{"id":292,"date":"2017-03-29T20:31:13","date_gmt":"2017-03-30T03:31:13","guid":{"rendered":"https:\/\/blogs.ubc.ca\/mrpletsch\/?p=292"},"modified":"2019-01-10T20:51:58","modified_gmt":"2019-01-11T03:51:58","slug":"class-aves","status":"publish","type":"post","link":"https:\/\/blogs.ubc.ca\/mrpletsch\/2017\/03\/29\/class-aves\/","title":{"rendered":"Class Aves"},"content":{"rendered":"<h3>General Characteristics<\/h3>\n<ul>\n<li>Toothless beak<\/li>\n<li>Amniotic egg with hard mineralized shell<\/li>\n<li>Tetrapod \u2013 feathered wings and scaly, clawed feet<\/li>\n<li>The youngest group of vertebrates appearing ~65 million years ago.<\/li>\n<li>Highly advanced and efficient systems<\/li>\n<li>~10,000 species today<\/li>\n<\/ul>\n<h3>Evolution of Birds<\/h3>\n<ul>\n<li>Evolved from reptiles \u2013 often called <u><b>AVIAN DINOSAURS<\/b><\/u><u><u><b>.<\/b><\/u><\/u>\n<p><figure id=\"attachment_293\" aria-describedby=\"caption-attachment-293\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-293 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves1-300x180.png\" alt=\"\" width=\"300\" height=\"180\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves1-300x180.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves1-552x331.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves1.png 663w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-293\" class=\"wp-caption-text\">Figure 1: Relationship to reptiles and, iin particular, the dinosaurs<\/figcaption><\/figure><\/li>\n<li>After the Creataceous-Palaeogene extinction event<u><b>, birds diversified from <\/b><\/u><u><b>theropod<\/b><\/u><u><u><b> dinosaurs<\/b><\/u><b> <\/b><\/u>(as they survived the event that killed all other dinosaurs)<\/li>\n<li><u><b><i>Archaeopteryx<\/i><\/b><\/u> is a transitional fossil between feathered dinosaurs and modern birds.<\/li>\n<\/ul>\n<p><a href=\"https:\/\/www.youtube.com\/watch?v=z4nuWLd2ivc\">Great Transitions &#8211; Origin of Birds<\/a><\/p>\n<p>Another great click-and-learn resource from HHMI &#8211; <a href=\"http:\/\/www.hhmi.org\/biointeractive\/comparative-anatomy-domestic-chicken\">Comparing Anatomy of the Domestic Chicken<\/a> &#8211; More evidence for the bird\/theropod relationship! Check it out!<\/p>\n<figure id=\"attachment_294\" aria-describedby=\"caption-attachment-294\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-294 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves2-300x150.png\" alt=\"\" width=\"300\" height=\"150\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves2-300x150.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves2-768x384.png 768w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves2-552x276.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves2.png 784w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-294\" class=\"wp-caption-text\">Figure 2: <em>Archeaopteryx<\/em><\/figcaption><\/figure>\n<h3>Major Evolutionary Advancement #1 &#8211; Feathers<\/h3>\n<p><b>Feathers<\/b><b> (integument)<\/b><\/p>\n<ul>\n<li>Evolved for <u><u><b>insulation\/ther<\/b><\/u><\/u><u><b>moregulation, displays, or water proofing<\/b><\/u>.<\/li>\n<li>Initial feathers could not have provided lift \u2013 <u><b>secondary function of feather evolution was flight<\/b><\/u><\/li>\n<li><u><b>Potentially evolved from scales <\/b><\/u>(debatable) however a 2006 study confirmed feather keratin in crocodile scales during early development.\n<p><figure id=\"attachment_295\" aria-describedby=\"caption-attachment-295\" style=\"width: 960px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-295\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves3.png\" alt=\"\" width=\"960\" height=\"333\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves3.png 960w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves3-300x104.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves3-768x266.png 768w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves3-552x191.png 552w\" sizes=\"auto, (max-width: 960px) 100vw, 960px\" \/><figcaption id=\"caption-attachment-295\" class=\"wp-caption-text\">Figure 3: Proposed evolution of feathers. Notice how stage 2 resembles down feathers we see tday<\/figcaption><\/figure><\/li>\n<li>Feathers are involved in <u><b>sexual displays <\/b><\/u>\u2013 <u><b>males<\/b><\/u> are often more colourful than <u><b>females<\/b><\/u>, which tend to be brown\/plain.\n<p><figure id=\"attachment_296\" aria-describedby=\"caption-attachment-296\" style=\"width: 300px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-296 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/Screen-Shot-2017-03-29-at-8.08.41-PM-300x185.png\" alt=\"\" width=\"300\" height=\"185\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/Screen-Shot-2017-03-29-at-8.08.41-PM-300x185.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/Screen-Shot-2017-03-29-at-8.08.41-PM-552x340.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/Screen-Shot-2017-03-29-at-8.08.41-PM.png 583w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-296\" class=\"wp-caption-text\">Figure 4: Male peacock<\/figcaption><\/figure><\/li>\n<li>Brighter colours\/completeness of feathers indicate fittest mate as that male has access to territory capable of facilitating the colour production.<\/li>\n<\/ul>\n<h4>Major Types of Feathers<\/h4>\n<p><strong>Contour feathers<\/strong><\/p>\n<ul>\n<li>Largest and most important<\/li>\n<li>Give bird its shape and colouring, while protecting the bird from physical\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 objects, wind, rain, etc.\n<p><figure id=\"attachment_297\" aria-describedby=\"caption-attachment-297\" style=\"width: 130px\" class=\"wp-caption alignright\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-297 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves5-130x300.png\" alt=\"\" width=\"130\" height=\"300\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves5-130x300.png 130w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves5.png 421w\" sizes=\"auto, (max-width: 130px) 100vw, 130px\" \/><figcaption id=\"caption-attachment-297\" class=\"wp-caption-text\">Figure 5: Flight and Tail feathers &#8211; notice the difference<\/figcaption><\/figure><\/li>\n<li>Includes flight and tail feathers<\/li>\n<\/ul>\n<p><strong>Down Feathers<\/strong><\/p>\n<ul>\n<li>Soft and fluffy!<\/li>\n<li>Not neatly arranged like contour feathers<\/li>\n<\/ul>\n<ul>\n<li>Found underneath the tough contour feathers<\/li>\n<li>Provide insulation for the bird<\/li>\n<\/ul>\n<p><strong>Filoplume<\/strong><\/p>\n<ul>\n<li>Much smaller \u2013 have only a few barbs at their tips.<\/li>\n<li>Believed to have a sensory function, allowing birds to keep their feathers in order.<\/li>\n<\/ul>\n<figure id=\"attachment_298\" aria-describedby=\"caption-attachment-298\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-298\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-1024x425.png\" alt=\"\" width=\"700\" height=\"291\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-1024x425.png 1024w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-300x124.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-768x318.png 768w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-1140x473.png 1140w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6-552x229.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves6.png 1500w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-298\" class=\"wp-caption-text\">Figure 6: Types of feathers<\/figcaption><\/figure>\n<p>It is important to note that while feathers are a major evolutionary advancement (i.e. derived character) that will be (potentially) reflected in evolutionary divergences in the future &#8211; birds are the youngest class of vertebrates and on a lineage separate from mammals, therefore feathers are unique to Class Aves (unlike our past major evolutionary advancements from previous classes). Even endothermy (below) evolved twice &#8211; once in mammals and one in birds!<\/p>\n<h3>Major Evolutionary Advancement #2 &#8211; Endothermy<\/h3>\n<ul>\n<li><u><b>Endothermy<\/b><\/u><b> (\u201c<\/b>Warm blooded\u201d)<\/li>\n<li><u><b>Regulate <\/b><\/u><u><b>their body temperature internally<\/b><\/u>. By maintaining a constant internal body temperature bodily functions occur at optimum levels of efficiency (this is known as <u><b>homeostasis<\/b><\/u> \u2013 more on this in bio 12 J)<\/li>\n<li><u><b>Allowed for decreased vulnerability to external temp. and be more active during night time<\/b><\/u> (i.e. avoid higher predation times)<\/li>\n<li><u><b>More food required <\/b><\/u>\u2013 most energy goes into maintaining temperature rather than growth.<\/li>\n<\/ul>\n<h3>General Anatomy<\/h3>\n<ul>\n<li>Bipedal with feathery wings. Dry scaly, clawed feet.<\/li>\n<li>Toothless beak for eating, fighting, and grooming.<\/li>\n<li><u><u><b>Strong, hollow bones (light weight). Many bones are fused together \u2013 birds typically have less bones than other terrestrial vertebrates.<\/b><\/u><\/u>\n<figure id=\"attachment_299\" aria-describedby=\"caption-attachment-299\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-299 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves7-300x204.png\" alt=\"\" width=\"300\" height=\"204\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves7-300x204.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves7-552x376.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves7.png 668w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-299\" class=\"wp-caption-text\">Figure 7: Example of a bird bone<\/figcaption><\/figure>\n<p><em>What benefits would hollow bones confer to members of class aves?<\/em><\/li>\n<\/ul>\n<h3>Physiology &#8211; Digestive System<\/h3>\n<ul>\n<li>Birds face special challenges when it comes to obtaining nutrition from food. They do not have teeth, so their digestive system must be able to process whole food.<\/li>\n<li>Many have organs called the <u><b>crop<\/b><\/u> and <u><b>gizzard<\/b><\/u>.<\/li>\n<li><b>Crop =<\/b> <u><b>enlarged area of the esophagus where food can be stored\/moistened before it enters the stomach or is <\/b><\/u><u><b>reguritated<\/b><\/u><u><b> for young<\/b><\/u>.<\/li>\n<li><b>Gizzard<\/b> = <u><b>Specialized part of stomach that contains small bits of gravel that help grind food down through muscle contractions<\/b><\/u>.<\/li>\n<li>Most have true cloaca.<\/li>\n<li>Birds have evolved a variety of beak types that reflect the vast variety in their diet, ranging from seeds and insects to fruits and nuts. The complexity of their digestive system (along with enzymes) allows for many different food sources to be consumed and digested. Because most birds fly, their metabolic rates are high (5-20x the resting metabolic rate of a running mammal) in order to efficiently process food.<\/li>\n<\/ul>\n<figure id=\"attachment_300\" aria-describedby=\"caption-attachment-300\" style=\"width: 542px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-300\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves8.png\" alt=\"\" width=\"542\" height=\"406\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves8.png 542w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves8-300x225.png 300w\" sizes=\"auto, (max-width: 542px) 100vw, 542px\" \/><figcaption id=\"caption-attachment-300\" class=\"wp-caption-text\">Figure 8: Digestive System of a bird<\/figcaption><\/figure>\n<h3>Physiology &#8211; Circulatory System<\/h3>\n<ul>\n<li>Four chambered heart with double loop circulation<\/li>\n<li>Complete separation of deoxygenated\/oxygenated blood<\/li>\n<li>Complete separation of oxygenated and deoxygenated blood \u2013 more efficient as blood that is circulated to the body is richer in O<sub>2<\/sub> content.<\/li>\n<li>Birds tend to have larger hearts than mammals (relative to body size and mass). The relatively large hearts of birds may be necessary to meet the high metabolic demands of flight.<\/li>\n<li>Avian hearts also pump more blood per unit time than mammalian hearts (cardiac output \u2013 blood pumped per minute is the highest of the vertebrates.<\/li>\n<li><em><strong><strong>Fun fact: <\/strong><\/strong>A hummingbird\u2019s heart can beat up to 1200 times a minute and takes up approximately 2.5% of the total weight of the animal \u2013 human hearts are around 0.5%!<\/em><\/li>\n<\/ul>\n<figure id=\"attachment_301\" aria-describedby=\"caption-attachment-301\" style=\"width: 267px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-301 size-medium\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/classaves9-267x300.png\" alt=\"\" width=\"267\" height=\"300\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/classaves9-267x300.png 267w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/classaves9-768x863.png 768w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/classaves9-552x620.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/classaves9.png 774w\" sizes=\"auto, (max-width: 267px) 100vw, 267px\" \/><figcaption id=\"caption-attachment-301\" class=\"wp-caption-text\">Figure 9: Typical circulatory system of a bird<\/figcaption><\/figure>\n<h3>Physiology &#8211; Respiration<\/h3>\n<ul>\n<li><u><b>Extremely efficient <\/b><\/u>\u2013 this is needed due to the high demand of flight.<\/li>\n<li>Respiration through lungs \u2013 however, bird lungs are connected to large <b>air sacs<\/b>.<\/li>\n<li><u><b>When a bird inhales, air travels into lungs and the posterior air sacs.<\/b><\/u><\/li>\n<li><u><b>When the bird exhales, the air stored in the posterior air sacs moves into the lungs for gas exchange.<\/b><\/u><\/li>\n<li>This means that birds have a <u><b>one way <\/b><\/u><b>respiratory system<\/b> and <b>gas exchange occurs during inhalation and exhalation.<\/b><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<figure id=\"attachment_303\" aria-describedby=\"caption-attachment-303\" style=\"width: 636px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-303\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/0216861fcfa41624e60edbe5c924e34041f055e1.gif\" alt=\"\" width=\"636\" height=\"288\" \/><figcaption id=\"caption-attachment-303\" class=\"wp-caption-text\">Figure 10: Respiration in birds (http:\/\/www.zmescience.com\/science\/biology\/breathing-mammals-birds-humans\/)<\/figcaption><\/figure>\n<figure id=\"attachment_304\" aria-describedby=\"caption-attachment-304\" style=\"width: 700px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-large wp-image-304\" src=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-1024x402.png\" alt=\"\" width=\"700\" height=\"275\" srcset=\"https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-1024x402.png 1024w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-300x118.png 300w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-768x302.png 768w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-1140x448.png 1140w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11-552x217.png 552w, https:\/\/blogs.ubc.ca\/mrpletsch\/files\/2017\/03\/aves11.png 1237w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><figcaption id=\"caption-attachment-304\" class=\"wp-caption-text\">Figure 11: Respiration in birds<\/figcaption><\/figure>\n<h3>Physiology &#8211; Reproduction<\/h3>\n<ul>\n<li><u><b>Internal fertilization and oviparous <\/b><\/u>(hard-shelled amniotic egg)<\/li>\n<li>Since birds have cloaca, birds \u201ccloacal kiss\u201d to transfer sperm to the female.<\/li>\n<li><u><b>90-95% of birds are socially monogamous<\/b><\/u>, meaning they have only one partner (although the key word is <b>social <\/b>rather than sexual).<\/li>\n<li><u><b>Most birds incubate their eggs \u2013a form a parental care.<\/b><\/u><\/li>\n<li>Bi-parental care is common \u2013 both males and females look after their eggs\/young equally<\/li>\n<li>Keep sex organs small during most of the year. <i>Why?<\/i><\/li>\n<li>3% of bird species&#8217; have penises. In the other 97%, the production of a protein kills off what would develop into a penis.<\/li>\n<\/ul>\n<p><em><strong>Fun Fact: <a href=\"https:\/\/www.youtube.com\/watch?v=l0EbkDNKN-E\">Explosive Sex Life of Ducks<\/a><\/strong><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p class=\"post-excerpt\">General Characteristics Toothless beak Amniotic egg with hard mineralized shell Tetrapod \u2013 feathered wings and scaly, clawed feet The youngest&#8230;<\/p>\n","protected":false},"author":48401,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1200970],"tags":[],"class_list":["post-292","post","type-post","status-publish","format-standard","hentry","category-biology-11"],"_links":{"self":[{"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/posts\/292","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/users\/48401"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/comments?post=292"}],"version-history":[{"count":1,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/posts\/292\/revisions"}],"predecessor-version":[{"id":305,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/posts\/292\/revisions\/305"}],"wp:attachment":[{"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/media?parent=292"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/categories?post=292"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.ubc.ca\/mrpletsch\/wp-json\/wp\/v2\/tags?post=292"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}