In the polyembryonic wasp Copidosoma floridanum, females commonly lay one male and one female egg in a lepidopteran host. Both sexes proliferate clonally within the growing host larva. Distinct larval castes develop from each wasp egg, the majority being 'reproductives' plus some 'soldiers' which sacrifice reproduction and attack competitors. Maturing mixed sex broods are usually female biased,...

In species that produce broods of multiple offspring, parents need to partition resources among simultaneously growing neonates that often differ in growth requirements. In birds, multiple ovarian follicles develop inside the female at the same time, resulting in a trade-off of resources among them and potentially limiting maternal ability for sex-specific allocation. We compared resource acqui...

Effects of environmental pollutants are most obvious when mortality is increased. However, there are other nonlethal factors that may affect population size significantly. Endocrine disruption as a mechanism of action for pollutants recently has received much attention. Observations of effects likely caused by endocrine disruptors in pulp mill effluents have been made on several fish species, e...

In polyandrous species females produce successive clutches with several males. Female barn owls (Tyto alba) often desert their offspring and mate to produce a 2(nd) annual brood with a second male. We tested whether copulating during chick rearing at the 1(st) annual brood increases the male's likelihood to obtain paternity at the 2(nd) annual breeding attempt of his female mate in case she des...

The morphology of larvae is a key factor influencing their behaviour, performance and ultimately survival. There evidence indicating significant morphological variability among broods, that this may be related to the size or conditions mother. However, maternal influence not consistent across decapod crustaceans. Using 35 broods from different mothers crab Hemigrapsus takanoi collected in same ...

Several ectoparasites parasitise nestlings decreasing their body condition, growth and survival. To minimise any loss of fitness due to ectoparasites, birds have developed a wide variety defence mechanisms, potentially including hatching asynchrony. According the Tasty Chick Hypothesis (TCH), cost parasitism would be reduced if tend eat on less immunocompetent nestlings, typically last-hatched ...

Parasitoid Nasonia wasps adjust their progeny sex ratio to the presence of conspecifics to optimize their fitness. Another trait under female control is the induction of offspring diapause. We analysed progeny sex ratios and the proportion of diapausing offspring of individual Nasonia females in host patches parasitized by two species, Nasonia vitripennis and Nasonia giraulti, in North American...

The reaction of wildlife to humans is known to differ with surroundings. In urban environments that provide suitable habitats for breeding birds, animals adapt to humans and their response is accordingly altered. This study examined the nest defense behavior of female Eurasian sparrowhawks (Accipiter nisus) during the breeding season in urban and rural areas of Prague. The females showed four d...

Knowledge of the ecology Eastern Black Rail (Laterallus jamaicensis jamaicensis) has remained nearly as elusive rail itself. Camera trapping methods facilitated first study breeding phenology and chick development, courtship brood rearing behaviors, flightless molt duration. Broods (n = 33) were observed between August 2015 - September 2019. Chicks capable flight at approximately 40 days after ...