Biology subjects

Ilic, M.

Publications and source records attributed to Ilic, M..

7 recordsLinked to original sources

bioRxiv2026

The Effective Visual Acuity of Butterflies in Flight

The spatial visual acuity of an eye is determined by both the spatial sampling density of the retina and the angular sensitivity of individual photoreceptors. In insect compound eyes, these are respectively characterised by the interommatidial angle, {Delta}{varphi}, and photoreceptor acceptance angle, {Delta}{rho}. During movement, however, finite photoreceptor integration times cause retinal image motion to broaden the effective acceptance angle, potentially degrading spatial resolution beyond its anatomical limit. This problem is especially acute in flying insects, which experience large rotational velocities during locomotion and must actively stabilise gaze to limit retinal image motion. Butterflies present a particularly demanding case because their flight is characterised by large, wingbeat-coupled thoracic oscillations. Here, we quantify how gaze stabilisation limits motion blur in freely flying Monarch butterflies Danaus plexippus by combining free-flight kinematic reconstruction of the head and thorax with separate intracellular measurements of photoreceptor acceptance angles and integration times from quiescent butterflies. We found that, without head compensation, thoracic oscillations would broaden the effective photoreceptor acceptance angle from its quiescent value of 2.17{degrees} to 9.38{degrees} during take-off. Compensatory head movements substantially reduced this motion-induced broadening, limiting the effective acceptance angle to 5.28{degrees}. Nevertheless, this 2.4-fold broadening of effective photoreceptor acceptance angle represents a substantial degradation of spatial acuity in flight, highlighting motion blur as an important constraint on the visual ecology of flying butterflies.

neuroscience↗

bioRxiv2026

Environmental drivers of heritable trait variation and lag of adaptation to climate in Hordeum murinum

1. Most plant species are genetically differentiated among populations, often reflected by phenotypic trait variation that corresponds to local adaptation. Yet the strength of local adaptation and heritable contribution to phenotypic traits vary across traits, species, and environments. Additionally, climate change is rapidly altering environmental conditions, and the climate may shift faster than populations can adapt or track the change via dispersal, resulting in adaptive lags. However, it remains unclear how widespread such adaptive lags are across plant species. 2. We focused on Hordeum murinum, an annual ruderal grass widespread in Europe. We combined continental-scale in situ measurements of 2070 plants across 207 populations with common garden experiments across two contrasting climates and two soil types to disentangle heritable variation from phenotypic plasticity and assess potential adaptive lags under climate change. 3. We found that heritable variation was pronounced in developmental traits, particularly flowering time and plant height, while seed weight, reproductive investment and SLA showed intermediate heritable contribution, and flag leaf area and total biomass were primarily plastic. Heritable trait variation was strongly associated with temperature at the populations origin, and trait clines were consistent with in situ patterns, suggesting that temperature is the main driver of genetic differentiation in H. murinum. However, we detected that fitness peaked in populations originating from warmer climates, indicating that evolutionary responses may not keep pace with rapid environmental shifts. 4. Synthesis: Our results highlight that H. murinum harbors substantial heritable variation, shaped primarily by temperature. However, the pace of evolutionary change may be insufficient to track ongoing climate change, leaving populations potentially vulnerable to future environmental conditions.

ecology↗

bioRxiv2026

Climate-driven in-situ trait variation in an annual ruderal grass across Europe

O_LIPlant functional traits link environmental conditions to plant performance and adaptation. Growing evidence shows that in-situ intraspecific trait variation can be as important as differences between species, yet large intraspecific datasets measured in situ are rare. While most studies focused on plant morphological traits, contents of elemental nutrients in the seeds received much less attention so far. C_LIO_LIWe conducted a large-scale in-situ study of the widespread ruderal grass Hordeum murinum. We sampled 2070 individuals from 207 populations from a large part of the native range in Europe and Northern Africa. In-situ, we measured seed ripening phenology and morphological traits, and analyzed the content of elemental nutrients in the seeds. C_LIO_LIWe found that Hordeum murinum grew larger, produced seeds later, and had heavier seeds in colder and wetter areas. Plants in denser vegetation were taller with heavier seeds but formed fewer spikes. Seed nutrient content generally declined with seed weight and was mainly driven by climate. Soil conditions had only minor effects on plant traits and seed nutrients. Population identity explained much of the variation, indicating a possible genetic component. C_LIO_LISynthesis: Our findings provide a comprehensive view of Hordeum murinum responding to environmental gradients across its European distribution. Climatic variables, especially temperature, are key drivers for reproductive success and seed nutrient content, while local environments, such as biotic pressures, are more critical for growth-related traits. These patterns indicate that H. murinum modulates its growth and reproductive investment along environmental gradients, balancing phenology, stress tolerance, and limited competitive capacity. C_LI

ecology↗

bioRxiv2025

Spectral Matched Filtering in the Butterfly Visuomotor System

Color provides an important dimension for object detection and classification. In most animals, color- and motion-vision are largely separated throughout early stages of visual processing. However, accumulating evidence indicates crosstalk between chromatic and achromatic pathways. Here we investigate the spectral sensitivity of the butterfly motion-vision pathway at the level of pre-motor descending neurons (DNs), which connect the brain to thoracic motor centres. Butterflies engage in fast agile flight within often-colorful visual ecologies, which may heighten evolutionary pressure to integrate color- and motion-vision. Indeed, we observed a separation of spectral sensitivities that matches the functional properties of butterfly DNs, such that wide-field optic flow-sensitive DNs involved in stabilisation reflexes have effectively broadband spectral responses, whilst target-selective DNs involved in target-tracking are comparatively narrowband and match conspecific wing coloration. Our findings demonstrate an integration of color- and motion-vision within a pre-motor neuronal bottleneck that controls behavior.

neuroscience↗

bioRxiv2025

Oncogene Silencing via ecDNA Micronucleation

Extrachromosomal DNA (ecDNA) contributes to cancer genome instability by enabling high-copy oncogene amplification, intratumoural heterogeneity and rapid genetic change. Micronuclei (MN) are frequently observed in chromosomally unstable cancers, yet their origins and relevance in ecDNA-driven tumours remain incompletely understood. Here, we investigate the relationship between ecDNA segregation errors and MN formation. We find that ecDNA frequently localizes to MN and represents a prominent source of MN content in ecDNA-positive cancer cells. Mitotic clustering of oncogene-bearing ecDNAs is associated with asymmetric inheritance and mis-segregation into MN. Transfer of oncogenes from ecDNA into MN is accompanied by reduced transcriptional output. Single-MN sequencing shows that individual MN are enriched for ecDNA to a degree that exceeds expectations from stochastic mis-segregation and that in MN oncogenes originating from multiple distinct ecDNAs coalesce. Using live-cell imaging, we observe that cells inheriting ecDNA-positive MN show limited proliferative capacity and an increased likelihood of cell death. In neuroblastoma patients with MYCN-amplified ecDNA, higher frequencies of ecDNA-positive MN at diagnosis are associated with improved event-free and overall survival. Together, these findings link ecDNA mis-segregation to MN formation and reduced cellular fitness, suggesting that ecDNA-positive MN may reflect a state of impaired oncogenic ecDNA function with potential relevance for clinical outcome.

cancer biology↗

bioRxiv2023

Weak interactions cause poor performance of common network inference models

O_LINetwork inference models have been widely applied in ecological, genetic and social studies to infer unknown interactions. However, little is known about how well the models perform and whether they produce reliable results when confronted with networks where weak interactions predominate and for different amounts of data. This is an important consideration as empirical interaction strengths are commonly skewed towards weaker interactions, which is especially relevant in ecological networks, and a number of studies suggest the importance of weak interactions for ensuring the dynamic stability of a system. C_LIO_LIHere we investigate four commonly used network methods (Bayesian Networks, Graphical Gaussian Models, L1-regularised regression with the least absolute shrinkage and selection operator, and Sparse Bayesian Regression) and employ network simulations with different interaction strengths to assess their accuracy and reliability. C_LIO_LIThe results show poor performance, in terms of the ability to discriminate between existing relationships and no relationships, in the presence of weak interactions, for all the selected network inference methods. C_LIO_LIOur findings suggest that though these models have some promise for network inference with networks that consist of medium or strong interactions and larger amounts of data, data with weak interactions does not provide enough information for the models to reliably identify interactions. Therefore, networks inferred from data of that type should be interpreted with caution. C_LI

ecology↗

bioRxiv2022

Opponent processing in the retinal mosaic of nymphalid butterflies

The eyes of nymphalid butterflies, investigated with incident illumination, show colourful facet reflection patterns, the eye shine, which is uniform or heterogeneous, dependent on the species. Facet colours suggest that the ommatidia contain different sets of photoreceptors and screening pigments, but how the colours and the cell characteristics are associated has not been clearly established. Here we analyse the retinae of two nymphalids, Apatura ilia, which has a uniform eyeshine, and Charaxes jasius, a species with a heterogeneous eye shine, using single-cell recordings, spectroscopy and optical pupillometry. Apatura has UV, blue and green-sensitive photoreceptors, allocated into three ommatidial types. The UV and blue-sensitive cells are long visual fibres (LVFs), receiving opponent input from the green-sensitive short visual fibres (SVFs). Charaxes has an expanded set of photoreceptors, allocated into three additional, red-reflecting ommatidial types. All red ommatidia contain green-sensitive LVFs, receiving opponent input from red receptors. In both species, the SVFs do not receive any opponent input. The simple retina of Apatura with three ommatidial types and two colour-opponent channels can support trichromatic vision. Charaxes has six ommatidial types and three colour-opponent channels. Its expanded receptor set can support tetrachromatic vision.

neuroscience↗