Speciation (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 - Speciation"></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, schöpfung"></td></tr> <tr><td><h2><i>Basic Ideas: </i>Speciation</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, schöpfung"> 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, schöpfung"></td> </tr> <tr> <td><h3 style="padding-top:16px;">Content</h3> <P><a href="../artikel/artikel.php?Sprache=en&Artikel=41241&l=1" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 vspace=4 style="vertical-align:middle" alt="">Mutation</a> and <a href="../artikel/artikel.php?Sprache=en&Artikel=41242&l=1" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 vspace=4 style="vertical-align:middle" alt="">selection</a> are basic processes of microevolution that lead to an <I>alteration</I> within the species. The <I>number</I> of species, however, is not increased by this means. But evolution does not only contain change in the course of time, but also the development of diversity, an increase of the number of species. So besides the alteration of species, speciation is a second elementary evolutionary process.</P> <P>This article explains under which circumstances speciation can take place, which processes occur and at which rate this is possible.</P><p><a href="#1"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> What is speciation?</a></p> <p><a href="#4"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> What happens during speciation?</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, schöpfung"> Founder effect, genetic drift and sympatric speciation</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, schöpfung"> Speed of speciation</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, schöpfung"> Summary</a></p> <p><a href="https://www.genesisnet.info/artikel/interessierte_druck.php?Sprache=en&Artikel=41244" target=_blank><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> 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, schöpfung"></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, schöpfung"><h3><a name="1"></a>What is speciation?</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Speciation means the splitting of a species into two or more species. It requires a geographical or ecological separation of the initial species. In each part of the separated populations the evolutional factors mutation, selection and recombination can show a different effect (pic. 66). If no crossbreeding occurs after a later reoverlapping of the populated areas, the one single former species has been separated into two (see pic. 67).</P></td> <td rowspan=3 valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=66" onclick="return Bild_Anzeigen('../bild.php?ID=66&Sprache=en',600,416);"><img src="../bilder/bild_66_k_en" width=138 height=95 border=1 alt="Pic. 66: Criteria of evolution and speciation (Click to magnify)" class=rb><br>Pic. 66: Criteria of evolution and speciation</a></div> </td></tr> <tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, schöpfung"><div class=textbild><a href="../bild.php?Sprache=en&ID=67" onclick="return Bild_Anzeigen('../bild.php?ID=67&Sprache=en',598,377);"><img src="../bilder/bild_67_en" width=400 height=252 border=0 alt="Pic. 67: Origin of two species (Zum Vergrößern anklicken)"><br>Pic. 67: Area of a population. Geographical separation of a population, divergence and finally genetic isolation: splitting into two species.</a></div></td> </tr> <tr><td valign="top"><P>First, we will examine a well proven example. In southern England new species developed on grounds that were contaminated with heavy metal from slag heaps. Picture 68 describes this process. The slag heaps are contaminated in a way that drifted seeds normally will die very soon or cannot even germinate at all (†). But very few will grow out and bear fruit: They form a new population on new habitat and their complete offspring is able to populate the contaminated slag heaps. It turned out that the slag heap plants hardly crossbreed any more with closely related forms of the surrounding, non-contaminated habitats from which they originally derived. With this genetic <B>isolation</B> took place, which means concerning the criterion of biospecies that new biological species developed (see article <a href="../artikel/artikel.php?Sprache=en&Artikel=41224&l=1" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 vspace=4 style="vertical-align:middle" alt="">concept of species</a>). <B>So until today new biological species can develop under natural circumstances.</B> Does this indicate a beginning macroevolution? The following paragraph deals with this question.</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, schöpfung"><div class=textbild><a href="../bild.php?Sprache=en&ID=68" onclick="return Bild_Anzeigen('../bild.php?ID=68&Sprache=en',800,268);"><img src="../bilder/bild_68" width=533 height=179 border=0 alt="Pic. 68: Slag heap plants (Zum Vergrößern anklicken)"><br>Pic. 68: Slag heap plants. Most of the seeds that fall on contaminated ground are not able to germinate or even will die (†). Only a few preadjusted seeds can grow up.</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, schöpfung"><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, schöpfung"></a></p><h3 style="padding-bottom:4px;"><a name="4"></a>What happens during speciation?</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>The slag heap plants mentioned above have been examined genetically. It turned out that the plants growing on polluted ground did not acquire any new features but that within these certain species the ability of toxitolerance existed before they populated on contaminated ground. Only species that show toxitolerance on normal locations as well were able to colonize contaminated ground. Toxitolerance is part of the natural variability of these species. (The number of toxitolerant species is too high for being explainable by spontaneous mutations.)</P> <P>Obviously, there was a selection of already toxitolerant forms. The exclusive (one-sided) selection leads to specialization (see pic. 69), which may be linked to a reduction of the crossbreedability with the normal form on unpolluted ground: Genetic isolation and in the end speciation take place. In this case genetic isolation can be effective for instance in a shift of flowering time.</P> <P>Here the toxitolerance can probably be explained by a reduced assimilation of mineral salts out of the ground; so it does not present an evolutional improvement, but rather a reduction, that turned out to be of advantage in this specific environment of contaminated ground.</P> <P>The process observed with slag heap plants shows just as similar cases that speciation cannot be seen as a beginning macroevolution, but is often connected to specialization and with this to an impoverishment of the gene pool. This is why repeated speciation rather leads to an impoverishment of the gene pool and so to a reduction of variability (see pic. 70). Although mutations can counteract the impoverishment of the gene pool, studies show that this at long sight cannot counter the trend to impoverishment. When the splitted species cannot react in a flexible way anymore to environmental changes because of their one-sided specialization, they are threatened with extinction.</P></td> <td rowspan=3 valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=69" onclick="return Bild_Anzeigen('../bild.php?ID=69&Sprache=en',774,416);"><img src="../bilder/bild_69_k_en" width=138 height=75 border=1 alt="Pic. 69: Extreme selection on contaminated ground. (Click to magnify)" class=rb><br>Pic. 69: Extreme selection on contaminated ground.</a></div> </td></tr> <tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, schöpfung"><div class=textbild><a href="../bild.php?Sprache=en&ID=70" onclick="return Bild_Anzeigen('../bild.php?ID=70&Sprache=en',800,319);"><img src="../bilder/bild_70_en" width=533 height=214 border=0 alt="Pic. 70: Specialization and impoverishment of the gene pool (Zum Vergrößern anklicken)"><br>Pic. 70: Repeated splitting off of parts of a population (R<sub>n</sub>) with a gene pool r<sub>n</sub> leads to specialization and impoverishment of the gene pool. </a></div></td> </tr> <tr><td valign="top"><P>We can record that <B>the development of new biological species is a microevolutionary process and does not give any hint of macroevolution.</B></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, schöpfung"><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, schöpfung"></a></p><h3 style="padding-bottom:4px;"><a name="6"></a>Founder effect, genetic drift and sympatric speciation</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Concerning the classical concept of speciation a geographical separation is necessary for the splitting off of a new species. A small founding group has to be separated from the population: <B>Founder effect</B>. The smaller the founding group the bigger the difference between the <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_6_1').style.display=='inline') { document.getElementById('Glossar_6_1').style.display='none'} else {document.getElementById('Glossar_6_1').style.display='inline'}; return false;">average<span id="Glossar_6_1" class="glossar"> (=alle Allele der Gene einer Art)</span></a> gene pools. Several genes appear in more than <a href="javascript:void();" title="Anklicken blendet Erklärung ein." onclick="if (document.getElementById('Glossar_6_2').style.display=='inline') { document.getElementById('Glossar_6_2').style.display='none'} else {document.getElementById('Glossar_6_2').style.display='inline'}; return false;">one<span id="Glossar_6_2" class="glossar"> (=Zustandsformen eines Gens)</span></a> allele within the gene pool. In a small founding group just a small, non-representative part may remain. This kind of coincidental shift within the allele frequency, not caused by selection, is called <B>genetic drift</B>. So the founding group often starts from a different genetic starting basis than the rest of the population. This means that from the start the conditions for speciation are given. Other mechanisms can lead to further microevolutive changes up to barriers of crossbreeding.</P> <P>More and more results seem to make speciation probable even without geographical separation. This process is called sympatric speciation (”in the same area”). If for instance parasites that are specialized on a certain host suddenly change this host on long term, they and their offspring are ecologically separated from the starting group and can microevolutionally develop isolated from each other.</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, schöpfung"><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, schöpfung"></a></p><h3 style="padding-bottom:4px;"><a name="7"></a>Speed of speciation</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Several studies have shown, that speciation can happen within few generations, if the output group is genetically polyvalent (various, many sided) and the founding group small and so genetically “one-sided”. The gene pool of a small founding population or the remaining population can rather easily be changed in a thoroughly and lasting way. This connection is based on numerous observations. Recalling the example of the slag heap plants that in several cases populated contaminated slag heaps as a new location, it is obvious that the development of a new biospecies took place within few generations. In this case, the majority of the population falls victim to the selection due to the enormously changed environment.</P> <P>The following example shows that even morphological changes can lead to new biospecies within very short time. Clarkie shows a loss mutant called <I>bicalyx</I> that has its petals transformed into sepal-like structures (pic. 71; a case of a so called homeotic mutation). This mutant became stably established in the open. This basic type repeatedly shows other mutants as well, that significantly reduce the fertility between mutants and parents – a step towards speciation. In combination with the <I>bicalyx</I>-mutant, this could easily lead to a new biospecies that would be clearly different from the parental species.</P> <P><B>Speciation by restriction of the modification pool.</B> This scarcely noticed model of speciation gives further hints on the possibility of quick speciation. It depends on the assumption that the basic forms of living biospecies once had a rather large <I>spectrum of modification</I> (possibilities of adaptation caused by environmental stimuli), that has been restricted more or less by loss mutations or founding eventsin the course of time (pic. 72). Specialized biological species develop through restriction of the original modification pool. This can be seen for instance by the fact, that the offspring can only populate rather specialized locations while the forerunner had a broad spectrum of possible locations. This approach formulated by Lönnig (1993) is especially of interest concerning the concept of basic types in creation science and is examined more closely in the <a href="../artikel/artikel.php?Sprache=en&Artikel=1200&l=1" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 vspace=4 style="vertical-align:middle" alt="">biology of basic types</a>. Because here the speciation is based on losses, it can possibly take place in short periods.</P></td> <td rowspan=2 valign="top" class=rb><div class=bild><a href="../bild.php?Sprache=en&ID=71" onclick="return Bild_Anzeigen('../bild.php?ID=71&Sprache=en',427,600);"><img src="../bilder/bild_71_k" width=138 height=193 border=1 alt="Pic. 71: Bicalyx-mutant of Clarkie (Click to magnify)" class=rb><br>Pic. 71: Bicalyx-mutant of Clarkie</a></div> </td></tr> <tr><td valign="top"><img src="s.gif" width="680" height="1" border="0" alt="evolution, schöpfung"><div class=textbild><a href="../bild.php?Sprache=en&ID=72" onclick="return Bild_Anzeigen('../bild.php?ID=72&Sprache=en',800,488);"><img src="../bilder/bild_72_en" width=533 height=335 border=0 alt="Pic. 72: Potential of modification of basic types (Zum Vergrößern anklicken)"><br>Pic. 72: Potential of modification of basic types, here concerning plants, that can only survive within the alpine belt and the types of spreading of avens.</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, schöpfung"><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, schöpfung"></a></p><h3 style="padding-bottom:4px;"><a name="9"></a>Summary</h3> </td> <td class=rb> </td></tr> <tr><td valign="top"><P>Speciation is not to be assumed as first steps of macroevolution. The only evident processes are of microevolutional nature. Empiric results indicate, that speciation leads to an impoverishment, specialization and dead end-development (increased danger of extinction) – and are not the beginning of further reaching variation.</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, schöpfung"><p><br>Translator: Sarah Aziz, 26.12.2009</p><p><a href="https://www.genesisnet.info/intern/mitarbeiter.php?Sprache=en&ID=18&Artikel=41244" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> Information about the translator</a></p><p><a href="https://www.genesisnet.info/kontakt/email.php?Sprache=en&Autor=18&Artikel=41244" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> 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=41244" target=main><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> 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=41244" target="_blank"><img src="../grafik/1_pfeil_weiss.gif" width=9 height=9 border=0 style="vertical-align:middle;" alt="evolution, schöpfung"> 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, schöpfung"></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/i41244_speciation.php" onclick="if (navigator.userAgent.toLowerCase().indexOf('msie')>-1) {window.external.AddFavorite('https://www.genesisnet.info/index.php?Sprache=en&Artikel=41244&l=1','Genesisnet - Speciation (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/i41244_speciation.php">by email</a>.</p><p style="color:#666666;white-space:break-word"> <br>© 2009, https://www.genesisnet.info/dateien_en/i41244.php</p></td> <td valign="top" class=rb> </td></tr> </table> </body>