Biology subjects

deMayo, J. A.

Publications and source records attributed to deMayo, J. A..

4 recordsLinked to original sources

bioRxiv2026

Transcriptomics of cold stress and recovery reveal strongly tissue-specific responses

Cellular stress responses are often characterized as conserved, cell-autonomous processes. However, it remains unclear whether stress responses are coordinated uniformly across tissues within complex organisms, particularly during ecologically relevant conditions. We investigated tissue- and stage-specific transcriptional responses to cold stress in Drosophila melanogaster. Adults and larvae were independently exposed to a gradual cooling and recovery time series, and three adult tissues (gut, ovary, brain) and one larval tissue (gut) were sampled at baseline, at two time points that spanned the critical thermal minimum (before and during chill coma), and after recovery to rearing temperature. Transcriptomic analyses revealed strongly tissue- and stage-specific responses to cold stress, with limited overlap in differentially expressed genes or functional enrichment across tissues. These results indicate that the organismal response to thermal stress at the transcriptional level is not coordinated by a unified transcriptional program, but rather by largely distinct, tissue-specific regulatory processes.

bioinformatics↗

bioRxiv2021

Experimental evolution reveals the synergistic genomic mechanisms of adaptation to ocean warming and acidification in a marine copepod

Metazoan adaptation to global change will rely on selection of standing genetic variation. Determining the extent to which this variation exists in natural populations, particularly for responses to simultaneous stressors, is therefore essential to make accurate predictions for persistence in future conditions. Here, we identify the genetic variation enabling the copepod Acartia tonsa to adapt to experimental ocean warming, acidification, and combined ocean warming and acidification (OWA) conditions over 25 generations. Replicate populations showed a strong and consistent polygenic response to each condition, targeting an array of adaptive mechanisms including cellular homeostasis, development, and stress response. We used a genome-wide covariance approach to partition the genomic changes into selection, drift, and lab adaptation and found that the majority of allele frequency change in warming (56%) and OWA (63%) was driven by selection but acidification was dominated by drift (66%). OWA and warming shared 37% of their response to selection but OWA and acidification shared just 1%. Accounting for lab adaptation was essential for not inflating a shared response to selection between all treatments. Finally, the mechanisms of adaptation in the multiple-stressor OWA conditions were not an additive product of warming and acidification, but rather a synergistic response where 47% of the allelic responses to selection were unique. These results are among the first to disentangle how the genomic targets of selection differ between single and multiple stressors and to demonstrate the complexity that non-additive multiple stressors will contribute to attempts to predict adaptive responses to complex environments.

evolutionary biology↗

bioRxiv2021

Rapid, but limited, zooplankton adaptation to simultaneous warming and acidification

Predicting the response of marine metazoans to climate change is hampered by a lack of studies on evolutionary adaptation, particularly to combined ocean warming and acidification (OWA). We provide evidence for rapid adaptation to OWA in the foundational copepod species, Acartia tonsa, by assessing changes in population fitness based on a comprehensive suite of life-history traits, using an orthogonal experimental design of nominal temperature (18{degrees}C, 22{degrees}C) and pCO2 (400, 2000 atm) for 25 generations (~1 year). Egg production and hatching success initially decreased under OWA, resulting in a 56% reduction in fitness. However, both traits recovered by the third generation and average fitness was reduced thereafter by only 9%. Antagonistic interactions between warming and acidification in later generations decreased survival, thereby limiting full fitness recovery. Our results suggest such interactions constrain evolutionary rescue and add complexity to predictions of the responses of metazoan populations to climate change.

evolutionary biology↗

bioRxiv2020

Global change adaptation limits future resilience

Adaptive evolution from standing genetic variation and physiological plasticity will fuel resilience in the geologically unprecedented warming and acidification of the earths oceans. For marine animals, however, we have much to learn about the mechanisms, interactions, and costs of adaptation. Here, using 20 generations of experimental evolution followed by three generations of reciprocal transplantation, we investigate the relationship between adaptation and plasticity in the marine copepod, Acartia tonsa, in future greenhouse conditions (high temperature, high CO2). We find highly parallel genetic adaptation to greenhouse conditions in genes related to stress response, gene expression regulation, actin regulation, developmental processes, and energy production. However, reciprocal transplantation showed that genetic adaptation resulted in a loss of transcriptional plasticity, reduced fecundity, and reduced population growth when greenhouse animals were returned to ambient conditions or reared in low food conditions, suggestive of genetic assimilation after 20 generations of adaptation. Despite the loss of plasticity at F21, after three successive transplant generations, greenhouse-adapted animals were able to match the ambient-adaptive transcriptional profile. Concurrent changes in allele frequencies and erosion of nucleotide diversity suggest that this recovery occurred via adaptation back to ancestral conditions. These results demonstrate the power of experimental evolution from natural populations to reveal the mechanisms, timescales of responses, consequences, and reversibility of complex, physiological adaptation. While plasticity facilitated initial survival in global change conditions, it eroded after 20 generations as populations genetically adapted, limiting resilience to new stressors and previously benign environments.

evolutionary biology↗