Mutation (Interested)

<body text="#000000" bgcolor="#FFFFFF"><script language="JavaScript"></script><table border=0 cellspacing=0 cellpadding=0 width=840 style="table-layout:fixed"> <colgroup><col width=118><col width=562><col width=160></colgroup> <tr> <td rowspan=4 valign="top" style="text-align:right;"><a name="0"></a><img src="../grafik/fg_u_103.gif" vspace=2 width=97 height=75 border=0 alt="Evolution: Biology - Mutation"></td> <td colspan=2 height=26> </td> </tr> <tr> <td colspan=2 height=26 class="kopfzeile"> <h1><a target="main" href="https://www.genesisnet.info/artikel/artikel.php?Sprache=en&Artikel=40000">Evolution: Biology</a></h1> </td> </tr> <tr><td colspan=2><img src="s.gif" width=1 height=2 border=0 alt="evolution, creation, mutation"></td></tr> <tr><td><h2><i>Basic Ideas: </i>Mutation</h2></td> <td valign="top" bgcolor="#E6E6E6"> <div class="muiep" style="padding-top:4px;"><a target="main" href="https://www.genesisnet.info/artikel/artikel.php?l=0&Artikel=41240&Sprache=en"><img src="../grafik/1_pfeil_grau.gif" width=9 height=9 border=0 alt="evolution, creation, mutation"> Overview </a></div> </td> </tr> </table> <table border=0 cellspacing=0 cellpadding=0 width=840> <colgroup><col width=680><col width=160></colgroup> <tr> <td colspan=2><img src="s.gif" width=1 height=2 border=0 alt="evolution, creation, mutation"></td> </tr> <tr> <td><h3 style="padding-top:16px;">Inhalt</h3> <P>This article explains which kinds of mutation are known, furthermore some examples are introduced and the validity concerning the development of new structures is discussed.</P><p><a href="#1"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Introduction – terms in overview</a></p> <p><a href="#3"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Mutation research</a></p> <p><a href="#5"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Advantageous changes?</a></p> <p><a href="#6"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> The “recurrent variation”</a></p> <p><a href="#7"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Mutations in developmental genes</a></p> <p><a href="#8"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Result</a></p> <p><a href="#9"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Literature</a></p> <p><a href="https://www.genesisnet.info/artikel/interessierte_druck.php?Sprache=en&Artikel=41241" target=_blank><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Show a printer-friendly version of this page   <img src="../grafik/drucker.gif" width="14" height="14" border="0" style="vertical-align:middle;" alt="evolution, creation, mutation"></a></p> </td> <td class=rb> </td> </tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><h3><a name="1"></a>Introduction – terms in overview</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Important terms in causal evolution research are gene pool, recombination, selection and genetic drift (pic 53). The <B>gene pool</B> – a virtual quantity – includes all genetic varieties <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_1_1').style.display=='inline') { document.getElementById('Glossar_1_1').style.display='none'} else {document.getElementById('Glossar_1_1').style.display='inline'}; return false;">(allele)<span id="Glossar_1_1" class="glossar"> (=Zustandsformen eines Gens)</span></a> within a single species. These varieties can be mixed in the offspring by crossbreeding: <B>recombination</B>. <B>Mutation</B> means an erratic, spontaneously occurring or artificially caused change of the genotype that may also lead to changes in the phenotype. <B>Selection</B> means the picking-out of those individuals that are adapted best to the environment and stands for varying success of the individual’s reproductive success. An accidental change of the gene pool, not caused by selection, is called <B>genetic drift</B>.</P></td> <td valign="top" class=rb> </td></tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><div class=textbild><a href="../bild.php?Sprache=en&ID=54" onclick="return Bild_Anzeigen('../bild.php?ID=54&Sprache=en',600,544);"><img src="../bilder/bild_54_en" width=400 height=363 border=0 alt="Pic. 54: The most im- portant factors of variation. (Zum Vergrößern anklicken)"><br>Pic. 54: The most important factors of variation. </a></div></td> <td valign="top" class=rb> </td></tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="3"></a>Mutation research</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Mutations are the only known source of evolutional changes. In the end, all other factors are only effective under the condition of mutative possibilities of change. This is why mutation research takes on a key role in causal evolution <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_3_1').style.display=='inline') { document.getElementById('Glossar_3_1').style.display='none'} else {document.getElementById('Glossar_3_1').style.display='inline'}; return false;">research<span id="Glossar_3_1" class="glossar"> (=Ursachenforschung)</span></a>. In the field Mutations occur spontaneously, that is without recognizable reason (as an example: pic. 55), but they can also be caused artificially under laboratory conditions, such as by treatment with chemicals, radiation or extreme temperature. However, it is not predictable in which <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_3_2').style.display=='inline') { document.getElementById('Glossar_3_2').style.display='none'} else {document.getElementById('Glossar_3_2').style.display='inline'}; return false;">genes<span id="Glossar_3_2" class="glossar"> (=Erbfaktoren, Abschnitte auf der DNS)</span></a> the mutations appear and in which “direction” the change will go.</P> <P>One must distinguish between <B>point mutations,</B> where only a single unit of the DNA is changed, and <B>chromosome mutations</B> (pic. 56), where whole parts of the DNA get lost, are turned, doubled or fitted in elsewhere. Even whole chromosomes or complete chromosome sets can be doubled by mutation.</P></td> <td valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=55" onclick="return Bild_Anzeigen('../bild.php?ID=55&Sprache=en',450,586);"><img src="../bilder/bild_55_k" width=138 height=180 border=1 alt="Pic. 55: Example for mutation. (Click to magnify)" class=rb><br>Pic. 55: Example for mutation.</a></div> </td></tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><div class=textbild><a href="../bild.php?Sprache=en&ID=56" onclick="return Bild_Anzeigen('../bild.php?ID=56&Sprache=en',800,670);"><img src="../bilder/bild_56_en" width=530 height=446 border=0 alt="Pic. 56: Five important chromosome mutations. (Zum Vergrößern anklicken)"><br>Pic. 56: Five important chromosome mutations.</a></div></td> <td class=rb> </td></tr> <tr><td valign="top"><P>Decade-long experiments with the fruit fly <I>Drosophila</I> brought forth hundreds of differently changed flies – but never (not even after a long period of time) a complex new structure was produced even remotely. The artificially caused mutation lead for instance to an altered eye- or body color, altered bristles, diversely formed eyes or deformed wings (pic. 57). Sometimes whole parts of the body appear at wrong places, e.g. legs instead of antennae or wings instead of halteres (pic. 57, down right). The mutations seen here are within the limits of microevolution, because only a variation or recombination of already existing components took place – not a development of new ones. The mutations did not lead to new species and the fruit flies can still crossbreed. So mutations mostly lead to defects, which is also the case with plant mutations. Concerning the intense mutation research on the thale cress <I>Arabidopsis</I>, Meinke et al. (1998) ascertained, that &bdquo;several thousand mutants of Arabidopsis defective in almost every aspect of plant growth and development have been identified over the past 20 years.“ on the other hand there are mutations that stay without phenotypic consequence (neutral mutation).</P></td> <td valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=57" onclick="return Bild_Anzeigen('../bild.php?ID=57&Sprache=en',533,533);"><img src="../bilder/bild_57_k" width=138 height=138 border=1 alt="Pic. 57: Mutations of Drosophila. (Click to magnify)" class=rb><br>Pic. 57: Mutations of Drosophila.</a></div> </td></tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="5"></a>Advantageous changes?</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Now the argument goes that disadvantageous mutations do not matter in the process of evolution, because they are eliminated again by selection. The decisive aspect is said to be, that mutations were advantageous from time to time. These mutations would are assumed to have prevailed within the populations and the process could be continued by further positive mutations.</P> <P>This argumentation is basically correct. Still the occurring of advantageous mutations is not equivalent to the development of new genetic information, but normally also goes back to defects, which turn out to be positive under certain environmental factors.</P> <P>An example shall help to illustrate this: Some of the insects that live on islands exposed to strong winds have vestigial wings or even none at all (pic. 58). For the indigenous insects this is an advantageous change, because a violent storm can blow them far out to the open sea while flying. If the wind does not turn, the insects mostly will not have the energy to fly back by their own and will die. So in this case it is better if the insects are unable to fly from the beginning. Also, the loss of motility is bearable, because there normally are fewer natural enemies on the islands than onshore. So all in all, the loss of wings is advantageous. Alone, it will not do any good to the understanding of evolution, because the advantage is based on a loss, that means the reduction of an organ – no upward development. Moreover, the loss of flight is positive only under specific circumstances; it is disadvantageous elsewise and such mutants are eliminated by selection immediately.</P> <P>The following conditions are known from biochemistry. If by means of mutation an enzyme can metabolize a new substance (new substrate affinity), this normally is at the expense of the (former) specificity of the substrate affinity: The exact coordination between enzyme and substrate gets lost. Newly acquired toxitolerance or antibiotic resistances can be based on metabolic defects that prevent the toxin from being infiltrated into essential metabolic processes.</P> <P>We can state that <B>mutations that are only “positive” under certain circumstances do not explain an evolution of new structures</B>, because they imply <I>losses</I>. So it is not the question whether or not advantageous mutations exist, but rather if new genetic material and new structures develop.</P></td> <td rowspan=3 valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=58" onclick="return Bild_Anzeigen('../bild.php?ID=58&Sprache=en',533,443);"><img src="../bilder/bild_58_k" width=138 height=115 border=1 alt="Pic . 58: Two examples of flightless insects. (Click to magnify)" class=rb><br>Pic . 58: Two examples of flightless insects.</a></div> </td></tr> <tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="6"></a>The “recurrent variation”</h3> </td> </tr> <tr><td valign="top"><P>A certain phenomenon has been observed throughout decades and various organisms: After some time the same mutations show up again and again. <B>Quite often, already existing mutations just reoccur.</B> Plant breeders found out, that artificially caused mutations show the same features and characteristics as the spontaneous mutations of wild plants. The number of <I>new</I> types of mutants decreases with further mutation experiments. The geneticist W.-E. Lönnig summarized this phenomenon as the “rule of recurrent variation”. Until now, over 5000 hereditary deviations are known from the human genome. Examples of recurrent variations of grain are thick ears, early ripeness, the missing of wax or pigments, shortened awns or mildew resistance.</P> <P>As a reason for the rule of recurrent variation of mutations, Lönnig suggests, that there is only a limited number of hereditary factors, which can lose their function partially or totally without being lethal.</P> <P>The recurrent variation of mutations indicates the <I>outlined</I> - rich but <I>limited</I> – changeability of living beings. The variety of mutations stays within the borders of <a href="../artikel/artikel.php?Sprache=en&Artikel=0&l=1" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 vspace=4 style="vertical-align:middle" alt="">basic types</a>.</P></td> </tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="7"></a>Mutations in developmental genes</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>The understanding of homeobox genes has been of some importance recently. Homeobox genes stand quite at the beginning of the <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_7_1').style.display=='inline') { document.getElementById('Glossar_7_1').style.display='none'} else {document.getElementById('Glossar_7_1').style.display='inline'}; return false;">ontogenetic<span id="Glossar_7_1" class="glossar"> (=concerning the individual development)</span></a> development cascade of whole organs. Therefore mutations in homeobox genes can have an enormous effect, for instance to the extent that whole organs are expressed in other parts of the body (see pic. 57, bottom right). But even homeobox genes are not capable of explaining the development of life´s structures, because they are only effective within already existing subsequent structures and development cascades.</P></td> <td rowspan=3 valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=57" onclick="return Bild_Anzeigen('../bild.php?ID=57&Sprache=en',533,533);"><img src="../bilder/bild_57_k" width=138 height=138 border=1 alt="Pic. 57: Mutations of Drosophila. (Click to magnify)" class=rb><br>Pic. 57: Mutations of Drosophila.</a></div> </td></tr> <tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="8"></a>Result</h3> </td> </tr> <tr><td valign="top"><P>Generally, mutation research has shown until now, that no new structures develop by mutation. They rather show effect within already existing complex structures or metabolic processes. The spectrum of mutations stays within the scope of microevolution.</P></td> </tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p style="padding-bottom:3px;text-align:right;"><a href="#0"><img src="../grafik/evo_top.gif" width=31 height=10 border=0 alt="evolution, creation, mutation"></a></p><h3 style="padding-bottom:4px;"><a name="9"></a>Literature</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>MEINKE, D.W.; Cherry, J.M.; Dean, C., Rounsley, S. D.; Koornneef, M.: <I>Arabidopsis thaliana</I>: A Model Plant for Genome Analysis. Science <I>282</I>, 678-682 (1998)</P> <P>LÖNNIG, W.-E. (1995) Mutationen: Das Gesetz der rekurrenten Variation. In: Mey, J., Schmidt, R. & Zibulla, S. (Hg) Streitfall Evolution. Stuttgart, pp. 149-165.</P></td> <td valign="top" class=rb> </td></tr> </table> <table border=0 cellspacing=0 cellpadding=0 width="840"> <colgroup><col width="680"><col width="160"></colgroup><tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, creation, mutation"><p><br>Translator: Sarah Aziz, 10.02.2009</p><p><a href="https://www.genesisnet.info/intern/mitarbeiter.php?Sprache=en&ID=18&Artikel=41241" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Information about the translator</a></p><p><a href="https://www.genesisnet.info/kontakt/email.php?Sprache=en&Autor=18&Artikel=41241" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Email to the translator</a></p><p><br>Author: Reinhard Junker</p><p><a href="https://www.genesisnet.info/intern/mitarbeiter.php?Sprache=en&ID=3&Artikel=41241" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Information about the author</a></p><hr size=1 color="#CCCCCC" style="margin-top:20px;margin-left:128px;margin-right:30px;"><p style="margin-bottom:0px;margin-top:10px;"><a href="https://www.genesisnet.info/artikel/interessierte_druck.php?Sprache=en&Artikel=41241" target="_blank"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, creation, mutation"> Show a printer-friendly version of this page   <img src="../grafik/drucker.gif" width="14" height="14" border="0" style="vertical-align:middle;" alt="evolution, creation, mutation"></a></p><hr size=1 color="#CCCCCC" style="margin-left:128px;margin-right:30px;"><p style="padding-top:7px;">Set a <a target=_top href="https://www.genesisnet.info/dateien_en/i41241_mutation.php" onclick="if (navigator.userAgent.toLowerCase().indexOf('msie')>-1) {window.external.AddFavorite('https://www.genesisnet.info/index.php?Sprache=en&Artikel=41241&l=1','Genesisnet - Mutation (Level: Basic Ideas)');} else {alert('Unfortunately this browser does not support this function.\n\nPlease click this link again with the RIGHT mouse button and select the appropriat entry of the context menu.');} return false;">bookmark (favorite)</a> on this page or send the location <a href="mailto:@?body=https://www.genesisnet.info/dateien_en/i41241_mutation.php">by email</a>.</p><p style="color:#666666;white-space:break-word"> <br>© 2009, https://www.genesisnet.info/dateien_en/i41241.php</p></td> <td valign="top" class=rb> </td></tr> </table> </body>