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Masatoshi Nei
(born January 2, 1931) is a Japanese-born American evolutionary biologist currently affiliated with the Department of Biology at Temple University as a Carnell Professor. He was, until recently, Evan Pugh Professor of Biology at Pennsylvania State University and Director of the Institute of Molecular Evolutionary Genetics; he was there from 1990 to 2015. Nei was born in 1931 in Miyazaki Prefecture, on Kyūshū Island, Japan. He was associate professor and professor of biology at Brown University from 1969 to 1972 and professor of population genetics at the Center for Demographic and Population Genetics, University of Texas Health Science Center at Houston (UTHealth), from 1972 to 1990. Acting alone or working with his students, he has continuously developed statistical theories of molecular evolution taking into account discoveries in molecular biology. He has also developed concepts in evolutionary theory and advanced the theory of mutation-driven evolution. Together with W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miyazaki Prefecture
is a prefecture of Japan located on the island of Kyūshū. Miyazaki Prefecture has a population of 1,073,054 (1 June 2019) and has a geographic area of 7,735 km2 (2,986 sq mi). Miyazaki Prefecture borders Ōita Prefecture to the north, Kumamoto Prefecture to the northwest, and Kagoshima Prefecture to the southwest. Miyazaki is the capital and largest city of Miyazaki Prefecture, with other major cities including Miyakonojō, Nobeoka, and Hyūga. Miyazaki Prefecture is located in southeastern Kyūshū on Japan's Pacific coast, with its coastline extending from Nobeoka near the entrance to the Bungo Channel to Shibushi Bay in Kushima. History Historically, after the Meiji Restoration, Hyūga Province was renamed Miyazaki Prefecture. In Japan, Miyazaki Prefecture was first created in 1873 when Mimitsu Prefecture was merged with parts of Miyakonojō Prefecture. The first Miyazaki existed only until 1876 when it was merged (back) into Kagoshima Prefecture. Under publ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Biology
Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions. The study of chemical and physical structure of biological macromolecules is known as molecular biology. Molecular biology was first described as an approach focused on the underpinnings of biological phenomena - uncovering the structures of biological molecules as well as their interactions, and how these interactions explain observations of classical biology. In 1945 the term molecular biology was used by physicist William Astbury. In 1953 Francis Crick, James Watson, Rosalind Franklin, and colleagues, working at Medical Research Council unit, Cavendish laboratory, Cambridge (now the MRC Laboratory of Molecular Biology), made a double helix model of DNA which changed the entire research scenario. They proposed the DNA structure based on previous research done by Ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Out Of Africa Theory
In paleoanthropology, the recent African origin of modern humans, also called the "Out of Africa" theory (OOA), recent single-origin hypothesis (RSOH), replacement hypothesis, or recent African origin model (RAO), is the dominant model of the geographic origin and early migration of anatomically modern humans (''Homo sapiens''). It follows the early expansions of hominins out of Africa, accomplished by ''Homo erectus'' and then ''Homo neanderthalensis''. The model proposes a "single origin" of ''Homo sapiens'' in the taxonomic sense, precluding parallel evolution in other regions of traits considered anatomically modern, but not precluding multiple admixture between ''H. sapiens'' and archaic humans in Europe and Asia. ''H. sapiens'' most likely developed in the Horn of Africa between 300,000 and 200,000 years ago, although an alternative hypothesis argues that diverse morphological features of ''H. sapiens'' appeared locally in different parts of Africa and converged due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutral Theory Of Molecular Evolution
The neutral theory of molecular evolution holds that most evolutionary changes occur at the molecular level, and most of the variation within and between species are due to random genetic drift of mutant alleles that are selectively neutral. The theory applies only for evolution at the molecular level, and is compatible with phenotypic evolution being shaped by natural selection as postulated by Charles Darwin. The neutral theory allows for the possibility that most mutations are deleterious, but holds that because these are rapidly removed by natural selection, they do not make significant contributions to variation within and between species at the molecular level. A neutral mutation is one that does not affect an organism's ability to survive and reproduce. The neutral theory assumes that most mutations that are not deleterious are neutral rather than beneficial. Because only a fraction of gametes are sampled in each generation of a species, the neutral theory suggests that a mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide Diversity
Nucleotide diversity is a concept in molecular genetics which is used to measure the degree of polymorphism within a population. One commonly used measure of nucleotide diversity was first introduced by Nei and Li in 1979. This measure is defined as the average number of nucleotide differences per site between two DNA sequences in all possible pairs in the sample population, and is denoted by \pi. An estimator for \pi is given by: : \hat = \frac \sum_ x_i x_j \pi_ = \frac \sum_^n \sum_^ 2 x_i x_j \pi_ where x_i and x_j are the respective frequencies of the i th and j th sequences, \pi_ is the number of nucleotide differences per nucleotide site between the i th and j th sequences, and n is the number of sequences in the sample. The term in front of the sums guarantees an unbiased estimator, which does not depend on how many sequences you sample. Nucleotide diversity is a measure of genetic variation. It is usually associated with other statistical measures of population d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fixation Index
The fixation index (FST) is a measure of population differentiation due to genetic structure. It is frequently estimated from genetic polymorphism data, such as single-nucleotide polymorphisms (SNP) or microsatellites. Developed as a special case of Wright's F-statistics, it is one of the most commonly used statistics in population genetics. Definition Two of the most commonly used definitions for FST at a given locus are based on 1) the variance of allele frequencies between populations, and on 2) the probability of Identity by descent. If \bar is the average frequency of an allele in the total population, \sigma^2_S is the variance in the frequency of the allele between different subpopulations, weighted by the sizes of the subpopulations, and \sigma^2_T is the variance of the allelic state in the total population, FST is defined as : F_ = \frac = \frac Wright's definition illustrates that FST measures the amount of genetic variance that can be explained by population stru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Distance
Genetic distance is a measure of the genetic divergence between species or between populations within a species, whether the distance measures time from common ancestor or degree of differentiation. Populations with many similar alleles have small genetic distances. This indicates that they are closely related and have a recent common ancestor. Genetic distance is useful for reconstructing the history of populations, such as the multiple human expansions out of Africa. It is also used for understanding the origin of biodiversity. For example, the genetic distances between different breeds of domesticated animals are often investigated in order to determine which breeds should be protected to maintain genetic diversity. Biological foundation In the genome of an organism, each gene is located at a specific place called the locus for that gene. Allelic variations at these loci cause phenotypic variation within species (e.g. hair colour, eye colour). However, most alleles do not hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudogenes
Pseudogenes are nonfunctional segments of DNA that resemble functional genes. Most arise as superfluous copies of functional genes, either directly by DNA duplication or indirectly by reverse transcription of an mRNA transcript. Pseudogenes are usually identified when genome sequence analysis finds gene-like sequences that lack regulatory sequences needed for transcription or translation, or whose coding sequences are obviously defective due to frameshifts or premature stop codons. Most non-bacterial genomes contain many pseudogenes, often as many as functional genes. This is not surprising, since various biological processes are expected to accidentally create pseudogenes, and there are no specialized mechanisms to remove them from genomes. Eventually pseudogenes may be deleted from their genomes by chance DNA replication or DNA repair errors, or they may accumulate so many mutational changes that they are no longer recognizable as former genes. Analysis of these degeneration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y Chromosome
The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or absence of Y that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the gene SRY, which triggers male development. The DNA in the human Y chromosome is composed of about 59 million base pairs, making it similar in size to chromosome 19. The Y chromosome is passed only from father to son. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest-evolving parts of the human genome. The human Y chromosome carries an estimated 100–200 genes, with between 45 and 73 of these being protein-coding. All single-copy Y-linked genes are hemizygous (present on only one chromosome) except in cases of aneuploidy such as XYY syndrome or XXYY syndrome. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a basic unit of heredity and the molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and noncoding genes. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes (many different genes) as well as gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Society For Molecular Biology And Evolution
The Society for Molecular Biology and Evolution (SMBE) is a scientific and academic organization founded in 1982 to support academic research in the field of molecular evolution. The society hosts an annual meeting, typically in June or July. It also supports satellite meetings throughout the year. The Society's first president was evolutionary biologist Walter M. Fitch. The current President is James McInerney. Publishing In 1983, the society began publishing the journal ''Molecular Biology and Evolution'' with Oxford University Press. The society began publishing a second journal, ''Genome Biology and Evolution'', in 2009. Past Presidents 2021: Harmit Malik 2020Marta Wayne 2019: Aoife McLysaght 2018: William F. Martin 2017: Laura Landweber 2016: Jianzhi (George) Zhang 2015: Joe Felsenstein 2014Brandon Gaut 2013Sudhir Kumar 2012: Charles Aquadro 2011: Ken Wolfe 2010: Jody Hey 2009: Michael Lynch 2008: Paul Sharp 2007: Deborah Charlesworth 2006: Montserrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
