Early developmental conditions are known to have life-long effects on an individual’s behavior, physiology and fitness. In altricial birds, a majority of these conditions, such as the number siblings amount food provisioned, controlled by parents. This opens up potential for parents adjust behavior their offspring according local post-natal circumstances. However, mechanisms underlying intergen...

Soldier-producing polyembryonic waSPS are the only social animals that develop as parasites inside the bodies of other insects. Characterizing the kin composition of broods is central to understanding the evolution of the soldier caste in these unique social insects. Here we studied the role of soldiers in mediating the outcome of competition among clones of the polyembryonic wasp Copidosoma fl...

Characterizing the mating systems of long-lived, economically important Pacific rockfishes comprising the viviparous Sebastes species flock is crucial for their conservation. However, direct assignment of mating success to sires is precluded by open, offshore populations and high female fecundity. We addressed this challenge by integrating paternity-assigned mating success of females with the a...

1. An increase of competition among adults or nestlings usually negatively affects breeding output. Yet little is known about the differential effects that competition has on the offspring sexes. This could be important because it may influence parental reproductive decisions. 2. In sexual size dimorphic species, two main contradictory mechanisms are proposed regarding sex-specific effects of c...

Abstract Annual population changes of most grouse, including the imperiled Attwater's prairie-chicken Tympanuchus cupido attwateri, are driven by annual reproductive success. Previous research identified poor survival chicks as a primary bottleneck for recovery this species. We evaluated relative importance 26 factors in 5 categories (weather and topography, habitat, plant phenology, time site,...

Abstract Sexual selection has been proposed to drive the evolution of elaborate phenotypic traits in males, which often confer success competition or mating. However, many species, both males and females display such traits. Studies examining how acts on sexes are scarce. In this study, we investigated whether plumage ornamentation is sexually selected lovely fairy-wren Malurus amabilis, a coop...

We investigated nestling sex ratio variation in the green-rumped parrotlet (Forpus passerinus), a small neotropical parrot breeding in central Venezuela. There are strong theoretical reasons to predict a female-biased sex ratio in this system according to the local resource hypothesis; juvenile males are philopatric and there are high levels of competition between male siblings for access to br...

The female perspective on reproductive strategies remains one of the most active areas of debate in biology. Even though a single mating is often sufficient to satisfy the fertilization needs of most females and the act of further mating incurs costs, multiple paternity within broods or clutches is a common observation in nature. Direct or indirect advantage to females is the most popular expla...

Differences in the growth rate of male and female offspring can result in different parental rearing costs for sons and daughters. Such differences may also influence the survival chances of male and female offspring when conditions are unfavourable. In birds, hatching asynchrony leads to hierarchical competition for food between siblings. Therefore, the sex of the chick in the first hatched po...