Wheat, wolfdogs and even modern humans owe something to hybridization
The liger kicked off a naming habit in the 1920s, and since then we have had wholphins, pumapards and the sturddlefish. Mixing species is far from a zoo curiosity. About a quarter of plant species hybridize with another, bread wheat arose that way, and our ancestors interbred with Neanderthals.
A hybrid is an offspring whose every cell carries genetic material from two different varieties, species or even genera. That distinguishes it from a chimera, where only some cells come from another organism. The Latin word hybrida described the young of a tame sow and a wild boar, and the English term spread in the 19th century. Hybrids are not always halfway between their parents; some show hybrid vigour and outgrow both.
Most animal species are kept apart by barriers that act before or after fertilization: different breeding seasons, courtship signals, body shapes, or rejection of sperm or embryos. Plants have their own, such as mismatched flowering times or blocked pollen tubes. Still, roughly 25 percent of plant species and 10 percent of animals are known to cross with at least one other. Hybrids can pass useful genes from one species into another by breeding back with a parent, a process called introgression.
In plants, hybridization often creates new species outright. A hybrid may double its chromosomes by keeping both parents' full genomes, which leaves it unable to breed with either parent. Wheat is one of the crops born this way. Farmers and gardeners have long exploited crosses, and a hybrid evening primrose, Oenothera lamarckiana, shaped early genetics, leading Hugo de Vries to blame mutation for its odd behaviour. Wild and domestic crosses include beefalo and wolfdogs, and crosses between separate families, such as chickens with guineafowl, are genuine but extremely rare.
Where ranges meet, hybrid zones form. Two North American subspecies of the butterfly Limenitis arthemis, the white admiral and the red-spotted purple, interbreed along a narrow belt across New England, southern Ontario and the Great Lakes. Conservationists argue over hybrids. Mixing can swamp a rare lineage, yet it can also rescue one by adding genetic diversity, and laws protecting endangered species often leave hybrids out.
Source: Hybrid (biology)
