Autumn passage of soaring birds over Dobrogea (Romania): a migration corridor in Southeast Europe


Authors marked in boldface are EvolEcol members.

Fülöp A, Daróczi SJ, Dehelean AS, Dehelean LA, Domahidi Z, Dósa A, Gyékény G, Hegyeli Z, Kis RB, Komáromi IS, Kovács I, Miholcsa T, Nagy AA, Nagy A, Ölvedi SZ, Papp T, Pârâu LG, Sándor AK, Sos T, Zeitz R 2018. Autumn passage of soaring birds over Dobrogea (Romania): a migration corridor in Southeast Europe. Ardea 106: 61-77.

Abstract

The Dobrogea region in southeastern Romania, which is part of the Eurasian- East African Flyway, is listed as one of the important migration corridors for soaring birds on the western coast of the Black Sea. However, our knowledge regarding migration intensity, phenology and geographical patterns of soaring birds over the area is poor. To determine the migration intensity and phenology of soaring birds, we recorded the autumn migration in the Măcin Mountains (northern Dobrogea) from mid-August to the end of October between 2002–2007. To describe the geographical patterns of migration at a regional scale, we recorded migration intensity in the second half of September in 2010 and 2011, simultaneously from 15 and 13 counting points, respectively, covering the entire region of Dobrogea. In the Măcin Mountains we recorded a mean number (±SD) of 11,297 ± 2333.5 (CV = 20.7%) migrating raptors per year, and of 21,367 ± 10,949.3 (51.2%) and 455.6 ± 43.6 (9.6%) migrating White Storks Ciconia ciconia and Black Storks Ciconia nigra, respectively. Migration phenology parameters varied across raptor and non-raptor species. Migration occurred over a broad front, covering all of Dobrogea. However, migration intensity was more pronounced in the western, central and eastern parts of the region, and was less intensive in the northern central areas. Overall, we recorded 30 migrating raptor species and three non-raptor species. The most abundant raptors were Common Buzzard Buteo buteo, European Honey Buzzard Pernis apivorus, Lesser Spotted Eagle Clanga pomarina, Eurasian Sparrowhawk Accipiter nisus and Western Marsh Harrier Circus aeruginosus. The three non-raptor species were White Stork, Black Stork and Great White Pelican Pelecanus onocrotalus. Our study provides the first general overview of the autumn passage of soaring birds over Dobrogea, highlighting the importance of this area as part of a global migration network.

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Demographic causes of adult sex ratio variation and their consequences for parental cooperation


Author marked in boldface is EvolEcol member.

L.J. Eberhart-Phillips, C. Küpper, M.C. Carmona-Isunza, O. Vincze, S. Zefania, M. Cruz-López, A. Kosztolányi, T.E.X. Miller, Z. Barta, I.C. Cuthill, T. Burke, T. Székely, J.I. Hoffman, O. Krüger (2018). Demographic causes of adult sex ratio variation and their consequences for parental cooperation. Nature Communications 9, 1651.

Abstract

The adult sex ratio (ASR) is a fundamental concept in population biology, sexual selection, and social evolution. However, it remains unclear which demographic processes generate ASR variation and how biases in ASR in turn affect social behaviour. Here, we evaluate the demographic mechanisms shaping ASR and their potential consequences for parental cooperation using detailed survival, fecundity, and behavioural data on 6119 individuals from six wild shorebird populations exhibiting flexible parental strategies. We show that these closely related populations express strikingly different ASRs, despite having similar ecologies and life histories, and that ASR variation is largely driven by sex differences in the apparent survival of juveniles. Furthermore, families in populations with biased ASRs were predominantly tended by a single parent, suggesting that parental cooperation breaks down with unbalanced sex ratios. Taken together, our results indicate that sex biases emerging during early life have profound consequences for social behaviour.

Fulltext avalaibe here.

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Global song divergence in barn swallows (Hirundo rustica): exploring the roles of genetic, geographic, and climatic distance in sympatry and allopatry


Author marked in boldface is EvolEcol member.

Wilkins M.R., Scordato E.S.C., Semenov G.A., Karaardıç H., Shizuka D., Rubtsov A., Pap P.L., Shen S-F., Rebecca J. (2018). Global song divergence in barn swallows (Hirundo rustica): exploring the roles of genetic, geographic, and climatic distance in sympatry and allopatry. Biological Journal of the Linnean Society in press.

Abstract

Divergence in acoustic signals plays an important role in the production and maintenance of biodiversity in numerous taxa. In this study, we assess patterns of acoustic divergence in geographically isolated and sympatric subspecies of barn swallows (Hirundo rustica), including analyses of whether song differentiation varies with geographic isolation, genetic distance, and climatic distance. We provide the first description of geographic variation in
song among five of six currently recognized barn swallow subspecies. Temporal traits
describing terminal trills were the most distinct song traits among subspecies, adding to
growing evidence that trills are important in speciation among many birds, insects, and fish. Across a ~6,000 km transect of Russia, acoustic distance was predicted by genetic and geographic distance, but not climatic distance. We also found no reproductive character displacement of song traits in a contact zone between H. r. rustica and H. r. tytleri. Based on patterns discovered in this study, we infer an important role of genetic drift and sexual selection in the gradual buildup of acoustic divergence, which is accelerated in small populations.

Keywords: acoustic adaptation – acoustic divergence – barn swallow – birdsong – ecological selection – Hirundo rustica – neutral drift – reproductive character displacement – sexual selection – speciation

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


Authors marked in boldface are EvolEcol 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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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 EvolEcol members.

Pap PL, Vincze 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

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Orsolya Vincze – researcher portrait


Orsolya Vincze was EvolEcol group member during her BSc and MSc at the Babeș-Bolyai University, Romania. Then she moved to the University of Debrecen, Hungary for her PhD, but all that time she continued to remain close to the EvolEcol group having significant contribution to many studies. Now close to her PhD defence, she came back to the EvolEcol group being employed as a full-time researcher in a national grant financed by the Romanian Ministry of Research.

Despite her young age and being at the beginning of her researcher career, Orsolya has many intriguing results published in high-ranking international journals, including a co-authored paper published in Nature. She was recently interviewed by Daniel David, the vice-rector of the Babeș-Bolyai University responsible for research, who asked her about what drove her towards biology, research and Babeș-Bolyai University, and what she is planning for the near future. The interview can be accessed here.

Enjoy!

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Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies


Authors marked in boldface are EvolEcol members.

Szentiványi T, Vincze O and Estók P 2017. Density-dependent sex ratio and sex-specific preference for host traits in parasitic bat flies. Parasites & Vectors 10: 405. pdf

DOI: 10.1186/s13071-017-2340-0

URL

Abstract:
Background

Deviation of sex ratios from unity in wild animal populations has recently been demonstrated to be far more prevalent than previously thought. Ectoparasites are prominent examples of this bias, given that their sex ratios vary from strongly female- to strongly male-biased both among hosts and at the metapopulation level. To date our knowledge is very limited on how and why these biased sex ratios develop. It was suggested that sex ratio and sex-specific aggregation of ectoparasites might be shaped by the ecology, behaviour and physiology of both hosts and their parasites. Here we investigate a highly specialised, hematophagous bat fly species with strong potential to move between hosts, arguably limited inbreeding effects, off-host developmental stages and extended parental care.

Results

We collected a total of 796 Nycteribia kolenatii bat flies from 147 individual bats using fumigation and subsequently determined their sex. We report a balanced sex ratio at the metapopulation level and a highly variable sex ratio among infrapopulations ranging from 100% male to 100% female. We show that infrapopulation sex ratio is not random and is highly correlated with infrapopulation size. Sex ratio is highly male biased in small and highly female biased in large infrapopulations. We show that this pattern is most probably the result of sex-specific preference in bat flies for host traits, most likely combined with a higher mobility of males. We demonstrate that female bat flies exert a strong preference for high host body condition and female hosts, while the distribution of males is more even.

Conclusions

Our results suggest that locally biased sex ratios can develop due to sex-specific habitat preference of parasites. Moreover, it is apparent that the sex of both hosts and parasites need to be accounted for when a better understanding of host-parasite systems is targeted.

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