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Compilospecies
A compilospecies is a genetically aggressive species which acquires the heredities of a closely related Sympatry, sympatric species by means of hybridisation (biology), hybridisation and comprehensive introgression. The target species may be incorporated to the point of despeciation, rendering it extinct. This type of genetic aggression is associated with species in newly disturbed habitats (such as Pioneer species, pioneering species), weed species and domestication. They can be diploid or Polyploidy, polyploid, as well as sexual or primarily asexual. The term compilospecies derives from the Latin word compilo, which means to seize, to collect, to rob or to plunder. A proposed explanation for the existence of such a species with weak reproductive barriers and frequent introgression is that it allows for genetic variation. An increase in the gene pool through viable hybrids can facilitate new phenotypes and the colonisation of novel habitats. The concept of compilospecies is not frequ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. Other ways of defining species include their karyotype, DNA sequence, morphology (biology), morphology, behaviour, or ecological niche. In addition, palaeontologists 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. About 14% of these had been described by 2011. All species (except viruses) are given a binomial nomenclature, two-part name, a "binomen". The first part of a binomen is the name of a genus to which the species belongs. The second part is called the specific name (zoology), specific name or the specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apomictic
In botany, apomixis is asexual reproduction, asexual development of seed or embryo without Fertilisation, fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils. Apomictically produced offspring are genetically identical to the parent plant, except in nonrecurrent apomixis. Its etymology is Greek for "away from" + "mixing". Normal asexual reproduction of plants, such as propagation from Cutting (plant), cuttings or leaves, has never been considered to be apomixis. In contrast to parthenocarpy, which involves seedless fruit formation without fertilization, apomictic fruits have viable seeds containing a proper embryo, with asexual origin. In flowering plants, the term "apomixis" is used in a restricted sense to mean agamospermy, i.e. cloning, clonal reproduction through seeds. Although agamospermy could theoretically occur in gymnosperms, it appears to be absent in that group. Apogamy is a related term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plant Taxonomy
Plant taxonomy is the science that finds, identifies, describes, classifies, and names plants. It is one of the main branches of taxonomy (the science that finds, describes, classifies, and names living things). Plant taxonomy is closely allied to plant systematics, and there is no sharp boundary between the two. In practice, "plant systematics" involves relationships between plants and their evolution, especially at the higher levels, whereas "plant taxonomy" deals with the actual handling of plant specimens. The precise relationship between taxonomy and systematics, however, has changed along with the goals and methods employed. Plant taxonomy is well known for being turbulent, and traditionally not having any close agreement on circumscription and placement of taxa. See the list of systems of plant taxonomy. Background Classification systems serve the purpose of grouping organisms by characteristics common to each group. Plants are distinguished from animals by various ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botanical Nomenclature
Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from taxonomy (biology), taxonomy. Plant taxonomy is concerned with grouping and classifying plants; Botany, botanical nomenclature then provides names for the results of this process. The starting point for modern botanical nomenclature is Carl Linnaeus, Linnaeus' ''Species Plantarum'' of 1753. Botanical nomenclature is governed by the ''International Code of Nomenclature for algae, fungi, and plants'' (''ICNafp''), which replaces the ''International Code of Botanical Nomenclature'' (''ICBN''). Fossil plants are also covered by the code of nomenclature. Within the limits set by that code there is another set of rules, the ''International Code of Nomenclature for Cultivated Plants, International Code of Nomenclature for Cultivated Plants (ICNCP)'' which applies to plant cultivars that have been deliberately altered or selected by humans (see cultigen). Botanical nomenclature is indep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Concepts
Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, origin, evolution, and distribution of life. Central to biology are five fundamental themes: the cell as the basic unit of life, genes and heredity as the basis of inheritance, evolution as the driver of biological diversity, energy transformation for sustaining life processes, and the maintenance of internal stability (homeostasis). Biology examines life across multiple levels of organization, from molecules and cells to organisms, populations, and ecosystems. Subdisciplines include molecular biology, physiology, ecology, evolutionary biology, developmental biology, and systematics, among others. Each of these fields applies a range of methods to investigate biological phenomena, including observation, experimentation, and mathematical modeling. Modern biology is grounded i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Armeria
''Armeria'' is a genus of flowering plants. These plants are sometimes known as "lady's cushion", "thrift", or "sea pink" (the latter because as they are often found on coastlines). The genus counts over a hundred species, mostly native to the Mediterranean, although '' Armeria maritima'' is an exception, being distributed along the coasts of the Northern Hemisphere, including Ireland, parts of the United Kingdom such as Cornwall, and the Pembrokeshire Coast National Park in Wales. Some are popular with gardeners as rockery A rock garden, also known as a rockery and formerly as a rockwork, is a garden, or more often a part of a garden, with a landscaping framework of rocks, stones, and gravel, with planting appropriate to this setting. Usually these are small ... plants. During the Second World War, the UK "thruppenny bit" coin (3 old pence), which had featured a portcullis on its reverse side, changed to a depiction of the thrift plant, as a means of reminding the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Draba
''Draba'' is a large genus of flowering plants in the family Brassicaceae, commonly known as whitlow-grasses (though they are not related to the true grasses). Species There are over 400 species: *'' Draba abajoensis'' Windham & Al-Shehbaz *'' Draba × abiskoensis'' O.E.Schulz *'' Draba × abiskojokkensis'' O.E.Schulz *'' Draba acaulis'' Boiss. *'' Draba affghanica'' Boiss. *'' Draba aizoides'' L. *'' Draba alajica'' Litv. *''Draba alberti'' Regel & Schmalh. *'' Draba albertina'' Greene *''Draba alchemilloides'' Gilg *'' Draba × algida'' Adams ex DC. *'' Draba alpina'' L. *'' Draba altaica'' (C.A.Mey.) Bunge *'' Draba alticola'' Kom. *'' Draba alyssoides'' Humb. & Bonpl. ex DC. *'' Draba × amandae'' O.E.Schulz *'' Draba × ambigua'' Ledeb. *'' Draba amoena'' O.E.Schulz *'' Draba amplexicaulis'' Franch. *''Draba aprica'' Beadle *''Draba arabisans'' Michx. *'' Draba araboides'' Wedd. *'' Draba araratica'' Rupr. *'' Draba arauquensis'' Santana *'' Draba arbuscula'' Hook.f. *'' Drab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helianthus
''Helianthus'' () is a genus comprising around 70 species of annual and perennial flowering plants in the daisy family Asteraceae commonly known as sunflowers. Except for three South American species, the species of ''Helianthus'' are native to North America and Central America. The best-known species is the common sunflower (''Helianthus annuus''). This and other species, notably Jerusalem artichoke (''H. tuberosus''), are cultivated in temperateness, temperate regions and some tropical regions, as food crops for humans, cattle, and poultry, and as ornamental plants. The species ''H. annuus'' typically grows during the summer and into early fall, with the peak growth season being mid-summer. Several perennial ''Helianthus'' species are grown in gardens, but have a tendency to spread rapidly and can become aggressive. On the other hand, the whorled sunflower, ''Helianthus verticillatus'', was listed as an endangered species in 2014 when the U.S. Fish and Wildlife Service issued ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reproductive Isolation
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, ethology, behaviors and physiology, physiological processes critical for speciation. They prevent members of different species from producing offspring, or ensure that any offspring are sterile. These barriers maintain the integrity of a species by reducing gene flow between related species.Strickberger, M. 1978. ''Genética''. Omega, Barcelona, España, p.: 874–879. .Futuyma, D. 1998. ''Evolutionary biology'' (3ª edición). Sinauer, Sunderland. The mechanisms of reproductive isolation have been classified in a number of ways. Zoologist Ernst Mayr classified the mechanisms of reproductive isolation in two broad categories: pre-zygotic for those that act before fertilization (or before mating in the case of animals) and post-zygotic for those that act after it.Mayr, E. 1963. ''Animal species and evolution''. Harvard University Press, Cambridge. The mechanisms are genetics, genetically controlle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene Flow
In population genetics, gene flow (also known as migration and allele flow) is the transfer of genetic variation, genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent allele frequencies and therefore can be considered a single effective population. It has been shown that it takes only "one migrant per generation" to prevent populations from diverging due to Genetic drift, drift. Populations can diverge due to Natural selection, selection even when they are exchanging alleles, if the selection pressure is strong enough. Gene flow is an important mechanism for transferring genetic diversity among populations. Migrants change the distribution of genetic diversity among populations, by modifying allele frequencies (the proportion of members carrying a particular variant of a gene). High rates of gene flow can reduce the genetic differentiation between the two groups, increasing homogeneity. Gene flow has b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zygosity
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same locus (genetics), loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal Sex-determination system#Chromosomal determination, sex-determination system. If both alleles of a diploid organism are the same, the organism is #Homozygous, homozygous at that locus. If they are different, the organism is #Heterozygous, heterozygous at that locus. If one allele is missing, it is #Hemizygous, hemizygous, and, if both alleles are missing, it is #Nullizygous, nullizygous. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytogenetic
Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology (a subdivision of human anatomy), that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. Techniques used include karyotyping, analysis of G-banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescence ''in situ'' hybridization (FISH) and comparative genomic hybridization (CGH). History Beginnings Chromosomes were first observed in plant cells by Carl Nägeli in 1842. Their behavior in animal (salamander) cells was described by Walther Flemming, the discoverer of mitosis, in 1882. The name was coined by another German anatomist, von Waldeyer in 1888. The next stage took place after the development of genetics in the early 20th century, when it was appreciated that the set of chromosomes (the karyotype) was the carrier of the genes. Levitsky seems to have be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
