# Tamás Székely (biologist)

Tamás Székely (born 24 May 1959) is a Hungarian evolutionary biologist and conservationist. He is the Professor of Biodiversity at the University of Bath and he holds an Honorary Professor position at the University of Debrecen, Hungary. He is also the Director of the Debrecen Biodiversity Centre. His 1999 article, Brood Desertion in Kentish Plover, laid the groundwork for the demographic hypothesis of sex roles' origin, demonstrating the social environment's influence on parental care dynamics. Székely has won multiple academic and conservation awards.
Székely is renowned for his theoretical and empirical contributions to the demographic hypothesis regarding the origin of sex roles. In 2007, Székely co-edited Sex, Size & Gender Roles, confirming Darwin's conjectures that sexual selection is a major contributor to the overall pattern of male-biased size dimorphism in mammals, birds, and reptiles. Alongside others, he identified that the distribution of size differences between sexes in birds and mammals is leptokurtic. Székely co-edited Social Behaviour in 2010, offering an integrative perspective on studying behavioral complexity. Alongside Allen J. Moore and Jan Komdeur, he coined the term systems biology approach. Additionally, he founded the Maio Biodiversity Foundation in Cabo Verde in 2010.

## Education

Tamás Székely commenced his studies at Kossuth Lajos University (now the University of Debrecen) in 1978, earning a diploma in teaching biology and chemistry. Between 1983 and 1986, he pursued his Ph.D. at the same institution, focusing on the temporal patterns of niche structure in forest passerine birds. His research during this time was significantly influenced by Professor Zoltán Varga’s integrative approach, emphasizing the role of phylogeny in ecological patterns.
In the late 1980s, Székely began studying shorebirds in Hungary’s Dél-Alföld region, particularly investigating the behavioral diversity of plovers and sandpipers. During this period, he regularly contributed to the Hungarian science magazine Élet és Tudomány, where he summarized international research for a broader Hungarian audience. In addition to his academic commitments, he worked at the Hungarian Ornithological Society in Budapest, frequently commuting between Budapest and Debrecen while developing his research and teaching at Kossuth Lajos University.
Following his doctoral studies, he undertook a postdoctoral research fellowship at the Edward Grey Institute of Field Ornithology at the University of Oxford from 1987 to 1988, where he explored reproductive strategies in birds within the emerging field of behavioral ecology.

## Research on Evolutionary Biology

Tamás Székely is recognized for his contributions to evolutionary biology, particularly in understanding sex roles, mating systems, and parental care strategies in birds. His research integrates fieldwork, mathematical modeling, and phylogenetic analyses to explore the ecological and evolutionary mechanisms driving behavioral diversity in vertebrates.

### The Demographic Hypothesis of Sex Role Evolution

Székely has played a key role in developing the demographic hypothesis of sex role evolution, which proposes that adult sex ratios (ASR) influence mating behaviors and parental care strategies. A 2022 study led by an international team, including Székely, demonstrated that ASR is the primary factor shaping sex roles in birds, while climate and life-history traits had no significant impact. This study, which analyzed data from 1,800 species, provided robust statistical support for the demographic hypothesis. Additionally, his research has shown that in plover populations with skewed sex ratios, one parent (typically the father) is more likely to take on sole parenting responsibilities, influencing behaviors such as divorce, infidelity, and parental roles.

### Sex Ratio Variation and Mating Systems

Székely and colleagues have extensively studied the role of sex ratio variation in shorebird mating systems. Their research confirmed that species with female-biased populations exhibit higher divorce rates, while promiscuity increases in male-dominated populations. Further investigations into monogamous and polygamous shorebirds revealed that polyandrous species exhibit faster Z chromosome evolution compared to monogamous species, suggesting that sexual selection accelerates genetic changes in these birds.

### Evolution of Parental Care and Reproductive Strategies

A major focus of Székely’s research has been on the trade-offs between parental investment and reproductive success. His studies on shorebirds have demonstrated that females assess environmental conditions and chick survival probabilities before deciding whether to continue care or desert their broods to seek new mating opportunities. His findings indicate that when one parent reduces its caregiving effort, the other compensates partially but not fully, ensuring offspring survival while preventing complete exploitation by one partner.
Additionally, his work has highlighted the impact of extreme environmental conditions on parental coordination. A 2011 study on Kentish plovers (Charadrius alexandrinus) found that in response to high temperatures, parents increased their turn-taking frequency during incubation to prevent egg overheating, showcasing how behavioral plasticity can mitigate environmental stress.

### Mating Systems and Speciation

Székely’s research has challenged the traditional view that promiscuity accelerates speciation. A study found that monogamous shorebirds tend to have more subspecies than their promiscuous counterparts, suggesting that higher mate dispersal reduces genetic divergence between populations. Further supporting this, research on polygamous plover species indicated lower genetic differentiation compared to monogamous species, highlighting the role of mating systems in shaping evolutionary trajectories.

### Brain Evolution and Cognitive Adaptation in Birds

Beyond sex roles, Székely has contributed to the study of avian brain evolution. In 2024, he co-authored a study mapping the evolutionary trajectory of bird intelligence, tracing brain size changes from the age of dinosaurs to the present. The findings suggest that while bird body sizes have generally decreased, their relative brain sizes have increased, potentially driving advanced social behaviors, vocalizations, and tool use.
His research has also explored the link between brain size and environmental adaptability. A 2016 study found that birds living in highly seasonal and unpredictable climates tend to have relatively larger brains, supporting the hypothesis that cognitive abilities play a role in adapting to extreme environment.

### Comparative Studies on Evolutionary Mechanisms

Székely has been instrumental in integrating advanced statistical methods into evolutionary biology research. His studies on weaver birds applied modern phylogenetic analyses to test hypotheses on social organization, confirming that diet and habitat strongly influence mating systems in these birds. He has also examined the functions of egg burial across species, showing that while Eurasian penduline tits bury eggs due to sexual conflict, their Chinese counterparts do so to prevent egg loss from strong winds.

### Evolution of Social Behavior in Birds

Székely and his research team have described the interactions between mate selection, parental care, and pair-bonding in non-human animals. A study published in IBIS confirmed that adult sex ratios strongly influence the evolution of monogamy and polygamy in shorebirds, reinforcing the demographic hypothesis of sex role evolution. Additionally, his research demonstrated that Kentish plover males exhibit stronger immune system activity than females, a factor that may contribute to their longer lifespan and influence mating strategies.

### Evolutionary Insights from Amphibians and Mammals

Expanding beyond birds, Székely has studied reproductive strategies in amphibians and mammals. His research on amphibians showed that species with larger eggs exhibit prolonged parental care, and male-biased size dimorphism correlates with increased paternal investment. In mammals, his studies have examined lifespan differences between sexes, challenging the assumption that male-male competition is the sole driver of shorter male lifespans, and instead highlighting the role of social structures and parental care.

## Conservation

Tamás Székely has made significant contributions to conservation biology, particularly in the study and protection of shorebirds, waterbirds, and marine fauna. His research extends beyond avian species, encompassing broader ecological concerns such as climate change, habitat loss, and biodiversity monitoring.

### Shorebird Conservation and Climate Change Impact

Székely and his research team have been instrumental in identifying both intrinsic and extrinsic factors contributing to shorebird population declines. A large-scale study conducted in collaboration with Wetlands International demonstrated that political governance plays a crucial role in shaping waterbird populations, often more so than economic factors like GDP. The research, which analyzed 2.4 million records from global bird censuses, found that countries with strong environmental policies had better conservation outcomes compared to those with weaker governance structures. Additionally, his research linked climate change to declining waterbird populations, revealing that rising temperatures are driving a poleward shift in species abundance, with birds at higher latitudes facing increased food scarcity and predation risks.

### Biodiversity Monitoring and Conservation Policy

Székely has played a key role in implementing biodiversity monitoring systems in Hungary. He founded and was the first director of the Debrecen Biodiversity Centre that integrates scientific data into local and national conservation policies, particularly in response to climate change and urbanization.

### Great Bustard Conservation

Beyond shorebirds, Székely has contributed to conservation efforts for the Great Bustard (Otis tarda). He was actively involved in the UK’s Great Bustard Reintroduction Project, where his research at the University of Bath helped refine conservation strategies related to optimal release timings, habitat selection, and post-release survival monitoring. His team also conducted fecal analysis studies on the feeding ecology of Great Bustards in the UK to inform habitat management strategies.

### Maio Biodiversity Foundation and Marine Conservation

In 2010, Székely founded the Maio Biodiversity Foundation (Fundação Maio Biodiversidade, FMB) in Cabo Verde, an NGO dedicated to wildlife conservation and sustainable development. The foundation actively engages local communities in conservation efforts, particularly for marine species such as sharks, whales, and sea turtles. Under Székely’s guidance, FMB successfully implemented a community-based sea turtle protection strategy in 2013. Before the initiative, Maio had the highest recorded mortality of nesting female loggerhead turtles (Caretta caretta) in Cape Verde, with 152 individuals killed in 2012. Following FMB’s intervention, the number dropped to 38 in 2013, with poached nests on protected beaches decreasing to just 2%. The organization also facilitated a twentyfold increase in loggerhead turtle nests between 2013 and 2018, reducing female mortality from 43% to 5%. The conservation initiatives by FMB played a pivotal role in the designation of Salina Porto Ingles, one of Cape Verde's key shorebird breeding sites, as a Ramsar Site.

### Antibiotic Resistance in Birds and Environmental Education

Székely's research has also addressed human-induced ecological impacts on birds. A study published in Current Biology highlighted the increasing prevalence of antibiotic-resistant bacteria in wild bird populations near urban environments. The study found that birds living close to human settlements are significantly more likely to carry Campylobacter jejuni, a pathogen that poses health risks to humans. His work also explored the effectiveness of environmental education programs, revealing that while such programs increased students’ knowledge of conservation issues, they did not necessarily lead to changes in environmental attitudes, emphasizing the need for improved educational strategies.

### Global Waterbird Conservation Efforts

Székely has contributed significantly to international waterbird conservation initiatives. Collaborating with Laura Williamson and other researchers, he analyzed data from 471 bird species, identifying critical global regions for targeted conservation efforts. The study emphasized the urgent need for habitat protection in East Africa, coastal China, and parts of South America.

### Research in Madagascar

Székely’s conservation work extends to Madagascar, where he has contributed to biodiversity and environmental management efforts. In collaboration with Dr. Peter Long, he helped establish a specialized research lab at the University of Toliara, aimed at training local students in satellite image analysis for conservation planning and resource management.

## Awards and recognition
### Awards

Tamás Székely has received multiple honors in recognition of his contributions to evolutionary biology, behavioral ecology, and conservation.
In 2017, he was awarded the Royal Society Wolfson Research Merit Award for his research on the evolution of sex roles in birds. That same year, he was named Honorary Professor of Debrecen University in Hungary. In 2019, he was elected a Foreign Member of the Hungarian Academy of Sciences, acknowledging his contributions to Hungarian science internationally. That year, he also received the Honorary Plaquette of Kazincbarcika City, a distinction awarded to individuals contributing to Hungarian academia and society.
In 2019, Székely was awarded an APEX Award by the Royal Society, the British Academy, and the Royal Academy of Engineering, with funding from the Leverhulme Trust, to study the impact of adult sex ratio (ASR) on social behavior in human societies. This project was conducted in collaboration with anthropologist Ruth Mace at University College London (UCL).
Székely was the principal investigator of Hungary’s Élvonal-funded international research project on shorebird social behavior, which was the only initiative based in Debrecen to receive this prestigious research support.
In 2020, the Hungarian Order of Merit (Magyar Érdemrend Tisztikeresztje) was conferred upon him, one of Hungary’s highest civilian honors.
In recognition of its conservation impact, the Maio Biodiversity Foundation (FMB), which Székely founded, was awarded the Medal of Merit by the President of Cape Verde in 2023 for its efforts in marine and terrestrial biodiversity conservation.

### Achievements

Throughout his career, Prof Székely's research has not only been recognised through awards, but his contributions to the field has improved our knowledge and understanding of the field of social behaviour. In 2010, Prof Szekely founded the FMB (Maio Biodiversity Foundation) conservation NGO in Cape Verde and lead the NGO as its president for 8 years. Prof Székely developed both a field methodology and research protocol for investigating shorebird social behaviour, which is now widely used around the globe [Szekely & Kosztolanyi 2006,. Through the use of this protocol, he analysed mathematically, experimentally and phylogenetically reproductive strategies. More recently, this has progressed into having developed a general framework for understanding the causes and consequences of adult sex ratio variation for social evolution. In addition, he identified sexual selection as a major driver of the Rensch's rule.

### Media

In 2020, Prof Szekely was recognised for his work on social behaviour by being interviewed for the "Staff Spotlight" (https://www.bath.ac.uk/announcements/staff-spotlight-on-tamas-szekely/ ). In addition, Prof Szekely's research has been in numerous news articles, such as the BBC "Sex role reversal: Female shorebirds rule the roost" (https://www.bbc.co.uk/news/science-environment-21741912 ), Audubon "The Arctic is no longer a safe haven for breeding shorebirds" (an American magazine (https://www.audubon.org/news/the-arctic-no-longer-safe-haven-breeding-shorebirds), Science News "Climate change may have made the Arctic deadlier for baby shorebirds" (https://www.sciencenews.org/article/climate-change-may-have-made-arctic-deadlier-baby-shorebirds), Science Daily "Decline in shorebirds linked to climate change, experts warn" (https://www.sciencedaily.com/releases/2018/11/181108142405.htm) and EukekAlert! "Decline in shorebirds linked to climate change, experts warn" (https://www.eurekalert.org/news-releases/600065).

## Selected publications
### Books

* Basic research planning, statistical and project evaluation methods in supra-individual biology (1995), co-editor.
* Sex, size and gender roles (2007), co-editor.
* Social behaviour: genes, ecology and evolution (2010), co-editor.

### Journal articles

* Genetic similarity between mates explains extra-pair parentage in three species of waders (2002), in Nature, co-author.
* Sexual selection explains Rensch's rule of size dimorphism in shorebirds (2004), in PNAS, co-author.
* Conflict over parental care (2005), in Trends in Ecology and Evolution, co-author.
* The evolution of sex roles in birds is related to adult sex ratio (2013), in Nature Communications, co-author.
* Adult sex ratio variation: implications for breeding system evolution (2014), in Journal of Evolutionary Biology, co-author.
* The evolution of parental cooperation in birds (2015), in PNAS, co-author.
* The genetic sex-determination system predicts adult sex ratios in tetrapods (2015), in Nature, co-author.
* Global pattern of nest predation is disrupted by climate change in shorebirds (2018), in Science, co-author.