Biology subjects

Kunze, C.

Publications and source records attributed to Kunze, C..

5 recordsLinked to original sources

bioRxiv2026

Trait-dependent species responses weaken the effects of response diversity on community stability

The diversity of species responses to environmental change (response diversity) is a key mechanism of ecological stability. However, anticipating where strong or weak stabilizing responses emerge is challenging because species responses can depend on the local community and the specific stability metric. Whether species traits can consistently inform on how species respond to disturbances - enabling less context-dependent predictions - remains an open question. To address this gap, we use microcosm experiments on marine phytoplankton to test how response diversity supports multiple aspects of community stability under pulse temperature changes, testing both an increase (heatwave) and a decrease in temperature (coldspell). We then map species traits to their responses in a community to identify which traits modulate and predict species sensitivities. Fundamental response diversity, based on the diversity of species responses to temperature measured in isolation, was a weak predictor of community stability, and relationships differed between disturbances (i.e., heatwave and coldspell). Instead, species traits were consistent predictors of species responses in communities. Small, fast-growing species were more tolerant and benefited from the disturbance, while large, slow-growing species were less tolerant and decreased in proportion - these patterns were consistent across disturbances and community compositions. These results suggest that strong trait-performance relationships might reduce the importance of response diversity for stability. But these findings also show that general species traits, such as size and growth rate, can predict which species, and how, contribute to community responses, providing an empirical basis to relate species traits to stability outcomes under climate change.

ecology↗

bioRxiv2025

Quantifying the net effect of biodiversity on stability

Understanding the relationship between biodiversity and both the functioning and stability of ecosystems has been a central focus of ecologists for decades. A step-change in our understanding of the biodiversity-ecosystem functioning relationship was enabled by explicit measurement of the additional functioning provided by biodiversity through comparing expected and observed yields in multi-species communities. However, we lack an equivalent measure for stability. Here, we quantify the net biodiversity effect on stability using model simulations and a microcosm experiment that exposed different phytoplankton species and their combinations to temperature increases and fluctuations. As an emergent property of communities, stability frequently exceeded the expected stability of the combined component species, leading to a net biodiversity effect on stability analogous to the effect on functioning. In our simulations, these effects depended on the strength of competitive interactions as well as species composition and their thermal niche. Experimentally, the stabilising effect of diversity was, however, non-linear, greatest for two-species combinations, and varied with both community composition and disturbance regime. Quantifying the net biodiversity effect on stability advances our mechanistic understanding of the biodiversity-stability relationship, and provides crucial information to support ecosystem management and conservation.

ecology↗

bioRxiv2023

Mapping the dynamics of epigenetic adaptation

A classical and well-established mechanism that enables cells to adapt to new and adverse conditions is the acquisition of beneficial genetic mutations. Much less is known about epigenetic mechanisms that allow cells to develop novel and adaptive phenotypes without altering their genetic blueprint. It has been recently proposed that histone modifications, such as heterochromatin-defining H3K9 methylation (H3K9me), normally reserved to maintain genome integrity, can be redistributed across the genome to establish new and potentially adaptive phenotypes. To uncover the dynamics of this process, we developed a precision engineered genetic approach to trigger H3K9me redistribution on-demand in fission yeast. This enabled us to trace genome-scale RNA and chromatin changes over time prior to and during adaptation in long-term continuous cultures. Establishing adaptive H3K9me occurs over remarkably slow time-scales relative to the initiating stress. During this time, we captured dynamic H3K9me redistribution events ultimately leading to cells converging on an optimal adaptive solution. Upon removal of stress, cells relax to new transcriptional and chromatin states rather than revert to their initial (ground) state, establishing a tunable memory for a future adaptive epigenetic response. Collectively, our tools uncover the slow kinetics of epigenetic adaptation that allow cells to search for and heritably encode adaptive solutions, with implications for drug resistance and response to infection.

genetics↗

bioRxiv2021

Alternate patterns of temperature variation bring about very different disease outcomes at different mean temperatures

The dynamics of host-parasite interactions are highly temperature-dependent and may be modified by increasing frequency and intensity of climate-driven heat events. Here, we show that altered patterns of temperature variance lead to an almost order-of-magnitude shift in thermal performance of host and pathogen life history traits over and above the effects of mean temperature and, moreover, that different temperature regimes affect these traits differently. We found that diurnal fluctuations of {+/-}3{degrees}C lowered infection rates and reduced spore burden compared to constant temperatures in our focal host Daphnia magna exposed to the microsporidium parasite Ordospora colligata. In contrast, a three-day heatwave (+6{degrees}C) did not affect infection rates, but increased spore burden (relative to constant temperatures with the same mean) at 16{degrees}C, while reducing burden at higher temperatures. We conclude that changing patterns of climate variation, superimposed on shifts in mean temperatures due to global warming, may have profound and unanticipated effects on disease dynamics.

ecology↗

bioRxiv2018

Salicylate increases fitness cost associated with MarA-mediated antibiotic resistance

Antibiotic resistance is generally associated with a fitness deficit resulting from the burden of producing and maintaining resistance machinery. This additional cost suggests that resistant bacteria will be outcompeted by susceptible bacteria in conditions without antibiotics. However, in practice this process is slow due in part to regulation that minimizes expression of these genes in the absence of antibiotics. This suggests that if it were possible to turn on their expression, the cost would increase, thereby accelerating removal of resistant strains. Experimental and theoretical studies have shown that environmental chemicals can change the fitness cost associated with resistance and therefore have a significant impact on population dynamics. MarA (multiple antibiotic resistance activator) is a clinically important regulator in Escherichia coli which activates downstream genes to increase resistance against multiple classes of antibiotics. Salicylate is an inducer of MarA which can be found in the environment and de-represses marAs expression. In this study, we sought to unravel the interplay between salicylate and the fitness cost of MarA-mediated antibiotic resistance. Using salicylate as a natural inducer of MarA, we found that a wide spectrum of concentrations can increase burden in resistant strains compared to susceptible strains. Induction resulted in rapid exclusion of resistant bacteria from mixed populations of antibiotic resistant and susceptible cells. A mathematical model captures the process and predicts its effect in various environmental conditions. Our work provides a quantitative understanding of salicylate exposure on the fitness of different MarA variants, and suggests that salicylate can lead to selection against MarA-mediated resistant strains. More generally, our findings show that natural inducers may serve to bias population membership and could impact antibiotic resistance and other important phenotypes.

systems biology↗