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Cytonuclear Discordance
Cytonuclear (or mito-nuclear) discordance describes the discrepancy in phylogenetic relationships using mitochondrial DNA (mtDNA) versus nuclear genes (or nuclear DNA, nDNA). In other words, mitochondrial and nuclear gene sequences may lead to different, if not contradictory, phylogenetic trees that show the relationships among 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), .... In theory, nuclear DNA and mtDNA sequences should lead to similar phylogenetic tree topologies among species but this is often not the case. Other terms for the concept are ''Nuclear-mitochondrial discordance'' or ''mito-nuclear discordance''. Examples An example are Australian rock-wallabies (''Petrogale'') in which several species form a monophyletic group with nDNA genes, but not with mtDNA. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetics
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data and observed heritable traits of DNA sequences, protein amino acid sequences, and morphology. The results are a phylogenetic tree—a diagram depicting the hypothetical relationships among the organisms, reflecting their inferred evolutionary history. The tips of a phylogenetic tree represent the observed entities, which can be living taxa or fossils. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the taxa represented on the tree. An unrooted tree diagram (a network) makes no assumption about directionality of character state transformation, and does not show the origin or "root" of the taxa in question. In addition to their use for inferring phylogenetic pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial DNA
Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in a eukaryotic cell; most of the DNA is in the cell nucleus, and, in plants and algae, the DNA also is found in plastids, such as chloroplasts. Mitochondrial DNA is responsible for coding of 13 essential subunits of the complex oxidative phosphorylation (OXPHOS) system which has a role in cellular energy conversion. Human mitochondrial DNA was the first significant part of the human genome to be sequenced. This sequencing revealed that human mtDNA has 16,569 base pairs and encodes 13 proteins. As in other vertebrates, the human mitochondrial genetic code differs slightly from nuclear DNA. Since animal mtDNA evolves faster than nuclear genetic markers, it represents a mainstay of phylogenetics and evolutionary biology. It als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear DNA
Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. It adheres to Mendelian inheritance, with information coming from two parents, one male and one female—rather than matrilineally (through the mother) as in mitochondrial DNA. Structure Nuclear DNA is a nucleic acid, a polymeric biomolecule or biopolymer, found in the nucleus of eukaryotic cells. Its structure is a double helix, with two strands wound around each other, a structure first described by Francis Crick and James D. Watson (1953) using data collected by Rosalind Franklin. Each strand is a long polymer chain of repeating nucleotides. Each nucleotide is composed of a five-carbon sugar, a phosphate group, and an organic base. Nucleotides are distinguished by their bases: purines, large bases that include adenine and gu ... [...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] |
Rock-wallaby
The rock-wallabies are the wallabies of the genus ''Petrogale''. Taxonomy The genus was established in 1837 by John Edward Gray in a revision of material at the British Museum of Natural History. Gray nominated his earlier description of ''Kangurus pencillatus'' as the type species, now recognised in the combination '' Petrogale penicillata'' (brush-tailed rock-wallaby). The author separated the species from the defunct genus ''Kangurus'', which he proposed to divide in his synopsis of the known macropod species. The following is a list of species, with common names, arranged by alliances of species groups: * Genus ''Petrogale'' ** ''P. brachyotis'' species group *** Short-eared rock-wallaby, ''Petrogale brachyotis'' *** Monjon, ''Petrogale burbidgei'' *** Nabarlek, ''Petrogale concinna'' *** Eastern short-eared rock-wallaby, ''Petrogale wilkinsi'' ** ''P. xanthopus'' species group *** Proserpine rock-wallaby, ''Petrogale persephone'' *** Rothschild's rock-wallaby, ''Pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operational Taxonomic Unit
An operational taxonomic unit (OTU) is an operational definition used to classify groups of closely related individuals. The term was originally introduced in 1963 by Robert R. Sokal and Peter H. A. Sneath in the context of numerical taxonomy, where an "operational taxonomic unit" is simply the group of organisms currently being studied. In this sense, an OTU is a pragmatic definition to group individuals by similarity, equivalent to but not necessarily in line with classical Linnaean taxonomy or modern evolutionary taxonomy. Nowadays, however, the term "OTU" is commonly used in a different context and refers to clusters of (uncultivated or unknown) organisms, grouped by DNA sequence similarity of a specific taxonomic marker gene (originally coined as mOTU; molecular OTU). In other words, OTUs are pragmatic proxies for "species" (microbial or metazoan) at different taxonomic levels, in the absence of traditional systems of biological classification as are available for macroscopic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthoptera
Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grasshoppers, locusts, and close relatives; and Ensifera – crickets and close relatives. More than 20,000 species are distributed worldwide. The insects in the order have incomplete metamorphosis, and produce sound (known as a " stridulation") by rubbing their wings against each other or their legs, the wings or legs containing rows of corrugated bumps. The tympanum, or ear, is located in the front tibia in crickets, mole crickets, and bush crickets or katydids, and on the first abdominal segment in the grasshoppers and locusts. These organisms use vibrations to locate other individuals. Grasshoppers and other orthopterans are able to fold their wings (i.e. they are members of Neoptera). Etymology The name is derived from the Gree ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcriptomics Technologies
Transcriptomics technologies are the techniques used to study an organism's transcriptome, the sum of all of its RNA transcripts. The information content of an organism is recorded in the DNA of its genome and expressed through transcription. Here, mRNA serves as a transient intermediary molecule in the information network, whilst non-coding RNAs perform additional diverse functions. A transcriptome captures a snapshot in time of the total transcripts present in a cell. Transcriptomics technologies provide a broad account of which cellular processes are active and which are dormant. A major challenge in molecular biology is to understand how a single genome gives rise to a variety of cells. Another is how gene expression is regulated. The first attempts to study whole transcriptomes began in the early 1990s. Subsequent technological advances since the late 1990s have repeatedly transformed the field and made transcriptomics a widespread discipline in biological sciences. There a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burmese Python
The Burmese python (''Python bivittatus'') is one of the largest species of snakes. It is native to a large area of Southeast Asia and is listed as Vulnerable on the IUCN Red List. Until 2009, it was considered a subspecies of the Indian python, but is now recognized as a distinct species. It is an invasive species in Florida as a result of the pet trade. Description The Burmese python is a dark-colored non-venomous snake with many brown blotches bordered by black down the back. In the wild, Burmese pythons typically grow to , while specimens of more than are unconfirmed. This species is sexually dimorphic in size; females average only slightly longer, but are considerably heavier and bulkier than the males. For example, length-weight comparisons in captive Burmese pythons for individual females have shown: at length, a specimen weighed , a specimen of just over weighed , a specimen of weighed , and a specimen of weighed . In comparison, length-weight comparisons for ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerastes (genus)
''Cerastes'' is a genus of small vipers found in the deserts and semi-deserts of northern North Africa eastward through Arabia and Iran. Three species are currently recognized by ITIS, and an additional recently described species is recognized by the Reptile Database.The Reptile Database. www.reptile-database.org. Common names for members the genus include horned vipers,Mallow D, Ludwig D, Nilson G. 2003. ''True Vipers: Natural History and Toxinology of Old World Vipers''. Malabar, Florida: Krieger Publishing Company. 359 pp. . North African desert vipers,Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Dubai: Ralph Curtis Books. Oriental Press. 192 pp. . and cerastes vipers. Parker HW, Grandison AGC. 1977. ''Snakes – a natural history''. Second Edition. London and Ithaca: British Museum (Natural History) and Cornell University Press. 108 pp. + 16 plates. LCCCN 76-54625. (cloth), (paper). Description ''Cerastes'' are small snakes, averaging less than in tota ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitochondrial Genetics
Human mitochondrial genetics is the study of the genetics of human mitochondrial DNA (the DNA contained in human mitochondria). The human mitochondrial genome is the entirety of hereditary information contained in human mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the "powerhouses" of the cell. Mitochondrial DNA (mtDNA) is not transmitted through nuclear DNA (nDNA). In humans, as in most multicellular organisms, mitochondrial DNA is inherited only from the mother's ovum. There are theories, however, that paternal mtDNA transmission in humans can occur under certain circumstances. Mitochondrial inheritance is therefore non-Mendelian, as Mendelian inheritance presumes that half the genetic material of a fertilized egg (zygote) derives from each parent. This allowed the creation of mitochondrial DNA haplogroups to study population genetics. Eighty percent of mitochondrial DNA codes for mitochond ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
