Hybrid (biology)

In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents, but can show hybrid vigour, 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 related the parent species are. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, physiological rejection of sperm cells or the developing embryo; some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering times, pollen vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and the structure of the chromosomes.

A few animal species and many plant species, are the result of hybrid speciation, including important crop plants such as wheat, where the number of chromosomes has been doubled. Human impact on the environment has resulted in an increase in the interbreeding between regional species, the proliferation of introduced species worldwide has resulted in an increase in hybridisation; this genetic mixing may threaten many species with extinction, while genetic erosion in crop plants may be damaging the gene pools of many species for future breeding. A form of intentional human-mediated hybridisation is the crossing of wild and domesticated species; this is common in modern agriculture. One such flower, Oenothera lamarckiana, was central to early genetics research into mutationism and polyploidy, it is more done in the livestock and pet trades. Human selective breeding of domesticated animals and plants has resulted is the development of distinct breeds. Hybrid humans existed in prehistory. For example and anatomically modern humans are thought to have interbred as as 40,000 years ago.

Mythological hybrids appear in human culture in forms as diverse as the Minotaur, blends of animals and mythical beasts such as centaurs and sphinxes, the Nephilim of the Biblical apocrypha described as the wicked sons of fallen angels and attractive women. The term hybrid is derived from Latin hybrida, used for crosses such as of a tame sow and a wild boar; the term came into popular use in English in the 19th century, though examples of its use have been found from the early 17th century. Conspicuous hybrids are popularly named with portmanteau words, starting in the 1920s with the breeding of tiger–lion hybrids. From the point of view of animal and plant breeders, there are several kinds of hybrid formed from crosses within a species, such as between different breeds. Single cross hybrids result from the cross between two true-breeding organisms which produces an F1 hybrid; the cross between two different homozygous lines produces an F1 hybrid, heterozygous. The F1 generation is phenotypically homogeneous, producing offspring that are all similar to each other.

Double cross hybrids result from the cross between two different F1 hybrids. Three-way cross hybrids result from the cross between an inbred line. Triple cross hybrids result from the crossing of two different three-way cross hybrids. Top cross hybrids result from the crossing of a top quality or pure-bred male and a lower quality female, intended to improve the quality of the offspring, on average. Population hybrids result from the crossing of plants or animals in one population with those of another population; these crosses between different breeds. In horticulture, the term stable hybrid is used to describe an annual plant that, if grown and bred in a small monoculture free of external pollen produces offspring that are "true to type" with respect to phenotype. Hybridisation can occur in the hybrid zones where the geographical ranges of species, subspecies, or distinct genetic lineages overlap. For example, the butterfly Limenitis arthemis has two major subspecies in North America, L. a. arthemis and L. a. astyanax.

The white admiral has a bright, white band on its wings, while the red-spotted purple has cooler blue-green shades. Hybridisation occurs between a narrow area across New England, southern Ontario, the Great Lakes, the "suture region", it is at these regions. Other hybrid zones have formed between described species of animals. From the point of view of genetics, several different kinds of hybrid can be distinguished. A genetic hybrid carries two different alleles of the same gene, where for instance one allele may code for a lighter coat colour than the other. A structural hybrid results from the fusion of gametes that have differing structure in at least one chromosome, as a result of structural abnormalities. A numerical hybrid results from the fusi

Fall Brook (Lackawanna River tributary)

Fall Brook is a tributary of the Lackawanna River in Susquehanna County and Lackawanna County, Pennsylvania, in the United States. It is 7.9 miles long and flows through Clifford Township in Susquehanna County and Fell Township, Carbondale Township, Carbondale in Lackawanna County. The watershed of the stream has an area of 12.4 square miles, making it one of the largest tributaries of the Lackwanna River. It is not designated as impaired, but does experience flow loss; the stream passes through the Fall Brook Gap. It flows over the Fall Brook Falls, which are 60 feet high. Fall Brook is situated within the Coal Region; the upper reaches of the watershed of Fall Brook are forested. However, some disturbed land is in the watershed's lower reaches. Lakes in the watershed include Fall Brook Lake. A number of sawmills were built along the stream in the 19th century and a number of bridges were constructed across it in the 20th century. Projects such as channelization and riprapping have been done on reaches of the stream in the second half of the 20th century.

Fall Brook is a Migratory Fishery. Wild trout reproduce within it. Fall Brook begins in a wetland near Birchtown in Susquehanna County, it flows south-southwest for a few tenths of a mile before crossing Pennsylvania Route 247 and turning south. The stream turns south-southwest again for several tenths of a mile, receiving an unnamed tributary from the right and exiting Clifford Township and Susquehanna County. Upon exiting Susquehanna County, Fall Brook enters Lackawanna County, it continues south-southwest for more than a mile, passing through another wetland and receiving several more unnamed tributaries: three from the left and one from the right. The stream turns south-southeast for several hundred feet before turning south-southwest again. After more than a mile, it turns southeast for a short distance and receives another unnamed tributary from the right before turning east-northeast. For the next several tenths of a mile, the stream flows east-northeast alongside Pennsylvania Route 106.

The stream turns east-southeast, entering a water gap and passing through Fall Brook Lake. After several tenths of a mile, it begins meandering south through the water gap for more than a mile, crossing Pennsylvania Route 106 several times. At the southern end of the water gap, it turns south and briefly passes through Carbondale Township before entering Carbondale. A few tenths of a mile further downstream, the stream turns south-southeast. After several tenths of a mile, it turns south-southwest and receives an unnamed tributary from the right; the stream turns south and reaches its confluence with the Lackawanna River. Fall Brook joins the Lackawanna River 28.30 miles upriver of its mouth. Fall Brook has no named tributaries. However, it has a number of unofficially named tributaries; these include "Mountain Mud Pond Run", "Sandy Banks Run", "Unnamed trib 1", "Unnamed trib 2", "Finch Hill Run", "Crystal Lake Creek", "Unnamed trib 3". Fall Brook is not designated as an impaired stream. However, the stream experiences flow loss to underground mine pools in Carbondale.

The flow loss is caused by past deep surface mining. In the summertime, reaches of the stream are dry in low flow conditions. Additionally, the lower reaches were affected by acid mine drainage as of the early 1990s. Around this time, the pH was found to be 6.9. At its mouth, the peak annual discharge of Fall Brook has a 10 percent chance of reaching 1,210 cubic feet per second, it has a 2 percent chance of reaching 2,300 cubic feet per second and a 1 percent chance of reaching 2,880 cubic feet per second. The peak annual discharge has a 0.2 percent chance of reaching 4,810 cubic feet per second. In the early 1900s, waste water from Murrins Colliery was discharged into Fall Brook. However, most of the stream's length was clear at that time, despite having one culm deposit in its vicinity; the city of Carbondale has had an NPDES permit to discharge stormwater into Fall Brook. The elevation near the mouth of Fall Brook is 1,024 feet above sea level; the elevation of the stream's source is between 1,740 feet above sea level.

Fall Brook begins on the Allegheny Plateau. It passes through a water gap known as the Fall Brook Gap; the Fall Brook Falls are on Fall Brook in the Fall Brook Gap in Carbondale Township. These falls. Additionally, the Fall Brook Glade is in the stream's watershed in Fell Township. Up to 0.25 miles downstream of the Fall Brook Falls, steep slopes with drops of 100 feet are present. Various groundwater seeps and ponds feed into the stream from Greenfield Township and Carbondale Township. Fall Brook flows through an artificial channel lined with riprap in some reaches; the stream enters coal-bearing rock formations at the Fall Brook Falls 1,300 feet above sea level. The stream is in the anthracite Coal Region, its substrate consists of boulders and sediment deposits from historic mining operations. The watershed of Fall Brook has an area of 12.4 square miles. The mouth of the stream is in the United States Geological Survey quadrangle of Carbondale. However, its source is in the quadrangle of Clifford.

Not counting the East Branch Lackawanna River and the West Branch Lackawanna River, Fall Brook is the fifth-largest tributary of the Lackawanna River. Most of the watershed is in Fell Township, Lackawanna County and Greenfield Township, Lackawanna County

Tony Chater

Anthony Philip John "Tony" Chater was a British newspaper editor and Communist activist. Born in Northampton, Chater attended Northampton Town and County Grammar School, joined the Communist Party of Great Britain whilst in the sixth form. Chater studied at Queen Mary, University of London in London, gaining a first and a PhD in chemistry in 1954. After a two years post-doctoral research fellowship at the Dominion Experimental Farm, a year at Brussels University studying biochemistry, he returned to Britain to teach at Northampton Technical High School Blyth Grammar School and from 1960 at the Luton College of Technology where he remained until 1969, he stood in the 1963 Luton by-election as a CPGB candidate, but was placed last gaining only 593 votes. Despite this, he stood in Luton again in 1966 and 1970, again without success. After being the Chair of the Communist Party of Great Britain during 1968–69, Chater began working full-time for the party as its head of press and publicity, in 1974 he swapped jobs with George Matthews becoming editor of the Morning Star, a daily paper associated with the party.

He attempted to get the party executive to prioritise increasing sales, with limited success. The paper, run by the People's Press Printing Society, the party were coming into open conflict by 1982, disagreeing on approaches to the shop stewards' movement; the following year, the revisionist party leadership attempted to remove Chater's supporters from the executive of the PPPS, but the reverse occurred, Chater's opponents were defeated instead. Chater, was expelled from the CPGB in January 1985. An opposition coalesced around Chater and Mick Costello, but they were defeated at the 1987 Party Congress and subsequently founded the Communist Party of Britain. Chater stood down as editor of the Morning Star in 1995, he died on 2 August 2016