{"id":640,"date":"2018-01-18T19:49:56","date_gmt":"2018-01-18T19:49:56","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/chapter\/constructing-an-animal-phylogenetic-tree\/"},"modified":"2024-04-26T18:27:46","modified_gmt":"2024-04-26T18:27:46","slug":"constructing-an-animal-phylogenetic-tree","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/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\nThe current understanding of evolutionary relationships between animal, or Metazoa, phyla begins with the distinction between \u201ctrue\u201d animals with true differentiated tissues, called Eumetazoa, and animal phyla that do not have true differentiated tissues (such as the sponges), called Parazoa. Both Parazoa and Eumetazoa evolved from a common ancestral organism that resembles the modern-day protists called choanoflagellates. These protist cells strongly resemble the sponge choanocyte cells today (Figure 1).\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\/2840\/2018\/01\/18194951\/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. Cells of the protist choanoflagellate resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.[\/caption]\r\n\r\nEumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals, and are thus classified into clade Bilateria or Radiata, respectively. As mentioned earlier, the cnidarians and ctenophores are animal phyla with true radial 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). Ecdysozoa includes nematodes and arthropods; they are so named for a commonly found characteristic among the group: exoskeletal molting (termed ecdysis). Lophotrochozoa is named for two structural features, each common to certain phyla within the clade. Some lophotrochozoan phyla are characterized by a larval stage called trochophore larvae, and other phyla are characterized by the presence of a feeding structure called a lophophore.\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\/2840\/2018\/01\/18194954\/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\/850fde25-e0c9-49ba-a15c-bf3f7a49450f\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>The current understanding of evolutionary relationships between animal, or Metazoa, phyla begins with the distinction between \u201ctrue\u201d animals with true differentiated tissues, called Eumetazoa, and animal phyla that do not have true differentiated tissues (such as the sponges), called Parazoa. Both Parazoa and Eumetazoa evolved from a common ancestral organism that resembles the modern-day protists called choanoflagellates. These protist cells strongly resemble the sponge choanocyte cells today (Figure 1).<\/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\/2840\/2018\/01\/18194951\/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. Cells of the protist choanoflagellate resemble sponge choanocyte cells. Beating of choanocyte flagella draws water through the sponge so that nutrients can be extracted and waste removed.<\/p>\n<\/div>\n<p>Eumetazoa are subdivided into radially symmetrical animals and bilaterally symmetrical animals, and are thus classified into clade Bilateria or Radiata, respectively. As mentioned earlier, the cnidarians and ctenophores are animal phyla with true radial 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). Ecdysozoa includes nematodes and arthropods; they are so named for a commonly found characteristic among the group: exoskeletal molting (termed ecdysis). Lophotrochozoa is named for two structural features, each common to certain phyla within the clade. Some lophotrochozoan phyla are characterized by a larval stage called trochophore larvae, and other phyla are characterized by the presence of a feeding structure called a lophophore.<\/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\/2840\/2018\/01\/18194954\/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_850fde25-e0c9-49ba-a15c-bf3f7a49450f\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/850fde25-e0c9-49ba-a15c-bf3f7a49450f?iframe_resize_id=assessment_practice_id_850fde25-e0c9-49ba-a15c-bf3f7a49450f\" 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-640\">\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. <strong>Provided by<\/strong>: OpenStax CNX. <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>: Download for free at http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8<\/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\",\"author\":\"\",\"organization\":\"OpenStax CNX\",\"url\":\"http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Download for free at http:\/\/cnx.org\/contents\/185cbf87-c72e-48f5-b51e-f14f21b5eabd@10.8\"}]","CANDELA_OUTCOMES_GUID":"7cfdb582-0adb-4a6a-b121-012205b4691f, 0f795ee1-4b31-450b-949a-9faa4b6de19b","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-640","chapter","type-chapter","status-publish","hentry"],"part":622,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapters\/640","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/wp\/v2\/users\/17"}],"version-history":[{"count":4,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapters\/640\/revisions"}],"predecessor-version":[{"id":3011,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapters\/640\/revisions\/3011"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/parts\/622"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapters\/640\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/wp\/v2\/media?parent=640"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/pressbooks\/v2\/chapter-type?post=640"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/wp\/v2\/contributor?post=640"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-nmbiology2\/wp-json\/wp\/v2\/license?post=640"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}