Evolution (in biology studies) means a change in the inherited traits of a population of organisms from one generation to the next. These changes are caused by a combination of three main processes: variation, reproduction, and selection. The properties on which the evolution is carried by genes that are passed to the descendants of a living thing and to be varied within a population. When organisms reproduce, their offspring will have the new properties. New properties can be obtained from the changes due to gene mutation or gene transfer between populations and between species. In species that reproduce sexually, new combinations of genes that are also produced by genetic recombination, which can increase variation between organisms. Evolution occurs when these inherited differences become more common or rare in a population.Evolution is driven by two main mechanisms, namely natural selection and genetic hanyutan. Natural selection is a process that causes terwaris properties that are useful for the survival and reproduction of organisms become more common in a population - and vice versa, the nature of the harm becomes more reduced. This occurs because individuals with advantageous traits are more likely to reproduce large, so that more individuals in the next generation that inherits the properties of this beneficial. [1] [2] After several generations, adaptations occur through a combination of small changes in the nature of the occur continuously and randomly by natural selection. [3] Meanwhile, genetic hanyutan (English: Genetic Drift) is a free process that produces random changes in the frequency characteristics of a population. Genetic Hanyutan generated by the probability whether a trait is inherited as an individual will survive and reproduce.
Although the changes produced by natural selection hanyutan and small, these changes will accumulate and lead to substantial changes in the organism. This process culminated in producing new species. [4] And in fact, the similarity between a single organism with other organisms mensugestikan that all the species that we know it originated from a common ancestor through divergent processes that happen slowly is. [1]
Documentation of facts carried out by a branch of evolutionary biology called evolutionary biology. This branch also develop and test theories that explain the causes of evolution. Study of the fossil record and the biodiversity of living organisms has convinced scientists in the mid-nineteenth century that species changed over time. [5] [6] However, the mechanisms that drive these changes remained unclear until the publication in 1859 by Charles Darwin, On the Origin of Species, explaining in detail the theory of evolution through natural selection. [7] Darwin's work was soon followed by a reception with the theory of evolution in the scientific community. [8] [9] [10] [11] In 1930, Darwin's theory of natural selection coupled with the theory of Mendelian inheritance, form the modern evolutionary synthesis, [12] that connects the unit of evolution (genes) with a mechanism of evolution (natural selection). Power of explanation and prediction of this theory encourages research that continually raises new questions, in which it has been a central principle of modern biology that provides a more thorough explanation of biological diversity on Earth. [9] [10] [13]
Although the theory of evolution is always associated with Charles Darwin, but the fact that evolutionary biology has been rooted since the time of Aristotle. Nevertheless, Darwin was the first scientist who sparked the theory of evolution that has been widely proven to face a well-established scientific testing. Until recently, Darwin's theory of evolution by natural selection is considered by the majority of the scientific community as the best in explaining the theory of evolution. [14]Table of contents
[Hide]
* 1 History of evolutionary thought
* 2 The genetic basis of evolution
* 3 Variation
3.1 Mutation
3.2 Types of sex and recombination
3.3 Genetics of populations
3.4 The flow of genes
* 4 The mechanism
o 4.1 The selection of natural
o 4.2 Hanyutan genetics
* 5 As a result of evolution
o 5.1 Adaptation
o 5.2 coevolution
o 5.3 Cooperation
o 5.4 The establishment of new species (speciation)
o 5.5 Extinction
* 6 The history of the evolution of life
o 6.1 The origin of life
o The common ancestor 6.2
o 6.3 The evolution of life
* 7 The response of social and cultural
* 8 Applications
* 9 References
* 10 External links
[Edit] History of evolutionary thought! Main article: History of evolutionary thoughtAlfred Wallace, known as the Father of Biogeography EvolutionCharles Darwin at age 51, some time after publishing the book On the Origin of Species.
The thoughts are like the common ancestor evolution and transmutation of species have existed since at least the 6th century BC when it is described in detail by a Greek philosopher, Anaximander. [15] Some people with the same thoughts include Empedocles, Lucretius, the Arab biologiawan Al-Jahiz, [16] Persian philosopher Ibn Miskawayh, Ikhwan As-Safa, [17] and the Chinese philosopher Zhuangzi. [18] Along with the development of biological knowledge in the 18th century, the concept of evolution began to be traced by some philosophers such as Pierre Maupertuis in Erasmus Darwin in 1745 and 1796. [19] Thought biologiawan Jean-Baptiste Lamarck about transmutation of species had a wide influence. Charles Darwin was formulating ideas on natural selection in 1838 and is still developing his theory in 1858 when Alfred Russel Wallace sent a similar theory in his letter "Letter from Ternate". Both were presented to the Linnean Society of London as two separate works. [20] In late 1859, the publication of Darwin, On the Origin of Species, natural selection explains in detail and provide evidence to encourage the widespread acceptance of evolution in the scientific community.
The debate continues regarding the mechanism of evolution, and Darwin can not explain the source of inherited variation that are selected by natural selection. Like Lamarck, he thought that parents pass on adaptations acquired during his life, [21] theory which was then known as Lamarckism. [22] In the 1880s, August Weismann experiments indicate that these changes are not inherited, and gradually abandoned Lamarkisme . [23] [24] In addition, Darwin could not explain how traits are passed from one generation to another. In 1865, Gregor Mendel discovered that inheritance of acquired traits can be predicted. [25] When Mendel's work was rediscovered in the 1900s, the incompatibility of the rate predicted by evolutionary geneticist and evolutionary models of the relationship crack biometrikawan Mendel and Darwin.
Nevertheless, it is the rediscovery of Gregor Mendel's work on genetics (which was unknown to Darwin and Wallace) by Hugo de Vries and others in the early 1900s that gave impetus to the understanding of how variation occurs in the nature of plants and animals. Natural selection uses these variations to form a diversity of properties observed in the adaptation of living organisms. Although geneticist Hugo de Vries and was initially very critical of the theory of evolution, the rediscovery of genetics and follow-up research ultimately provide a solid foundation of evolution, even more convincing than when the theory was first proposed. [26]
The contradiction between Darwin's theory of evolution through natural selection with Mendel's work together in the 1920s and 1930s by the biologiawan evolution as JBS Haldane, Sewall Wright, and especially Ronald Fisher, who compiled the basics of population genetics. The result is a combination of evolution through natural selection with Mendelian inheritance of the modern evolutionary synthesis. [27] In the 1940s, the identification of DNA as genetic material by Oswald Avery et al. and publication of DNA structure by James Watson and Francis Crick in 1953, provides the physical basis of this inheritance. Since then, genetics and molecular biology at the core of evolutionary biology and have revolutionized phylogenetic. [12]
At the beginning of its history, mainly from biologiawan evolutionary scientists in the field of taxonomy-oriented. Along with the development of modern evolutionary synthesis, evolutionary biology attract more scientists from other fields of biological science. [12] The study of evolutionary biology today involves a scientist who dwell in the fields of biochemistry, ecology, genetics, and physiology. The concept of evolution is also used further in areas such as psychology, medicine, philosophy, and computer science.[Edit] The basis of genetic evolutionMain article for this section are: Introduction to evolution, Genetics, and HeredityStructure of DNA. Nucleotide bases at the center, surrounded by sugar-phosphate chains in the form of a double helix.
The evolution of organisms occurs through changes in inherited traits. Eye color in humans, for example, are traits that are inherited. [28] The nature of inherited genes and controlled by the overall gene in an organism's genome is called genotype. [29]
The overall characteristics observed in the behavior and structure of organisms called the phenotype. These properties originate from the interaction of genotype with the environment. [30] Therefore, not every aspect of the phenotype of an organism are inherited. The resulting dark-colored skin from drying sun comes from the interaction between a person's genotype with the sun; that dark skin color will not be inherited to the descendants of that person. Even so, people have different responses to sunlight, and is caused by differences in the genotype. Examples are individuals with albino trait that will not darken his skin and is very sensitive to sunburn. [31]
Inherited traits passed down between generations via DNA, a molecule that can store genetic information. [29] DNA is a polymer consisting of four types of nucleotide bases. The order of bases in DNA molecules determines specific genetic information. Sections of DNA molecules that determine a functional unit called a gene; different genes have different base sequences. In the cell, long strands of DNA associated with proteins, forming dense structures called chromosomes. Specific location on a chromosome known as the locus. If the DNA sequences at a locus varies between individuals, different shapes in this sequence is referred to as alleles. DNA sequences can change through mutations, producing new alleles. If a mutation occurs in genes, new alleles may affect individual properties that are controlled by genes, causing changes in the organism phenotype. However, when this example shows how allele and the nature of work in some cases, most of the properties is more complex and controlled by the interaction of many genes. [32] [33][Edit] VariationMain article for this section are: Genetic diversity and population genetics
Phenotype of an individual organism resulting from genotype and environmental influences such organisms. Substantial phenotypic variation in a population caused by differences in genotype. [33] The modern evolutionary synthesis defines evolution as a change from time to time on this genetic variation. The frequency of a particular allele will fluctuate, becoming more common or less common relative to other forms of that gene. The driving force of evolutionary work by encouraging changes in the frequency of this allele in one direction or another. Variation disappears when an allele reaches fixation point, ie when he disappeared from a population or a whole he has replaced the ancestral allele. [34]
Variation comes from mutations of genetic material, migration between populations (gene flow), and changes in the composition of genes through sexual reproduction. Variations also come from the substitution of genes between different species; for example through horizontal gene transfer in bacteria and hybridization in plants. [35] Although there are variations that occur continuously through these processes, most of the species genome is identical in all individuals of species them. [36] However, even small changes in genotype can result in dramatic changes in phenotype. For example, chimpanzees and humans differ only in 5% of its genome. [37][Edit] MutationsMain article for this section are: Mutation and Molecular EvolutionDoubling the chromosome
Genetic variation comes from random mutations that occur in the genomes of organisms. Mutations are changes in the cell genome and the DNA sequence caused by radiation, viruses, transposons, mutagenic chemicals, as well as errors during the process of meiosis or DNA replication. [38] [39] [40] mutagen-mutagen produces some kind of change in DNA sequence . This can result in changes in gene products, preventing the gene function, atupun no effect at all. Studies in the fly Drosophila melanogaster suggest that if a mutation changing the protein produced by a gene, 70% of these mutations have a detrimental effect and the rest neutral or slightly beneficial. [41] Because adverse effects of mutations on the cell, the organism has a repair mechanism DNA to eliminate mutations. [38] Therefore, the optimal mutation rate for a species is a compromise pay high mutation rate of disadvantage, for a fee of metabolic systems to reduce the rate of mutations, such as DNA repair enzymes. [42] Some species, such as retroviruses have a speed mutation is high, so apparently the offspring will have the mutated gene. [43] Mutations were chosen so quickly as the virus is able to constantly and rapidly evolving, so it can avoid the human immune system response. [44]
Mutations can involve large fragments of DNA duplication, which is the main source of raw material for evolving new genes, with tens to hundreds of genes duplicated in animal genomes every million years. [45] Most genes are part of the same ancestral gene family is more large. [46]
Gene is produced by several methods, commonly through the ancestral gene duplication and mutation or by recombining parts of different genes, forming new combinations with new functions. [47] [48] For example, the human eye uses four genes to produce structures that can sense light : three for the cone cells, and one for the stem cells; whole originated from one single ancestral gene. [49] The advantage of gene duplication (or even the whole genome) is that the overlap or excessive functions on multiple genes allows alleles maintained (if not be harmful), thereby increasing genetic diversity. [50]
Changes in chromosome number may involve even larger mutations, a segment of DNA in chromosomes is lost then reorganized. For example, two chromosomes in the genus Homo united to form human chromosome 2; pernyatuan this does not occur in lineages other apes, and retained as two separate chromosomes. [51] The most important role of this chromosomal rearrangement in evolution is likely to accelerate the divergence of populations into a new species by making populations do not breed with each other, thereby maintaining the genetic differences between these populations. [52]
DNA sequences that can move in the genome, such as transposons, a major part in the genetic material of plants and animals, and can have an important role in genome evolution. [53] For example, more than one million copies of Alu sequences present in the human genome, and sequence -sequence has been used to perform functions such as regulation of gene expression. [54] Another effect of moving the DNA sequence of this is when he moves in a genome, it can mutate or mendelesi existing genes, thus generating genetic diversity. [55][Edit] Sex and recombinationMain article for this section are: genetic recombination and sexual reproduction
In asexual organisms, genes are inherited together, or linked, because he can not mix with genes of other organisms during reproduction. Offspring of sexual organisms contain random mixtures ancestral chromosome segregation generated through freely. In the process of genetic recombination-related, sexual organisms can also bertukarganti DNA between the two corresponding chromosomes. [56] recombination and segregation re not mengubahan allele frequencies, but the change which alleles are associated with each other, producing offspring with new combinations of alleles. [57 ] When the process is increased variation in any individual's offspring, genetic mixing can be predicted to produce no effect, increase, or reduce the genetic variation in populations, depending on how the various alleles in the population is distributed. For example, if two alleles were randomly distributed in a population, then sex will not give effect to the variation. However, if the two alleles tend to be found as a pair, then genetic mixing will balance the non-random distribution of these, and from time to time to make the organism in the population become more similar to each other. [57] The overall effect of gender on the natural variation is not clear , but recent research suggests that sex usually increases genetic variation and can increase the rate of evolution. [58] [59]
Recombination allows the same alleles are adjacent to each other on a strand of DNA is inherited independently. However, the rate of recombination is low, because in humans with a piece of one million base pairs of DNA, there is one in a hundred chance of recombination events occur per generation. As a result, adjacent genes on chromosome do not always drawn back away from one another, so it tends to be inherited together. [60] This tendency is measured by finding how often two alleles of different genes are found together, the so-called imbalance linkage (linkage disequilibrium) . A set of alleles are usually inherited together as a group referred to as haplotypes.
Sexual reproduction helps eliminate harmful mutations and retain beneficial mutations. [61] As a result, when alleles can not be separated by recombination (eg mammalian Y chromosome is passed down from father to son), accumulate detrimental mutations. [62] [63] In addition, recombination and segregation can re-produce individuals with new combinations of genes and profitable. This positive effect is balanced by the fact that this process can cause mutations and separate beneficial combinations of genes. [61][Edit] Genetics of populationsPeppered white BetulariaPeppered black Betularia
From the standpoint of genetics, evolution is change in allele frequency in the population who share the gene pool (gene pool) from one generation to another generation. [64] A population is a localized group of individuals which is the same species. For example, all the moths with the same species living in an isolated forest represent a population. A single gene in this population may have alternate forms that are responsible for phenotypic variation between organisms. An example is the gene responsible for the color of the moth has two alleles: black and white. Gene pool is a whole set of alleles at a single population, so that each allele appears in the gene pool a few times. The fraction of genes in the gene pool which is a particular allele is referred to as allele frequencies. Evolution occurs when there is a change in allele frequency in a population of organisms that breed with each other; as an example for the black allele in a population of moths becoming more common.
To understand the mechanisms that cause a population to evolve, it is useful to consider what conditions are required by a population not to evolve. Hardy-Weinberg principle states that the frequency of alleles (variations in a gene) on a sufficiently large population will remain constant if the thrust contained in this population was a random rearrangement of alleles during the formation of sperm or egg cell and a random combination of alleles of these sex cells during fertilization. [65] as this population is said to be in Hardy-Weinberg equilibrium and did not evolve. [66][Edit] The flow of genesMain article for this section are: gene flow, hybrid, and horizontal gene transferMale lion left the group in which he was born, and headed to a new group to mate. This leads to gene flow between groups of lions.
Gene flow is the exchange of genes between populations, which is usually the same species. [67] Examples of gene flow within a species include the migration and proliferation of the organism or the exchange of pollen. Gene transfer between species includes the formation of hybrid organisms and horizontal gene transfer.
Migration into or out of a population can change allele frequencies, and increase the genetic variation in a population. Immigration may add new genetic material into the gene pool that already exist in a population. Conversely, emigration can eliminate the genetic material. Because the reproductive separation between the two populations berdivergen needed to happen speciation, gene flow can slow this process by spreading genetic differ between populations. Gene flow blocked by mountain ranges, oceans, and deserts. Even men like building the Great Wall of China can block the flow of plant genes. [68]
Depending on the extent to which the two species have been berdivergen since their most recent common ancestor, it is possible the two species to produce offspring, as in horses and donkeys are the results of mating mixtures produce mules. [69] Hybrids are usually sterile, because two different sets of chromosomes do not can pair up during meiosis. In this case, closely related species can mate with each other regularly, but the resulting hybrid will be selected out, and the two species remain distinct. However, an affordable hybrid breed is sometimes formed, and this new species can have properties between the two ancestral species or a whole new phenotype. [70] The importance of hybridization in the formation of new species of animals is not clear, although some cases have been found on many types of animals, [71] Hyla versicolor is an example of an animal that has been well studied. [72]
Hybridization is an important way of speciation in plants, since polyploidy (having more than two copies on each chromosome) can be tolerated in plants than animals. [73] [74] on hibdrid polyploidy is very important because it allows reproduction, with two sets of chromosomes different, each chromosome can be paired with an identical partner during meiosis. [75] Poliploid Yeng also have more genetic diversity, which allows it to avoid inbreeding depression (inbreeding depression) in small populations. [76]
Horizontal gene transfer is the transfer of genetic material from one organism to another organism that is not its offspring. It is most common in bacteria. [77] In the field of medicine, this is contributing to antibiotic resistance. When the bacteria gain resistance gene, he will quickly transfer them to other species. [78] horizontal gene transfer from bacteria to eukaryotes such as yeasts Saccharomyces cerevisiae and the beetle Callosobruchus chinensis may also occur. [79] [80] Examples of large-scale transfers are in eukaryotes bdelloid rotifers, which appears to have received genes from bacteria, fungi, and plants. [81] Viruses can also carry DNA between organisms, allowing gene transfer between domains. [82] large-scale gene transfer has occurred between the ancestral eukaryote cell with prokaryotes during the acquisition of chloroplasts and mitochondria. [83][Edit] Mechanism
The main mechanism for generating evolutionary change is natural selection and genetics hanyutan. Natural selection favored genes that enhance survival and reproductive capacity. Hanyutan genetics is a random change in allele frequency, caused by a random sample (random sampling) the generation of genes during reproduction. Gene flow is the transfer of genes within and between populations. The relative importance of natural selection and genetics hanyutan in a population vary, depending on the strength of selection and effective population size, which is the number of individuals who are capable to proliferate. [84] Natural selection usually dominates on large populations, while hanyutan dominate in population genetics small. Hanyutan genetic dominance in small populations may even lead to fixation of mutations that little harm. [85] Therefore, by changing population size can dramatically affect the direction of evolution. Population bottleneck, where populations are shrinking for a while and loss of genetic variation, leading to a more uniform population. [34] bottle neck caused by changes in gene flow, such as decreased migration, expansions into new habitats, or population subdivision. [ 84][Edit] Natural selectionMain article for this section include: Natural Selection and Fitness (biology)Natural selection population of dark-colored skin.
Natural selection is a process in which genetic mutations that increase the survival and reproduction of an organism to be (and remain) more common than genarasi generation to another in a population. He is often referred to as a mechanism that "proved himself" because:
* Variation in populations of organisms are inherited.
* Organisms produce more offspring than can survive
* Offspring-offspring vary in their ability to survive and reproduce.
These conditions produce competition between organisms to survive and reproduce. Therefore, organisms with traits more favorable will be more likely to pass on its nature, whereas an unfavorable likely will not be passed on to the next generation.
Central concept of natural selection is the evolutionary fitness of organisms. Fitness measure the contribution of genetic evolution of organisms on the next generation. However, this is not the same as the total number of offspring, but fitness measures the proportion of such generation to carry the genes of an organism. [86] Therefore, if an allele increases fitness more than the other alleles, then in each generation, is becoming more common allele in the population. Examples of properties that can improve fitness is to increase survival and fecundity. Conversely, the lower fitness caused by alleles that are less beneficial or detrimental result of this allele becomes more rare. [2] It is important to note that the fitness of an allele is not a fixed characteristic. If the environment changes, the properties that were previously neutral or harmful can be a lucrative and previously profitable can be detrimental. [1].
Natural selection in a population for a trait whose value varies, for example height, can be categorized into three types. The first is directional selection (directional selection), which is the average shear value of properties within a certain time interval, for example, organisms tend to be higher. [87] Second, the selection breaker (disruptive selection), a selection of extreme value, and often result in two different values becoming more common (by selecting out the average value). This occurs when either the short or long-organisms beneficial, whereas higher organisms with no medium. Third, selection pemantap (stabilizing selection), the selection of extreme values, causing a decrease in the variation around the average value. [88] This can cause organisms to slowly have the same height.
The special case of natural selection is sexual selection, which is a selection for traits that increase mating success by increasing the attractiveness of an organism. [89] The properties that evolved through sexual selection primarily found in males of some species of animals. Although this trait can decrease the survival of individual males (eg deer antlers are large and bright colors can attract predators), [90] This survival disadvantage is balanced by higher reproductive success in penjantan. [91]
Areas of active research in the field of evolutionary biology at present is the unit of selection, with natural selection works proposed at the gene level, cells, individual organisms, groups of organisms, and even species. [92] [93] From these models, nothing is exclusive, and selection can work on several levels simultaneously. [94] Under the individual level, a gene called transposons try menkopi himself across the genome. [95] Selection at a level above the individual, such as group selection, may allow the evolution of co- the operation. [96][Edit] Hanyutan geneticsMain article for this section are: Hanyutan genetics and effective population sizeSimulation hanyutan 20 alleles that are not genetically linked to the number of population 10 (top) and 100 (bottom). Hanyutan reach fixation faster on smaller populations.
Hanyutan ingsut genetics or a genetic change in allele frequency from one generation to the next that occurs because alleles in offspring are a random sample (random sample) from his parents: but that he also occur because of the role of probability in determining whether an individual will survive and reproduce or not. [34] In mathematical terms, alleles potentially experienced pilot error (sampling error). Therefore, when there is no thrust selective or relatively weak, allele frequencies tend to "menghanyut" up or down at random (random step). Hanyutan is stopped when an allele eventually becomes fixed, either because it disappears from the population, or replacing the whole other allele. Hanyutan genetics can therefore eliminate some alleles from a population by chance alone. Even at ketidadaan selective force, hanyutan genetics can lead to two separate populations with the same genetic structure menghanyut into two divergent populations with different sets of alleles. [97]
Time for an allele to become fixed by genetic hanyutan depends on population size, with fixation occurring more rapidly in smaller populations. [98] Measurement of the appropriate population is the effective population size, which is defined by Sewall Wright as the theoretical number representing the number of breeding individuals which will show the same degree of proliferation was observed.
Although natural selection is responsible for the adaptation, the relative importance of natural selection and genetics hanyutan in driving evolutionary change in general is a field of research in evolutionary biology. [99] This investigation suggested by the neutral theory of molecular evolution, which proposed that most evolutionary change is the result of the fixation neutral mutations that do not have an immediate effect on the fitness of an organism. [100] Thus, in this model, most genetic changes in populations sebuat is the result of constant pressure and hanyutan genetic mutation. [101][Edit] As a result of evolution
Evolution influences every aspect of the shape and behavior of organisms. The most visible is the physical and behavioral adaptations caused by natural selection. These adaptations help improve your fitness with activities like finding food, avoiding predators, and attract the opposite sex. Organisms can also respond to selection by berkooperasi each other, usually by helping each other in a symbiosis. In the long term, evolution produces new species through splitting ancestral populations of organisms into new groups that will not be mixed mating.
As a result of evolution are sometimes divided into macroevolution and microevolution. Macroevolution is evolution that occurs at levels above species, such as extinction and speciation. While microevolution is a small evolutionary changes, such as the adaptation that occurs within species or populations. In general, macroevolution is considered as a long-term consequences of microevolution. [102] Thus, the difference between microevolution to macroevolution is not so much with exception of the time involved in the process. [103] However, in macroevolution, the properties of the whole species is important. For example, variations in large numbers among individuals allows a species rapidly adapt to new habitats, reduce the possibility of extinction. While a broad geographic range increases the likelihood of speciation by making some populations become isolated. In this sense, microevolution and macroevolution can involve selection at different levels, with microevolution work on genes and organisms, versus macroevolution who worked on the entire species and affect the rate of speciation and extinction. [104] [105] [106]
There is a misconception that evolution is "progressive", but natural selection does not have long-term goals and do not necessary result in greater complexity. [107] Although complex species evolved from evolution, this occurs as a side effect of increasing the number of organisms, and simple forms of life remain more common. [108] For example, a large majority of species are microscopic prokaryotes that make up half the world's biomass despite its small, [109] as well as a majority of the biodiversity of the earth. [110] The organism is therefore the simplest life forms dominant in the earth in its history until now. Complex life seems to be more diverse because it is more easily observed. [111][Edit] Adaptation
! For more details on this topic, see Adaptation.
Adaptation is the structure or behavior that improve the function of certain organs, causing the organism to better survive and reproduce. [7] It was caused by a combination of random changes in small-scale nature of the organism is continuously followed by natural selection the most suitable variant of the its environment. [112] This process can lead to the addition of new traits or loss of ancestral traits. An example is the adaptation of bacteria to antibiotic selection through genetic changes that cause antibiotic resistance. This can be achieved by altering the drug target or enhance the activity of transporters that pump drugs out of cells. [113] Another example is the bacterium Escherichia coli evolved to be capable of using citric acid as a nutrient in a long-term laboratory experiments, [114] or the Flavobacterium managed to produce enzymes that allow these bacteria to grow on the waste production of nylon. [115] [116]
However, many traits that seems to be a simple adaptation is actually a eksaptasi, ie, a structure that was originally adapted for specific functions, but by chance have other functions in the evolutionary process. [117] An example is the African lizard Holaspis guentheri who developed head shape is very flat to be able to hide in the crevices of cracks, as can be seen in close relatives of this species. However, in this species, the head becomes very flat, so it helps the species glide from tree to tree. [117] Another example is the use of enzymes of glycolysis and the metabolism of xenobiotics as a structural protein called crystalline (crystallin) in the eye lens of the organism. [118] [119]Baleen whale skeleton, labeled a and b is the fin leg bone which is an adaptation of the front leg bone, while c indicates vestigial leg bones. [120]
When adaptation occurs through the slow modification of existing structures, with the internal organizational structure can have very different functions in related organisms. This is the result of ancestral structures that are adapted to function in different ways. Bones in bat wings for example, is structurally similar to human hands and fin seals because of the same ancestral structure that has five fingers. Idiosyncratic anatomical features other is the bone in the wrist formed pandas to "thumb" false, indicating that an organism's evolutionary lineage can limit what adaptations are possible. [121]
During adaptation, some structures may lose function initially and become vestigial structures. [122] The structure may have a small function or no function in the species present, but has a clear function in ancestral species or other closely related species. Examples include pseudogenes, [123] the rest of the eye that does not work on the blind cave fish, [124] wings on the bird can not fly, [125] and the presence of hip bones in whales and snakes. [126] Examples of vestigial structures in humans include wisdom teeth, [127] the coccyx, [122] and appendix (appendix vermiformis). [122]
Field of the present investigation on evolutionary developmental biology is based on the adaptation and development eksaptasi. [128] This research addresses the origins and evolution of embryonic development, and how modifications of development and this development process produces new traits. [129] Studies in the field This suggests that evolution can alter development and generate new structures, such as the bone structure of the embryo that develops into the jaw in some animals than to the middle ear in mammals. [130] It is possible for structures that have been lost during the evolutionary process came back because of changes in developmental genes, such as mutation in chickens that causes tooth growth similar to alligator teeth. [131] It is increasingly clear that most changes in the form of the organism caused by changes in the level and timing of expression of a small set of genes is maintained. [132][Edit] coevolutionMain article for this section are: coevolution
Interactions between organisms can produce both conflict nor Mr koopreasi. When the interaction between pairs of species, such as the pathogen with the host or predator to prey, these species have developed a set of adaptations that bersepadan. In this case, the evolution of one species causes adaptations of species to two. Changes in the two species then leads to re-adaptation of the first species. Cycles of selection and response is known as coevolution. [133] An example is the production of tetrodotoxin in the newt Taricha granulosa and the evolution of tetrodotoxin resistance in predators, the snake Thamnophis sirtalis. In the predator-prey pairs, the evolutionary arms race has resulted in high levels of toxins in the prey and high resistance to poisons predators. [134][Edit] CooperationMain article for this section are: Cooperation (evolution)
However, not all interactions between species involve conflict. [135] In most cases, developing a mutually beneficial interaction. For example, extreme cooperation that exist between plants with mycorrhizal fungi that grow on plant roots and help plants absorb nutrients from the soil. [136] This is a reciprocal relationship, with the plant providing sugars from photosynthesis to the fungi. In this case, fungi actually grow inside the plant cell, allowed to exchange nutrients with the host when sending a signal that suppresses the immune system of plants. [137]
Coalitions between organisms of the same species are also growing. This extreme case is eusosialitas found in social insects, like bees, termites, and ants, where sterile insects feed and maintain a number of organisms in a colony that can reproduce. On a smaller scale somatic cells that make up the body of an animal limit their reproduction in order to maintain a stable organism, so that then can support a small number of germ cells of animals to produce offspring. In this case, somatic cells respond to specific signals that instruct it to grow or die. If cells ignore these signals and then multiplying this uncontrolled growth will lead to cancer. [38]
Cooperation within the species is estimated to grow through the process of selection relatives (kin selection), in which one organism plays the breeding of relatives. [138] These activities are selected because of an individual who "helped" contain alleles that promote assistance activities, it is possible that his relatives "also "containing this allele, so that these alleles will be inherited. [139] Other processes that promote cooperation include group selection, in which cooperation provides benefits to the organism. [140][Edit] The formation of new species (speciation)Main article for this section are: SpeciationFour mechanisms of speciation.
Speciation is the process of a species berdivergen into two or more species. [141] It has been observed many times in a controlled laboratory conditions and in the wild. [142] In organisms that reproduce sexually, resulting speciation by reproductive isolation followed by genealogical divergence. There are four mechanisms of speciation. The most commonly occurs in animals is alopatrik speciation, which occurs in populations initially isolated geographically, such as through habitat fragmentation or migration. Selection under such conditions can produce rapid changes in appearance and behavior of organisms. [143] [144] Since the selection and hanyutan work freely in an isolated population, the separation will eventually produce organisms that can mate will not intervene. [145 ]
The second mechanism peripatrik speciation is speciation, which occurs when small populations of organisms become isolated in a new environment. This is different from alopatrik speciation in terms of population size is smaller than the population of elders. In this case, the founder effect causes rapid speciation through genetic hanyutan rapid and selection of a small gene pool. [146]
The third mechanism of speciation is speciation parapatrik. He is similar to the speciation peripatrik in terms of size of small populations that go into a new habitat, but differ in the absence of physical separation between the two populations. This speciation resulting from the evolution of the genetic mechanism that reduces the flow between two populations. [141] In general, this occurs when there are drastic changes in the environmental habitat of species elders. One example is the grass Anthoxanthum odoratum, which can experience parapatrik speciation in response to localized metal pollution from mining. [147] In this case, plants have evolved to become resistant to high levels of metals in the soil. Sorting out against intermarrying with elder populations result in changes in flowering time, causing reproductive isolation. Selection out of a hybrid between the two populations could lead to "reinforcement", which is an evolutionary trait that promotes marriage within the species, as well as the transitional character, which occurs when two species become more different in appearance. [148]Geographical isolation of the Galapagos Islands Finch birds produce more than a dozen new species.
The fourth mechanism of speciation is speciation simpatrik, where berdivergen species without geographic isolation or changes in habitat. This mechanism is quite rare because only with a little gene flow will eliminate genetic differences between one part of the population with other populations. [149] In general, simpatrik speciation in animals requires the evolution of the genetic and non-random mating, reproductive isolation allowed to grow. [ 150]
One type of speciation simpatrik involves crossbreeding two related species, producing a hybrid species. This is not common in animals because the animals usually sterile hybrid. In contrast, cross-breeding usually occurs in plants, because plants often double the number of chromosomes, forming poliploid. This allows the chromosomes of each species form pairs of equivalent elders during meiosis. [151] One example of this speciation event is when the plant Arabidopsis thaliana and Arabidopsis arenosa cross mate, produce new species Arabidopsis suecica. [152] This occurred around 20,000 years then, [153] and the speciation process has been repeated in the laboratory, allowing the study of genetic mechanisms involved in this process. [154] Actually, the doubling of chromosomes in the species is a major cause of reproductive isolation, because half of the multiple chromosomes would not match when the spouse with organisms that are not multiple chromosomes. [74][Edit] ExtinctionMain article for this section are: ExtinctionFossil tarbosaurus. Non-dinosaurs that died of bird in the Cretaceous-Tertiary extinction event at the end of the Cretaceous.
Extinction is an overall loss of species occurrence. Extinction is not an unusual event, because the species regularly appear through speciation and disappear through extinction. [155] In fact, almost all species of animals and plants that once lived on earth have become extinct, [156] and extinction seems to be the ultimate fate of all species. [157] The extinction has occurred continuously throughout the history of life, although sometimes the extinction rate increased sharply in the mass extinction event. [158] Cretaceous-Tertiary extinction event is one example of well-known mass extinction, in which the dinosaurs became extinct. But the events of the earlier Permian-Triassic extinction Peristiwan worse, with about 96 percent of species became extinct. [158] Holocene extinction event is a mass extinction associated with human expansion into all the earth for several thousand years. The rate of extinction of the present 100-1000 times greater than the background rate, and up to 30 percent of species could become extinct in the mid-21 th century. [159] Human activity is now a major cause of extinction events in progress. [160] In addition to that global warming may further accelerate the pace of extinction. [161]
The role of extinction in evolution depends on the type of extinction. Causes of extinction persitiwa "low level" constantly (which is the majority of cases extinction) are unclear and are probably the result of competition between species of limited resources (the principle of avoid-competitiveness). [12] If the competition from other species alter the probability of a species become extinct, this can produce species selection as one of the levels of natural selection. [92] was also the important events of mass extinction, but instead act as a selective force, he drastically reduced the diversity and encourage the rapid evolution of a sudden and speciation in a creature that saved from extinction. [158][Edit] History of the evolution of life! Main article: History of the evolution of life[Edit] The origin of lifeMain article for this section are: abiogenesis and the RNA world hypothesis
The origin of life is a precursor of biological evolution, but understanding of the evolution of organisms that occur instantaneously appear and investigate how this occurs does not depend on understanding how life began. [162] current scientific consensus is that the complex biochemical compounds, which menyusus life, derived from more simple chemical reactions. But not yet clear how it occurred. [163] Not exactly sure how the earliest development of life, the structure of the first life, or the identity and characteristics of the last universal ancestor and ancestral gene pool. [164] [165] Therefore, no there is scientific consensus that exactly how life began, but there are several proposals that involve self-replicating molecules (eg RNA) [166] and assembly of simple cells. [167][Edit] common ancestorMain article for this section are: Proof of the common ancestor, common ancestor, and Homology (biology)Hominoids are descended from a common ancestor.
All organisms on Earth are descended from a common ancestor or ancestral gene pool of the same. [168] The species is also present in the process of evolution with its diversity is the result of a series of speciation and extinction events. [169] common ancestor organism was first deduced from the four simple facts about organisms. First, that these organisms have a geographic distribution that can not be explained by local adaptation. Second, the form of biodiversity is not a totally different organisms from each other, but in the form of organisms that are similar morphologically to each other. Third, vestigial traits with no clear function has a resemblance to the ancestral nature of that function clear. Finally, these organisms can be classified on the basis of this similarity into hierarchical groups. [7]
These species also left a note past their evolutionary history. Fossils, along with anatomy that can be compared to the organisms present, is a record of morphology and anatomy. [170] By comparing the anatomy of the species are already extinct in the modern species, paleontologists can attract these species lineages. However, this approach only works in organisms that have a hard body parts, such as shells, skeletons, or teeth. Furthermore, because prokaryotes such as bacteria and arkaea has only limited similarity with the morphology, fossils of prokaryotes do not provide information about their ancestors.
More recently, evidence of the common ancestor comes from studies of biochemical similarities between species. For example, all the cells of living in this world has a basic set of nucleotide and amino acid the same. [171] The development of molecular genetics has revealed a note left on the genome evolution of organisms, so it can be known when the species berdivergen through molecular clock produced by mutations. [ 172] For example, DNA sequence comparisons have revealed genetic kinship between humans and chimps and when the common ancestor of these two species never existed. [173][Edit] The evolution of lifeMain articles See also: Timeline of evolutionEvolutionary tree showing the divergence of modern species from common ancestors that are in the middle [174] Three different colored domains, with the color blue is a bacterium, is arkaea green, and red are the eukaryotes.
Although there is uncertainty how life originated, it is generally accepted that prokaryotic life on earth about 3-4 billion years ago. [175] [176] There is a lot of changes in cell morphology or organization that occurs in these organisms for several billion years to the future. [177]
Eukaryotes are major developments in the evolution of the cell. It stems from ancient bacteria that prokaryotic cells engulfed by the ancestors of the cooperative association called endosymbiosis. [83] [178] The bacteria are ingested and then undergo coevolution of host cells, the bacteria evolved into mitochondria or hidrogenosom. [179] Ingestion both separately on organisms similar to cyanobacteria resulted in the formation of chloroplasts in algae and plants. [180] It is not known when the first eukaryotic cells appeared, although these cells appeared about 1.6 to 2.7 billion years ago.
The history of life is still a eukaryotes, prokaryotes, and unicellular arkaea to about 610 billion years ago, when multicellular organisms began to appear in the ocean during the period of Ediacara. [175] [181] Evolution multiselularitas occur in many separate events, occurring in organisms diverse as sponges, brown algae, cyanobacteria, slime molds, and miksobakteri. [182]
Immediately after the emergence of multicellular organisms, a large amount of biological diversity appears within a period of more than about 10 million years in perstiwa known as the Cambrian explosion. At this time, the majority of types of modern animals appeared in the fossil record, as well as the lineage of the extinct animals. [183] Some of the factors driving the Cambrian explosion has been proposed, including the accumulation of oxygen in the atmosphere from photosynthesis. [184] About 500 million years ago , plants and fungi colonized the land, and soon followed by arthropods and other animals. [185] Amphibians first appeared around 300 million years ago, followed by amniotic, then mammals around 200 million years ago, and about 100 million years of bird the past. However, despite the evolution of large animals, these organisms are similar to the organism early in the process of evolution continued to dominate the earth, with the majority of Earth's biomass and species of prokaryotes. [110]
[Edit] The response of social and culturalMain article for this section are: Effects of social evolution theoryAlong with the acceptance of "Darwinism" is widespread in the 1870s, caricature of Charles Darwin with an ape or monkey body symbolized evolution. [186]
In the 19th century, especially since the publication of Darwin's book "The Origin of Species", the thought that life had evolved into a lot of criticism and controversial themes. However, this controversy generally revolves around the implications of evolutionary theory in the field of philosophy, social, and religious. Within the scientific community, the fact that organisms evolve has been widely accepted and not challenged. However, evolution is still a concept debated by some religious groups. [187]
When various religious groups trying to connect their teaching with the theory of evolution through the various concepts of theistic evolution, there are many supporters ciptaanisme who believe that evolution contradicts the creation myth found in the teachings of their religion. [188] As already predicted by Darwin, the implications of the most controversial is the origin of man. In some countries, particularly in the United States, the conflict between religion and science have prompted the creation-evolution controversy, religious conflict focusing on politics and education. [189] When other scientific fields such as cosmology [190] and earth sciences [191] also contrary to the literal interpretation of many religious texts, evolutionary biologists have a more significant opposition.
Some examples of unwarranted controversy associated with the theory of evolution is "social Darwinism", a term given to Malthusianism theory developed by Herbert Spencer on the terbugar survival rate (survival of the fittest) in society, and by others to claim that social inequality, racism, and imperialism therefore justified. [192] However, these ideas contradict Darwin's own view, along with contemporary philosophers and scientists think this thinking is not the mandate of the theory of evolution and supported by the data. [193] [194][Edit] ApplicationsMain article for this section are: artificial selection and evolutionary computing
The main applications in the field of technological evolution is artificial selection, the selection of certain traits in a population of organisms is deliberate. Humans for several thousand years have used artificial selection on domesticated plants and animals. [195] More recently, artificial selection like this has become an important part in genetic engineering, with selected markers such as antibiotic resistance genes are used to manipulate DNA in molecular biology.
Because evolution can produce and process highly optimized network, it has many applications in computer science. In computer science, evolutionary simulations using evolutionary algorithms and artificial life started by Nils Aall Barricelli in the 1960s, and later extended by Alex Fraser who publishes a variety of scientific work on the simulation of artificial selection. [196] artificial selection becomes optimization method known extensively by the work of Ingo Rechenberg in the 1960s and early 1970s, the use of evolution strategies to solve complex engineering problems. [197] The main genetic algorithm, became popular by the writings of John Holland. [198] Along with the increasing academic interest, the increase in computer capabilities allow practical applications, including automatic evolution of computer programs. [199] evolutionary algorithm is now used to solve multidimensional problems. Completion of this algorithm is more efficient than using software produced by human designers. In addition, he also used to optimize the design of the system. [200][Edit] References
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