News


01.09.2019 – EUROPEAN ORNITHOLOGICAL CONGRESS

The 12th European Ornithologists’ Union Congress organised by our team just ended in Cluj-Napoca. We are delighted to say that the congress was a huge success, attracting over 400 participants from 37 countries, with every continent of the world being represented. We heard 158 scientific presentations and enjoyed 172 scientific posters exhibited at the congress.

Members of the PCE grant played key roles in organising the event, Péter L. Pap (main organiser), Csongor I. Vágási (organiser), Orsolya Vincze (organiser), Janka Pénzes (volunteer).

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10.07.2019 – FIELD SEASON 2019

The second field season within the framework of this major research project, financed by the Romanian Ministry of Education just ended. We had a very fruitful field season, catching XX individuals of YY species. We conducted fielwork at various sites across the country, from southern-Romania to the Fagaras Mountain.​_

 

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31.06.2019 – Workshop

Our team member, Orsolya Vincze participated at the Species360 workshop, in Kerteminde, Denmark between 26-29 June. The workshop was intended to discuss research opportunities provided by the Species360 database, especially focusing on sex-specific differences in demography across birds and mammals.

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10.06.2019 – New publication!

Within the framework of this review article we discuss the complex interactions between actuarial senescence and cancer.

Eco‐evolutionary perspectives of the dynamic relationships linking senescence and cancer

Authors marked in boldface are PCE members. Authors with asterisk are undergrad students.

Jean‐François Lemaître, Samuel Pavard, Mathieu Giraudeau, Orsolya Vincze, Geordie Jennings, Rodrigo Hamede, Beata Ujvari, Frédéric Thomas

Abstract
1. Evidence for actuarial senescence (i.e. the decrease in survival with increasing age) is now widespread across the tree of life. However, demographic senescence patterns are highly variable both between and within species. To understand these variations, there is an urgent need to go beyond aggregated mortality rates and to investigate how age‐specific causes of mortality in animals interact with age‐ specific physiological performance. We address this question in the context of cancers.
2. Cancer is a leading cause of death in human populations and has recently been shown to be more prevalent across species than previously thought. Since anthropogenic perturbations drastically increase cancer rates in wild populations of animals, deciphering the complex interactions between senescence and cancer now constitutes a key challenge in evolutionary ecology.
3. Based on classical evolutionary theories of ageing, we first demonstrate that the occurrence of cancers might constitute an underestimated piece of the life‐history jigsaw. We propose that the selection for an increased allocation of resources towards growth and reproduction during early life might potentially favour cancer development, a life‐history pathway that might be functionally mediated by the process of immunosenescence. While we discuss the relevance of other proximate mechanisms suggesting that cancer arises as a direct consequence of senescence, we also argue that cancer itself can promote senescence by notably increasing the amount of resources required for somatic maintenance.
4. Contrary to theoretical predictions, recent empirical evidence suggests that senescence is an asynchronous process among physiological functions. At the same time, the timing of occurrence varies widely between the different types of cancers. We suggest that similar evolutionary forces might shape the synchronicity of senescence and cancer patterns, which emphasize the tight and complex relationships linking these processes.
5. We propose a conceptual background to lay down the foundations and the directions of future research projects aiming to disentangle the dynamic relationship between the evolution of cancer and senescence. We argue that studies embracing these research directions will markedly improve our understanding of both cancer prevalence and timing at the individual, population and species level.

KEYWORDS: ageing, carcinogenesis, immunosenescence, life history, oncobiota, trade‐off, tumour

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06.06.2019 – New publication!

Ageing is the result of the gradual accumulation of a wide range of molecular and cellular damages, resulting  in decreased physical and mental capacity, a growing risk of disease, and ultimately, death. Cancer is key hallmark of the aging phenotype and is known to be strongly linked to physiological mechanisms that appear to be associated with life-history evolution. In a recent article, we discuss how the cancer might have contributed to major evolutionary adaptations, such as the evolution of sexual reproduction.

Transmissible cancer and the evolution of sex 

Authors marked in boldface are PCE members. Authors with asterisk are undergrad students.

Frédéric Thomas, Thomas Madsen, Mathieu Giraudeau , Dorothée Misse , Rodrigo Hamede, Orsolya Vincze, Francois Renaud, Benjamin Roche, Beata Ujvari

Abstract
The origin and subsequent maintenance of sex and recombination are among the most elusive and controversial problems in evolutionary biology. Here, we propose a novel hypothesis, suggesting that sexual reproduction not only evolved to reduce the negative effects of the accumulation of deleterious mutations and processes associated with pathogen and/or parasite resistance but also to prevent invasion by transmissible selfish neoplastic cheater cells, henceforth referred to as transmissible cancer cells. Sexual reproduction permits systematic change of the multicellular organism’s genotype and hence an enhanced detection of transmissible cancer cells by immune system. Given the omnipresence of oncogenic processes in multicellular organisms, together with the fact that transmissible cancer cells can have dramatic effects on their host fitness, our scenario suggests that the benefits of sex and concomitant recombination will be large and permanent, explaining why sexual reproduction is, despite its costs, the dominant mode of reproduction among eukaryotes.

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15.12.2018 – Mobility

One of our team members, Orsolya Vincze has obtained funding for a mobility from the Romanian Ministry of Research and Education. She spent 1 month one of the world leading labs studying the evolution of cancer, the CREEC (Centre de Recherches Ecologiques et Evolutives sur le Cancer), Montpellier, France. Cancer is tightly linked with ageing, as well as with physiological mechanisms studied by our team, such as immunity and oxidative physiology. During the mobility a promising collaboration has been estaboilished between our and the french team that we hope will last long and will be mutually beneficial to both parties.

Visit the website of the group here: https://www.creec.fr/fr/

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01.12.2018 – Mobility

Our team member, Janka Pénzes has just completed a 2-month Erasmus scholarship, working in the lab of Gábor Árpád Czirják at the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany. Janka traveled to Germany in order to learn new lab techniques, namely to conduct assays of bacteria killing capacity. She took with her the blood samples we collected on the field in 2018 and we are delighted to announce that she returned home with a ready-to-analyse database! We are very excited to explore this novel physiological measure, both regarding its variance across and within species.

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01.10.2018 – New publication!

Our recent publication on the link between oxidative stress and life-history variants provides a pioneering study that shows a strong cross-species correlation between oxidative physiology and life-history evolution. This study is based on an unprecedented database on oxidative physiology in 88 wild bird species, collected on the field by our research team. See a short summary of this work bellow:

Longevity and life history coevolve with oxidative stress in birds

Authors marked in boldface are PCE members. Authors with asterisk are undergrad students.

Vágási CIVincze O, Pătraș L, Osváth GPénzes J*, Haussmann MF, Barta Z, Pap PL 2018. Longevity and life history coevolve with oxidative stress in birds. Functional Ecology (in press).

Summary
1. The mechanisms that underpin the evolution of ageing and life histories remain elusive. Oxidative stress, which results in accumulated cellular damages, is one of the mechanisms suggested to play a role.
2. In this paper we set out to test the ‘oxidative stress theory of ageing’ and the ‘oxidative stress hypothesis of life histories’ using a comprehensive phylogenetic comparison based on an unprecedented dataset of oxidative physiology in 88 free-living bird species.
3. We show for the first time that bird species with longer lifespan have higher non-enzymatic antioxidant capacity and suffer less oxidative damage to their lipids. We also found that bird species featuring a faster pace-of-life either feature lower non-enzymatic antioxidant capacity or are exposed to higher levels of oxidative damage, while adult annual mortality does not relate to oxidative state.
4. These results reinforce the role of oxidative stress in the evolution of lifespan and also corroborate the role of oxidative state in the evolution of life histories among free-living birds.

Key-words: ageing, antioxidants, comparative biology, life history, lifespan, lipid peroxidation, mortality, oxidative damage

 

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15.07.2018 – FIELD SEASON 2018

We have successfully completed the field season in 2018. We collected blood samples from 218 individual birds belonging to various bird species during their breeding periods. Samples are currently processed in the laboratory to develop an extensive immunological and oxidative stress database. Samples were collected in various places across the country, including Dobrogea, the Danube Delta and the Carpathian Mountains in order to cover a wide range of habitats and capture birds from a wide taxonomic scale.

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15.09.2018

SEX-SPECIFIC LIFE HISTORIES AND PHYSIOLOGY OF BIRDS AND MAMMALS

Our research team is focusing on building an extensive database concerning the sex-specific life-histories and physiology of birds and mammals. During the last couple months we have collected physiology and demography data from various bird and mammal species from literature and online resources. Our database covers both wild and captive populations of various animal species and builds on extensive online resources, such as the Zoological Information Management System (ZIMS, a global database of captive animals).

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09.10.2018

SCIENTIFIC LITERATURE

An important paper has been published in the prestigious Ecology Letters about the sexual dimorphism in immune responsiveness in the animal kingdom as evidenced by a meta-analysis.

The article entitled “Sexual dimorphism in immunity across animals: a meta-analysis” can be accessed here.

Abstract
In animals, sex differences in immunity are proposed to shape variation in infection prevalence and intensity among individuals in a population, with females typically expected to exhibit superior immunity due to life-history trade-offs. We performed a systematic meta-analysis to investigate the magnitude and direction of sex differences in immunity and to identify factors that shape sex-biased immunocompetence. In addition to considering taxonomic and methodological effects as moderators, we assessed age-related effects, which are predicted to occur if sex differences in immunity are due to sex-specific resource allocation trade-offs with reproduction. In a meta-analysis of 584 effects from 124 studies, we found that females exhibit a significantly stronger immune response than do males, but the effect size is relatively small, and became non-significant after controlling for phylogeny. Female-biased immunity was more pronounced in adult than immature animals. More recently published studies did not report significantly smaller effect sizes. Among taxonomic and methodological subsets of the data, some of the largest effect sizes were in insects,further supporting previous suggestions that testosterone is not the only potential driver of sex differences in immunity. Our findings challenge the notion of pervasive biases towards female-biased immunity and the role of testosterone in driving these differences.

Keywords
Immune response, immunity, life-history, sexual dimorphism.

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12.02.2018 – New publication!

Experimental increase in baseline corticosterone level reduces oxidative damage and enhances innate immune response

Authors marked in boldface are PCE members.

Vágási CI, Pătraș L, Pap PL, Vincze O, Mureșan C, Németh J and Lendvai ÁZ 2018. Experimental increase in baseline corticosterone level reduces oxidative damage and enhances innate immune response. PLoS One 13: e0192701. URL

Abstract
Glucocorticoid (GC) hormones are significant regulators of homeostasis. The physiological effects of GCs critically depend on the time of exposure (short vs. long) as well as on their circulating levels (baseline vs. stress-induced). Previous experiments, in which chronic and high elevation of GC levels was induced, indicate that GCs impair both the activity of the immune system and the oxidative balance. Nonetheless, our knowledge on how mildly elevated GC levels, a situation much more common in nature, might influence homeostasis is limited. Therefore, we studied whether an increase in GC level within the baseline range suppresses or enhances condition (body mass, hematocrit and coccidian infestation) and physiological state (humoral innate immune system activity and oxidative balance). We implanted captive house sparrows Passer domesticus with either 60 days release corticosterone (CORT) or control pellets. CORT-treated birds had elevated baseline CORT levels one week after the implantation, but following this CORT returned to its pre-treatment level and the experimental groups had similar CORT levels one and two months following the implantation. The mass of tail feathers grown during the initial phase of treatment was smaller in treated than in control birds. CORT implantation had a transient negative effect on body mass and hematocrit, but both of these traits resumed the pre-treatment values by one month post-treatment. CORT treatment lowered oxidative damage to lipids (malondialdehyde) and enhanced constitutive innate immunity at one week and one month post-implantation. Our findings suggest that a relatively short-term (i.e. few days) elevation of baseline CORT might have a positive and stimulatory effect on animal physiology.

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06.01.2018 – New publication!

Oxidative physiology of reproduction in a passerine bird: a field experiment

This paper got accepted in Behavioural Ecology and Sociobiology.Authors marked in boldface are PCE members.

Pap PLVincze O, Fülöp A, Székely-Béres O, Pătraș L, Pénzes J and Vágási CI 2018. Oxidative physiology of reproduction in a passerine bird: a field experiment. Behavioural Ecology and Sociobiology (in press).

Abstract:

Organisms face resource trade-offs to support their parental effort and survival. The life history oxidative stress hypothesis predicts that an individual’s redox state modulates the trade-off between current and residual fitness, but this has seldom been tested experimentally in non-captive organisms. In this study, we manipulated the brood size in breeding pairs of barn swallows (Hirundo rustica) and found that females tending enlarged broods had increased levels of plasma oxidative damage (malondialdehyde concentration). This effect, however, was not accompanied by either a depletion, or defensive upregulation in antioxidants (glutathione, total antioxidant capacity and uric acid) that may explain the increase in oxidative damage. Brood size manipulation and the level of plasma oxidative damage during brood-rearing are not translated into decreased annual return rate, which does not support the oxidative stress hypothesis of life-history trade-offs. On the contrary, we found that female’s oxidative damage and total glutathione levels, an important intracellular non-enzymatic antioxidant measured at hatching decreased and correlated positively, respectively with annual return rate, suggesting that oxidative condition at hatching might be a more important contributor to fitness than the oxidative physiology measured during chick rearing. We also show that individual traits and ecological factors, such as the timing of breeding and the abundance of blood-sucking nest mites, correlated with the redox state of males and females during brood care.

Keywords: Antioxidants, Barn swallows, Life-history trade-offs, Lipid peroxidation, Oxidative stress, Parasitism