Wing morphology, flight type and migration distance predict accumulated fuel load in birds


Authors marked in boldface are EvolEcol members.

Vincze OVágási CI, Pap PL, Palmer C, Møller AP 2018. Wing morphology, flight type and migration distance predict accumulated fuel load in birds. Journal of Experimental Biology (in press).

Abstract
Birds often accumulate large fat and protein reserves to fuel long-distance flights. While it is well known that species that fly the longest accumulate the largest amounts of fuel, considerable cross-species variation in fuel load is seen after controlling for overall migration distance. It remains unclear whether this variation can be explained by aerodynamic attributes of different species, despite obvious ecological and conservation implications. Here we collected data on wing morphology, flight type, migration distance and fuel load from 213 European bird species and explored three questions: (1) Does maximum fuel load relate to migration distance across species?; (2) Does wing morphology, as described by wing aspect ratio and wing loading, influence maximum fuel load, and; (3) Does flight type influence maximum fuel load? Our results indicate that maximum fuel load increases with migration across species, but residual variance is high. Our results indicate that maximum fuel load is also correlated with migration distance, but again residual variance is high. The latter variance is explained by aspect ratio and flight type, while wing loading and body mass explain little variance. Birds with slender wings accumulate less fuel than species with low wing aspect ratio when covering a similar migration distance. Continuously flapping species accumulate the largest amounts of fuel, followed by flapping and soaring, flapping and gliding species, while the smallest fuel loads were observed in birds with passerine-type flight. These results highlight complex eco-evolutionary adaptations to migratory behaviour, pointing toward the importance of energy-minimisation.

Key-words: aspect ratio; fat reserves; flight range; flight type; wing loading

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Vane macrostructure of primary feathers and its adaptations to flight in birds


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

Pap PL, Vincze O, Vágási CI, Salamon Z*, Pándi A*, Bálint B*, Nord A, Nudds RL, Osváth G 2018. Vane macrostructure of primary feathers and its adaptations to flight in birds. Biological Journal of the Linnean Society (in press).

Abstract
The selection pressures that drive flight feather morphology are poorly understood. Using a phylogenetic comparative approach and data from 178 species of birds, we investigated whether both the position along the wing length and flight feather length affected vane structure. We found that barb density was lower on distal primaries than proximal primaries of the leading feather vane. In contrast, on the trailing vane only the mid point barb density differed and, here, it showed denser barbs on the distal primaries. This difference was a denser at the feather base than the tip. Barb angle was higher along the full length of the leading edge vane on the proximal than compared with the distal primaries. Overall, barb density decreased from base to tip on both trailing and leading vanes on both the proximal and distal primaries. In general barb angle was less acute at the feather base than at the tip. Broadly, barbs were denser in continuous flapping fliers than in soarers and the angle of barbs on both the proximal and distal primaries was affected by flight type. We could not, however, identify consistent differences in the pattern of barb angle change among flight style groups. Our findings add new perspectives to our understanding of the functional morphology of flight feather vane, but we still have limited knowledge on how aerodynamic forces, particularly during take-off and landing, affect the morphology of the feather vane.

Additional keywords: barb angle – barb density – flight – flight feathers – functional morphology – feather vane

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Longevity and life history coevolve with oxidative stress in birds


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

Vágási CI, Vincze O, Pătraș L, Osváth G, Pénzes 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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Autumn passage of soaring birds over Dobrogea (Romania): a migration corridor in Southeast Europe


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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


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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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