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Hybrid Sterility
The mechanisms of reproductive isolation are a collection of evolutionary mechanisms, behaviors and 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 genetically controlled and can appear in species wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Maturity
Sexual maturity is the capability of an organism to reproduce. In humans it might be considered synonymous with adulthood, but here puberty is the name for the process of biological sexual maturation, while adulthood is based on cultural definitions. Most multicellular organisms are unable to sexually reproduce at birth (animals) or germination (e.g. plants): depending on the species, it may be days, weeks, or years until they have developed enough to be able to do so. Also, certain cues may trigger an organism to become sexually mature. They may be external, such as drought (certain plants), or internal, such as percentage of body fat (certain animals). (Such internal cues are not to be confused with hormones, which directly produce sexual maturity – the production/release of those hormones is triggered by such cues.) Role of reproductive organs Sexual maturity is brought about by a maturing of the reproductive organs and the production of gametes. It may also be accompanied ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Ananassae
''Drosophila ananassae'' is a species In biology, a species is the basic unit of 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 s ... of fruit fly that is a useful model organism for genetic studies because it is easily cultured in the laboratory, and was one of 12 fruitfly genomes sequenced for a large comparative study. References External links ''Drosophila ananassae'' at FlyBase''Drosophila ananassae'' at Ensembl Genomes Metazoa* A {{Drosophilidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Simulans
''Drosophila simulans'' is a species of fly closely related to ''D. melanogaster'', belonging to the same ''melanogaster'' species subgroup. Its closest relatives are ''D. mauritiana'' and ''D. sechellia''. Taxonomy This species was discovered by the fly geneticist Alfred Sturtevant in 1919, when he noticed that the flies used in Thomas Hunt Morgan's laboratory at the Columbia University were actually two distinct species: ''D. melanogaster'' and ''D. simulans''. Males differ in the external genitalia, while trained observers can separate females using colour characteristics. ''D. melanogaster'' females crossed to ''D. simulans'' males produce sterile F1 females and no F1 males. The reciprocal cross produces sterile F1 males and no female progeny. ''Drosophila simulans'' was found later to be closely related to two island endemics, ''D. sechellia'' and ''D. mauritiana''. ''D. simulans'' will mate with these sister species to form fertile females and sterile males, a fact that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and life history evolution. As of 2017, five Nobel Prizes have been awarded to drosophilists for their work using the insect. ''D. melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with only four pairs of chromosomes, and large number of offspring per generation. It was originally an African species, with all non-African lineages having a common origin. Its geographic range includes all continents, including islands. ''D. melanogaster'' is a common pest in homes, restaurants, and othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chorthippus
''Chorthippus'' is a large genus of acridid grasshoppers with around 230 described species. The genus may be subdivided into subgenera including: ''Altichorthippus'', ''Chorthippus'' and ''Glyptobothrus'', with other species not placed. Species The ''Orthoptera Species File'' includes: # '' Chorthippus abchasicus'' Ramme, 1939 # '' Chorthippus acroleucus'' (Müller, 1924) (white-tipped grasshopper) # '' Chorthippus aktaci'' Ünal, 2010 # ''Chorthippus albomarginatus'' (De Geer, 1773) (lesser marsh grasshopper) type species (as ''Acrydium albomarginatum'' De Geer = ''C. albomarginatus albomarginatus'') # '' Chorthippus albonemus'' Zheng & Tu, 1964 # '' Chorthippus almoranus'' Uvarov, 1942 # '' Chorthippus alticola'' Ramme, 1921 (alpine grasshopper) # '' Chorthippus alxaensis'' Zheng, 2000 # '' Chorthippus amplilineatus'' Ma & Guo, 1995 # ''Chorthippus amplimedilocus'' Zheng & Yang, 1997 # '' Chorthippus amplintersitus'' Liu, 1981 # '' Chorthippus angulatus'' Tarbinsky, 1927 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Zealand Cicada Song
New is an adjective referring to something recently made, discovered, or created. New or NEW may refer to: Music * New, singer of K-pop group The Boyz (South Korean band), The Boyz Albums and EPs * New (album), ''New'' (album), by Paul McCartney, 2013 * New (EP), ''New'' (EP), by Regurgitator, 1995 Songs * New (Daya song), "New" (Daya song), 2017 * New (Paul McCartney song), "New" (Paul McCartney song), 2013 * New (No Doubt song), "New" (No Doubt song), 1999 *"new", by Loona from ''Yves (single album), Yves'', 2017 *"The New", by Interpol from ''Turn On the Bright Lights'', 2002 Acronyms * Net economic welfare, a proposed macroeconomic indicator * Net explosive weight, also known as net explosive quantity * Network of enlightened Women, a conservative university women's organization * Next Entertainment World, a South Korean film distribution company Identification codes * Nepal Bhasa language ISO 639 language code * New Century Financial Corporation (NYSE stock abbreviation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecious
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only about half the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. Dioecy is a dimorphic sexual system, alongside gynodioecy and androdioecy. In zoology In zoology, dioecious species may be opposed to hermaphroditic species, meaning that an individual is either male or female, in which case the synonym gonochory is more often used. Most animal species are dioecious (gon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tradescantia Subaspera
''Tradescantia subaspera'', the zigzag spiderwort, is a species of flowering plant in the family Commelinaceae, native to the eastern United States. Its zigzagging stems and wider leaves distinguish it from ''Tradescantia virginiana ''Tradescantia virginiana'', the Virginia spiderwort, is a species of flowering plant in the family Commelinaceae. It is the type species of ''Tradescantia'' native to the eastern United States. It is commonly grown in many gardens and also found ...''. It is recommended for shady naturalistic garden settings. It has three petals which are violet-blue to purple in color. Flowers bloom May to September. Subtaxa The following varieties are accepted: *''Tradescantia subaspera'' var. ''montana'' *''Tradescantia subaspera'' var. ''subaspera'' References subaspera Garden plants of North America Endemic flora of the United States Flora of Illinois Flora of Missouri Flora of the Southeastern United States Flora of Indiana Flora of Pennsylvania ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tradescantia Canaliculata
''Tradescantia ohiensis'', commonly known as bluejacket or Ohio spiderwort, is an herbaceous plant species in the genus ''Tradescantia'' native to eastern and central North America. It is the most common and widely distributed species of ''Tradescantia'' in the United States, where it can be found from Maine in the northeast, west to Minnesota, and south to Texas and Florida. It also has a very small distribution in Canada in extreme southern Ontario near Windsor.Turner, B.L. (2006). Texas species of ''Tradescantia'' (Commelinaceae). Phytologia 88: 312-331. Distinguishing features of the species include glaucous leaves and stems, leaves forming an acute angle with the stems, sepals with hairs lacking glands which are confined to the apex if present at all, and a relatively tall habit (up to about 115 cm). Typical habitats for the plant include roadsides, along railroads, and in fields and thickets. Less typically it can occur in woods, and sometimes along streams. As with ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inter-species Mating
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 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bufo Fowleri
Fowler's toad (''Anaxyrus fowleri'') is a species of toad in the family Bufonidae. The species is native to North America, where it occurs in much of the eastern United States and parts of adjacent Canada. It was previously considered a subspecies of Woodhouse's toad (''Anaxyrus woodhousii'', formerly ''Bufo woodhousii'').Fowler's Toad. Natural Resources Canada. Etymology The specific name, ''fowleri'', is in honor of naturalist Samuel Page Fowler (1800–1888) from |
