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Recurrent Evolution
Recurrent evolution is the repeated evolution of a particular trait, character, or mutation. Most evolution is the result of drift, often interpreted as the random chance of some alleles being passed down to the next generation and others not. Recurrent evolution is said to occur when patterns emerge from this stochastic process when looking across multiple distinct populations. These patterns are of particular interest to evolutionary biologists, as they can demonstrate the underlying forces governing evolution. Recurrent evolution is a broad term, but is usually used to describe recurring regimes of selection within or across lineages. While most commonly used to describe recurring patterns of selection, it can also be used to describe recurring patterns of mutation; for example, transitions are more common than transversions. The concept encompasses both convergent evolution and parallel evolution, and can be used to describe the observation of similar repeating changes through ... [...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] |
Genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of 'junk' DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been sequenced and various regions have been annotated. The International Human Genome Project reported the sequence of the genome for ''Homo sapiens'' in 200The Human Genome Project although the initial "finished" sequence was missing 8% of the genome consisting mostly of repetitive sequences. With advancements in technology that could handle sequenci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diglossopis
''Diglossopis'' was a genus of blue flowerpiercers in the family Thraupidae. They are now usually placed in the genus '' Diglossa''. They were formerly classified in the bunting and American sparrow family Emberizidae, more recent studies have shown it to belong in the Thraupidae. They are restricted to highland forest and woodland from Venezuela and Colombia, through Ecuador and Peru, to Bolivia. Species list * Indigo flowerpiercer, ''Diglossopis indigotica'' – based on mtDNA Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial DNA ..., belongs in the genus ''Diglossa''. * Golden-eyed flowerpiercer, ''Diglossopis glauca''. * Bluish flowerpiercer, ''Diglossopis caerulescens''. * Masked flowerpiercer, ''Diglossopis cyanea''. References * Mauck, & Burns (2009). ''Phylogeny, biogeograp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diglossa (bird)
''Diglossa'' is a genus in the family Thraupidae. They are commonly known as flowerpiercers because of their habit of piercing the base of flowers to access nectar that otherwise would be out of reach. This is done with their highly modified bill, which is typically upswept, with a hook at the tip. Most members of the genus ''Diglossa'' are found in highlands of South America (especially the Andes), but two species are found in Central America. Taxonomy and species list The genus ''Diglossa'' was introduced by the German naturalist Johann Georg Wagler in 1832 with the cinnamon-bellied flowerpiercer (''Diglossa baritula'') as the type species. The genus name is from the Ancient Greek ''diglōssos'' meaning "double-tongued" or "speaking two languages". The genus now includes 18 species. * Golden-eyed flowerpiercer, ''Diglossa glauca'' * Bluish flowerpiercer, ''Diglossa caerulescens'' * Masked flowerpiercer, ''Diglossa cyanea'' * Indigo flowerpiercer, ''Diglossa indigotica'' * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cheilostomatida
Cheilostomatida, also called Cheilostomata, is an order of Bryozoa in the class Gymnolaemata. They are exclusively marine, colonial invertebrate animals. Cheilostome colonies are composed of calcium carbonate and grow on a variety of surfaces, including rocks, shells, seagrass and kelps. The colony shapes range from simple encrusting sheets to erect branching and even unattached forms. As in other bryozoan groups, each colony is composed of a few to thousands of individual polypides. Each individual has a U-shaped gut, and no respiratory, circulatory, or nerve system. Unique among bryozoans, cheilostome polypides are housed in a box-shaped zooids, which do not grow larger once the zooid is mature. The opening through which the polypide protrudes is protected by a calcareous or chitinous lidlike structure, an operculum. Cheilostomes possess avicularia, which have modified the operculum into a range of mandibles (possibly for defense) or hair-like setae (possibly for cleaning). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (biology)
In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the same time and belong to a panmictic population (one with random mating). Ford E.B. 1965. ''Genetic polymorphism''. Faber & Faber, London. Put simply, polymorphism is when there are two or more possibilities of a trait on a gene. For example, there is more than one possible trait in terms of a jaguar's skin colouring; they can be light morph or dark morph. Due to having more than one possible variation for this gene, it is termed 'polymorphism'. However, if the jaguar has only one possible trait for that gene, it would be termed "monomorphic". For example, if there was only one possible skin colour that a jaguar could have, it would be termed monomorphic. The term polyphenism can be used to clarify that the different forms arise from the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eusocial
Eusociality (from Greek εὖ ''eu'' "good" and social), the highest level of organization of sociality, is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform at least one behavior characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms. Eusociality exists in certain insects, crustaceans, and mammals. It is mostly observed and studied in the Hymenoptera (ants, bees, and wasps) and in Blattodea (termites). A colony has caste differences: queens and reproductive males take the roles of the so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selection Pressure
Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of change occurring in processes investigated by evolutionary biology, but the formal concept is often extended to other areas of research. In population genetics, selective pressure is usually expressed as a selection coefficient. Amino acids selective pressure It has been shown that putting an amino acid bio-synthesizing gene like ''HIS4'' gene under amino acid selective pressure in yeast causes enhancement of expression of adjacent genes which is due to the transcriptional co-regulation of two adjacent genes in Eukaryota. Antibiotic resistance Drug resistance in bacteria is an example of an outcome of natural selection. When a drug is used on a species of bacteria, those that cannot resist die and do not produce offspring, while tho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bermuda
) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , established_title2 = English settlement , established_date2 = 1609 (officially becoming part of the Colony of Virginia in 1612) , official_languages = English , demonym = Bermudian , capital = Hamilton , coordinates = , largest_city = Hamilton , ethnic_groups = , ethnic_groups_year = 2016 , government_type = Parliamentary dependency under a constitutional monarchy , leader_title1 = Monarch , leader_name1 = Charles III , leader_title2 = Governor , leader_name2 = Rena Lalgie , leader_title3 = Premier , leader_name3 = Edward David Burt , legislature = Parliament , upper_house = Senate , lower_house = House of Assembly , area_km2 = 53.2 , area_sq_mi = 20.54 , area_rank = , percent_water = 27 , elevation_max_m = 79 , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenic Bacterium
Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and are often beneficial but others can cause infectious diseases. The number of these pathogenic species in humans is estimated to be fewer than a hundred. By contrast, several thousand species are part of the gut flora present in the digestive tract. The body is continually exposed to many species of bacteria, including beneficial commensals, which grow on the skin and mucous membranes, and saprophytes, which grow mainly in the soil and in decaying matter. The blood and tissue fluids contain nutrients sufficient to sustain the growth of many bacteria. The body has defence mechanisms that enable it to resist microbial invasion of its tissues and give it a natural immunity or innate resistance against many microorganisms. Pathogenic bacteria are specially adapted and endowed with mechanisms for overcoming the norm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and does ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
