Large-brained birds suffer less oxidative damage

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Seasonal Patterns and Relationships among Coccidian Infestations, Measures of Oxidative Physiology, and Immune Function in Free-Living House Sparrows over an Annual Cycle

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Host space, not energy or symbiont size, constrains feather mite abundance across passerine bird species

13 Pág.Comprehending symbiont abundance among host species is a major ecological endeavour, and the metabolic theory of ecology has been proposed to understand what constrains symbiont populations. We parameterized metabolic theory equations to investigate how bird species' body size and the body size of their feather mites relate to mite abundance according to four potential energy (uropygial gland size) and space constraints (wing area, total length of barbs and number of feather barbs). Predictions were compared with the empirical scaling of feather mite abundance across 106 passerine bird species (26,604 individual birds sampled), using phylogenetic modelling and quantile regression. Feather mite abundance was strongly constrained by host space (number of feather barbs) but not by energy. Moreover, feather mite species' body size was unrelated to the body size of their host species. We discuss the implications of our results for our understanding of the bird-feather mite system and for symbiont abundance in general.Funding was provided by the Ministry of Science and Innovation (research project CGL2011-24466 to R.J., and CGL2015-69650-P to R.J. and D.S.). Manecorro Ringing Station (ICTS-RBD-CSIC) received economic support from Junta de Andalucía. We thank Doñana National Park for the authorizations and support during the preparation of the ringing programmes. We thank all the ringers who helped us measure the primaries at Manecorro Ringing Station. J.D. was supported by the European Commission (H2020-MSCA-IF-2019, INTROSYM:886532). S.F.-G. was supported by the Spanish Ministry of Economy and Competitiveness (CGL2010-15734/BOS). L.Z.G. was supported by a found from the National Research, Development, and Innovation Office—NKFIH (K-135841). O.G. was supported by the Spanish Ministry of Economy (Ref. CGL2014-56041-JIN). M.M.L. was supported by ‘la Caixa’ Foundation (grant ID100010434). H.C.P. was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant. J.C.S. was supported by funds from the Ministry of Science and Innovation (CGL-2020 PID2020- 114907GB-C21). C.I.V. was supported by the Romanian Ministry of Research, Innovation and Digitization (CNCS-UEFISCDI; project no. PN-III-P1-1.1-TE-2021-0502). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)Peer reviewe

A vedlés költségei: tollak minősége, jelzések és fiziológia

Plumage is the most remarkable peculiarity of birds, which defines their appearance. Besides, plumage has multifaceted effects on avian life provided that (i) birds abound in physiological adaptations related to being feathered and flight capable, and (ii) the functionality of the plumage influences reproductive and survival success. Feathers are dead appendages, so they can be repaired only by exchange. The process of periodic plumage exchange is called moult. This also means that the structural and material properties of the feathers are defined during their growth and their quality declines afterwards. Low-quality or damaged feathers lose their functionality, which ultimately can adversely affect the fitness of their bearer. Surprisingly though moult and feather quality is largely overlooked by avian ecologists. In this thesis, my aims were to study the costs of moult and feather quality with special attention paid to understand the correlation between different feather quality traits, the dependence of moult on resources, condition and parasite infestation, the conflict between moult and immune function, and the elaboration of plumage ornaments used in signalization. A madarak legszembetűnőbb ismertetője a tollazat, amely meghatározza hordozója küllemét. Emellett sokrétű hatása van a madarak életére tudva, hogy (i) számos fiziológiai adaptáció a tollal való borítottság és ezzel kapcsolatos repülési képesség eredménye, valamint (2) a tollazat számos funkciója összefügg a túlélési és élettartam alatti szaporodási sikerrel. A tollak elhalt epidermális struktúrák, melyek minősége csupán lecseréléssel javítható. A tollazat szabályos időközönkénti felújítását nevezzük vedlésnek. Ebből következik, hogy a tollak szerkezeti és anyagi tulajdonságai a vedléskor való növesztésük alatt alakulnak ki és ezután állapotuk kötelezően hanyatlik. Gyenge minőségű vagy megrongálódott tollak képtelenek maradéktalanul ellátni szerepüket, aminek a fentiek értelmében negatív következményei lehetnek az egyed rátermettségére. Meglepő tehát, hogy a sokrétű sikerességgel kapcsolatos hatásai ellenére a madarak vedlése és tollminősége egy hiányosan kutatott ágazata az ornitológiának és madárökológiának. Értekezésemben a madarak vedlésének és a jó minőségű tollazat fejlesztésének költségeit keresem, különös tekintettel a tollminőséget jelző változók összefüggéseire, a vedlés forrásigényére, kondíciótól és fertőzöttségtől való függésére, illetve immuntevékenységgel való csereviszonyára, valamint a tollazati jelzések növesztésére.N