{"id":4397,"date":"2017-03-28T22:57:44","date_gmt":"2017-03-28T22:57:44","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/wm-biology2\/?post_type=chapter&#038;p=4397"},"modified":"2024-04-26T01:40:31","modified_gmt":"2024-04-26T01:40:31","slug":"asexual-reproduction","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wm-biology2\/chapter\/asexual-reproduction\/","title":{"raw":"Asexual Reproduction","rendered":"Asexual Reproduction"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Discuss asexual reproduction methods<\/li>\r\n<\/ul>\r\n<\/div>\r\nAsexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multi-celled organisms. <b>Asexual reproduction<\/b> produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. A single individual can produce offspring asexually and large numbers of offspring can be produced quickly.\r\n\r\nIn a stable or predictable environment, asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment. In an unstable or unpredictable environment asexually-reproducing species may be at a disadvantage because all the offspring are genetically identical and may not have the genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may allow for a speedy response to environmental changes if individuals have mutations. An additional advantage of asexual reproduction is that colonization of new habitats may be easier when an individual does not need to find a mate to reproduce. There are a number of ways that animals reproduce asexually.\r\n<h2>Fission<\/h2>\r\n<b>Fission<\/b>, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps (Figure 1a) also reproduce through fission.\r\n<h2>Budding<\/h2>\r\n<b>Budding<\/b> is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 1b, whereas in coral budding, the bud does not detach and multiplies as part of a new colony.\r\n\r\n[caption id=\"attachment_3039\" align=\"aligncenter\" width=\"1024\"]<img class=\"size-large wp-image-3039\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09200813\/Figure_43_01_01ab-1024x341.jpg\" alt=\"Image A shows many coral polyps clustered together. Each Polyp is cup-shaped, with tentacles radiating out from the rim. Illustration B shows a hydra, which has a stalk-like body with tentacles growing out the top. A smaller hydra is budding from the side of the stalk.\" width=\"1024\" height=\"341\" \/> Figure 1. (a)\u00a0Coral polyps reproduce asexually by fission. (b) Hydra reproduce asexually through budding. (credit a: G. P. Schmahl, NOAA FGBNMS Manager)[\/caption]\r\n\r\n<div class=\"textbox\">\r\n\r\nWatch a video of a hydra budding. Note that there is no audio in this video.\r\n\r\nhttps:\/\/youtu.be\/wfbhwq95Duc\r\n\r\nYou can view the <a href=\"https:\/\/oerfiles.s3.us-west-2.amazonaws.com\/WM+Biology\/transcripts\/BuddingHydra_DescriptiveTranscript.html\" target=\"_blank\" rel=\"noopener\">descriptive transcript for \"Budding In Hydra\" here (opens in new window)<\/a>.\r\n\r\n<\/div>\r\n<h2>Fragmentation<\/h2>\r\n[caption id=\"attachment_3040\" align=\"alignright\" width=\"400\"]<img class=\"wp-image-3040\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09200925\/Figure_43_01_03.jpg\" alt=\" Illustration shows a sea star with one long arm and four very short arms.\" width=\"400\" height=\"337\" \/> Figure 2.\u00a0Sea stars can reproduce through fragmentation. The large arm, a fragment from another sea star, is developing into a new individual.[\/caption]\r\n\r\n<b>Fragmentation<\/b> is the breaking of the body into two parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow.\r\n\r\nFor example, in many sea stars, asexual reproduction is accomplished by fragmentation. Figure 2\u00a0illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean. Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans.\r\n\r\nNote that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed.\r\n<h2>Parthenogenesis<\/h2>\r\n<b>Parthenogenesis<\/b> is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees use parthenogenesis to produce haploid males (drones) and diploid females (workers). If an egg is fertilized, a queen is produced. The queen bee controls the reproduction of the hive bees to regulate the type of bee produced.\r\n\r\nSome vertebrate animals\u2014such as certain reptiles, amphibians, and fish\u2014also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females have been isolated from males.\r\n<div class=\"textbox tryit\">\r\n<h3>Try It<\/h3>\r\nhttps:\/\/assess.lumenlearning.com\/practice\/dc4cbd77-0db0-4bdc-b87f-a8c6f1faf725\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Discuss asexual reproduction methods<\/li>\n<\/ul>\n<\/div>\n<p>Asexual reproduction occurs in prokaryotic microorganisms (bacteria) and in some eukaryotic single-celled and multi-celled organisms. <b>Asexual reproduction<\/b> produces offspring that are genetically identical to the parent because the offspring are all clones of the original parent. A single individual can produce offspring asexually and large numbers of offspring can be produced quickly.<\/p>\n<p>In a stable or predictable environment, asexual reproduction is an effective means of reproduction because all the offspring will be adapted to that environment. In an unstable or unpredictable environment asexually-reproducing species may be at a disadvantage because all the offspring are genetically identical and may not have the genetic variation to survive in new or different conditions. On the other hand, the rapid rates of asexual reproduction may allow for a speedy response to environmental changes if individuals have mutations. An additional advantage of asexual reproduction is that colonization of new habitats may be easier when an individual does not need to find a mate to reproduce. There are a number of ways that animals reproduce asexually.<\/p>\n<h2>Fission<\/h2>\n<p><b>Fission<\/b>, also called binary fission, occurs in prokaryotic microorganisms and in some invertebrate, multi-celled organisms. After a period of growth, an organism splits into two separate organisms. Some unicellular eukaryotic organisms undergo binary fission by mitosis. In other organisms, part of the individual separates and forms a second individual. This process occurs, for example, in many asteroid echinoderms through splitting of the central disk. Some sea anemones and some coral polyps (Figure 1a) also reproduce through fission.<\/p>\n<h2>Budding<\/h2>\n<p><b>Budding<\/b> is a form of asexual reproduction that results from the outgrowth of a part of a cell or body region leading to a separation from the original organism into two individuals. Budding occurs commonly in some invertebrate animals such as corals and hydras. In hydras, a bud forms that develops into an adult and breaks away from the main body, as illustrated in Figure 1b, whereas in coral budding, the bud does not detach and multiplies as part of a new colony.<\/p>\n<div id=\"attachment_3039\" style=\"width: 1034px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-3039\" class=\"size-large wp-image-3039\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09200813\/Figure_43_01_01ab-1024x341.jpg\" alt=\"Image A shows many coral polyps clustered together. Each Polyp is cup-shaped, with tentacles radiating out from the rim. Illustration B shows a hydra, which has a stalk-like body with tentacles growing out the top. A smaller hydra is budding from the side of the stalk.\" width=\"1024\" height=\"341\" \/><\/p>\n<p id=\"caption-attachment-3039\" class=\"wp-caption-text\">Figure 1. (a)\u00a0Coral polyps reproduce asexually by fission. (b) Hydra reproduce asexually through budding. (credit a: G. P. Schmahl, NOAA FGBNMS Manager)<\/p>\n<\/div>\n<div class=\"textbox\">\n<p>Watch a video of a hydra budding. Note that there is no audio in this video.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Budding In Hydra\" width=\"500\" height=\"375\" src=\"https:\/\/www.youtube.com\/embed\/wfbhwq95Duc?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>You can view the <a href=\"https:\/\/oerfiles.s3.us-west-2.amazonaws.com\/WM+Biology\/transcripts\/BuddingHydra_DescriptiveTranscript.html\" target=\"_blank\" rel=\"noopener\">descriptive transcript for &#8220;Budding In Hydra&#8221; here (opens in new window)<\/a>.<\/p>\n<\/div>\n<h2>Fragmentation<\/h2>\n<div id=\"attachment_3040\" style=\"width: 410px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-3040\" class=\"wp-image-3040\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1223\/2017\/02\/09200925\/Figure_43_01_03.jpg\" alt=\"Illustration shows a sea star with one long arm and four very short arms.\" width=\"400\" height=\"337\" \/><\/p>\n<p id=\"caption-attachment-3040\" class=\"wp-caption-text\">Figure 2.\u00a0Sea stars can reproduce through fragmentation. The large arm, a fragment from another sea star, is developing into a new individual.<\/p>\n<\/div>\n<p><b>Fragmentation<\/b> is the breaking of the body into two parts with subsequent regeneration. If the animal is capable of fragmentation, and the part is big enough, a separate individual will regrow.<\/p>\n<p>For example, in many sea stars, asexual reproduction is accomplished by fragmentation. Figure 2\u00a0illustrates a sea star for which an arm of the individual is broken off and regenerates a new sea star. Fisheries workers have been known to try to kill the sea stars eating their clam or oyster beds by cutting them in half and throwing them back into the ocean. Unfortunately for the workers, the two parts can each regenerate a new half, resulting in twice as many sea stars to prey upon the oysters and clams. Fragmentation also occurs in annelid worms, turbellarians, and poriferans.<\/p>\n<p>Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed.<\/p>\n<h2>Parthenogenesis<\/h2>\n<p><b>Parthenogenesis<\/b> is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees use parthenogenesis to produce haploid males (drones) and diploid females (workers). If an egg is fertilized, a queen is produced. The queen bee controls the reproduction of the hive bees to regulate the type of bee produced.<\/p>\n<p>Some vertebrate animals\u2014such as certain reptiles, amphibians, and fish\u2014also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females have been isolated from males.<\/p>\n<div class=\"textbox tryit\">\n<h3>Try It<\/h3>\n<p>\t<iframe id=\"assessment_practice_dc4cbd77-0db0-4bdc-b87f-a8c6f1faf725\" class=\"resizable\" src=\"https:\/\/assess.lumenlearning.com\/practice\/dc4cbd77-0db0-4bdc-b87f-a8c6f1faf725?iframe_resize_id=assessment_practice_id_dc4cbd77-0db0-4bdc-b87f-a8c6f1faf725\" 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-4397\">\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":3,"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":"f3126120-eb4f-467f-8287-2dd223fad713, c20ab619-896d-4e2e-a6e6-05da2b7c5c7d","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-4397","chapter","type-chapter","status-publish","hentry"],"part":3801,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4397","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\/4397\/revisions"}],"predecessor-version":[{"id":8550,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4397\/revisions\/8550"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/parts\/3801"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapters\/4397\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/media?parent=4397"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/pressbooks\/v2\/chapter-type?post=4397"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/contributor?post=4397"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/wm-biology2\/wp-json\/wp\/v2\/license?post=4397"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}