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data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none">Coevolutionary principle regerding parasites and hosts</div> <figure typeof="mw:File/Thumb"><a href="/wiki/File:EichlersRule.jpg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/7a/EichlersRule.jpg/320px-EichlersRule.jpg" decoding="async" width="320" height="257" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/7a/EichlersRule.jpg/480px-EichlersRule.jpg 1.5x, //upload.wikimedia.org/wikipedia/commons/7/7a/EichlersRule.jpg 2x" data-file-width="546" data-file-height="439" /></a><figcaption>When comparing host sister clades we tend to find taxonomically richer parasite fauna on the taxonomically richer group of hosts.</figcaption></figure> <p><b>Eichler's rule</b> is one of several <a href="/wiki/Biological_rules" title="Biological rules">coevolutionary rules</a> which states that <a href="/wiki/Parasite" class="mw-redirect" title="Parasite">parasites</a> tend to be highly specific to their hosts, and thus it seems reasonable to expect a positive co-variation between the taxonomic richness of hosts and that of their parasites. </p> <div class="mw-heading mw-heading2"><h2 id="History">History</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Eichler%27s_rule&action=edit&section=1" title="Edit section: History"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>A rule to describe the taxonomic relationship between parasites and their hosts was developed in 1942 by Wolfdietrich Eichler (1912–1994), a German authority in zoology and <a href="/wiki/Parasitology" title="Parasitology">parasitology</a> who served as a professor of parasitology at <a href="/wiki/Leipzig_University" title="Leipzig University">Leipzig University</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-Eichler_1942_2-0" class="reference"><a href="#cite_note-Eichler_1942-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> The principle was later dubbed 'Eichler's rule'. It is one of the first three <a href="/wiki/Biological_rules" title="Biological rules">coevolutionary rules</a>, created in opposition to <a href="/wiki/Heinrich_Fahrenholz" title="Heinrich Fahrenholz">Heinrich Fahrenholz</a>'s research into coevolution.<sup id="cite_ref-Klassen_3-0" class="reference"><a href="#cite_note-Klassen-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Research">Research</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Eichler%27s_rule&action=edit&section=2" title="Edit section: Research"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>As a part of their 2012 study, Vas and his co-authors tested Eichler's rule, and concluded that exceptionally strong correlational evidence supports the positive co-variation between the species richness of avian and mammalian families and the generic richness of their parasitic <a href="/wiki/Lice" class="mw-redirect" title="Lice">lice</a>.<sup id="cite_ref-Vas_4-0" class="reference"><a href="#cite_note-Vas-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>In volume nine of <i><a href="/wiki/Advances_in_Parasitology" title="Advances in Parasitology">Advances in Parasitology</a></i>, parasitologist W. Grant Inglis posited that, when studying the co-variation between the taxonomic richness of hosts and parasites, it is easier to study parasites than free-living host organisms.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Eichler%27s_rule&action=edit&section=3" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output 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.cs1-maint{color:#18911f}}</style><cite id="CITEREFEichler1966" class="citation journal cs1">Eichler, Wolfdietrich (1966). <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/2411393">"Two New Evolutionary Terms for Speciation in Parasitic Animals"</a>. <i>Systematic Zoology</i>. <b>15</b> (3): <span class="nowrap">216–</span>218. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F2411393">10.2307/2411393</a>. <a href="/wiki/ISSN_(identifier)" class="mw-redirect" title="ISSN (identifier)">ISSN</a> <a rel="nofollow" class="external text" href="https://search.worldcat.org/issn/0039-7989">0039-7989</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/2411393">2411393</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/5924358">5924358</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Systematic+Zoology&rft.atitle=Two+New+Evolutionary+Terms+for+Speciation+in+Parasitic+Animals&rft.volume=15&rft.issue=3&rft.pages=%3Cspan+class%3D%22nowrap%22%3E216-%3C%2Fspan%3E218&rft.date=1966&rft_id=info%3Apmid%2F5924358&rft.issn=0039-7989&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F2411393%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.2307%2F2411393&rft.aulast=Eichler&rft.aufirst=Wolfdietrich&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F2411393&rfr_id=info%3Asid%2Fen.wikipedia.org%3AEichler%27s+rule" class="Z3988"></span></span> </li> <li id="cite_note-Eichler_1942-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-Eichler_1942_2-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFEichler1942" class="citation journal cs1">Eichler, W. (1942). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20170304041639/http://phthiraptera.info/sites/phthiraptera.info/files/39548.pdf">"Die Entfaltungsregel und andere Gesetzmäßigkeiten in den parasitogenetischen Beziehungen der Mallophagen und anderer ständiger Parasiten zu ihren Wirten"</a> <span class="cs1-format">(PDF)</span>. <i><a href="/wiki/Zoologischer_Anzeiger" title="Zoologischer Anzeiger">Zoologischer Anzeiger</a></i>. <b>136</b>: <span class="nowrap">77–</span>83. Archived from <a rel="nofollow" class="external text" href="http://phthiraptera.info/sites/phthiraptera.info/files/39548.pdf">the original</a> <span class="cs1-format">(PDF)</span> on 2017-03-04<span class="reference-accessdate">. Retrieved <span class="nowrap">2012-12-28</span></span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Zoologischer+Anzeiger&rft.atitle=Die+Entfaltungsregel+und+andere+Gesetzm%C3%A4%C3%9Figkeiten+in+den+parasitogenetischen+Beziehungen+der+Mallophagen+und+anderer+st%C3%A4ndiger+Parasiten+zu+ihren+Wirten&rft.volume=136&rft.pages=%3Cspan+class%3D%22nowrap%22%3E77-%3C%2Fspan%3E83&rft.date=1942&rft.aulast=Eichler&rft.aufirst=W.&rft_id=http%3A%2F%2Fphthiraptera.info%2Fsites%2Fphthiraptera.info%2Ffiles%2F39548.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AEichler%27s+rule" class="Z3988"></span></span> </li> <li id="cite_note-Klassen-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-Klassen_3-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFKlassen1992" class="citation journal cs1">Klassen, G. J. (1992). <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/1635016/">"Coevolution: a history of the macroevolutionary approach to studying host-parasite associations"</a>. <i>The Journal of Parasitology</i>. <b>78</b> (4): <span class="nowrap">573–</span>587. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.2307%2F3283532">10.2307/3283532</a>. <a href="/wiki/JSTOR_(identifier)" class="mw-redirect" title="JSTOR (identifier)">JSTOR</a> <a rel="nofollow" class="external text" href="https://www.jstor.org/stable/3283532">3283532</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/1635016">1635016</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=The+Journal+of+Parasitology&rft.atitle=Coevolution%3A+a+history+of+the+macroevolutionary+approach+to+studying+host-parasite+associations&rft.volume=78&rft.issue=4&rft.pages=%3Cspan+class%3D%22nowrap%22%3E573-%3C%2Fspan%3E587&rft.date=1992&rft_id=info%3Apmid%2F1635016&rft_id=https%3A%2F%2Fwww.jstor.org%2Fstable%2F3283532%23id-name%3DJSTOR&rft_id=info%3Adoi%2F10.2307%2F3283532&rft.aulast=Klassen&rft.aufirst=G.+J.&rft_id=https%3A%2F%2Fpubmed.ncbi.nlm.nih.gov%2F1635016%2F&rfr_id=info%3Asid%2Fen.wikipedia.org%3AEichler%27s+rule" class="Z3988"></span></span> </li> <li id="cite_note-Vas-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-Vas_4-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFVasCsorba,_G.Rozsa,_L.2012" class="citation journal cs1">Vas, Z.; Csorba, G.; Rozsa, L. (2012). <a rel="nofollow" class="external text" href="http://www.zoologia.hu/list/Vas_Csorba_Rozsa_2012.pdf">"Evolutionary co-variation of host and parasite diversity – the first test of Eichler's rule using parasitic lice (Insecta: Phthiraptera)"</a> <span class="cs1-format">(PDF)</span>. <i>Parasitology Research</i>. <b>111</b> (1): <span class="nowrap">393–</span>401. <a href="/wiki/Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs00436-012-2850-9">10.1007/s00436-012-2850-9</a>. <a href="/wiki/PMID_(identifier)" class="mw-redirect" title="PMID (identifier)">PMID</a> <a rel="nofollow" class="external text" href="https://pubmed.ncbi.nlm.nih.gov/22350674">22350674</a>. <a href="/wiki/S2CID_(identifier)" class="mw-redirect" title="S2CID (identifier)">S2CID</a> <a rel="nofollow" class="external text" href="https://api.semanticscholar.org/CorpusID:14923342">14923342</a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=Parasitology+Research&rft.atitle=Evolutionary+co-variation+of+host+and+parasite+diversity+%E2%80%93+the+first+test+of+Eichler%27s+rule+using+parasitic+lice+%28Insecta%3A+Phthiraptera%29&rft.volume=111&rft.issue=1&rft.pages=%3Cspan+class%3D%22nowrap%22%3E393-%3C%2Fspan%3E401&rft.date=2012&rft_id=https%3A%2F%2Fapi.semanticscholar.org%2FCorpusID%3A14923342%23id-name%3DS2CID&rft_id=info%3Apmid%2F22350674&rft_id=info%3Adoi%2F10.1007%2Fs00436-012-2850-9&rft.aulast=Vas&rft.aufirst=Z.&rft.au=Csorba%2C+G.&rft.au=Rozsa%2C+L.&rft_id=http%3A%2F%2Fwww.zoologia.hu%2Flist%2FVas_Csorba_Rozsa_2012.pdf&rfr_id=info%3Asid%2Fen.wikipedia.org%3AEichler%27s+rule" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation book cs1"><a rel="nofollow" class="external text" href="https://books.google.com/books?id=yovuRdSJmWwC&q=eichler%27s+rule&pg=PA201"><i>Advances in Parasitology</i></a>. Academic Press. 1971-03-31. <a href="/wiki/ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <a href="/wiki/Special:BookSources/978-0-08-058055-5" title="Special:BookSources/978-0-08-058055-5"><bdi>978-0-08-058055-5</bdi></a>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=book&rft.btitle=Advances+in+Parasitology&rft.pub=Academic+Press&rft.date=1971-03-31&rft.isbn=978-0-08-058055-5&rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DyovuRdSJmWwC%26q%3Deichler%2527s%2Brule%26pg%3DPA201&rfr_id=info%3Asid%2Fen.wikipedia.org%3AEichler%27s+rule" class="Z3988"></span></span> </li> </ol></div></div> <div class="navbox-styles"><style data-mw-deduplicate="TemplateStyles:r1129693374">.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output 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href="/wiki/Template:Biological_rules" title="Template:Biological rules"><abbr title="View this template">v</abbr></a></li><li class="nv-talk"><a href="/wiki/Template_talk:Biological_rules" title="Template talk:Biological rules"><abbr title="Discuss this template">t</abbr></a></li><li class="nv-edit"><a href="/wiki/Special:EditPage/Template:Biological_rules" title="Special:EditPage/Template:Biological rules"><abbr title="Edit this template">e</abbr></a></li></ul></div><div id="Biological_rules32" style="font-size:114%;margin:0 4em"><a href="/wiki/Biological_rules" title="Biological rules">Biological rules</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Rules</th><td class="navbox-list-with-group navbox-list navbox-odd vlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Allen%27s_rule" title="Allen's rule">Allen's rule</a> <span class="wrap"><span style="font-size:85%;">Shorter appendages in colder climates</span></span></li> <li><a href="/wiki/Bateson%27s_rule" class="mw-redirect" title="Bateson's rule">Bateson's rule</a> <span class="wrap"><span style="font-size:85%;">Extra limbs mirror their neighbours</span></span></li> <li><a href="/wiki/Bergmann%27s_rule" title="Bergmann's rule">Bergmann's rule</a> <span class="wrap"><span style="font-size:85%;">Larger bodies in colder climates</span></span></li> <li><a href="/wiki/Cope%27s_rule" title="Cope's rule">Cope's rule</a> <span class="wrap"><span style="font-size:85%;">Bodies get larger over time</span></span></li> <li><a href="/wiki/Deep-sea_gigantism" title="Deep-sea gigantism">Deep-sea gigantism</a> <span class="wrap"><span style="font-size:85%;">Larger bodies in deep-sea animals</span></span></li> <li><a href="/wiki/Dollo%27s_law_of_irreversibility" title="Dollo's law of irreversibility">Dollo's law</a> <span class="wrap"><span style="font-size:85%;">Loss of complex traits is irreversible</span></span></li> <li><a class="mw-selflink selflink">Eichler's rule</a> <span class="wrap"><span style="font-size:85%;">Parasites co-vary with their hosts</span></span></li> <li><a href="/wiki/Emery%27s_rule" title="Emery's rule">Emery's rule</a> <span class="wrap"><span style="font-size:85%;">Insect social parasites are often in same genus as their hosts</span></span></li> <li><a href="/wiki/Fahrenholz%27s_rule" class="mw-redirect" title="Fahrenholz's rule">Fahrenholz's rule</a> <span class="wrap"><span style="font-size:85%;">Host and parasite phylogenies become congruent</span></span></li> <li><a href="/wiki/Foster%27s_rule" title="Foster's rule">Foster's rule</a> (<a href="/wiki/Insular_gigantism" class="mw-redirect" title="Insular gigantism">Insular gigantism</a>, <a href="/wiki/Insular_dwarfism" title="Insular dwarfism">Insular dwarfism</a>) <span class="wrap"><span style="font-size:85%;">Small species get larger, large species smaller, after colonizing islands</span></span></li> <li><a href="/wiki/Gause%27s_law" class="mw-redirect" title="Gause's law">Gause's law</a> <span class="wrap"><span style="font-size:85%;">Complete competitors cannot coexist</span></span></li> <li><a href="/wiki/Gloger%27s_rule" title="Gloger's rule">Gloger's rule</a> <span class="wrap"><span style="font-size:85%;">Lighter coloration in colder, drier climates</span></span></li> <li><a href="/wiki/Haldane%27s_rule" title="Haldane's rule">Haldane's rule</a> <span class="wrap"><span style="font-size:85%;">Hybrid sexes that are absent, rare, or sterile, are heterogamic</span></span></li> <li><a href="/wiki/Harrison%27s_rule" title="Harrison's rule">Harrison's rule</a> <span class="wrap"><span style="font-size:85%;">Parasites co-vary in size with their hosts</span></span></li> <li><a href="/wiki/Kin_selection" title="Kin selection">Hamilton's rule</a> <span class="wrap"><span style="font-size:85%;">Genes increase in frequency when relatedness of recipient to actor times benefit to recipient exceeds reproductive cost to actor</span></span></li> <li><a href="/wiki/Kleiber%27s_law" title="Kleiber's law">Kleiber's law</a> <span class="wrap"><span style="font-size:85%;">An animals metabolic rate decreases with its size</span></span></li> <li><a href="/wiki/Willi_Hennig" title="Willi Hennig">Hennig's progression rule</a> <span class="wrap"><span style="font-size:85%;">In cladistics, the most primitive species are found in earliest, central, part of group's area</span></span></li> <li><a href="/wiki/Jarman%E2%80%93Bell_principle" title="Jarman–Bell principle">Jarman–Bell principle</a> <span class="wrap"><span style="font-size:85%;">The correlation between the size of an animal and its diet quality; larger animals can consume lower quality diet</span></span></li> <li><a href="/wiki/Jordan%27s_rule" title="Jordan's rule">Jordan's rule</a> <span class="wrap"><span style="font-size:85%;">Inverse relationship between water temperature and no. of fin rays, vertebrae</span></span></li> <li><a href="/wiki/Lack%27s_principle" title="Lack's principle">Lack's principle</a> <span class="wrap"><span style="font-size:85%;">Birds lay only as many eggs as they can provide food for</span></span></li> <li><a href="/wiki/Rapoport%27s_rule" title="Rapoport's rule">Rapoport's rule</a> <span class="wrap"><span style="font-size:85%;">Latitudinal range increases with latitude</span></span></li> <li><a href="/wiki/Rensch%27s_rule" title="Rensch's rule">Rensch's rule</a> <span class="wrap"><span style="font-size:85%;">Sexual size dimorphism increases with size when males are larger, decreases with size when females are larger</span></span></li> <li><a href="/wiki/Rosa%27s_rule" title="Rosa's rule">Rosa's rule</a> <span class="wrap"><span style="font-size:85%;">Groups evolve from character variation in primitive species to a fixed character state in advanced ones</span></span></li> <li><a href="/wiki/Ivan_Schmalhausen" title="Ivan Schmalhausen">Schmalhausen's law</a> <span class="wrap"><span style="font-size:85%;">A population at limit of tolerance in one aspect is vulnerable to small differences in any other aspect</span></span></li> <li><a href="/wiki/Countershading" title="Countershading">Thayer's law</a> <span class="wrap"><span style="font-size:85%;">The top of an animals coloration is darker than the bottom</span></span></li> <li><a href="/wiki/Thorson%27s_rule" title="Thorson's rule">Thorson's rule</a> <span class="wrap"><span style="font-size:85%;">No. of eggs of benthic marine invertebrates decreases with latitude</span></span></li> <li><a href="/wiki/Leigh_Van_Valen" title="Leigh Van Valen">Van Valen's law</a> <span class="wrap"><span style="font-size:85%;">Probability of extinction of a group is constant over time</span></span></li> <li><a href="/wiki/Von_Baer%27s_laws_(embryology)" title="Von Baer's laws (embryology)">von Baer's laws</a> <span class="wrap"><span style="font-size:85%;">Embryos start from a common form and develop into increasingly specialised forms</span></span></li> <li><a href="/wiki/Samuel_Wendell_Williston" title="Samuel Wendell Williston">Williston's law</a> <span class="wrap"><span style="font-size:85%;">Parts in an organism become reduced in number and specialized in function</span></span></li></ul> </div></td><td class="noviewer navbox-image" rowspan="2" style="width:1px;padding:0 0 0 2px"><div><span typeof="mw:File"><a href="/wiki/Bergmann%27s_rule" title="Bergmann's rule"><img alt="Bergmann's rule illustrated with a map and graph" src="//upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Bergmann%27s_Rule.svg/160px-Bergmann%27s_Rule.svg.png" decoding="async" width="160" height="149" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Bergmann%27s_Rule.svg/240px-Bergmann%27s_Rule.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Bergmann%27s_Rule.svg/320px-Bergmann%27s_Rule.svg.png 2x" data-file-width="512" data-file-height="476" /></a></span></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Related</th><td class="navbox-list-with-group navbox-list navbox-even vlist" style="width:100%;padding:0"><div style="padding:0 0.25em"> <ul><li><a href="/wiki/Countergradient_variation" title="Countergradient variation">Countergradient variation</a> <span style="font-size:85%;">Where genetics opposes environment as a factor</span></li> <li><a href="/wiki/Gigantothermy" title="Gigantothermy">Gigantothermy</a> <span style="font-size:85%;">Large ectothermic animals more easily maintain constant body temperature</span></li></ul> </div></td></tr></tbody></table></div>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=0" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" 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