorial combination of four stressors over the course of 15 serial transfers. Rapid fitness increases were accompanied by the accumulation of mutations in genes and pathways related to specific stressors. Trade-offs evolved rapidly, with the order and mode of trade-off evolution varying between environments due to the inherent physiological and genetic basis of resistance to each stressor. Compensatory evolution for maladaptation as a result of initial trade-offs was typically mediated by fine-tuning of genes associated with the initially adapted environmental component, rather than those associated with the maladapted trait. As environmental complexity increased, mutations had increasingly broader effects across multiple biological processes. Although shared mutations at the individual SNP level were rare, recurrent mutations affecting the same genes and putative biological processes were abundant across environmental complexity. Our results suggest that adaptation in complex environments follows genetic trajectories shaped by pleiotropy and trade-offs, but these trajectories may impose lasting constraints on future adaptation.

evolutionary biology↗

bioRxiv2021

Epigenetic switching outcompetes genetic mutations during adaptation to fluctuating environments

Epigenetic inheritance allows for the emergence of phenotypic plasticity in clonal populations and enables the rapid stochastic switching between distinct phenotypes. In natural environments, where stress conditions can recurrently fluctuate, clones with an epigenetic control of genes targeted by selection should be fitter than clones that rely solely on genetic mutation. To test this prediction, we engineered switcher and non-switcher yeast strains, where the uracil biosynthesis gene URA3 is under fluctuating selection. Competitions of clones with an epigenetically controlled URA3 with clones without switching ability (SIR3 knock-out), show that epigenetic switching dominates under rapidly changing stresses. We further show that this advantage depends both on the switching rate and the period of environmental fluctuations. Remarkably, epigenetic clones with a high, but not with a low, rate of switching can co-exist with non-switchers even under a constant selective pressure, consistent with different constraints on the evolution of the rate of epigenetic switching.

evolutionary biology↗