{"id":6451,"date":"2011-12-08T17:44:31","date_gmt":"2011-12-08T21:44:31","guid":{"rendered":"https:\/\/esa.org\/esablog\/?p=6451"},"modified":"2011-12-08T17:44:31","modified_gmt":"2011-12-08T21:44:31","slug":"tinkering-with-worm-sex-to-shed-light-on-evolution","status":"publish","type":"post","link":"https:\/\/esa.org\/esablog\/2011\/12\/08\/tinkering-with-worm-sex-to-shed-light-on-evolution\/","title":{"rendered":"Tinkering with worm sex to shed light on evolution"},"content":{"rendered":"<p><strong> <\/strong><em>This post contributed by Nadine Lymn, ESA Director of Public Affairs<\/em><\/p>\n<p><a href=\"https:\/\/esa.org\/esablog-preprod\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-6452 img-fluid\" title=\"hermaphrodite C. elegans\" src=\"https:\/\/esa.org\/esablog-preprod\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans.jpg\" alt=\"\" width=\"568\" height=\"425\" srcset=\"https:\/\/esa.org\/esablog\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans.jpg 1388w, https:\/\/esa.org\/esablog\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans-300x225.jpg 300w, https:\/\/esa.org\/esablog\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans-1024x767.jpg 1024w, https:\/\/esa.org\/esablog\/wp-content\/uploads\/sites\/90\/2011\/12\/hermaphrodite-C.-elegans-768x575.jpg 768w\" sizes=\"auto, (max-width: 568px) 100vw, 568px\" \/><\/a><\/p>\n<p>The roundworm <em>Caenorhabditis elegans (C. elegans<\/em>) is a tiny laboratory animal that researchers have worked with for decades.\u00a0 As a hermaphrodite, <em>C. elegans<\/em> makes both sperm and eggs and can reproduce by self-fertilization. \u00a0In contrast to humans, where hermaphrodites are rare, for <em>C. elegans<\/em>, this is its normal state.\u00a0\u00a0 However, male individuals, with only male gonads, can also occur and these individuals must mate with a hermaphrodite in order to reproduce, as shown in the video below.<\/p>\n<div class=\"embed-responsive embed-responsive-16by9\" data-video-type=\"youtube\"><iframe class=\"embed-responsive-item\" src=\"https:\/\/www.youtube.com\/embed\/cXx35u7zLxs?modestbranding=0&amp;rel=0&amp;showinfo=0&amp;iv_load_policy=3&amp;enablejsapi=1\"><\/iframe><\/div>\n<p>A central question in evolution is how variations in the genes responsible for determining gender can exist since there seems to be so little room for error; if the mutation goes awry and negatively affects reproductive ability, a species could be in serious trouble.<\/p>\n<p>A new <a href=\"https:\/\/www.msu.edu\/%7Eidworkin\/publications\/ChandlerEXPERIMENTAL%20EVOLUTION%20OF%20THE%20CAENORHABDITIS%20ELEGANS%20SEX%20DETERMINATION%20PATHWAYEvolution.pdf\">paper<\/a> published in the journal <em>Evolution<\/em> took a closer look.\u00a0 \u00a0Michigan State University researchers Christopher Chandler and Ian Dworkin and colleagues at Iowa State University used worms that had already been mutated in previous experiments.\u00a0 One mutation determined that at a specific temperature, the larvae will become a hermaphrodite.\u00a0 At a higher specific temperature, the larvae\u2014while still genetically a hermaphrodite\u2014becomes a male, and at temperatures in between, intersex individuals arise, sporting both male and hermaphrodite characteristics.\u00a0\u00a0 These intersex individuals are different from the normal, hermaphrodite <em>C. elegans<\/em>, in that they are truly mixed up\u2014they have some characteristics of both the hermaphrodite and male versions of <em>C. elegans<\/em>.\u00a0\u00a0 Chandler, Dworkin, and colleagues exposed the worms to the intermediate temperatures, creating populations of intersex individuals.<\/p>\n<p>As described in a <a href=\"http:\/\/www.nsf.gov\/discoveries\/disc_images.jsp?cntn_id=122381&amp;org=NSF\">press release<\/a> about the research, these characteristics made reproduction difficult, though still possible. Chandler and colleagues allowed these populations to reproduce for 50 generations, creating a strong selection for individuals still able to function sexually. \u00a0Then the researchers measured the later generations\u2019 sex ratio and fertility.\u00a0 They found that these later populations had more typical <em>C. elegans<\/em> sex ratios and higher fertility, despite the fact that they were still subjected to the intermediate temperatures that had rendered their predecessors intersex animals.\u00a0 As explained in the press release, other genes were evolving to compensate for changes in the sex determination genes, in a way that allowed individual worms to develop either as a male or a hermaphrodite, instead of as an intersex animal.<\/p>\n<p>In other words, <em>C. elegans<\/em> was able to make up for the negative mutations brought out by the artificial conditions created by the researchers.\u00a0 In their paper\u2019s conclusion, the authors note that their experiment, funded by the National Science Foundation, demonstrates that \u201corganisms can accommodate deleterious developmental mutations on relatively short time scales\u201d and that the mechanisms underlying these changes \u201cmay not be as predictable or repeatable as one might expect.\u201d<\/p>\n<p>At least in a lab setting, the worms were able to compensate for the negative mutations, and likely in more than one way.<\/p>\n<p><span class=\"Z3988\" title=\"ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.jtitle=Evolution&amp;rft_id=info%3Adoi%2F10.1111%2Fj.1558-5646.2011.01420.x&amp;rfr_id=info%3Asid%2Fresearchblogging.org&amp;rft.atitle=EXPERIMENTAL+EVOLUTION+OF+THE+CAENORHABDITIS+ELEGANS+SEX+DETERMINATION+PATHWAY&amp;rft.issn=00143820&amp;rft.date=2011&amp;rft.volume=&amp;rft.issue=&amp;rft.spage=0&amp;rft.epage=0&amp;rft.artnum=http%3A%2F%2Fdoi.wiley.com%2F10.1111%2Fj.1558-5646.2011.01420.x&amp;rft.au=Chandler%2C+C.&amp;rft.au=Chadderdon%2C+G.&amp;rft.au=Phillips%2C+P.&amp;rft.au=Dworkin%2C+I.&amp;rft.au=Janzen%2C+F.&amp;rfe_dat=bpr3.included=1;bpr3.tags=Biology%2CEcology+%2F+Conservation%2CEcology\">Chandler, C., Chadderdon, G., Phillips, P., Dworkin, I., &amp; Janzen, F. (2011). EXPERIMENTAL EVOLUTION OF THE CAENORHABDITIS ELEGANS SEX DETERMINATION PATHWAY <span style=\"font-style: italic\">Evolution<\/span> DOI: <a rev=\"review\" href=\"http:\/\/dx.doi.org\/10.1111\/j.1558-5646.2011.01420.x\">10.1111\/j.1558-5646.2011.01420.x<\/a><\/span><br>\n\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This post contributed by Nadine Lymn, ESA Director of Public Affairs The roundworm Caenorhabditis elegans (C. elegans) is a tiny laboratory animal that researchers have worked with for decades.\u00a0 As a hermaphrodite, C. elegans makes both sperm and eggs and can reproduce by self-fertilization. \u00a0In contrast to humans, where hermaphrodites are rare, for C. elegans, this is its normal state.\u00a0\u00a0&#8230;<\/p>\n","protected":false},"author":41,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[1330,102,543,1331,235,1332,104,935],"class_list":["post-6451","post","type-post","status-publish","format-standard","hentry","category-research","tag-c-elegans","tag-evolution","tag-genes","tag-genetic-variation","tag-reproduction","tag-sex-determination","tag-species","tag-worm"],"_links":{"self":[{"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/posts\/6451","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/users\/41"}],"replies":[{"embeddable":true,"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/comments?post=6451"}],"version-history":[{"count":0,"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/posts\/6451\/revisions"}],"wp:attachment":[{"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/media?parent=6451"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/categories?post=6451"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/esa.org\/esablog\/wp-json\/wp\/v2\/tags?post=6451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}