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Interbreed
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different breeds, varieties, species or genera through sexual reproduction. Hybrids are not always intermediates between their parents (such as in blending inheritance), 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. Species are reproductively isolated by strong barriers to hybridisation, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neanderthals
Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the "causes of Neanderthal disappearance about 40,000 years ago remain highly contested," demographic factors such as small population size, inbreeding and genetic drift, are considered probable factors. Other scholars have proposed competitive replacement, assimilation into the modern human genome (bred into extinction), great climatic change, disease, or a combination of these factors. It is unclear when the line of Neanderthals split from that of modern humans; studies have produced various intervals ranging from 315,000 to more than 800,000 years ago. The date of divergence of Neanderthals from their ancestor ''H. heidelbergensis'' is also unclear. The oldest potential Neanderthal bones date to 430,000 years ago, but the classification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaic Human Admixture With Modern Humans
There is evidence for interbreeding between archaic and modern humans during the Middle Paleolithic and early Upper Paleolithic. The interbreeding happened in several independent events that included Neanderthals and Denisovans, as well as several unidentified hominins. In Eurasia, interbreeding between Neanderthals and Denisovans with modern humans took place several times. The introgression events into modern humans are estimated to have happened about 47,000–65,000 years ago with Neanderthals and about 44,000–54,000 years ago with Denisovans. Neanderthal-derived DNA has been found in the genomes of most or possibly all contemporary populations, varying noticeably by region. It accounts for 1–4% of modern genomes for people outside Sub-Saharan Africa, although estimates vary, and either none or possibly up to 0.3% — according to recent research — for those in Africa. It is highest in East Asians, intermediate in Europeans, and lower in Southeast Asians. Accord ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can reproduction, produce Fertility, fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology (biology), morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a binomial nomenclature, two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wolfdog
A wolfdog is a canine produced by the mating of a domestic dog (''Canis familiaris'') with a gray wolf (''Canis lupus''), eastern wolf (''Canis lycaon''), red wolf (''Canis rufus''), or Ethiopian wolf (''Canis simensis'') to produce a hybrid. Admixture There are a range of experts who believe that they can tell the difference between a wolf, a dog, and a wolfdog, but they have been proven to be incorrect when providing their evidence before courts of law. Admixture between domestic dogs and other subspecies of gray wolves are the most common wolfdogs since dogs and gray wolves are considered the same species, are genetically very close and have shared vast portions of their ranges for millennia. Such admixture in the wild have been detected in many populations scattered throughout Europe and North America, usually occurring in areas where wolf populations have declined from human impacts and persecutions. At the same time, wolfdogs are also often bred in captivity fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hybrid Speciation
Hybrid speciation is a form of speciation where hybridization between two different species leads to a new species, reproductively isolated from the parent species. Previously, reproductive isolation between two species and their parents was thought to be particularly difficult to achieve, and thus hybrid species were thought to be very rare. With DNA analysis becoming more accessible in the 1990s, hybrid speciation has been shown to be a somewhat common phenomenon, particularly in plants. In botanical nomenclature, a hybrid species is also called a nothospecies. Hybrid species are by their nature polyphyletic. Ecology A hybrid may occasionally be better fitted to the local environment than the parental lineage, and as such, natural selection may favor these individuals. If reproductive isolation is subsequently achieved, a separate species may arise. Reproductive isolation may be genetic, ecological, behavioral, spatial, or a combination of these. If reproductive isolation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments. Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations.Based on definition from: Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use. Like other scientists, biologists use t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Mixing
Genetic pollution is a controversial 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. Conservation biologists and conservationists have used the term to describe gene flow from domestic, feral, and non-native species into wild indigenous species, which they consider undesirable. They promote awareness of the effects of introduced invasive species that may "''hybridize with native species, causing genetic pollu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Impact On The Environment
Human impact on the environment (or anthropogenic impact) refers to changes to biophysical environments and to ecosystems, biodiversity, and natural resources caused directly or indirectly by humans. Modifying the environment to fit the needs of built environment, society is causing severe effects including global warming, environmental degradation (such as ocean acidification), Holocene extinction, mass extinction and biodiversity loss, ecological crisis, and ecological collapse. Some human activities that cause damage (either directly or indirectly) to the environment on a global scale include population growth, overconsumption, overexploitation, pollution, and deforestation. Some of the problems, including global warming and biodiversity loss, have been proposed as representing Global catastrophic risk, catastrophic risks to the survival of the human species. The term ''anthropogenic'' designates an effect or object resulting from human activity. The term was first used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beefalo
Beefalo constitute a hybrid offspring of domestic cattle (''Bos taurus''), usually a male in managed breeding programs, and the American bison (''Bison bison''), usually a female in managed breeding programs. The breed was created to combine the characteristics of both animals for beef production. Beefalo are primarily cattle in genetics and appearance, with the breed association defining a full Beefalo as one with three-eighths (37.5%) bison genetics, while animals with higher percentages of bison genetics are called "bison hybrids". History Accidental crosses were noticed as long ago as 1749 in the Southern states of North America, during British colonization. Cattle and bison were first intentionally crossbred during the mid- 19th century. One of the first efforts to cross-breed bison and domestic cattle was in 1815 by Mr. Robert Wickliffe of Lexington, Kentucky. Mr. Robert Wickliffe's experiments continued for up to 30 years. Another early deliberate attempt to cross-b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Breeding
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, cultivars, or breeds. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals. In animal breeding, techniques such as inbreeding, linebreeding, and outcrossing are utilized. In plant breeding, similar methods are used. Charles Darwin discussed how selective breeding had been successful in producing change over ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Domesticated Animals
This page gives a list of domesticated animals, also including a list of domestication of animals, animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includes species which are semi-domesticated, undomesticated but Captive breeding, captive-bred on a commercial scale, or commonly wild-caught, at least occasionally captive-bred, and Tame animal, tameable. In order to be considered fully domesticated, most species have undergone significant Heredity, genetic, Behavior, behavioural and Morphology (biology), morphological changes from their wild ancestors, while others have changed very little from their wild ancestors despite hundreds or thousands of years of potential selective breeding. A number of factors determine how quickly any changes may occur in a species, but there is not always a desire to improve a species from its wild form. Domestication is a gradual process ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oenothera Lamarckiana
''Oenothera glazioviana'' is a species of flowering plant in the evening primrose family known by the common names large-flowered evening-primrose and redsepal evening primrose. ''Oenothera lamarckiana'' was formerly believed to be a different species, but is now regarded as a synonym of ''Oe. glazioviana''. The plant can be found in scattered locations worldwide, mostly as an introduced species. It originated in Brazil. It has long been cultivated as an ornamental plant. In some locations it has become an invasive species. Description ''Oenothera glazioviana'' is generally a biennial herb producing an erect stem approaching in maximum height. It is roughly hairy in texture, the hairs with reddish blistering or glandular bases. The crinkly leaves are up to 15 centimeters long. The inflorescence is a showy spike of many large flowers. When in bud the long red sepals are visible. When in bloom each flower has four bright yellow petals up to 5 centimeters long which fade or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
