In evolutionary biology, an evolutionary tradeoff is a situation in which evolution cannot advance one part of a biological system without distressing another part of it. In this context, tradeoffs refer to the process through which a trait increases in fitness at the expense of decreased fitness in another trait. A much agreed-on theory on what causes evolutionary tradeoffs is that due to resource limitations (e.g. energy, habitat/space, time) the simultaneous optimization of two traits cannot be achieved. Another commonly accepted cause of evolutionary tradeoffs is that the characteristics of increasing the fitness in one trait negatively affects the fitness of another trait.[1][2] This negative relationship is found in traits that are antagonistically pleiotropic (one gene responsible for multiple traits that are not all beneficial to the organism) or when linkage disequilibrium is present (non-random association of alleles at different loci during the gametic phase).[3]