Female birds may optimize reproduction by modifying clutch size and the timing for the onset of incubation. We measured fecal estradiol-17beta (E) and progesterone (P) in laying canaries to better understand how onset of incubation might regulate clutch size. Both E and P rose sharply to maxima 1 day before the first egg was laid. Thereafter, E steadily declined, but P remained high through 2 d...

Most species of marine turtle breed every loggerhead turtles. The median interval between nesting seasons for green turtles was 3 years, and for loggerhead two or more years and it is the norm for females to lay more than one clutch of eggs within a nesting season. turtles it was 2 years. Utilizing these parameters and available data from other beaches that are monitored Knowing the interval be...

Physiological trade-offs mediated by limiting energy, resources or time constrain the simultaneous expression of major functions and can lead to the evolution of temporal separation between demanding activities. In birds, plumage renewal is a demanding activity, which accomplishes fundamental functions, such as allowing thermal insulation, aerodynamics and socio-sexual signaling. Feather renewa...

An optimal clutch control of a one-way assistant transmission (OCAT) for electrical vehicles is presented in this study. The OCAT consists fictional and clutch. working principle the to shift automatically speed ratio by automatic disengagement engagement characters Since torques launch conditions that are generated motor highly oscillates, desired performances can represent changes also oscill...

Life-history theory suggests that the variation in the seasonal timing of reproduction within populations may be explained on the basis of individual optimization. Optimal breeding times would vary between individuals as a result of trade-offs between fitness components. The existence of such trade-offs has seldom been tested empirically. We experimentally investigated the consequences of alter...

We examined the relationship between local water conditions (measured as the percent of total area of basins covered by water) and clutch size, egg volume, and hatchling mass of Mallards (Anas platyrhynchos) and Gadwalls (A. strepera) on four study sites in the Prairie Pothole Region of North Dakota and Minnesota, 1988–1994. We also examined the relationship between pond density and clutch size...

We describe a method for the rearing of the oligophagous herbivore Hadena bicruris, and its gregarious koinobiont endoparasitoid Microplitis tristis under laboratory conditions. With flowers from the host food plant Silene latifolia available, female moths lay on average 414 eggs during their lifetime, starting at day 3 after eggression and with a peak number per night on day 8. Caterpillars ca...

Many cell movements occur via polymerization of the actin cytoskeleton beneath the plasma membrane at the front of the cell, forming a protrusion called a lamellipodium, while myosin contraction squeezes forward the back of the cell. In what is known as the "molecular clutch" description of cell motility, forward movement results from the engagement of the acto-myosin motor with cell-matrix adh...