Paternal attractiveness and the effects of differential allocation of parental investment

The differential allocation hypothesis (DAH) predicts that an individual should vary its reproductive investment according to the attractiveness of its mate. A recently revised version of the DAH makes explicit that investment can be positive, i.e. higher for the offspring of attractive males which should be of higher quality, or negative, i.e. higher for offspring of unattractive males, for example compensating for inheriting poor paternal genes. Moreover, investment can be made by the father and the mother. Here, we tested whether experimental manipulation of male attractiveness affected parental investment at different reproductive stages and thus influenced fitness-related traits in offspring. In two aviaries, all male zebra finches, Taeniopygia guttata, were given red leg rings to increase attractiveness and in two aviaries all males received green leg rings to decrease attractiveness. This controlled for assortative mating between treatments. Ring colour was merely an experimental manipulation of male attractiveness, not paternal quality, so we might expect additional investment to elevate offspring quality. Eggs were cross-fostered between and within treatments to allow differentiation of effects of investment in eggs and nestlings. Clutch and brood sizes were standardized. Both positive and negative investment were observed: Eggs from red-ringed fathers had higher yolk to albumen ratios than eggs from green-ringed fathers. Nestlings from eggs laid and incubated by parents in the red-ringed group had higher hatching masses than those in the green-ringed group. Both parents in the green-ringed group fed nestlings more frequently than red-ringed parents. Offspring performance was influenced by the treatment of both foster and biological parents, but combined effects of these different investment patterns on fitness-related traits were ambiguous. Male attractiveness appeared to affect patterns of reproductive investment but not consistently across all forms of reproductive investment suggesting that the costs and benefits of differential allocation vary among individuals and across contexts

Tyrosine Kinase Syk Non-Enzymatic Inhibitors and Potential Anti-Allergic Drug-Like Compounds Discovered by Virtual and In Vitro Screening

In the past decade, the spleen tyrosine kinase (Syk) has shown a high potential for the discovery of new treatments for inflammatory and autoimmune disorders. Pharmacological inhibitors of Syk catalytic site bearing therapeutic potential have been developed, with however limited specificity towards Syk. To address this topic, we opted for the design of drug-like compounds that could impede the interaction of Syk with its cellular partners while maintaining an active kinase protein. To achieve this challenging task, we used the powerful potential of intracellular antibodies for the modulation of cellular functions in vivo, combined to structure-based in silico screening. In our previous studies, we reported the anti-allergic properties of the intracellular antibody G4G11. With the aim of finding functional mimics of G4G11, we developed an Antibody Displacement Assay and we isolated the drug-like compound C-13, with promising in vivo anti-allergic activity. The likely binding cavity of this compound is located at the close vicinity of G4G11 epitope, far away from the catalytic site of Syk. Here we report the virtual screen of a collection of 500,000 molecules against this new cavity, which led to the isolation of 1000 compounds subsequently evaluated for their in vitro inhibitory effects using the Antibody Displacement Assay. Eighty five compounds were selected and evaluated for their ability to inhibit the liberation of allergic mediators from mast cells. Among them, 10 compounds inhibited degranulation with IC50 values ≤10 µM. The most bioactive compounds combine biological activity, significant inhibition of antibody binding and strong affinity for Syk. Moreover, these molecules show a good potential for oral bioavailability and are not kinase catalytic site inhibitors. These bioactive compounds could be used as starting points for the development of new classes of non-enzymatic inhibitors of Syk and for drug discovery endeavour in the field of inflammation related disorders

Pre-laying vocal activity as a signal of male and nest stand quality in goshawks

In this study we examined male vocalisation patterns as a measure of individual and nest stand quality in goshawk Accipiter gentilis. We related the male call rate at dawn (considered to be part of a reproductive strategy) to breeding success and nest stand structure. We recorded the two main chattering-type calls of nine goshawks during the 3 months preceding egg-laying (January-March). Nest stand characteristics were assessed by means of six parameters of nest trees and four parameters of the forest stands within a 1-ha plot. The vocalisations varied significantly among individuals: successful breeders had longer vocalisations and began vocalising earlier than failed ones. Males that successfully reproduced also differed significantly from unsuccessful ones in nest stand characteristics. The results indicate that dawn vocal activity may be considered a honest advertisement of male quality, as well as the quality of its nest stand, expressed by breeding success. The conservation concerns we may gain about territory quality in relation to male vocal activity are also discussed.Peer Reviewe

Maternal influence on eggshell maculation: implications for cryptic camouflaged eggs

Published online: 20 August 2015. Abstract in English and GermanEgg camouflage may explain the adaptive significance of avian eggshell pigmentation in ground-nesting species. Eggshell maculation (spots) is predominantly due to protoporphyrin, but both biliverdin (antioxidant) and protoporphyrin (pro-oxidant) may be present in spotted eggshells. Because of their role in oxidative stress, the deposition of eggshell pigments might be condition-dependent. However, because of the fitness benefits of eggshell coloration, cryptic eggshell appearance should be strongly conserved in ground-nesting species regardless of female condition and eggshell pigment concentrations. We investigated whether Japanese quails (Coturnix coturnix japonica) maintained eggshell maculation under food restriction. We quantified eggshell maculation (i.e., percentage of spot coverage) using digital photography, and both protoporphyrin and biliverdin concentrations of eggs laid by females either on a food-restricted or an ad libitum diet. Females on a high quality diet, which are known to decrease the deposition of eggshell protoporphyrin, decreased eggshell maculation compared with food-restricted females that maintained it. For the first time, we propose an experimental study which suggests that eggshell maculation depends on female body condition and that manipulating eggshell maculation may be the strategy used by females to potentially optimize egg camouflage. = Die Tarnung von Eiern könnte die adaptive Bedeutung der Pigmentierung der Eierschale bodenbrütender Vögel erklären. Die Befleckung der Eierschale ist hauptsächlich auf Protoporphyrin zurückzuführen, aber sowohl Biliverdin (ein Antioxidant) als auch Protoporphyrin (ein Prooxidant) können in gefleckten Eierschalen enthalten sein. Aufgrund der Rolle von Eierschalenpigmenten bei oxidativem Stress könnte ihre Einlagerung in die Eierschale konditionsabhängig sein. Aufgrund der Fitnessvorteile einer Färbung der Eierschale sollte ein kryptisches Aussehen der Eier bei Bodenbrütern jedoch hochkonserviert sein, unabhängig von der Kondition der Weibchen und der Konzentration der Eierschalenpigmente. Wir haben untersucht, ob Japanwachteln (Coturnix coturnix japonica) die Befleckung ihrer Eierschale bei Futterknappheit beibehielten. Wir haben die Eierschalenbefleckung (d.h. den Anteil der Abdeckung mit Flecken) mit Hilfe digitaler Fotografie quantifiziert sowie die Protoporphyrin- und Biliverdin-Konzentrationen der Eier von Weibchen ermittelt, die entweder eingeschränkt oder ad libitum Futter erhielten. Weibchen mit hochwertiger Kost, die bekannterweise die Einlagerung von Protoporphyrin in die Eierschale reduzieren, reduzierten die Befleckung der Eierschale im Vergleich zu Weibchen mit eingeschränkter Kost, welche sie beibehielten. Zum ersten Mal liefern wir eine experimentelle Studie ab, die darauf hindeutet, dass die Befleckung der Eierschale von der Kondition des Weibchens abhängt und dass Weibchen die Befleckung der Eierschale beeinflussen könnten, als Strategie, um die Tarnung der Eier potenziell zu optimieren.Camille Duval, Phillip Cassey, P. George Lovell, Ivan Mikšík, S. James Reynolds, Karen A. Spence

Effects of singing on copulation success and egg production in brown-headed cowbirds, Molothrus ater

We examined the relationship between singing and reproductive success in cowbirds. We amassed data from 17 captive flocks (164 males, 167 females) that we have studied over 4 years. For each flock, we conducted extensive observations on social interactions as the birds competed, courted, and reproduced. We collected and incubated all eggs laid during the breeding season and performed parentage analyses on the 7 flocks with the highest levels of egg production. Finally, we measured males' song quality in playback tests. Here, we assessed what aspects of singing were associated with 1) copulation success and 2) offspring production. Results differed for these 2 measures of reproductive success because of high variance in egg production within and across groups. The overall amount of songs males directed to females, a measure of courtship persistence, was the one variable strongly associated with males' copulation success. For offspring production, there was significant between-flock variability that was more pronounced than the within-group variability. The one variable that was found to be strongly associated with eggs laid within and across groups was the amount of countersinging males produced; a measure of male--male singing competition. Song attractiveness did not predict any unique variance in either measure of reproductive success. The relationship between female egg production and male competition suggests that females may be trading off current versus future reproduction based on the opportunities available in groups to evaluate males' competitive abilities. Copyright 2010, Oxford University Press.