Tamás Székely

University of Bath | UB · Department of Life Sciences

Background: Evolutionary divergence and genetic variation are often linked to differences in microbial community structure and diversity. While environmental factors and diet heavily influence gut microbial communities, host species contributions are harder to quantify. Closely related species living in sympatry provide a unique opportunity to inve...

Sex chromosomes determine male and female phenotypes, and the resulting sex differences can have significant impacts on ecology and life history. One manifestation of this link is that ZZ/ZW sex-determination systems are associated with more male-skewed adult sex ratio (ASR, proportion of males in the adult population) than XY/XX systems across tet...

Size differences between males and females are common across the tree of life (termed sexual size dimorphism; SSD), and have fundamental implications for ecology, life history and behaviour of both sexes. Conventionally, SSD is thought to evolve in response to sex‐specific sexual selection but more recent work suggests that ecological processes can...

A combination of life history traits and environmental conditions has been highlighted as the main drivers of avian breeding success. While drivers of breeding success are well known in some species, especially birds in northern, temperate regions; species in other parts of the world have received relatively little attention. In this study, we used...

Humans are radically altering global ecology, and one of the most apparent human-induced effects is urbanization, where high-density human habitats disrupt long-established ecotones. Changes to these transitional areas between organisms, especially enhanced contact among humans and wild animals, provide new opportunities for the spread of zoonotic...

Males and females often differ in ecology, behaviour and lifestyle, and these differences are expected to lead to sex differences in parasite susceptibility. However, neither the sex differences in parasite prevalence, nor their ecological and evolutionary drivers have been investigated across a broad range of taxa using phylogenetically corrected...

Biparental care can be favoured when offspring care by both parents provides a stronger fitness incentive to parents than deserting their offspring. In species with precocial offspring, the burden of care is ex- pected to be comparatively low, facilitating desertion by one parent and uniparental care by the aban- doned partner. However, care patter...

In mammals, sexual size dimorphism often reflects the intensity of sexual selection, yet its connection to genomic evolution remains unexplored. Gene family size evolution can reflect shifts in the relative importance of different molecular functions. Here, we investigate the associate between brain development gene repertoire to sexual size dimorp...

Gut microbiotas have important impacts on host health, reproductive success, and survival. While extensive research in mammals has identified the exogenous (e.g. environment) and endogenous (e.g. phylogeny, sex and age) factors that shape the gut microbiota composition and functionality, yet avian systems remain comparatively less understood. Shore...

Gut microbiotas have important impacts on host health, reproductive success, and survival. While extensive research in mammals has identified the exogenous (e.g. environment) and endogenous (e.g. phylogeny, sex, and age) factors that shape the gut microbiota composition and functionality, yet avian systems remain comparatively less understood. Shor...

Males and females generally differ in resource investment strategies to maximise reproductive output, sometimes at the expense of important systemic processes such as self-maintenance and immune activity. Here, we used wild Lethrus apterus, a sexually dimorphic beetle with parental care, to investigate the influence of sex roles (e.g., offspring pr...

Among vertebrates, ray-finned fishes (Actinopterygii) display the highest diversity in parental care, and their diversification has been hypothesized to be related to phylogenetic changes in fertilization modes. Using the most comprehensive, sex-specific data from 7600 species of 62 extant orders of ray-finned fishes, we inferred ancestral states a...

In birds, males are homogametic and carry two copies of the Z chromosome (‘ZZ’), while females are heterogametic and exhibit a ‘ZW’ genotype. The Z chromosome evolves at a faster rate than similarly sized autosomes, a phenomenon termed ‘fast-Z evolution’. This is thought to be caused by two independent processes—greater Z chromosome genetic drift o...

Supporting Informating for: Gilles, M., Kosztolányi, A., Rocha, A. D., Cuthill, I. C., Székely, T., & Caspers, B. A. (2024). No sex difference in preen oil chemical composition during incubation in Kentish plovers. PeerJ, 12, e17243.

Data and code from: Gilles, M., Kosztolányi, A., Rocha, A. D., Cuthill, I. C., Székely, T., & Caspers, B. A. (2024). No sex difference in preen oil chemical composition during incubation in Kentish plovers. PeerJ, 12, e17243.

Males and females often have different roles in reproduction, although the origin of these differences has remained controversial. Explaining the enigmatic reversed sex roles where males sacrifice their mating potential and provide full parental care is a particularly long-standing challenge in evolutionary biology. While most studies focused on ec...

Preen oil, the secretion from the uropygial gland of birds, may have a specific function in incubation. Consistent with this, during incubation, the chemical composition of preen oil is more likely to differ between sexes in species where only one sex incubates than in species where both sexes incubate. In this study, we tested the generality of th...

Despite tremendous efforts in the past decades, relationships among main avian lineages remain heavily debated without a clear resolution. Discrepancies have been attributed to diversity of species sampled, phylogenetic method and the choice of genomic regions1–3. Here we address these issues by analysing the genomes of 363 bird species⁴ (218 taxon...

Migrating animals are thought to be important spillover sources for novel pathogens. Haemosporidians (malaria-related parasites) are one such group of pathogens that commonly spillover into novel host communities if competent vectors are present. In birds, shorebirds (sandpipers, plovers and allies) perform some of the longest avian migrations, yet...

Social behaviour is thought to be a major component of survival, reproduction, and resilience of populations. Thus, it is a key component in management and conservation of wild populations. In polygynous breeding species, group size influences the reproductive success of males and females, and hence it is essential to understand the environmental a...

Divergent selection in the face of gene flow is usually associated with a heterogeneous genomic landscape of divergence in nascent species pairs. However, multiple factors, such as divergent selection and local recombination rate variation, can influence the formation of these genomic island. This conundrum can be solved through examination of the...

Global biodiversity loss is a major environmental concern. The wildlife on islands are particularly vulnerable to threats posed by alien predators, habitat loss and overexploitation. Effective conservation management of vulnerable species requires reliable information on vital population rates for all life stages and an understanding of key environ...

Agricultural intensification has affected wildlife across Europe, triggering steep declines and regional extinctions of farmland birds. Effective conservation activities are essential for the preservation of biodiversity in an agricultural landscape, but current efforts have not succeeded in halting these declines. Here we investigate a ground-nest...

Understanding the main ecological factors of the nesting habitat of shorebirds is of great significance in relation to their protection and habitat management. Habitat loss and change due to a lack of water threaten the biodiversity of shorebirds, with impacts likely to be most pronounced in arid lands. We collected the data of 144 nesting sites an...

The ecological and life history drivers of the diversification of reproductive modes in early vertebrates are not fully understood. Sharks, rays and chimaeras (group Chondrichthyes) have an unusually diverse variety of reproductive modes and are thus an ideal group to test the factors driving the evolution of reproductive complexity. Here, using 96...

Males and females often exhibit different behaviours during mate acquisition, pair-bonding and parenting, and a convenient label to characterize these behaviours is sex role. The diverse roles that male and female shorebirds (plovers, sandpipers and allies) exhibit in mating and parenting have played a key role in advancing mainstream theories in a...

Behavioural variations associated with breeding—termed reproductive strategies—are some of the striking behaviours that have occupied naturalists for 1000s of years. How an animal seeks, competes for and/or chooses a mate? Do they breed with a single partner, or do they change partners between breeding events? How and when do they look after their...

To execute environmental education effectively, the success and impacts of educational activities must be assessed. In areas of high biodiversity there is generally a lack of evaluation of the impact of environmental education. In this study we investigate the effect of a one-time classroom activity on student knowledge of local environmental issue...

Human behaviour is dramatically changing global ecology. Nowhere is this more apparent than in urbanization, where novel high human density habitats are disrupting long established ecotones. Resultant changes to the transitional areas between organisms, especially enhanced contact between humans and wild animals, provides new opportunities for the...

Simple Summary: In response to the harsh natural environment in the arid lands of Xinjiang, China, Kentish plover Charadrius alexandrinus populations in different regions show flexibility in their breeding strategies to cope with the changeable environment. Of our three study areas, one (Taitema Lake) is distinctly characterized by barren terrains...

Due to the influence of bio-geographical and environmental factors, as well as anthropogenic landscape features, organisms show different reproductive strategies among different populations. There is a lack of detailed information on the reproductive biology of Kentish plover Charadrius alexandrinus in arid lands in Central Asia. In this study, we...

Due to the influence of bio-geographical and environmental factors, as well as anthropogenic landscape features, organism shows different reproductive strategies among different populations. There is lack of detailed information on the reproductive biology of Kentish plover Charadrius al-exandrinus in arid lands in Central Asia. In this study, we s...

The immense diversity of plumage coloration exhibited by birds is the result of either pigments deposited in the feathers or microstructural arrangements of feather barbules. Some of the most common pigments are carotenoids, which produce bright yellow, orange, and red colors. Carotenoids differ from other pigments since birds cannot synthesize the...

The adult sex ratio (ASR, the proportion of males in the adult population) is an emerging predictor of reproductive behaviour, and recent studies in birds and humans suggest it is a major driver of social mating systems and parental care. ASR may also influence genetic mating systems. For instance male-skewed ASRs are expected to increase the frequ...

In biparental Charadriinae plovers, male and female incubation duties often resemble daily routines, with males typically incubating at night and females incubating during the day. By analysing incubation behaviour in three Arctic populations of Common Ringed Plover Charadrius hiaticula, we show that these diel routines are lost in the 24-h sunligh...

Arctic environments are changing rapidly and if we are to understand the resilience of species to future changes, we need to investigate alterations in their life histories. Egg size and egg shape are key life-history traits, reflecting parental investment as well as influencing future reproductive success. Here we focus on egg characteristics in t...

Tropical islands harbour a disproportionally high number of endemic species, which face increasing threats due to habitat loss, disturbance and introduced alien predators. Long-term demographic studies are needed to understand how such threats may impact on population productivity. We report an investigation of a key demographic parameter, nest sur...

The Kentish Plover Charadrius alexandrinus Linnaeus 1758 is a common shorebird in Eurasia and North Africa that breeds in a variety of habitats, exhibits different extents of migratory behaviour, and is an emerging model species of breeding system evolution. Here we focus on the resident population found across the southern tip of India and Sri Lan...

For species without parental care, such as sea turtles, nest site selection is particularly important for embryo development, hatchling survival and, ultimately, reproductive success. We conducted an 8-year (2012–2019) capture–mark–recapture study of the re-nesting behaviour of loggerhead turtles Caretta caretta to identify both inter- and intra-be...

Polygamy and purifying selection in birds - supplementary material

Parental care can enhance offspring survival but may impose significant costs to parents. The costs and benefits of care are key to understanding patterns of parental care, where parents can benefit by having their partner increase investment in care, while reducing their own effort. However, investigating the costs and benefits of parental care in...

Good genes theories of sexual selection predict that polygamy will be associated with more efficient removal of deleterious alleles (purifying selection), due to the alignment of sexual selection with natural selection. On the other hand, runaway selection theories expect no such alignment of natural and sexual selection, and may instead predict le...

The immense diversity of plumage coloration exhibited by birds is the result of either pigments deposited in the feathers or microstructural arrangements of feather barbules. Some of the most common pigments are carotenoids that produce bright yellow, orange and red colors. Carotenoids differ from other pigments since birds cannot synthesize them d...

Parental care is one of the most diverse social behaviours, and caring by the male, female or both parents is essential for successful reproduction of many organisms. Theoretical and empirical studies suggest that parental sex roles are associated with biased sex ratios. However, there is considerable debate on the causal relationship between paren...

Converging lines of inquiry from across the social and biological sciences target the adult sex ratio (ASR; the proportion of males in the adult population) as a fundamental population-level determinant of behavior. The ASR, which indicates the relative number of potential mates to competitors in a population, frames the selective arena for competi...

Agricultural intensification has affected wildlife across Europe, usually prompting steep declines and regional extinctions in farmland birds. Effective conservation activities are essential for preservation of biodiversity in agricultural landscape, but despite the efforts, the halting (or reversing) the decline of farmland species are still rare....

Complex parenting has been proposed to contribute to the evolutionary success of vertebrates. However, the evolutionary routes to complex parenting and the role of parenting in vertebrate diversity are still contentious. Although basal vertebrates provide clues to complex reproduction, these are often understudied. Using 181 species that represent...

Crook published a landmark study on the social organization of weavers (or weaverbirds, family Ploceidae) that contributed to the emergence of sociobiology, behavioral ecology, and phylogenetic comparative methods. By comparing ecology, spatial distribution, and mating systems, Crook suggested that the spatial distribution of food resources and bre...

Egg burial behaviour, that is, when parents bury the eggs with a layer of nest material during the egg-laying stage, has been described in various egg-laying animals. Several functions of egg burial have been described in animals with different life histories and breeding traits, but rarely reveal distinctive functions between sister species. In th...

In animals, species differ remarkably in parental care strategies. For instance, male-only care is prevalent in teleost fishes, while biparental care predominates in birds and female-only care is widespread in mammals. Understanding the origin and maintenance of diversified parental care systems is a key challenge in evolutionary ecology. It has be...

It has long been suggested that tropical species are generally more colourful than temperate species, but whether latitudinal gradients in organismal colourfulness exist remains controversial. Here we quantify global latitudinal trends in colourfulness (within-individual colour diversity) by collating and analysing a photographic dataset of whole-b...

Worldwide populations of shorebirds are declining, associated with a complex interplay of climate change, predation, human disturbance and habitat degradation. Comprehensive information on the distribution and breeding ecology of shorebird populations is crucial to understand and mitigate these threats. Kazakhstan, the largest country in Central As...

Data on ecology, life histories, behaviour and body sizes of birds are summarised. We aimed for extracting data separately for males and females, whenever possible. If several data points were available for a given species, we included the ones that were extracted from breeding individuals, or had larger sample sizes. We hope this datafile - the re...

Sex roles describe sex differences in courtship, mate competition, social pair‐bonds and parental care. A key challenge is to identify associations among the components and the drivers of sex roles. Here, we investigate sex roles using data from over 1800 bird species. We found extensive variation and lability in proxies of sex roles, indicating re...

(1) Background: The objective of this study was to uncover genomic causes of parental care. Since birds do not lactate and, therefore, do not show the gene expressional changes required for lactation, we investigate gene expression associated with parenting in caring and non-caring females in an avian species, the small passerine bird zebra finch (...

Females and males often exhibit different survival in nature, and it has been hypothesized that sex chromosomes may play a role in driving differential survival rates. For instance, the Y chromosome in mammals and the W chromosome in birds are often degenerated, with reduced numbers of genes, and loss of the Y chromosome in old men is associated wi...

Crook published a landmark study on the social organization of weavers (or weaverbirds, family Ploceidae) that contributed to the emergence of sociobiology, behavioral ecology, and phylogenetic comparative methods. By comparing ecology, spatial distribution, and mating systems, Crook suggested that the spatial distribution of food resources and bre...

Smell is a sensory modality that is rarely considered in birds, but evidence is mounting that olfaction is an important aspect of avian behaviour and ecology. The uropygial gland produces an odoriferous secretion (preen oil) that can differ seasonally and between the sexes. These differences are hypothesized to function in olfactory camouflage, i.e...

Data and code for the systematic review and the comparative analyses from: Grieves, L. A., Gilles, M., Cuthill, I. C., Szekely, T., MacDougall-Shackleton, E. A., & Caspers, B. (2022). Olfactory camouflage and communication in birds. Biological Reviews.

Every year, many wild animals undertake long-distance migration to breed in the north, taking advantage of seasonally high pulses in food supply, fewer parasites, and lower predation pressure in comparison with equatorial latitudes. Growing evidence suggests that climate-change-induced phenological mismatches have reduced food availability. Further...

Males and females often exhibit differences in behaviour, life histories and ecology, many of which typically are reflecting in their brains. Neuronal protection and maintenance include complex processes led by the microglia, which also interacts with metabolites such as hormones or immune components. Despite increasing interest in sex-specific bra...