The peripheral layer of the egg has long been recognized as a region with special properties. Several types of experiments argue for the existence of an egg cortex (reviewed in Wilson, 1925; Chambers and Chambers, 1961; Hiramoto, 1970; Vacquier, 1981). We can cite in chronological order: micromanipulations of the egg with rods and micropipettes; low speed centrifugation experiments that stratif...

To determine the genetic basis of the resistance of Schistosoma mansoni to praziquantel (PZQ) and to understand whether the resistance is dominant or recessive trait, a schistosome cross was undertaken between a PZQ-susceptible and a PZQ-resistant isolate using infections of the single-sex cercariae which were identified by a direct W1-specific PCR technique. The resistances of F1 and F2 genera...

Genetic correlations are often predictive of correlated responses of one trait to selection on another trait. There are examples, however, in which genetic correlations are not predictive of correlated responses. We examine how well a cross-environment genetic correlation predicts correlated responses to selection and the evolution of phenotypic plasticity in the seed beetle Stator limbatus. Th...

Experiments show that Heliconius butterflies are less likely to oviposit on host plants that possess eggs or egglike plant structures. These egg mimics are an unambiguous example of a plant trait evolved in response to a host-restricted group of insect herbivores.

Cichlid fishes are a textbook example of rapid speciation and exuberant diversity--this applies especially to haplochromines, a lineage with approximately 1800 species. Haplochromine males uniquely possess oval, bright spots on their anal fin, called 'egg-spots' or 'egg-dummies'. These are presumed to be an evolutionary key innovation that contributed to the tribe's evolutionary success. Egg-sp...

Routine, upgrading, and intersecting cross-breeding strategies are three methods frequently used in poultry breeding. But, till now, comparative assessment of the effects on improvement geese economic traits with these is largely unknown. Here, using Carlos goose Zi goose, were employed compared. The main traits, including egg production capability, quality, growth performance, meat down feathe...

Diapause is an adaptive trait that delays development or reproduction under unfavourable circumstances. The northern corn rootworm,Diabrotica barberi Smith & Lawrence, an important maize, Zea mays L., pest in the Diabroticite species complex, overwinters in diapause during the egg stage. Some NCR populations are adapted to crop rotation by expressing an extended diapause (ED) trait that delays ...

Egg quality is a complex biological trait and a major determinant of reproductive fitness in all animals. This study delivered the first proteomic portraits of egg quality in zebrafish, a leading biomedical model for early development. Egg batches of good and poor quality, evidenced by embryo survival for 24 h, were sampled immediately after spawning and used to create pooled or replicated samp...

in this study, the effects of culban seed (vicia peregrine l.) on live body weight, feed intake, feed efficiency, egg production, egg quality characteristics, egg yolk fatty acid profiles and yolk cholesterol content in laying hens were investigated. the experiment consists of seven treatment groups with ten replications containing one laying hen in each and for 32 weeks old seventy laying hen ...

Species' life history traits, including maturation age, number of reproductive bouts, offspring size and number, reflect adaptations to diverse biotic and abiotic selection pressures. A striking example of divergent life histories is the evolution of either iteroparity (breeding multiple times) or semelparity (breed once and die). We analysed published data on salmonid fishes and found that sem...