this study carried out in a factorial layout on completely randomaized block design with three replications, to evaluate the above- and below- ground competition between sesame (sesamum indicum) and pigweed (amaranthus retroflexus), and their impacts on sesame yield and yield component. the experimental treatments were all combination of crop-weed competition (shoot competition, root competitio...

Most females mate with many males. This can be costly, but the benefits to females are often unclear. A new study raises the possibility that females could benefit through an unconventional genetic pathway, while also showing that males can inadvertently increase rival males' fitness in surprising ways.

aim: this study investigates the intraspecific competition, for food and density amongst larvae of anopheles stephensi (main malaria vector in south iran). material & methods: the effects of 4 selected food quantities (1x,2x,4x,6x) and 5 larval densities (0.1 to 3 larva/cm2) were tested individually or in combination on 7 biological indexes of the vector and the results were statistically ...

Sexual selection theory predicts that sperm competition will push males to produce more, smaller sperm. Paradoxically, in the fruitfly Drosophila bifurca sperm competition is rife but males produce few, giant sperm--the largest known. A recent study reconciles the evolution of giant sperm with theory.