{"id":1820,"date":"2017-01-30T23:20:27","date_gmt":"2017-01-30T23:20:27","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=1820"},"modified":"2024-04-25T19:05:18","modified_gmt":"2024-04-25T19:05:18","slug":"constructing-an-animal-phylogenetic-tree","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/constructing-an-animal-phylogenetic-tree\/","title":{"raw":"Constructing an Animal Phylogenetic Tree","rendered":"Constructing an Animal Phylogenetic Tree"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Interpret the metazoan phylogenetic tree<\/li>\r\n<\/ul>\r\n<\/div>\r\n<p id=\"fs-idp68396496\">The current understanding of evolutionary relationships among animal, or\u00a0<strong><span id=\"term1046\" data-type=\"term\">Metazoa<\/span><\/strong>, phyla begins with the distinction between animals with\u00a0<em data-effect=\"italics\">true differentiated tissues<\/em>, called\u00a0<strong><span id=\"term1047\" data-type=\"term\">Eumetazoa<\/span><\/strong>, and animal phyla that do not have true differentiated tissues, such as the sponges (<strong><span id=\"term1048\" data-type=\"term\">Porifera<\/span><\/strong>) and the Placozoa. Similarities between the feeding cells of sponges (choanocytes) and choanoflagellate protists (Figure 1) have been used to suggest that Metazoa evolved from a common ancestral organism that resembled the moderncolonial choanoflagellates.<\/p>\r\n\r\n\r\n[caption id=\"attachment_2301\" align=\"aligncenter\" width=\"741\"]<img class=\"size-full wp-image-2301\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/01214759\/Figure_27_03_01.jpg\" alt=\"The image on the left shows a choanoflagellate, which is a single-celled protest. The image on the right shows a sponge choanocyte cell that lines in inside of a sponge. The two cells appear identical. Both are egg-shaped with a cone at the back end. A flagellum juts out from the wide part of the cone.\" width=\"741\" height=\"286\" \/> Figure 1.\u00a0<span class=\"os-caption\">Cells of the protist choanoflagellate clade closely resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.<\/span>[\/caption]\r\n<p id=\"fs-idp93832224\">Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals, and are thus classified into the clades Bilateria and Radiata, respectively. As mentioned earlier, the cnidarians and ctenophores are animal phyla with true radial, biradial, or rotational symmetry. All other Eumetazoa are members of the Bilateria clade. The bilaterally symmetrical animals are further divided into deuterostomes (including chordates and echinoderms) and two distinct clades of protostomes (including ecdysozoans and lophotrochozoans) (Figure 2).\u00a0<strong><span id=\"term1049\" data-type=\"term\">Ecdysozoa<\/span><\/strong>\u00a0includes nematodes and arthropods; they are so named for a commonly found characteristic among the group: the physiological process of exoskeletal\u00a0<em data-effect=\"italics\">molting<\/em>\u00a0followed by the \u201cstripping\u201d of the outer cuticular layer, called\u00a0<em data-effect=\"italics\">ecdysis<\/em>.\u00a0<strong><span id=\"term1050\" data-type=\"term\">Lophotrochozoa<\/span><\/strong>\u00a0is named for two structural features, each common to certain phyla within the clade. Some lophotrochozoan phyla are characterized by a larval stage called\u00a0<em data-effect=\"italics\">trochophore larvae<\/em>, and other phyla are characterized by the presence of a feeding structure called a\u00a0<em data-effect=\"italics\">lophophore<\/em>\u00a0(thus, the shorter term, \u201clopho-trocho-zoa\u201d).<\/p>\r\n\r\n\r\n[caption id=\"attachment_2304\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-2304\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/01214910\/Figure_27_03_02ab-1024x372.jpg\" alt=\"Part a shows cockroaches. Part b shows phoronids, whose body is a slender stalk anchored to the ocean floor. Fine tentacles radiate from the top of the stalk. The tentacles and stalk resemble a flower.\" width=\"1024\" height=\"372\" \/> Figure 2. Animals that molt their exoskeletons, such as these (a) Madagascar hissing cockroaches, are in the clade Ecdysozoa. (b) Phoronids are in the clade Lophotrochozoa. The tentacles are part of a feeding structure called a lophophore. (credit a: modification of work by Whitney Cranshaw, Colorado State University, Bugwood.org; credit b: modification of work by NOAA)[\/caption]\r\n\r\n<div class=\"textbox\"><a href=\"http:\/\/www.open.edu\/openlearn\/nature-environment\/natural-history\/tree-life\" target=\"_blank\" rel=\"noopener\">Explore an interactive tree of life here.<\/a> Zoom and click to learn more about the organisms and their evolutionary relationships.<\/div>\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/0f0e9a50-b3f6-4816-bd65-f1dbb18a0f84\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Interpret the metazoan phylogenetic tree<\/li>\n<\/ul>\n<\/div>\n<p id=\"fs-idp68396496\">The current understanding of evolutionary relationships among animal, or\u00a0<strong><span id=\"term1046\" data-type=\"term\">Metazoa<\/span><\/strong>, phyla begins with the distinction between animals with\u00a0<em data-effect=\"italics\">true differentiated tissues<\/em>, called\u00a0<strong><span id=\"term1047\" data-type=\"term\">Eumetazoa<\/span><\/strong>, and animal phyla that do not have true differentiated tissues, such as the sponges (<strong><span id=\"term1048\" data-type=\"term\">Porifera<\/span><\/strong>) and the Placozoa. Similarities between the feeding cells of sponges (choanocytes) and choanoflagellate protists (Figure 1) have been used to suggest that Metazoa evolved from a common ancestral organism that resembled the moderncolonial choanoflagellates.<\/p>\n<div id=\"attachment_2301\" style=\"width: 751px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2301\" class=\"size-full wp-image-2301\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/01214759\/Figure_27_03_01.jpg\" alt=\"The image on the left shows a choanoflagellate, which is a single-celled protest. The image on the right shows a sponge choanocyte cell that lines in inside of a sponge. The two cells appear identical. Both are egg-shaped with a cone at the back end. A flagellum juts out from the wide part of the cone.\" width=\"741\" height=\"286\" \/><\/p>\n<p id=\"caption-attachment-2301\" class=\"wp-caption-text\">Figure 1.\u00a0<span class=\"os-caption\">Cells of the protist choanoflagellate clade closely resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.<\/span><\/p>\n<\/div>\n<p id=\"fs-idp93832224\">Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals, and are thus classified into the clades Bilateria and Radiata, respectively. As mentioned earlier, the cnidarians and ctenophores are animal phyla with true radial, biradial, or rotational symmetry. All other Eumetazoa are members of the Bilateria clade. The bilaterally symmetrical animals are further divided into deuterostomes (including chordates and echinoderms) and two distinct clades of protostomes (including ecdysozoans and lophotrochozoans) (Figure 2).\u00a0<strong><span id=\"term1049\" data-type=\"term\">Ecdysozoa<\/span><\/strong>\u00a0includes nematodes and arthropods; they are so named for a commonly found characteristic among the group: the physiological process of exoskeletal\u00a0<em data-effect=\"italics\">molting<\/em>\u00a0followed by the \u201cstripping\u201d of the outer cuticular layer, called\u00a0<em data-effect=\"italics\">ecdysis<\/em>.\u00a0<strong><span id=\"term1050\" data-type=\"term\">Lophotrochozoa<\/span><\/strong>\u00a0is named for two structural features, each common to certain phyla within the clade. Some lophotrochozoan phyla are characterized by a larval stage called\u00a0<em data-effect=\"italics\">trochophore larvae<\/em>, and other phyla are characterized by the presence of a feeding structure called a\u00a0<em data-effect=\"italics\">lophophore<\/em>\u00a0(thus, the shorter term, \u201clopho-trocho-zoa\u201d).<\/p>\n<div id=\"attachment_2304\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-2304\" class=\"size-large wp-image-2304\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/01214910\/Figure_27_03_02ab-1024x372.jpg\" alt=\"Part a shows cockroaches. Part b shows phoronids, whose body is a slender stalk anchored to the ocean floor. Fine tentacles radiate from the top of the stalk. The tentacles and stalk resemble a flower.\" width=\"1024\" height=\"372\" \/><\/p>\n<p id=\"caption-attachment-2304\" class=\"wp-caption-text\">Figure 2. Animals that molt their exoskeletons, such as these (a) Madagascar hissing cockroaches, are in the clade Ecdysozoa. (b) Phoronids are in the clade Lophotrochozoa. The tentacles are part of a feeding structure called a lophophore. (credit a: modification of work by Whitney Cranshaw, Colorado State University, Bugwood.org; credit b: modification of work by NOAA)<\/p>\n<\/div>\n<div class=\"textbox\"><a href=\"http:\/\/www.open.edu\/openlearn\/nature-environment\/natural-history\/tree-life\" target=\"_blank\" rel=\"noopener\">Explore an interactive tree of life here.<\/a> Zoom and click to learn more about the organisms and their evolutionary relationships.<\/div>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_0f0e9a50-b3f6-4816-bd65-f1dbb18a0f84\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/0f0e9a50-b3f6-4816-bd65-f1dbb18a0f84?iframe_resize_id=assessment_practice_id_0f0e9a50-b3f6-4816-bd65-f1dbb18a0f84\" frameborder=\"0\" style=\"border:none;width:100%;height:100%;min-height:300px;\"><br \/>\n\t<\/iframe>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1820\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Biology 2e. <strong>Provided by<\/strong>: OpenStax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\">http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":17,"menu_order":8,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Biology 2e\",\"author\":\"\",\"organization\":\"OpenStax\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Access for free at https:\/\/openstax.org\/books\/biology-2e\/pages\/1-introduction\"}]","CANDELA_OUTCOMES_GUID":"3e80555e-5dce-4599-8626-9aa9ce0448cc, d62e9708-3f99-4985-9205-9b36583ad4cf","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1820","chapter","type-chapter","status-publish","hentry"],"part":21,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/1820","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":11,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/1820\/revisions"}],"predecessor-version":[{"id":8414,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/1820\/revisions\/8414"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/parts\/21"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/1820\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=1820"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=1820"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=1820"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=1820"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}