Biology subjects

Szulkin, M.

Publications and source records attributed to Szulkin, M..

8 recordsLinked to original sources

bioRxiv2025

Bird colours in urban mosaics: a study of two passerines

O_LIUrban environments are characterized by markedly altered conditions, which can exert a negative impact on the organisms that inhabit them. Among phenotypic traits most sensitive to urbanization is the colourful plumage of birds. C_LIO_LIOne of the best studied examples might be the urban dullness phenomenon, described for carotenoid-based traits, referring to colours being subdued in urban areas. In contrast, melanin-based and structural colouration are still understudied in the context of urbanization. Moreover, much research focused on changes in mean trait expression, while the effect on phenotypic variation, vital from an eco-evolutionary perspective, was rarely studied in this context. C_LIO_LIHere, we examined urbanization-driven differences in expression and phenotypic variation of carotenoid-based, melanin-based and structural colours of two urban adapters, the great tit (Parus major) and the blue tit (Cyanistes caeruleus). Importantly, birds were sampled across multiple urban and suburban habitats, and replicated in eight Polish cities, located in the under-studied Central and Eastern European region. C_LIO_LIWe found a consistent decrease in mean carotenoid chroma of great tit breast plumage in more heavily urbanized habitats. This trait was also characterized by higher urban phenotypic variation, which could stem from greater environmental heterogeneity in cities. In blue tits, we observed reduced brightness of breast feathers in urban city centres, and an increased brightness of blue tail feathers in more urbanized habitats. C_LIO_LIOur study sheds light on the complex pattern of colour trait sensitivity to urbanization and emphasizes the need for examining a wider range of species to gain greater insight into the eco-evolutionary processes acting in urban ecosystems. C_LI

ecology↗

bioRxiv2025

Avian promiscuity in the last European primeval forest

Primeval forests provide a reference baseline to understand the origins and evolution of mating systems because they offer a unique, undisturbed environment where ecological interactions and natural selection play out in their original context. We established rates of extra-pair paternity (EPP) for two bird species referential to evolutionary ecology: blue tits (Cyanistes caeruleus) and great tits (Parus major), breeding in natural cavities in Biaowie[z]a National Park, the sole remnant of European lowland primeval forests. Genotype-by-sequencing of 889 blue tits and 1,256 great tits revealed that 48% of blue tit broods and 39% great tit broods were of mixed paternity, with 15% blue tit and 14% great tit nestlings not sired by their social father. These referential levels align with median values of EPP reported in nestbox studies in secondary and managed forests, suggesting that certain reproductive strategies are advantageous across diverse environments. Observed promiscuity levels did not affect reproductive success or parental investment, indicating no or limited adaptive value for promiscuity in the context of a primeval forest ecosystem. Our study underscores how primeval habitats provide unparalleled insights into natural selection and mating strategies in wild populations, highlighting the stability and resilience of these strategies across different environmental contexts.

ecology↗

bioRxiv2025

Gut microbiome variation in juvenile blue tits in a European urban mosaic.

Urbanisation transforms natural environments, impacting not only wild animals living in cities but also the microorganisms they are hosting. To better understand urban-driven variation in microbiological composition and diversity in the gut of birds developing in urban areas, we collected faecal samples from blue tit Cyanistes caeruleus nestlings using nestboxes distributed across the capital city of Warsaw, Poland. Sampling included a variety of urban habitats, a suburban village and a natural forest area. Microbiome analysis unveiled a pattern of reduced alpha and beta diversity in urbanised settings driven by impervious surfaces. Additionally, we observed that this effect was year-dependent, therefore highlighting the importance of temporal replication in ecological research. Furthermore, comparing two cavity types (natural and human-made), we demonstrated that artificial nestboxes, a tool widely used in field ecology, can impact the microbiome assembly in nestlings. Our results align with and expand upon earlier insights in great tit Parus major gut microbiome variation inferred in the same urban study system on a species ecologically related to the blue tit, confirming the pervasive impact of urbanisation on the avian gut microbiome.

ecology↗

bioRxiv2024

Continent-wide drivers of spatial synchrony in age structure across wild great tit populations

Spatio-temporal variation in age structure influences population dynamics, yet we have limited understanding of the spatial scale at which its fluctuations are synchronised between populations. Using 32 great tit populations, spanning 3200km and >130,000 birds across 67 years, we quantify spatial synchrony in breeding age structure and its drivers. We show that larger clutch sizes, colder winters and summers, and larger beech crops lead to younger populations. We report distant-dependent spatial synchrony of age structure, which is maintained at approximately 650km. Despite covariation with age structure, reproductive and environmental variables do not influence the scale of synchrony, except for a moderate effect of beech masting. We suggest that local ecological and density-dependent dynamics impact how environmental variation interacts with age structure, influencing estimates of the environments effect on spatial synchrony. Our analyses demonstrate the operation of synchrony in age structure over large scales, with implications for age-dependent demography in populations.

ecology↗

bioRxiv2024

Comparing approaches to quantify urbanization on a multicontinental scale

Urbanization is an increasingly prevalent driver of environmental, ecological, and evolutionary change in both terrestrial and aquatic systems, and it is important that our sampling designs accurately capture this urban environmental change. Common approaches to sampling urban environments include: urban-nonurban transects, which sample along urbanization gradients; random points, which sample locations at random within an area of interest; and systematic points, which sample locations based on a regularly-spaced grid from a predetermined starting point within the area of interest. Presently, we lack a comparative analysis of the efficacy of these different sampling designs in capturing variation in urban environments. Here, we compare the environmental variation captured by transect- and point-based sampling designs in 136 cities across six continents. We quantified and compared a common set of environmental variables for each sampling design, with variables capturing landcover, climate, and socioeconomic facets of urban environments. Mean landcover and socioeconomic metrics consistently differed among sampling designs, in contrast to climate variables that primarily varied among cities. Additionally, changes in environmental variables with distance from the city centre depended on the sampling design, with this distance-by-sampling design interaction present in 27%-51% of cities, depending on the environmental variable. This implies that the rate of environmental change along urban-nonurban gradients frequently depends on the sampling design used. We also examined potential causes of deviations between transect- and point-based sampling designs and identified human population density and city area as common predictors of deviations between transect- and point-sampling designs. Our results show that sampling design can dictate how the urban environment is characterized, with sampling design as important - or more important - as the selected environmental variable. We further developed R code so researchers can implement these methods as they develop and validate sampling designs in novel or unstudied urban environments.

ecology↗

bioRxiv2022

Plumage colouration differs between offspring raised in natural cavities and nestboxes

Most of our knowledge on hole-nesting birds, including plumage colouration (an important component of visual signalling), comes from studies on populations breeding in human-provided nestboxes. However, as demonstrated in comparative studies, multiple parameters, such as cavity dimensions and microclimatic conditions, differ between natural and artificial cavities. Despite this, no study so far examined the impact of cavity type on plumage colouration to verify whether extrapolation of results from birds growing in nestboxes is justified. Here, we examined the impact of cavity type - natural cavities vs. nestboxes - on the carotenoid-based colouration of blue tit (Cyanistes caeruleus) and great tit (Parus major) nestlings. We found clear differences in plumage colouration depending on the type of cavity in which the birds developed. Our study adds to the growing body of evidence confirming that varying properties of natural cavities and nestboxes might influence nestling physiology, leading to phenotypic differences in the long-term.

ecology↗

bioRxiv2021

Alterations to the Gut Microbiota of a Wild Juvenile Passerine in an Urban Mosaic

Urbanisation is a major anthropogenic perturbation that progressively alters multiple environmental parameters, thereby presenting novel evolutionary challenges to wild populations. Symbiotic microorganisms residing in the gastrointestinal tracts (gut) of vertebrates have well-established mutual connections with the physiology of their hosts and respond quickly to environmental alterations. However, the impacts of anthropogenic changes and urbanisation on gut microbiota remain poorly understood, especially in early development. To address this knowledge gap, we investigated the gut microbiota in juvenile great tits (Parus major) in an urban mosaic. First, we compared the microbiota of nestlings reared in artificial nest boxes or natural cavities. Next, we analysed microbiota variations employing two distinct urbanisation frameworks, (i) the classical urban/rural dichotomy and (ii) gradual changes in the amount of impervious surface area (ISA) in the urban space and identified the environmental variables that predicted the changes in the microbial communities. Alpha diversity was influenced by cavity type and by the amount of impervious surface surrounding the breeding location. Alpha diversity was also positively correlated with the tree cover density. Beta diversity differed between urban and rural sites, and these alterations covaried with sound pollution, the distance to the city centre and the distance to the closest road. Overall, the microbial communities reflect and are possibly influenced by the heterogeneous environmental modifications that are typical of the urban space. Strikingly, the choice of framework used to define the urban space can influence the outcomes of studies investigating animal-microbe symbiosis. Our results open new perspectives from which the potential function of microbial symbionts in the adaptation of their hosts to anthropogenic stress can be investigated.

ecology↗

bioRxiv2021

Testing for parallel genomic and epigenomic footprints of adaptation to urban life in a passerine bird

Identifying the molecular mechanisms involved in rapid adaptation to novel environments and determining their predictability are central questions in Evolutionary Biology and pressing issues due to rapid global changes. Complementary to genetic responses to selection, faster epigenetic variations such as modifications of DNA methylation may play a substantial role in rapid adaptation. In the context of rampant urbanization, joint examinations of genomic and epigenomic mechanisms are still lacking. Here, we investigated genomic (SNP) and epigenomic (CpG methylation) responses to urban life in a passerine bird, the Great tit (Parus major). To test whether urban evolution is predictable (i.e parallel) or involves mostly non-parallel molecular processes among cities, we analysed three distinct pairs of city and forest Great tit populations across Europe. Results reveal a polygenic response to urban life, with both many genes putatively under weak divergent selection and multiple differentially methylated regions (DMRs) between forest and city great tits. DMRs mainly overlapped transcription start sites and promotor regions, suggesting their importance in the modulation gene expression. Both genomic and epigenomic outliers were found in genomic regions enriched for genes with biological functions related to nervous system, immunity, behaviour, hormonal and stress responses. Interestingly, comparisons across the three pairs of city-forest populations suggested little parallelism in both genetic and epigenetic responses. Our results confirm, at both the genetic and epigenetic levels, hypotheses of polygenic and largely non-parallel mechanisms of rapid adaptation in new environments such as urbanized areas.

genomics↗