Crossbreeding is also done for the purpose of heterosis (hybrid vigor). It is second only to maize in exploiting the principles of heterosis and crossbreeding. In such instances, outcrossing should result in heterosis. Inbreeding depression and heterosis suggest the presence of genetic dominance effects for "g". Maize was the first species where heterosis was widely used to produce hybrids. In 1908, George Harrison Shull described heterosis, also known as hybrid vigor. The advantage of diploidy, heterosis, only exists in the diploid life generation. Exceptionally little information exists on the use of molecular markers to predict heterosis in triticale. Nearly all field corn (maize) grown in most developed nations exhibits heterosis. Genetic rescue can occur through multiple pathways, including heterosis and adaptive evolution. Wolfdogs are usually healthier than either parent due to heterosis. They found that hybrids ran faster than either parent, perhaps due to heterosis. Sometimes people working on a dog breeding program find no useful heterosis. The concept of heterosis is also applied in the production of commercial livestock. Caracu crosses maintain the advantages with heterosis.