In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera. Hybrids are not always intermediates between their parents, but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are.
Cicer is a genus of the legume family, Fabaceae, and the only genus found in tribe Cicereae. It is included within the IRLC, and its native distribution is across the Middle East and Asia. Its best-known and only domesticated member is Cicer arietinum, the chickpea.
George Wells Beadle was an American geneticist. In 1958 he shared one-half of the Nobel Prize in Physiology or Medicine with Edward Tatum for their discovery of the role of genes in regulating biochemical events within cells. He also served as the 7th President of the University of Chicago.
John F. Doebley is an American botanical geneticist whose main area of interest is how genes drive plant development and evolution. He has spent the last two decades examining the genetic differences and similarities between teosinte and maize and has cloned the major genes that cause the visible differences between these two very different plants.
Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Introgression is a long-term process, even when artificial; it may take many hybrid generations before significant backcrossing occurs. This process is distinct from most forms of gene flow in that it occurs between two populations of different species, rather than two populations of the same species.
Hugh Iltis was a professor of botany and director of the herbarium at the University of Wisconsin–Madison. While he is most noted as a scientist for his role in the discovery of perennial teosinte, a wild diploid relative of modern maize, he is also remembered as an outspoken environmental conservationist.
Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be used in some broader ways. It is related to the population genetics concept of gene flow, and genetic rescue, which is genetic material intentionally introduced to increase the fitness of a population. It is called genetic pollution when it negatively impacts the fitness of a population, such as through outbreeding depression and the introduction of unwanted phenotypes which can lead to extinction.
Evolutionary developmental biology (evo-devo) is the study of developmental programs and patterns from an evolutionary perspective. It seeks to understand the various influences shaping the form and nature of life on the planet. Evo-devo arose as a separate branch of science rather recently. An early sign of this occurred in 1999.
Maize, also known as corn in North American and Australian English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native Americans planted it alongside beans and squashes in the Three Sisters polyculture. The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen, and female inflorescences called ears which yield grain, known as kernels or seeds. In modern varieties, these are usually yellow or white; other varieties can be of many colors.
Teosintes are several wild species of grass in the genus Zea which are critical components of maize evolution.
Zohapilco is in the Central Highlands of Mexico at Tlapacoya Hill, on the edge of Lake Chalco from 5500 – 2200BC. The similar site of Tlapacoya is nearby.
Guilá Naquitz Cave in Oaxaca, Mexico, is the site of early domestication of several food crops, including teosinte, squash from the genus Cucurbita, bottle gourds, and beans. This site is the location of the earliest known evidence for domestication of any crop on the continent, Cucurbita pepo, as well as the earliest known domestication of maize.
Zea diploperennis, the diploperennial teosinte, is a species of grass in the genus Zea and a teosinte. It is perennial.
Zea luxurians, also referred to by the common names Maíz de Monte, Florida teosinte and Guatemalan teosinte, is a species of flowering plant in the family Poaceae. It is a true grass and a teosinte.
Zea nicaraguensis is an annual, true grass species in the genus Zea. It is considered to be phenotypically the most distinctive, as well as the most threatened teosinte. This teosinte thrives in flooded conditions along 200 m of a coastal estuarine river in northwest Nicaragua at the Reserva Natural de Apacunca. Virtually all populations of teosinte are either threatened or endangered with Z. nicaraguensis being the most endangered, it survives as about 6000 plants in an area of 200 x 150 m. The Mexican and Nicaraguan governments have taken action in recent years to protect wild teosinte populations, using both in situ and ex situ conservation methods. Currently, a large amount of scientific interest exists in conferring beneficial teosinte traits, such as insect resistance, perennialism, and flood tolerance, to cultivated maize lines, although this is very difficult due to linked deleterious teosinte traits.
Zea perennis, the perennial teosinte, is a true grass species in the genus Zea and a teosinte.
The Cytodeme is the total assembly of organisms that use an identical suite of chromosomes to carry their genes. The term was first printed in the 1950s in a book by Heslop-Harrison. Discussing the Deme Terminology - he continued "cytodeme, a population differing in some distinctive cytological feature from others." In most cases the suite is composed of several pairs of homologous chromosomes with or without a pair of sex chromosomes. Since the only acceptable proof of the identity (homology) of chromosomes lies in their ability to pair fully from end to end during meiosis it follows that:
- In asexual taxa membership of a cytodeme can only be presumed on such evidence as visual similarity of chromosomal ideotype, but never proved.
- In sexual taxa all of the members of one cytodeme are fully intercompatible yielding the fertile progeny which proves their membership.
Domestication syndrome refers to two sets of phenotypic traits that are common to either domesticated animals, or domesticated plants. These traits were identified by Charles Darwin in The Variation of Animals and Plants Under Domestication.
The agricultural weed syndrome is the set of common traits which make a plant a successful agricultural weed. Most of these traits are not, themselves, phenotypes but are instead methods of rapid adaptation. So equipped, plants of various origins - invasives, natives, mildly successful marginal weeds of agriculture, weeds of other settings - accumulate other characteristics which allow them to compete in an environment with a high degree of human management.
