Editing Modern synthesis (20th century) (section)

==Elements of the synthesis==
===Fisher and Haldane's mathematical population genetics, 1918–1930===
{{main|A Mathematical Theory of Natural and Artificial Selection}}

In 1918, R. A. Fisher wrote "[[The Correlation between Relatives on the Supposition of Mendelian Inheritance]],"<ref>{{cite journal |last=Fisher |first=Ronald A. |author-link=Ronald Fisher |date=January 1919 |title=XV.—The Correlation between Relatives on the Supposition of Mendelian Inheritance |journal=[[Transactions of the Royal Society of Edinburgh]] |volume=52 |issue=2 |pages=399–433 |doi=10.1017/S0080456800012163 |s2cid=181213898 |oclc=4981124|url=https://zenodo.org/record/1428666 }} "Paper read by J. Arthur Thomson on July 8, 1918 to the Royal Society of Edinburgh."</ref> which showed how continuous variation could come from a number of discrete [[locus (genetics)|genetic loci]]. In this and other papers, culminating in his 1930 book ''[[The Genetical Theory of Natural Selection]]'',<ref>{{harvnb|Fisher|1999}}</ref> Fisher showed how Mendelian genetics was consistent with the idea of evolution by natural selection.<ref name="Larson221-243">{{harvnb|Larson|2004|pp=221–243}}</ref>{{efn|Fisher also analysed [[sexual selection]] in his book, but his work was largely ignored, and Darwin's case for such selection misunderstood<!--e.g. by Huxley-->, so it formed no substantial part of the modern synthesis.<ref>{{cite journal |last1=Hosken |first1=David J. |last2=House |first2=Clarissa M. |title=Sexual Selection |journal=[[Current Biology]] |date=25 January 2011 |volume=21 |issue=2 |pages=R62–R65 |doi=10.1016/j.cub.2010.11.053 |pmid=21256434|s2cid=18470445 |doi-access=free |bibcode=2011CBio...21..R62H }}</ref>}}

In the 1920s, [[A Mathematical Theory of Natural and Artificial Selection|a series of papers]] by [[J. B. S. Haldane]] analyzed real-world examples of natural selection, such as the [[Peppered moth evolution|evolution of industrial melanism in peppered moths]].<ref name="Larson221-243" /> and showed that natural selection could work even faster than Fisher had assumed.<ref name="Bowler325-339">{{harvnb|Bowler|2003|pp=325–339}}</ref> Both of these scholars, and others, such as Dobzhansky and Wright, wanted to raise biology to the standards of the physical sciences by basing it on mathematical modeling and empirical testing. Natural selection, once considered unverifiable, was becoming predictable, measurable, and testable.<ref name=Smocovitis122>{{harvnb|Smocovitis|1996|pp=122–132}}</ref>

===De Beer's embryology, 1930===

The traditional view is that [[developmental biology]] played little part in the modern synthesis,<ref>{{harvnb|Smocovitis|1996|p=192}}</ref> but in his 1930 book ''[[Embryos and Ancestors]]'', the evolutionary embryologist [[Gavin de Beer]] anticipated [[evolutionary developmental biology]]<ref name="Held">{{cite book |last1=Held |first1=Lewis I. |author-link=Lewis I. Held |title=How the Snake Lost its Legs. Curious Tales from the Frontier of Evo-Devo |date=2014 |publisher=[[Cambridge University Press]] |isbn=978-1-107-62139-8 |page=67 |title-link=How the Snake Lost its Legs }}</ref> by showing that evolution could occur by [[heterochrony]],<ref>{{harvnb|Gould|1977|pp=221–222}}</ref> such as in [[paedomorphosis|the retention of juvenile features in the adult]].<ref>{{cite journal |last1=Hall |first1=B. K. |title=Evo-Devo: evolutionary developmental mechanisms |journal=[[International Journal of Developmental Biology]] |date=2003 |volume=47 |issue=7–8 |pages=491–495 |pmid=14756324 |citeseerx=10.1.1.113.5158 }}</ref> This, de Beer argued, could cause apparently sudden changes in the [[fossil record]], since embryos fossilise poorly. As the gaps in the fossil record had been used as an argument against Darwin's gradualist evolution, de Beer's explanation supported the Darwinian position.<ref>{{Cite journal |author=Ingo Brigandt |year=2006 |title=Homology and heterochrony: the evolutionary embryologist Gavin Rylands de Beer (1899-1972) |journal=[[Journal of Experimental Zoology]] |volume=306B |issue=4 |pages=317–328 |doi=10.1002/jez.b.21100 |url=https://www.ualberta.ca/~brigandt/de_Beer.pdf |archive-url=https://web.archive.org/web/20061104004810/http://www.ualberta.ca/~brigandt/de_Beer.pdf |archive-date=2006-11-04 |url-status=live |pmid=16506229|bibcode=2006JEZB..306..317B }}</ref>
However, despite de Beer, the modern synthesis largely ignored embryonic development when explaining the form of organisms, since population genetics appeared to be an adequate explanation of how such forms evolved.<ref name=Gilbert1991>{{cite journal |last1=Gilbert |first1=Scott F. |author1-link=Scott F. Gilbert |author2=Opitz, J. M. |author3=Raff, R. A. |title=Resynthesizing evolutionary and developmental biology |journal=[[Developmental Biology (journal)|Developmental Biology]] |date=1996 |volume=173 |issue=2 |pages=357–372 |doi=10.1006/dbio.1996.0032|pmid=8605997|doi-access=free}}</ref><ref>{{cite book |last=Adams |first=M. |date=1991 |chapter=Through the looking glass: The evolution of Soviet Darwinism |title=New Perspectives in Evolution |editor1=Warren, L. |editor2=Koprowski, H. |publisher=Liss/Wiley |pages=[https://archive.org/details/newperspectiveso0000unse_u1t1/page/37 37–63] |isbn=978-0-471-56068-5 |chapter-url=https://archive.org/details/newperspectiveso0000unse_u1t1/page/37}}</ref>{{efn|Though [[C. H. Waddington]] had called for [[embryology]] to be added to the synthesis in his 1953 paper "Epigenetics and Evolution".<ref name=Smocovitis153/>}}

===Wright's adaptive landscape, 1932===

[[File:fitness-landscape-cartoon.png|thumb|[[Sewall Wright]] introduced the idea of a [[fitness landscape]] with local optima.]]

{{further|Population genetics#History}}

The population geneticist [[Sewall Wright]] focused on combinations of genes that interacted as complexes, and the effects of [[inbreeding]] on small relatively isolated populations, which could be subject to [[genetic drift]]. In a 1932 paper, he introduced the concept of an [[Fitness landscape|adaptive landscape]] in which phenomena such as cross breeding and genetic drift in small populations could push them away from adaptive peaks, which would in turn allow natural selection to push them towards new adaptive peaks.<ref name="Larson221-243" /><ref>{{harvnb|Wright|1932|pp=[http://www.esp.org/books/6th-congress/facsimile/contents/6th-cong-p356-wright.pdf 356–366]}}</ref> Wright's model appealed to field naturalists such as Theodosius Dobzhansky and Ernst Mayr who were becoming aware of the importance of geographical isolation in real world populations.<ref name="Bowler325-339" /> The work of Fisher, Haldane and Wright helped to found the discipline of theoretical population genetics.<ref name="auto1">{{cite journal |last1=Rose |first1=Michael R. |author-link1=Michael R. Rose |last2=Oakley |first2=Todd H. |date=November 24, 2007 |title=The new biology: beyond the Modern Synthesis |url=http://www.biologydirect.com/content/pdf/1745-6150-2-30.pdf |archive-url=https://web.archive.org/web/20140321054654/http://www.biologydirect.com/content/pdf/1745-6150-2-30.pdf |archive-date=2014-03-21 |url-status=live |journal=Biology Direct |volume=2 |issue=30 |pages=30 |doi=10.1186/1745-6150-2-30 |pmc=2222615 |pmid=18036242 |doi-access=free }}</ref><ref>{{cite book |author=Huxley, Julian |author-link=Julian Huxley |year=1942 |title=Evolution: The Modern Synthesis |url=https://archive.org/details/in.ernet.dli.2015.280031 |publisher=[[Allen & Unwin]]}}</ref><ref>{{cite book |author=Ridley, Matt |author-link=Matt Ridley |year=1996 |title=Evolution |edition=2nd |publisher=Blackwell Science |isbn=978-0632042920}}</ref>

===Dobzhansky's evolutionary genetics, 1937===

{{further|Genetics and the Origin of Species}}

[[File:Drosophila pseudoobscura-Male.png|thumb|left|''[[Drosophila pseudoobscura]]'', the fruit fly which served as [[Theodosius Dobzhansky]]'s [[model organism]]]]

[[Theodosius Dobzhansky]], an immigrant from the [[Soviet Union]] to the [[United States]], who had been a postdoctoral worker in Morgan's fruit fly lab, was one of the first to apply genetics to natural populations. He worked mostly with ''[[Drosophila pseudoobscura]]''. He says pointedly: "Russia has a variety of climates from the Arctic to sub-tropical... Exclusively laboratory workers who neither possess nor wish to have any knowledge of living beings in nature were and are in a minority."<ref>{{harvnb|Mayr|Provine|1998|p=231}}</ref> Not surprisingly, there were other [[Russia]]n geneticists with similar ideas, though for some time their work was known to only a few in the [[Western world|West]]. His 1937 work ''[[Genetics and the Origin of Species]]''<ref>{{harvnb|Dobzhansky|1937}}</ref> was a key step in bridging the gap between population geneticists and field naturalists. It presented the conclusions reached by Fisher, Haldane, and especially Wright in their highly mathematical papers in a form that was easily accessible to others.<ref name="Larson221-243"/><ref name="Bowler325-339"/> Further, Dobzhansky asserted the physicality, and hence the biological reality, of the mechanisms of inheritance: that evolution was based on material genes, arranged in a string on physical hereditary structures, the [[chromosome]]s, and [[genetic linkage|linked]] more or less strongly to each other according to their actual physical distances on the chromosomes. As with Haldane and Fisher, Dobzhansky's "evolutionary genetics"<ref>{{harvnb|Smocovitis|1996|p=127}}</ref> was a genuine science, now unifying cell biology, genetics, and both micro and macroevolution.<ref name=Smocovitis122/> His work emphasized that real-world populations had far more genetic variability than the early population geneticists had assumed in their models and that genetically distinct sub-populations were important. Dobzhansky argued that natural selection worked to maintain genetic diversity as well as by driving change. He was influenced by his exposure in the 1920s to the work of [[Sergei Chetverikov]], who had looked at the role of recessive genes in maintaining a reservoir of genetic variability in a population, before his work was shut down by the rise of [[Lysenkoism]] in the [[Soviet Union]].<ref name="Larson221-243"/><ref name="Bowler325-339"/> By 1937, Dobzhansky was able to argue that mutations were the main source of evolutionary changes and variability, along with chromosome rearrangements, effects of genes on their neighbours during development, and polyploidy. Next, genetic drift (he used the term in 1941), selection, migration, and geographical isolation could change gene frequencies. Thirdly, mechanisms like ecological or sexual isolation and hybrid sterility could fix the results of the earlier processes.<ref>{{cite book |last=Eldredge |first=Niles |title=Unfinished Synthesis: Biological Hierarchies and Modern Evolutionary Thought |url=https://books.google.com/books?id=fEYdRMjhPC4C&pg=PR9 |year=1985 |publisher=[[Oxford University Press]] |isbn=978-0-19-536513-9 |page=17}}</ref>

===Ford's ecological genetics, 1940===

[[File:Callimorpha.dominula.jpg|thumb|[[E. B. Ford]] studied [[Polymorphism (biology)#Scarlet tiger moth|polymorphism]] in the [[scarlet tiger moth]] for many years.]]

{{further|Ecological genetics}}

[[E. B. Ford]] was an experimental naturalist who wanted to test natural selection in nature, virtually inventing the field of [[ecological genetics]].<ref name=Ford1964>{{harvnb|Ford|1964}}</ref> His work on natural selection in wild populations of butterflies and moths was the first to show that predictions made by R. A. Fisher were correct. In 1940, he was the first to describe and define [[Polymorphism (biology)#Genetic polymorphism|genetic polymorphism]], and to predict that [[Human blood group systems|human blood group polymorphisms]] might be maintained in the population by providing some protection against disease.<ref name=Ford1964/><ref>{{harvnb|Ford|1975}}</ref> His 1949 book ''Mendelism and Evolution''<ref>{{cite book|last1=Ford|first1=E. B.|author-link1=E. B. Ford|title=Mendelism and Evolution |date=1949 |publisher=[[Methuen (publisher)|Methuen]]}}</ref> helped to persuade Dobzhansky to change the emphasis in the third edition of his famous textbook ''Genetics and the Origin of Species'' from drift to selection.<ref>{{harvnb|Dobzhansky|1951}}</ref>

===Schmalhausen's stabilizing selection, 1941===
{{further|Stabilizing selection}}

[[Ivan Schmalhausen]] developed the theory of [[stabilizing selection]], the idea that selection can preserve a trait at some value, publishing a paper in Russian titled "Stabilizing selection and its place among factors of evolution" in 1941 and a monograph ''Factors of Evolution: The Theory of Stabilizing Selection''<ref>{{cite book |last1=Schmalhausen |first1=Ivan I. |last2=Dordick |first2=Isadore (trans.)|author-link1=Ivan Schmalhausen |editor1-last=Dobzhansky|editor1-first=Theodosius |editor1-link=Theodosius Dobzhansky |title=Factors of Evolution. The Theory of Stabilizing Selection |date=1949 |publisher=[[Blakiston Company]] |location=Philadelphia and Toronto}}</ref> in 1945. He developed it from J. M. Baldwin's 1902 concept that changes induced by the environment will ultimately be replaced by hereditary changes (including the [[Baldwin effect]] on behaviour), following that theory's implications to their Darwinian conclusion, and bringing him into conflict with Lysenkoism. Schmalhausen observed that stabilizing selection would remove most variations from the norm, most mutations being harmful.<ref name=Levit2006>{{cite journal | last=Levit | first=Georgy S. |author2=Hossfeld, Uwe |author3=Olsson, Lennart | title=From the 'Modern Synthesis' to Cybernetics: Ivan Ivanovich Schmalhausen (1884–1963) and his Research Program for a Synthesis of Evolutionary and Developmental Biology | journal=[[Journal of Experimental Zoology]] | volume=306B | issue=2006 | pages=89–106 | year=2006 | pmid=16419076 | doi=10.1002/jez.b.21087| s2cid=23594114 }}</ref><ref name=Adams1988>{{cite journal |author=Adams, M. B. |title=A Missing Link in the Evolutionary Synthesis. I. I. Schmalhausen. Factors of Evolution: The Theory of Stabilizing Selection |journal=Isis |date=June 1988 |volume=79 |issue=297 |pages=281–284 |doi=10.1086/354706 |pmid=3049441|s2cid=146660877 }}</ref><ref>{{cite journal |last1=Glass |first1=Bentley |title=Reviews and Brief Notices Factors of Evolution. The Theory of Stabilizing Selection. I. I. Schmalhausen, Isadore Dordick, Theodosius Dobzhansky |journal=[[Quarterly Review of Biology]] |date=December 1951 |volume=26 |issue=4 |pages=384–385 |doi=10.1086/398434}}</ref> Dobzhansky called the work "an important missing link in the modern view of evolution".{{sfn|Mayr|Provine|1998|p=ix}}

===Huxley's popularising synthesis, 1942===

{{main|Evolution: The Modern Synthesis}}

[[File:Julian Huxley 1964.jpg|thumb|upright|[[Julian Huxley]] presented a serious but popularising version of the theory in his 1942 book ''[[Evolution: The Modern Synthesis]]''.]]

In 1942, [[Julian Huxley]]'s serious but popularising<ref name=Ruse/><ref name=Lamm>{{cite web |last1=Lamm |first1=Ehud |title=Review of Julian Huxley, Evolution: The Modern Synthesis – The Definitive Edition, with a new foreword by Massimo Pigliucci and Gerd B. Müller |publisher=[[MIT Press]] |url=http://www.ehudlamm.com/huxley.pdf |archive-url=https://web.archive.org/web/20111224104526/http://www.ehudlamm.com/huxley.pdf |archive-date=2011-12-24 |url-status=live |access-date=21 August 2017}}</ref> book ''[[Evolution: The Modern Synthesis]]''{{sfn|Huxley|2010}} introduced a name for the synthesis and intentionally set out to promote a "synthetic point of view" on the evolutionary process. He imagined a wide synthesis of many sciences: genetics, developmental physiology, ecology, systematics, palaeontology, cytology, and mathematical analysis of biology, and assumed that evolution would proceed differently in different groups of organisms according to how their genetic material was organised and their strategies for reproduction, leading to progressive but varying evolutionary trends.<ref name=Lamm/> His vision was of an "evolutionary humanism",<ref name=Smocovitis138/> with a system of ethics and a meaningful place for "Man" in the world grounded in a unified theory of evolution which would demonstrate progress leading to humanity at its summit. Natural selection was in his view a "fact of nature capable of verification by observation and experiment", while the "period of synthesis" of the 1920s and 1930s had formed a "more unified science",<ref name=Smocovitis138/> rivalling physics and enabling the "rebirth of Darwinism".<ref name=Smocovitis138>{{harvnb|Smocovitis|1996|pp=138–153}}</ref>

However, the book was not the research text that it appeared to be. In the view of the philosopher of science [[Michael Ruse]], and in Huxley's own opinion, Huxley was "a generalist, a synthesizer of ideas, rather than a specialist".<ref name=Ruse>{{harvnb|Ruse|1996|pp=328–338}}</ref> Ruse observes that Huxley wrote as if he were adding empirical evidence to the mathematical framework established by Fisher and the population geneticists, but that this was not so. Huxley avoided mathematics, for instance not even mentioning [[Fisher's fundamental theorem of natural selection]]. Instead, Huxley used a mass of examples to demonstrate that natural selection is powerful and that it works on Mendelian genes. The book was successful in its goal of persuading readers of the reality of evolution, effectively illustrating topics such as [[island biogeography]], [[speciation]], and competition. Huxley further showed that the appearance of long-term [[orthogenesis|orthogenetic trends]] – predictable directions for evolution – in the fossil record were readily explained as [[allometry|allometric growth]] (since parts are interconnected). All the same, Huxley did not reject orthogenesis out of hand, but maintained a belief in progress all his life, with ''[[Homo sapiens]]'' as the endpoint, and he had since 1912 been influenced by the [[vitalism|vitalist]] philosopher [[Henri Bergson]], though in public he maintained an atheistic position on evolution.<ref name=Ruse/> Huxley's belief in progress within evolution and evolutionary humanism was shared in various forms by Dobzhansky, Mayr, Simpson and Stebbins, all of them writing about "the future of Mankind". Both Huxley and Dobzhansky admired the palaeontologist priest [[Pierre Teilhard de Chardin]], Huxley writing the introduction to Teilhard's 1955 book on orthogenesis, ''[[The Phenomenon of Man]]''. This vision required evolution to be seen as the central and guiding principle of biology.<ref name=Smocovitis138/>

===Mayr's allopatric speciation, 1942===

{{main|Systematics and the Origin of Species|Allopatric speciation}}

[[File:Ernst Mayr PLoS.jpg|thumb|left|[[Ernst Mayr]] argued that [[allopatric speciation|geographic isolation]] was needed to provide sufficient [[reproductive isolation]] for [[speciation|new species to form]].]]

[[Ernst Mayr]]'s key contribution to the synthesis was ''[[Systematics and the Origin of Species]]'', published in 1942.<ref>{{harvnb|Mayr|1999}}</ref> It asserted the importance of and set out to explain population variation in evolutionary processes including speciation. He analysed in particular the effects of [[Taxon|polytypic]] species, geographic variation, and isolation by geographic and other means.<ref>{{cite journal |last1=Hey |first1=Jody |last2=Fitch |first2=Walter M. |last3=Ayala |first3=Francisco J. |title=Systematics and the origin of species: An introduction |journal=[[PNAS]] |date=2005 |volume=102 |issue=supplement 1 |pages=6515–6519 |doi=10.1073/pnas.0501939102 |pmid=15851660|bibcode=2005PNAS..102.6515H |pmc=1131868 |doi-access=free }}</ref> Mayr emphasized the importance of [[allopatric speciation]], where geographically isolated sub-populations diverge so far that [[reproductive isolation]] occurs. He was skeptical of the reality of [[sympatric speciation]] believing that geographical isolation was a prerequisite for building up intrinsic (reproductive) isolating mechanisms. Mayr also introduced the [[Species problem#Biological species concept|biological species concept]] that defined a species as a group of interbreeding or potentially interbreeding populations that were reproductively isolated from all other populations.<ref name="Larson221-243" /><ref name="Bowler325-339" /><ref>{{harvnb|Mayr|Provine|1998|pp=33–34}}</ref>{{sfn|Mayr|1982}} Before he left [[Germany]] for the United States in 1930, Mayr had been influenced by the work of the German biologist [[Bernhard Rensch]], who in the 1920s had analyzed the geographic distribution of polytypic species, paying particular attention to how variations between populations correlated with factors such as differences in climate.<ref>{{harvnb|Rensch|1947}}; {{harvnb|Rensch|1959}}</ref><ref>{{cite web |url=http://people.wku.edu/charles.smith/chronob/RENS1900.htm |title=Rensch, Bernhard (Carl Emmanuel) (Germany 1900-1990) |last=Smith |first=Charles H. |author-link=Charles H. Smith (historian of science) |work=Some Biogeographers, Evolutionists and Ecologists: Chrono-Biographical Sketches |publisher=[[Western Kentucky University]]  |access-date=14 December 2017}}</ref><ref>{{harvnb|Mayr|Provine|1998|pp=298–299, 416}}</ref>

[[File:Equine evolution.jpg|thumb|upright=1.2|[[George Gaylord Simpson]] argued against the naive view that [[evolution of the horse|evolution such as of the horse]] took place in a "straight-line". He noted that any chosen line is one path in a complex branching tree, [[natural selection]] having no [[orthogenesis|imposed direction]].]]

===Simpson's palaeontology, 1944===

[[George Gaylord Simpson]] was responsible for showing that the modern synthesis was compatible with palaeontology in his 1944 book ''[[Tempo and Mode in Evolution]]''. Simpson's work was crucial because so many palaeontologists had disagreed, in some cases vigorously, with the idea that natural selection was the main mechanism of evolution. It showed that the trends of linear progression (in for example the [[evolution of the horse]]) that earlier palaeontologists had used as support for [[Lamarckism#Neo-Lamarckism|neo-Lamarckism]] and orthogenesis did not hold up under careful examination. Instead, the [[fossil#Dating|fossil record]] was consistent with the irregular, branching, and non-directional pattern predicted by the modern synthesis.<ref name="Larson221-243" /><ref name="Bowler325-339" />

===Society for the Study of Evolution, 1946===

During [[World War II]], Mayr edited a series of bulletins of the Committee on Common Problems of Genetics, Paleontology, and Systematics, formed in 1943, reporting on discussions of a "synthetic attack" on the interdisciplinary problems of evolution. In 1946, the committee became the Society for the Study of Evolution, with Mayr, Dobzhansky and Sewall Wright the first of the signatories. Mayr became the editor of its journal, ''[[Evolution (journal)|Evolution]]''. From Mayr and Dobzhansky's point of view, suggests the historian of science Betty Smocovitis, Darwinism was reborn, evolutionary biology was legitimised, and genetics and evolution were synthesised into a newly unified science. Everything fitted into the new framework, except "heretics" like [[Richard Goldschmidt]] who annoyed Mayr and Dobzhansky by insisting on the possibility of [[mutationism|speciation by macromutation]], creating "hopeful monsters". The result was "bitter controversy".<ref name=Smocovitis153>{{harvnb|Smocovitis|1996|pp=153–171}}</ref>

[[File:Polyploidization.svg|thumb|[[Speciation]] via [[polyploidy]]: a [[diploid]] cell may fail to separate during [[meiosis]], producing diploid [[gamete]]s, which self-fertilize to produce a fertile tetraploid [[zygote]] that cannot interbreed with its parent species.]]

===Stebbins's botany, 1950===

The botanist [[G. Ledyard Stebbins]] extended the synthesis to encompass [[botany]]. He described the important effects on [[speciation]] of [[Hybridisation (biology)|hybridization]] and [[polyploidy]] in plants in his 1950 book ''[[Variation and Evolution in Plants]]''. These permitted evolution to proceed rapidly at times, polyploidy in particular evidently being able to create new species effectively instantaneously.<ref name="Larson221-243" /><ref name=Smocovitis2001>{{cite journal | last1=Smocovitis | first1=V. B. | year=2001 | title=G. Ledyard Stebbins and the evolutionary synthesis | journal=[[Annual Review of Genetics]] | volume=35 | pages=803–814 | doi=10.1146/annurev.genet.35.102401.091525 | pmid=11700300}}</ref>