Animal Kingdom Evolution

1. Animal Kingdom Evolution 5 Defining characteristics of the animal kingdom: 1) Heterotrophic eukaryotes; ingestion 2) Lack cell walls; collagen 3) Nervous & muscular tissue 4) Sexual; diploid; cleavage; blastula; gastrulation; larvae; metamorphosis 5) Regulatory genes: Hox genes

2. Animal phylogeny • *Monophyletic; colonial flagellated protist ancestor • First split • 1- Parazoa vs. Eumetazoa dichotomy: • *(Parazoa)~ no true tissues example sponges • *(Eumetazoa)~ true tissues • all other animals

3. Parazoa *Parazoa: No true tissues • Invertebrates • No true tissues, unspecialized cells: *Sponges Closest lineage to protists • Phylum Porifera

4. Phylum: Porifera(“pore bearer”) • *Sessile (attached to bottom) • Spongocoel (central cavity) • *Osculum (large opening) • Choanocytes (flagellated collar cells) • *Hermaphroditic (produce both sperm and eggs)

5. Eumetazoa: True Tissues: Everything but sponges • 2nd split – Body Symmetry • Radiata vs.Bilateria dichotomy: 1) *radial body symmetry *Cnidaria (hydra; ‘jellyfish’; sea anemones) & *Ctenophora (comb jellies) 2) *bilateral body symmetry (also: **cephalization) • all other animals

6. Eumetazoa The Radiata, Diploblastic • Radial symmetry • Phy: Cnidaria (hydra, jellies, sea anemones, corals) • *No mesoderm; gastrovascular cavity (GVC)(sac with a central digestive cavity) • Hydrostatic skeleton (fluid held under pressure) • Polyps and medusa • Cnidocytes (cells used for defense and prey capture) • Nematocysts (stinging capsule) • Phy: Ctenophora (comb jellies)

7. 3. Gasturlation: diploblastic vs. triploblastic • 3- Gastrulation: germ layer development; ectoderm (outer), mesoderm (middle), endoderm (inner) • diploblastic-2 layers; no mesoderm; • Radiata • Phy: Cnidaria (hydra, jellies, sea anemones, corals) • triploblastic-all 3 layers • *bilateria symmetry • All others

8. 4- Acoelomate, Pseudocoelomate, and Coelomate • All are triploblastic animals • *acoelomates solid body, no body cavity • (Platyhelminthes-flatworms) • mesoderm but, GVC with only one opening • *Some cephalization • *pseudocoelomates body cavity, but not lined with mesoderm called • (Rotifers); *1st with a complete digestive track • Parthenogenesis: type of reproduction in which females produce offspring from unfertilized eggs • Coelomate: true coelom (body cavity) lined with mesoderm called • Phy: Nematoda (roundworms) • Complete digestive track; no circulatory system

9. Animal phylogeny5 • *Protostomes • Phylogenetics debated…. 1)Phy: Nemertea (proboscis and ribbon worms) • *Complete digestion and closed circulatory system (blood) 2) Phy: the lophophorates (sea mats, tube worms, lamp shells)

10. The Coelomates: Protostomes, II 3) Phy: Mollusca (snails, slugs, squid, octopus, clams, oysters, chiton) • Soft body protected by a hard shell of calcium carbonate • Foot (movement), visceral mass (internal organs); mantle (secretes shell); radula (rasp-like scraping organ) • Ciliated trochophore larvae (related to Annelida?)

11. The Coelomates: Protostomes, III 4) Phy: Annelida (earthworms, leeches, marine worms) • True body segmentation (specialization of body regions) • Closed circulatory system • Metanephridia: excretory tubes • “Brainlike” cerebral ganglia • *Hermaphrodites, but cross- fertilize

12. The Coelomates: Protostomes, IV 5) Phy: Arthropoda trilobites (extinct); crustaceans (crabs, lobsters, shrimps); spiders, scorpions, ticks (arachnids); insects (entomology) • *2 out of every 3 organisms (most successful of all phyla) • *Segmentation, • *hard exoskeleton (cuticle)~ molting, • *jointed appendages; open circulatory system (hemolymph); • *extensive cephalization

13. Insect characteristics • Outnumber all other forms of life combined • Malpighian tubules: outpocketings of the digestive tract (excretion) • Tracheal system: branched tubes that infiltrate the body (gas exchange) • *Metamorphosis…... • *•incomplete: young resemble adults, then molt into adulthood (grasshoppers) • *•complete: larval stages (looks different than adult); larva to adult through pupal stage

14. The Coelomates: *Deuterostomes, I • 1) Phy: Echinodermata (sea stars, sea urchins, sand dollars, sea lilies, sea cucumbers, sea daisies) • Spiny skin; sessile or slow moving • Often pentaradial • Water vascular system by hydraulic canals (tube feet)

15. Deuterostomes • Next branch • Chordates • *Notochord: longitudinal, flexible rod located between the digestive and the nerve cord • *Dorsal, hollow nerve cord; eventually develops into the brain and spinal cord • *Pharyngeal slits; become modified for gas exchange, jaw support, and/or hearing • *Muscular, postanal tail

16. Invertebrate chordates • Both suspension feeders….. • Subphy: Urochordata (tunicates; sea squirt); mostly sessile & marine • Subphy: Cephalochordata (lancelets); marine, sand dwellers • *Importance: vertebrates closest relatives; in the fossil record, appear 50 million years before first vertebrate • *Paedogenesis: development of sexual maturity in a larva (link with vertebrates?)

17. Subphylum: Vertebrata • Retain chordate characteristics with specializations…. • *Neural crest: group of embryonic cells near dorsal margins of closing neural tube • *Pronounced cephalization: concentration of sensory and neural equipment in the head • *Cranium and vertebral column • *Closed circulatory system with a ventral chambered heart

18. Vertebrate diversity • Phy: Chordata • Subphy: Vertebrata • Superclass: Agnatha jawless vertebrates (hagfish, lampreys) • *Most primitive, living vertebrates

19. Vocabulary tetrapods (‘4-footed’) amniotes (shelled egg)

20. Superclass Gnathostomata, I • Placoderms (extinct): first with hinged jaws and paired appendages • Class: Chondrichthyes~ *Sharks, skates, rays • *Cartilaginous fishes; well developed jaws and paired fins; continual water flow over gills (gas exchange); lateral line system (water pressure changes) • *Life cycles: • *Oviparous- eggs hatch outside mother’s body • *Ovoviviparous- retain fertilized eggs; nourished by egg yolk; young born live • *Viviparous- young develop within uterus; nourished by placenta

21. Superclass Gnathostomata, III • Class: Amphibia • *1st tetrapods on land • Frogs, toads, salamanders, caecilians • Metamorphosis; lack shelled egg;moist skin for gas exchange

22. Superclass Gnathostomata, IV • Class: Reptilia • Lizards, snakes, turtles, and crocodilians • *Amniote (shelled) egg with extraembryonic membranes (gas exchange, waste storage, nutrient transfer); • absence of feathers, hair, and mammary glands; *ectothermic; scales with protein keratin (waterproof); lungs; ectothermic (dinosaurs endothermic?)

23. Superclass Gnathostomata, V • Class: Aves • Birds • *Flight adaptations: wings (honeycombed bone); feathers (keratin); toothless; one ovary • *Evolved from reptiles (amniote egg and leg scales); endothermic *(4-chambered heart) • Archaeopteryx (stemmed from an ancestor that gave rise to birds)

24. Superclass Gnathostomata, VI • Class: Mammalia • *Mammary glands; hair (keratin); endothermic; 4-chambered heart; large brains; teeth differentiation • *Evolved from reptilian stock before birds • *Monotremes (egg-laying): platypus; echidna • *Marsupials (pouch): opossums, kangaroos, koalas • *Eutherian (placenta): all other mammals

25. Order: Primates (evolution) • *Characteristics: hands & feet for grasping; large brains, short jaws, flat face; parental care and complex social behaviors • Suborder: Prosimii •lemurs, tarsiers • Suborder: Anthropoidea •monkeys, apes, humans (opposable thumb) • *45-50 million years ago • *Paleoanthropology: study of human origins • *Hominoid: great apes & humans • Hominid (narrower classification): √ australopithecines (all extinct) *√ genus Homo (only 1 exant, sapiens)

26. Human evolution • Misconceptions: • 1- Chimp ancestor (2 divergent branches) • 2- Step-wise series (coexistence of human species) • 3- Trait unison(all traits at once) vs. mosaic evolution(over time) (*bipedalism, upright, enlarged brain)

27. The first humans • Ape-human split (5-7 mya) • Australopithecus; “Lucy” (4.0 mya) • Homo habilis; “Handy Man” (2.5 mya) • Homo erectus; first to migrate (1.8 mya) • Neanderthals (200,000 ya) • Homo sapiens (100,000 ya?) • Multiregional model (parallel evolution) • “Out of Africa” (replacement evolution)

28. Tissues: groups of cells with a common structure and function (4 types) • Anatomy: structure • Physiology: function • Type 1- Epithelial: outside of body and lines organs and cavities; held together by tight junctions • basement membrane: dense mat of extracellular matrix • Simple: single layer of cells • Stratified: multiple tiers of cells • Cuboidal (like dice) • Columnar (like bricks on end) • Squamous (like floor tiles) • Glandular (can secrete) mucous membrane

29. Connective Tissue (6 kinds) • Type 2- Connective Tissue: bind and support other tissues; scattered cells through matrix 3 kinds of fibers: • A-Collagenous fibers (collagen protein) non elastic B-Elastic fibers (elastin protein) C-Reticular fibers (thin branched collagen fibers) • Loose connective tissue: binds epithelia to underlying tissue; holds organs (has all 3 fiber types) • Two types of cells dominate • 1-Fibroblasts- secretes the protein for extracellular fibers • 2-Macrophages- amoeboid WBC’s; phagocytosis • Adipose tissue (specialized form)- fat storage; insulation

30. Connective Tissue, Type II • Fibrous connective tissue: parallel bundles of cells • 1-Tendons- muscles to bones • 2-Ligaments- bones to bones; joints (BOBOLI) • Cartilage: collagen in a rubbery matrix (chondroitin); flexible support • Bone: mineralized tissue by osteoblast cells • Blood: liquid plasma matrix; erythrocytes (RBC’s) carry O2; leukocytes (WBC’s) immunity

31. Nervous Tissue, Type III • 3-Nervous: senses stimuli and transmits signals from 1 part of the animal to another • *Neuron: functional unit that transmits impulses • *Cell body (contains nucleus) • *Dendrites: transmit impulses from tips to rest of neuron • *Axons: transmit impulses toward another neuron or effector

32. Muscle Tissue (3 kinds) • 4- Muscle: capable of contracting when stimulated by nerve impulses; myofibrils composed of proteins actin and myosin; 3 types: • A- Skeletal: voluntary movement (striated) • B- Cardiac: contractile wall of heart (branched striated) • C- Smooth: involuntary activities (no striations)

33. Internal regulation • Interstitial fluid: internal fluid environment of vertebrates; exchanges nutrients and wastes • *Homeostasis: “steady state” or internal balance • *Negative feedback: change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation; i.e., body temperature • *Positive feedback: physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change; i.e., uterine contractions at childbirth

34. Metabolism: sum of all energy-requiring biochemical reactions • *Catabolic processes of cellular respiration • Calorie; kilocalorie/C • *Endotherms: bodies warmed by metabolic heat • *Ectotherms: bodies warmed by environment • Basal Metabolic Rate (BMR): minimal rate powering basic functions of life (endotherms) • Standard Metabolic Rate (SMR): minimal rate powering basic functions of life (ectotherms)

35. Chapter 48 ~ Nervous System

36. Neurons Glial cells Axon Dendrite Synapse Neurotransmitters Action potential Motor neurons Interneurons Sensory neurons Myelin sheath Schwann cells Reflex arc http://outreach.mcb.harvard.edu/animations/synaptic.swf The Nervous System

37. Nervous systems • Effector cells~ muscle or gland cells • Nerves~ bundles of neurons wrapped in connective tissue • Central nervous system (CNS)~ brain and spinal cord • Peripheral nervous system (PNS)~ sensory and motor neurons

38. Structural Unit of Nervous System • Neuron~ structural and functional unit • Cell body~ nucelus and organelles • Dendrites~ impulses from tips to neuron • Axons~ impulses toward tips • Myelin sheath~ supporting, insulating layer • Schwann cells~ PNS support cells • Synaptic terminals~ neurotransmitter releaser • Synapse~ neuron junction

41. Simple Nerve Circuit http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0016-swf_reflex_arc.swf • Sensory neuron: convey information to spinal cord • Interneurons: information integration • Motor neurons: convey signals to effector cell (muscle or gland) • Reflex: simple response; sensory to motor neurons • Ganglion (ganglia): cluster of nerve cell bodies in the PNS • Supporting cells/glia: nonconductiong cell that provides support, insulation, and protection

43. Neural signaling http://bcs.whfreeman.com/thelifewire/content/chp44/4403s.swf http://outreach.mcb.harvard.edu/animations/actionpotential.swf • Membrane potential(voltage differences across the plasma membrane) • *Intracellular/extracellular ionic concentration difference • K+ diffuses out (Na+ in); large anions cannot follow….selective permeability of the plasma membrane • Net negative charge of about -70mV

44. http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf Neural signaling http://www.mind.ilstu.edu/curriculum/neurons_intro/flash_electrical.php?modGUI=232&compGUI=1827&itemGUI=3158 • Excitable cells~ cells that can change membrane potentials (neurons, muscle) • Resting potential~ the unexcited state of excitable cells • Gated ion channels (open/close response to stimuli): photoreceptors; vibrations in air (sound receptors); chemical (neurotransmitters) & voltage (membrane potential changes) • Graded Potentials (depend on strength of stimulus): • 1- Hyperpolarization (outflow of K+); increase in electrical gradient; cell becomes more negative • 2- Depolarization (inflow of Na+); reduction in electrical gradient; cell becomes less negative

45. Neural signaling • Threshold potential: if stimulus reaches a certain voltage (-50 to -55 mV)…. • The action potential is triggered…. • Voltage-gated ion channels (Na+; K+) • 1-Resting state •both channels closed • 2-Threshold •a stimulus opens some Na+ channels • 3-Depolarization•action potential generated •Na+ channels open; cell becomes positive (K+ channels closed) • 4-Repolarization•Na+ channels close, K+ channels open; K+ leaves •cell becomes negative • 5-Undershoot•both gates close, but K+ channel is slow; resting state restored • Refractory period~ insensitive to depolarization due to closing of Na+ gates

46. Neural signaling • “Travel” of the action potential is self-propagating • Regeneration of “new” action potentials only after refractory period • Forward direction only • Action potential speed: • 1-Axon diameter (larger = faster; 100m/sec) • 2-Nodes of Ranvier (concentration of ion channels); saltatory conduction; 150m/sec

47. Synaptic communication • Presynaptic cell: transmitting cell • Postsynaptic cell: receiving cell • Synaptic cleft: separation gap • Synaptic vesicles: neurotransmitter releasers • Ca+ influx: caused by action potential; vesicles fuse with presynaptic membrane and release…. • Neurotransmitter http://www.bayareapainmedical.com/neurtrns.html

48. Neurotransmitters http://www.blackwellpublishing.com/matthews/neurotrans.html • Acetylcholine (most common) •skeletal muscle • Biogenic amines(derived from amino acids) •norepinephrine •dopamine •serotonin • Amino acids • Neuropeptides(short chains of amino acids) •endorphin

49. Nervous System (know this slide) • Central Nervous System • Crainial Nerves • Spinal Nerves • Peripheral Nervous System • Sensory (afferent) Division • Sensing external environment • Sensing internal environment • Motor (Efferent) Division • Autonomic Nervous System • Sympathetic Nervous System • increase energy consumption • Parasympathetic Nervous System • conservation of energy • Somatic Nervous System • voluntary, conscious control, muscles

50. Vertebrate PNS