Uropygial gland size: a marker of phenotypic quality that shows no senescence in a long-lived seabird

Abstract

Studies of senescence in the wild have traditionally focused on traits like survival or fecundity. Although efforts to measure other salient phenotypic traits and markers of relevant physiological processes are rapidly increasing, traits related to selfmaintenance remain understudied in the context of aging. Uropygial or preen gland is a holocrine gland, exclusive to birds, directly linked to self-maintenance of the quality of plumage. We measured the size of uropygial glands of common gulls (Larus canus) in a cross sectional manner in order to test whether it shows the similar age-related decline as reproductive traits previously recorded in this species. Gulls with larger glands started breeding earlier in the season, indicating that gland size is a marker of individual phenotypic quality. We found a senescent decline in the onset of breeding and the size of white wing patches, a sexually dimorphic ornamental trait, while in contrast, preen gland increased with advancing age. This finding supports the view of life-history theory that in long-lived species whose lifetime reproductive success depends heavily on lifespan, self-maintenance is prioritized over reproduction. Altogether our results support the concept that senescence in the wild can be asynchronous for traits related to maintenance versus reproduction.

Salivary corticosterone reflects plasmatic levels in a wild seabird

“…All of these birds were caught between the 14 th and 25 th of May, between 10 am and 7 pm, and released immediately after sampling. To minimise the post manipulation nest abandonment, all birds were caught from nests using spring traps after the tenth day of incubation, as previously described and done in the same colony [36][37][38].…”

Variation of uropygial gland volume and malaria infection between urban-rural environment in the house sparrow

“…Aunque son varios los estudios que han analizado los posibles factores que promueven las variaciones de tamaño de la glándula uropigial (ej. Møller, et al 2010;Pap et al 2010;Vincze et al 2013;Jacob et al 2014;Urvik et al 2018;Møller y Laursen 2019), su conocimiento es aún limitado. Dado que el desarrollo de la glándula uropigial podría tener un alto coste energético (Piault et al 2008;Pap et al 2013;Moreno-Rueda 2015), solo aquellos individuos en óptimas condiciones podrían invertir más recursos en defensas antimicrobianas (ej.…”

Comparative morphology and histochemistry of the uropygial gland of the endangered and endemic Hooded Grebe (Podiceps gallardoi, Podicipediformes)

“…It has been reported that the size of the UG is dynamic (e.g. increasing in size from non-breeding to breeding season (Pap et al, 2010;Vincze et al, 2013), and increasing size with age (Urkiv et al, 2018). Even though these modifications might be due to changes in the indexes of cell proliferation and cell death that lead to tissue restructuring, this dynamism could be facilitated by the presence of elastic fibres.…”