Age-related change in melanin-based coloration of Barn owls (Tyto alba): females that become more female-like and males that become more male-like perform better

Ornament expression fluctuates with age in many organisms. Whether these changes are adaptively plastic is poorly known. In order to understand the ultimate function of melanin-based ornaments, we studied their within-individual fluctuations and their covariation with fitness-related traits. In barn owls (Tyto alba), individuals vary from reddish-brown pheomelanic to white and from immaculate to marked with black eumelanic spots, males being less reddish and less spotted than females. During the first molt, both sexes became less pheomelanic, females displayed larger spots and males fewer spots, but the extent of these changes was not associated with reproduction. At subsequent molts, intra-individual changes in melanin-based traits covaried with simultaneous reproduction changes. Adult females bred earlier in the season and laid larger eggs when they became scattered with larger spots, while adults of both sexes produced larger broods when they became whiter. These results suggest that the production of melanin pigments and fitness-related life history traits are concomitantly regulated in a sex-specific way.

Linking melanism to brain development: expression of a melanism-related gene in barn owl feather follicles covaries with sleep ontogeny.

BACKGROUND: Intra-specific variation in melanocyte pigmentation, common in the animal kingdom, has caught the eye of naturalists and biologists for centuries. In vertebrates, dark, eumelanin pigmentation is often genetically determined and associated with various behavioral and physiological traits, suggesting that the genes involved in melanism have far reaching pleiotropic effects. The mechanisms linking these traits remain poorly understood, and the potential involvement of developmental processes occurring in the brain early in life has not been investigated. We examined the ontogeny of rapid eye movement (REM) sleep, a state involved in brain development, in a wild population of barn owls (Tyto alba) exhibiting inter-individual variation in melanism and covarying traits. In addition to sleep, we measured melanistic feather spots and the expression of a gene in the feather follicles implicated in melanism (PCSK2). RESULTS: As in mammals, REM sleep declined with age across a period of brain development in owlets. In addition, inter-individual variation in REM sleep around this developmental trajectory was predicted by variation in PCSK2 expression in the feather follicles, with individuals expressing higher levels exhibiting a more precocial pattern characterized by less REM sleep. Finally, PCSK2 expression was positively correlated with feather spotting. CONCLUSIONS: We demonstrate that the pace of brain development, as reflected in age-related changes in REM sleep, covaries with the peripheral activation of the melanocortin system. Given its role in brain development, variation in nestling REM sleep may lead to variation in adult brain organization, and thereby contribute to the behavioral and physiological differences observed between adults expressing different degrees of melanism.

Female plumage spottiness and parasite resistance in the barn owl (Tyto alba)

The hypothesis that extravagant ornaments signal parasite resistance has received support in several species for ornamented males but more rarely for ornamented females. However, recent theories have proposed that females should often be under sexual selection, and therefore females may signal the heritable capacity to resist parasites. We investigated this hypothesis in the socially monogamous barn owl, Tyto alba, in which females exhibit on average more and larger black spots on the plumage than males, and in which males were suggested to choose a mate with respect to female plumage spottiness. We hypothesized that the proportion of the plumage surface covered by black spots signals parasite resistance. In line with this hypothesis, we found that the ectoparasitic fly, Carnus hemapterus, was less abundant on young raised by more heavily spotted females and those flies were less fecund. In an experiment, where entire clutches were cross-fostered between nests, we found that the fecundity of the flies collected on nestlings was negatively correlated with the genetic mother's plumage spottiness. These results suggest that the ability to resist parasites covaries with the extent of female plumage spottiness. Among females collected dead along roads, those with a lot of black spots had a small bursa of Fabricius. Given that parasites bigger the development of this immune organ, this observation further suggests that more spotted females are usually less parasitized. The same analyses performed on male plumage spottiness all provided non-significant results. To our knowledge, this study is the first one showing that a heritable secondary sexual characteristics displayed by females reflects parasite resistance.

Corticosterone shifts reproductive behaviour towards self-maintenance in the barn owl and is linked to melanin-based coloration in females.

Trade-offs between the benefits of current reproduction and the costs to future reproduction and survival are widely recognized. However, such trade-offs might only be detected when resources become limited to the point where investment in one activity jeopardizes investment in others. The resolution of the trade-off between reproduction and self-maintenance is mediated by hormones such as glucocorticoids which direct behaviour and physiology towards self-maintenance under stressful situations. We investigated this trade-off in male and female barn owls in relation to the degree of heritable melanin-based coloration, a trait that reflects the ability to cope with various sources of stress in nestlings. We increased circulating corticosterone in breeding adults by implanting a corticosterone-releasing-pellet, using birds implanted with a placebo-pellet as controls. In males, elevated corticosterone reduced the activity (i.e. reduced home-range size and distance covered within the home-range) independently of coloration, while we could not detect any effect on hunting efficiency. The effect of experimentally elevated corticosterone on female behaviour was correlated with their melanin-based coloration. Corticosterone (cort-) induced an increase in brooding behaviour in small-spotted females, while this hormone had no detectable effect in large-spotted females. Cort-females with small eumelanic spots showed the normal body-mass loss during the early nestling period, while large spotted cort-females did not lose body mass. This indicates that corticosterone induced a shift towards self-maintenance in males independently on their plumage, whereas in females this shift was observed only in large-spotted females.

Recueil de pièces, manuscrites et imprimées, mémoires, actes royaux, comptes, suppliques, etc., concernant le Béarn, la Navarre, le pays de Soule, le Dauphiné, la Bresse, la Bourgogne, la Lorraine, le Ponthieu, la Normandie et le Berry.

Contient : Pièces relatives au Béarn, et principalement à la réunion du Béarn à la Couronne de France (f. 1), — et au pays de Soule (f. 45). — Navarre, etc. : Supplique orig. des députés des Trois États de la Basse-Navarre (f. 77) ; Pièces diverses, comptes, etc., concernant le domaine de Navarre, notamment : « Estat des sommes que le Roy veult et entend estre doresnavant paiées aux gens de son Conseil d'Estat et privé de ses maison et finances de Navarre et ancien domaine...», 1607 ; « Advis de ce qui se peult faire pour la réduction des officiers de la maison de Navarre et Béarn... » ; Baux du domaine de Navarre ; Pièces relatives aux revenus ecclésiastiques du Béarn ; « Estat de la recepte et despence du domaine de la maison de Navarre, pour l'année 1619 » ; « Mémoire du nomé Du BOURG, touchant les forests de l'antien domaine de Navarre, au resort de Thoulouze » ; Copies d'actes de Henri IV ; Mémoire orig., signé Hurault « de Maisse », concernant une adjudication de l'ancien domaine de Navarre ; Pièces relatives à Bayonne (f. 218), — à Tartas (f. 222), — à Saint-Béat (f. 224), — à Blaye (f. 226). — Dauphiné : « Extrait d'un Registre aux archifs de la Chambre des Comptes et Cour des Finances du Dauphiné, institué [intitulé] Homagia Chalançonis , 1489 et 1490 » (f. 250) ; Pièces relatives à la Bresse (f. 260). — Bourgogne : « Du duché de Bourgogne, et de ceux qui l'ont tenue et possédée... » (f. 282). — Lorraine : « Mémoire au Roy..., des choses qui ce sont passées au gouvernement et ville de Toul » [contre le sieur de Vannes], orig. signé « Vuiry » (f. 294) ; « Remonstrances qu'il fault faire au Roy, pour conserver la ville de Toul en son obéissance... » ; Copie d'un acte de Charles-Quint, 1521 ; Pièces relatives à l'évêché de Metz (f. 316), — notamment, actes orig. de Georges de Bade, évêque de Metz, 1473 (f. 318 et 351) ; « Articles proposez au nom du Roy par Mr [Louis] d'Auzance à Mr le cardinal de Lorraine, pour le suject de la ville et ecclésiastiques de Metz, avec les responses dudict cardinal..., 1565 » ; « Mémoire pour la ville de Verdun, et comme elle est venue souz l'obéissance du Roy... » ; Pièce concernant Épinal, 1463 (f. 349). — Ponthieu : Extraits relatifs à l'abbaye de Sain t-Josse-aux-Bois (f. 352) ; Prisée du comté de Boulogne, 1477 (f. 356). — Normandie : Copie d'un arrêt du Parlement de Rouen, 1643 (f. 374). — Berry : Copie d'un acte de Charles VII pour Issoudun, 1423 (f. 440)

Les fors de Béarn, recueil de textes relatifs à la législation béarnaise, comprenant.

Contient : 1 « Los fors anciaas de Bearn » ; 2 « Lo for de Morlaas » ; 3 « Lo poblacion d'Oloron » ; 4 « Rubrica. Lo for d'Ossau » ; 5 « Rubrica. Lo fo d'Aspe » ; 6 « Los dretz qui lo vescomte ha en Aspe » ; 7 « Lo fors de Baretors » ; 8 « Las taxations de las cartas feytes sober los segramentz » ; 9 « Statutz de cort mayor feytz deu temps de mos. Mathiu, comte de Foixs ensa » ; 10 « De talhe de caperaas spitales et christiaas » ; 11 « Ordenance feyte en cort major en lo temps de moss. Archambaud et madone Ysabe, comtesse de Foixs » ; 12 « Forme de manar la cort mayor » ; 13 « Lo for que dejuus fo en judyament produsit sus l'apeu qui ere per dabant la cort deu senescal entre Jehanet de Maseres de La Enveye et per sa partie et contre Audine et Condoi de Lalane de Germeneus » ; 14 Charte de paix de clerc à laïc, 13 juillet 1368 [Note : Le texte imprimé porte : 12 juillet (page 268.)] ; 15 Rubrique des amendes, ayant pour titre : « Breves de leys degudes au Senhor sego[n] lo for » ; 16 « La carte deu pont de Nabarencxs » ; 17 « Las observances de Bearn sus thiensers, trubes et patz » ; 18 « Aquest article juus struit tracte suus hostes auterya et jura moss. Gaston, vescomte de Bearn, en son nabet advenement, lo XII jorn de julh M. IIIIC. XXXVI » ; a « Secse lo conde de las monedas et avaluades temps per temps et mees per mees et an per an, en los paguementz valhatz et recebutz, qui un cascun an dejuus struitz se fasen », 1401-1422 n. st ; b « Secse la valor de l'aur en lo autres temps dejuus struitz », 1402-1420 n. st ; c « Secse l'avaluement de l'aur a Tolose », 1416-1420 n. st ; d Mention que le livre a appartenu « magistro Johanni de Furteria, jurium vaccalareo », et commencement d'un acte de l'évêque de Dax, Bertrand de Borie, « de Boyria », adressé à Arnaud « de Dabanto », fils de Jean ; e Diverses notes et mentions

Mélanges sur le Béarn.

Contient : Testaments et contrats de mariage des comtes de Béarn ; Institutions de la Bigorre ; Traité entre Jean II, roi de Navarre, et Gaston IV, comte de Foix ; Mémoire concernant le succession du comté de Foix ; Extrait du Trésor des chartes de Pau ; Testament de François-Phoebus, comte de Foix ; Domaine de Béarn ; Traités et pièces concernant l'histoire de Béarn et de Bigorre, principalement aux XIVe et XVe siècles ; Absolution accordée par Charles VIII à Alain d'Albret ; Histoire de Navarre. — 519. Histoire de Bigorre ; Accord entre Louis de Sancerre, connétable de France, et Archembaud, captal de Buch

« Copie des lettres écrittes par HENRY IV, roy de France et de Navarre, et de sa propre main, à Corizandre d'Andoins, sa maîtresse, à laquelle Il rend compte de tous les combats ... depuis son départ de Béarn jusques à la conquête entière de la couronne de France. » (1587-1598).

Contient : « Discours de Henri IV, composé et prononcé par lui-même à Amiens, le 22 aoùt 1594, aux députés de Beauvais qui vinrent lui aporter... la soumission de leur ville »