BIO202 Ch34 Deuterostomes PDF

CHAPTER 34: DEUTEROSTOMES General Biology II (BIO202) © McGraw-Hill 1  CHAPTER OUTLINE  Phylum Echinodermata  Phylum Chordata 2 ECHINODERM PHYLOGENY © McGraw-Hill 3...

CHAPTER 34: DEUTEROSTOMES General Biology II (BIO202) © McGraw-Hill 1  CHAPTER OUTLINE  Phylum Echinodermata  Phylum Chordata 2 ECHINODERM PHYLOGENY © McGraw-Hill 3 ECHINODERMS: SEA URCHINS, SEA STARS, BRITTLE STARS, AND SAND DOLLARS Radially symmetrical (and quite active) at the adult stage; Bilateral as larvae © McGraw-Hill 4  PHYLUM ECHINODERMATA  Exclusively marine  Coelomates with a deuterostomes pattern of development and an endoskeleton made of calcium carbonate plates and covered by living tissue  Pentaradial symmetry: have 5 axes of symmetry  Include sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers  Origin remains unclear: Thought to have evolved from bilaterally symmetrical ancestors because larvae are bilaterally symmetrical The free-swimming bilateral larva of Adult see star (pentaradial) the common sea star, Asterias rubens. Pentaradial symmetry 5  ECHINODERM BODY PLAN  A unique feature of echinoderms is the hydraulic system that aids in movement or feeding. This fluid-filled system, called a water-vascular system, is a modification of one of several coelomic spaces and is composed of a central ring canal from which radial canals extend.  The madreporite is the opening/entrance of the water vascular system. Central ring canal 6  ECHINODERM BODY PLAN  Radial canals transport liquid to the tube feet.  As the ampulla in each tube foot contracts, the tube foot extends and can attach to the substrate.  When the muscles in the tube feet contract, the tube foot bends, pulling the animal forward. 7  ECHINODERM BODY PLAN  Symmetry: Pentaradial as adult, bilateral as larva Oral surface defines mouth All systems are organized with branches radiating from the center Nervous system is nerve ring with branches No centralization of function 8  CHAPTER OUTLINE  Phylum Echinodermata  Phylum Chordata 9  PHYLUM CHORDATA  Chordate endoskeleton is very different from echinoderm endoskeleton Chordate endoskeleton is truly internal Echinoderm endoskeleton is functionally similar to arthropod exoskeleton (hard shell and muscles attached to its inner surface)  Includes fishes, amphibians, reptiles, birds, and mammals 10  THE CHORDATES © McGraw-Hill 11  ALL CHORDATES HAVE ALL 4 OF THESE CHARACTERISTICS AT SOME TIME IN THEIR LIVES 1. Nerve cord Differentiate into the brain and spinal cord in vertebrates 2. Notochord Flexible rod May be replaced by the vertebral column 3. Pharyngeal slits (connects the pharynx with the external environment) Better termed Pharyngeal pouches in terrestrial vertebrates where they don’t actually connect to the outside 4. Postanal tail at least during embryonic development (nearly all other animals have The four principal features of the chordates, a terminal anus). as shown in a generalized embryo. 12  OTHER CHORDATE CHARACTERISTICS  Other characteristics also distinguish chordates Chordate muscles are arranged in segmented blocks called somites Most chordates have an internal skeleton against which the muscles work A mouse embryo. At 11.5 days of development, the mesoderm is already divided into segments called somites (dark stain in this photo), reflecting the segmented nature of all chordates. 13  THE 3 CHORDATE SUBPHYLA 2 Nonvertebrate subphyla (1 & 2) that do not form vertebrae or other bones, and 1 vertebrate phylum. Tunicates 1. Urochordata (Tunicates) 2. Cephalochordata (Lancelets; Notochord persists throughout animal’s life) 3. Vertebrata Lancelets 14  TUNICATES HAVE CHORDATE LARVAL FORMS  Most tunicates are immobile as adults, with only the larvae having a notochord and nerve cord  Larvae have a tadpole-like form (oval body with broad tail) and are free-swimming  As adults, they typically lose the tail, notochord and nerve cord. 15  CHARACTERISTICS OF CHORDATES: EXAMPLE OF THE LANCELET © McGraw-Hill  Vertebrates, tunicates, and lancelets are chordates, coelomate animals with a flexible rod, the notochord, that provides resistance to muscle contraction and permits rapid lateral body movements.  Pharyngeal slits or pouches (reflecting their aquatic ancestry and present habitat in some) and a hollow dorsal nerve cord. In nearly all vertebrates, the notochord is replaced during embryonic development by the vertebral column. Lancelets occur mostly in shallow water. Notochord runs the entire length of the dorsal nerve cord and persist throughout the animal’s life. 16  SUBPHYLUM VERTEBRATA  Vertebrates are chordates with a spinal column  Distinguished from nonvertebrates by: Vertebral column – Encloses and protects the dorsal nerve cord Head – Distinct and well-differentiated possessing sensory organs 17  VERTEBRATES ALSO HAVE…  Neural crest – unique group of embryonic cells that forms many vertebrate structures (develop from the neural tube)  Internal organs – liver, kidneys, endocrine glands, heart, and closed circulatory system  Endoskeleton – made of cartilage or bone Makes possible great size and extraordinary movement. © McGraw-Hill 18  MAJOR CHARACTERISTICS OF VERTEBRATES Adult vertebrates are characterized by an internal skeleton of cartilage or bone, including a vertebral column and a skull. Several other internal and external features are characteristic of vertebrates. 19  HISTORY OF THE VERTEBRATES  The first vertebrates appeared in the oceans about 545 MYA Mouth at one end, fin (flattened appendage) at the other.  Jawed fishes soon became dominant  Amphibians invaded the land  Reptiles replaced them as the dominant land vertebrates  Birds and mammals became dominant after Cretaceous mass extinction (period of time about 65 MYA, when dinosaurs and other types of reptiles abruptly disappeared) 20 PHYLOGENY OF THE LIVING VERTEBRATES Some of the key characteristics that evolved among the vertebrate groups are shown in this phylogeny. 21  PATTERNS OF EVOLUTION DIVERGENT EVOLUTION CONVERGENT EVOLUTION Populations from common Populations with different ancestor evolve different ancestors evolve similar phenotype phenotypes Homologous structures– same Analogous – structures of different evolutionary origin but now differ in origin used for the same purpose structure and function (e.g. (e.g. appendages of shark and whales). appendages of hippos and whales). 22  MONO/PARA/POLYPHYLETIC ANIMAL GROUPS Monophyletic: includes the most recent common ancestor of a group of organisms, and all of its descendants Polyphyletic: does not include the common ancestor of all members of the taxon Paraphyletic: includes the most recent common ancestor, but not all of its descendants 23  FISHES  Most diverse vertebrate group  Fishes include species in different classes  Over half of all vertebrates  Provided the evolutionary basis for invasion of land by amphibians 24  FISHES CHARACTERISTICS 1. Vertebral column Hagfish and lamprey are the exceptions 2. Jaws and paired appendages Hagfish and lamprey are the exception 3. Internal gills (have tissue rich in blood vessels allowing for gas exchange) 4. Single-loop blood circulation (heartgillsbodyheart) 5. Nutritional deficiencies Inability to synthesize aromatic amino acids has been inherited by all their vertebrate descendants So fishes must consume them in their food 25  HISTORY OF THE FISHES  The first fishes had mouths with no jaws; Agnatha (includes all jawless fishes) Extant as hagfish (class Myxini) and lampreys (class Petromyzontida) Ostracoderms are now extinct  The development of jaws occurred in the late Silurian period (438 to 408 MYA) Jaws evolved from the anterior gill arches that were made of cartilage used to hold the slits open 26  EVOLUTION OF THE JAW  Jaws evolved from the anterior gill arches of ancient, jawless fishes. Evolution of the jaw: https://www.viddler.com/embed/b457eb0a/?f=1&autoplay=0&player=arpe ggio&secret=90576092&loop=0&nologo=0&hd=0 27 TWO MAJOR GROUPS OF BONY FISHES (Cartilagenous fish will be described in the lab) Ray-finned fishes (class Actinopterygii) Parallel bony rays support and stiffen each fin There are no muscles within the fins Lobe-finned fishes (class Sarcopterygii) Fins consist of a long fleshy muscular lobe Supported by central core of bones with fully articulated joints as well as rays Almost certainly the amphibian ancestors The coelacanth, a lobe-finned fish was discovered in the western Indian Ocean in 1938. This coelacanth represents a group of fishes thought to have been extinct for about 70 million years. 28  INQUIRY QUESTION What advantages do lobed fins have over ray fins? Lobe-finned fishes are able to move their fins independently, whereas ray-finned fishes must move their fins simultaneously. This ability to “walk” with their fins indicates that lobe-finned fishes are most certainly the ancestors of amphibians. 29  CLASS AMPHIBIA  First vertebrates to walk on land  Direct descendants of fishes 30 CLASS AMPHIBIA 31  5 DISTINGUISHING AMPHIBIAN FEATURES 1. Legs – adaptation to life on land 2. Lungs – most possess a pair of lungs 3. Cutaneous respiration – supplement lungs 4. Pulmonary veins – separate pulmonary circuit allows higher pressure blood to tissues 5. Partially divided heart – improves separation of pulmonary and systemic circuits 32  SUCCESSFUL INVASION OF LAND BY VERTEBRATES  Required several adaptations Legs to support body’s weight Lungs to extract oxygen from air Redesigned heart and circulatory system to drive larger muscles Reproduction still in water to prevent egg drying System to prevent whole body desiccation 33  ICHTHYOSTEGA © McGraw-Hill  Amphibians evolved from lobe- finned fish  Ichthyostega was one of the first amphibians  Sturdy forelegs, flipper-shaped hindlimbs Moved like a seal Ichthyostega, one of the first amphibian. Fish-like in overall appearance, but had efficient  Long, broad, overlapping ribs limbs for crawling on land. form solid cage for lungs and heart 34  TIKTAALIK  In 2006, a transitional fossil was found between fish and Ichthyostega  Had gills and scales like a fish, but a neck like an amphibian  Shoulder, forearm, and wrist bones were like those of amphibians, but at the end of the limb was a lobed fin, rather than the toes of an amphibian 35  CLASS REPTILIA  Over 10,000 living species  All living reptiles exhibit three key features 1. Amniotic eggs, which are watertight 2. Dry skin, which covers body and prevents water loss 3. Thoracic breathing, which increases lung capacity 36 MAJOR ORDERS OF REPTILES (for illustration only; no need to memorize) 37 MAJOR ORDERS OF REPTILES (continued) (for illustration only; no need to memorize) 38  AMNIOTIC EGGS  Reptiles, birds, and mammals are amniotes  The amniotic egg has four membranes Chorion: Outermost layer, allows gas exchange Amnion: Encases embryo in fluid- filled cavity Yolk sac: Provides food via blood vessels Allantois: Contains excreted wastes from the embryo 39  ANAPSIDS, SYNAPSIDS, AND DIAPSIDS  Reptiles dominated earth for 250 million years  Reptiles are distinguished by the number of holes on side of the skull behind eye orbit 0 (anapsids), 1 (synapsids): rose to dominance first; mostly now extinct except mammals 2 (diapsids): - included the largest animals to that point and the first bipedal animal; - gave rise to crocodiles, pterosaurs, dinosaurs, and birds 40  DINOSAURS Dinosaurs dominated for over 150 million years Became extinct 65 MYA Except bird descendants Asteroid’s impact Mounted skeleton of Afrovenator. This bipedal carnivore was about 30 feet long and lived in Africa about 130 mya. 41  MODERN REPTILES  Modern reptiles developed two important characteristics Internal fertilization Sperm fertilizes egg before protective membranes are formed Improved circulation Oxygen is provided to the body more efficiently Septum in heart extended to create partial wall Crocodiles, birds, and mammals have completely divided 4- chambered heart 42  BIRDS (CLASS AVES*)  Birds are the most diverse of all terrestrial vertebrates More than 10,000 species  Success lies in unique structure – feather (which developed from reptilian scales) 43 * pronounced ei-veez  BIRDS AND REPTILES  Birds still retain many reptilian traits They lay amniotic eggs They have scales on feet and lower legs  Two major distinguishing traits Feathers Modified scales of keratin Provide lift for flight and conserve heat Flight skeleton Bones are thin and hollow Many are fused for rigidity – anchor strong flight muscles Breastbone provides attachment site for flight muscles 44  FEATHERS  Feathers developed from reptile scales  Linked structures provide continuous surface and a sturdy but flexible shape 45  ARCHAEOPTERYX  Archaeopteryx is the first known bird Had skull with teeth and a long reptilian tail Feathers on wings and tail One theropod line evolved to become bird Forelimbs nearly identical to those of theropods ("beast-footed" dinosaurs)  Feather probably evolved for insulation 46  THEROPOD DESCENDANTS  Most paleontologists agree that birds are the direct descendants of theropod dinosaurs (which were the most fearsome land predators the Earth has ever seen!), a clade that includes T-rex. 47  CLASS MAMMALIA  There are about 5,000 species of mammals Lowest number among fishes, amphibians, reptiles or birds Almost 4,000 species are rodents, bats, shrews, or moles © McGraw-Hill 48  2 FUNDAMENTALLY MAMMALIAN TRAITS 1. Hair Long, keratin-rich filaments that extend from hair follicles Insulation, camouflage, sensory structure 2. Mammary glands Females possess mammary glands that secrete milk 49  HISTORY OF MAMMALS  Mammals have been around since the time of the dinosaurs, about 220 MYA First animals were tiny, shrew-like, insect-eating, tree- dwelling creatures May have been nocturnal – large eye sockets  Mammals reached their maximum diversity in the Tertiary period (lasting from 65 to 2 MYA), after mass extinction of dinosaurs. Over the last 15 million years, there was a decline in the total number of mammalian species due to changes in world climate 50  2 SUBCLASSES OF MAMMALS 1. Prototheria (most primitive) (for example, the group of monotremes) Lay shelled eggs (oviparous) Only living group is the monotremes 2. Theria Viviparous – young are born alive Two living groups Marsupials or pouched mammals (Kangaroos, Opossum, Koalas) Placental mammals= Largest group of mammals (Dogs, cats, humans, horses) 51  MONOTREMES  Lay shelled eggs  Like reptiles, have single opening (cloaca) for feces, urine, and reproduction  Lack well-developed nipples  Only three living species: 2 echidna species (left) Duck-billed platypus (right) Short-nosed echidna Duck-billed platypus 52  MARSUPIALS  Major difference is pattern of embryonic development Short-lived placenta After birth, it crawls into marsupial pouch, latches onto nipple, and continues to develop  Kangaroo – isolation of Australia  Opossum – only North American marsupial 53 Kangaroo Opossum  PLACENTAL MAMMALS  Produce a true placenta that nourishes the embryo throughout its development Forms from both fetal and maternal tissues Young undergo a considerable period of development before they are born  Includes most living mammals, including humans Lion Dolphin 54  THE PLACENTA  The placenta Characteristic of the largest group of mammals (placental mammals) Evolved from membranes in the amniotic egg. The chorion (outermost part of the amniotic egg) forms most of the placenta Serves as the provisional lungs, intestine, and kidneys of the fetus, without ever mixing maternal and fetal blood  The umbilical cord evolved from the allantois. 55  EVOLUTION OF PRIMATES  Primates are the mammals that gave rise to our own species  Evolved two features that allowed them to succeed as arboreal (tree-dwelling) insectivores: 1. Grasping fingers and toes First digit (thumb) is opposable in many 2. Binocular vision Eyes are shifted toward the front of the face Lets brain judge distances precisely Anthropoids Prosimians lorises, tarsiers 56  LIVING PRIMATES: PROSIMIANS  Now considered to be paraphyletic (A paraphyletic group consists of the most recent common ancestor and some of its descendants)  Lemurs, lorises and tarsiers  Large eyes with increased visual acuity (keenness of perception)  Most are small and nocturnal A lemur A lorises A tarsier 57  LIVING PRIMATES: ANTHROPOIDS  Include monkeys, apes, and humans  Almost all diurnal (high daytime activity) Changes in eye design include color vision  Expanded brain  Live in groups with complex social interactions They care for young for extended period This allowed for a long childhood period of learning and brain development 58  ANTHROPOID HISTORY  30 MYA New World monkeys migrated to South America. All arboreal (living in trees); many have prehensile (capable of grasping) tail. Old World monkeys and hominids remained in Africa. 59  HOMINOIDS  Hominoids include Apes -Gibbon, orangutan, gorilla, and chimpanzee -have larger brains than monkeys and lack tails -Paraphyletic group – some apes are more closely related to hominids Hominids -Humans, orangs, gorillas, and chimps (i.e., all apes except gibbons) -Soon after the gorilla lineage diverged, the common ancestor of all hominids split off from the chimpanzee line to begin the evolutionary journey leading to humans. 60  Mammals Prototheria Theria (Monotremes) Marsupials Placental mammals Primates Prosimians Anthropoids (lorises, lemurs, Monkeys Hominoids tarsiers) (new world, old world) Apes Hominins (Australopithecus Homo) Gibbons Chimpanzees Orangutans Gorillas 61 Hominids A PRIMATE EVOLUTIONARY TREE Prosimians 62  WITHIN HOMINIDS: APES VS. HOMININS  The common ancestor of hominids (i.e. chimps + orangs + gorillas + hominins) is thought to have been an arboreal climber  Hominins became bipedal, walking upright  Apes evolved knuckle-walking (by contrast, monkeys, which are non- hominoid anthropoids, walk using the palm of their hands)  Differences related to bipedal locomotion  Human vertebral column is more curved  Human spinal cord exits from bottom of skull, rather than the back  Humans carry much of the body’s weight on the lower limbs 63  EARLY HOMININS  Genus Australopithecus 7 species Older and smaller-brained  Genus Homo 3–7 species (depending how they are counted).  Several even older lineages In every case where the fossils allow a determination, the hominins are bipedal, the hallmark of hominid evolution 64 HOMININ FOSSIL HISTORY 65  MODERN HUMANS  Modern humans first appeared in Africa about 700,000 years ago  Three species are thought to have evolved Homo heidelbergensis (oldest) Coexisted with H. erectus Homo neanderthalensis Shorter and stockier than modern humans Homo sapiens (“wise man”)  Some lump all 3 into H. sapiens 66  HUMAN RACES  Human beings are differentiated in their traits as they have spread throughout the world  All humans are capable of mating with one another and producing fertile offspring  Humans are visually oriented; consequently, we have relied on visual cues – primarily skin color– to define races  Constant gene flow has prevented subspecies of humans from forming 67  HOMO SAPIENS  Only surviving hominin  Progressive increase in brain size  Effective making and use of tools Refined and extended conceptual thought Use of symbolic language  Extensive cultural experience We change and mold our world rather than change evolutionarily in response to the environment 68  GROUPINGS OF HUMANS  Groupings based on overall genetic similarity are different from those based on skin color or other visual features 69  The End © McGraw-Hill 70