Vertebrate Diversity

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Vertebrate Diversity

• Chapter 34

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Chordate Phylogeny
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Phylum Chordata

• Bilaterian deuterostomes
• Derived characteristics
• Notochord
• In all embryos and some adults, between digestive
  tube and nerve cord
• Provides skeletal support, reduced in humans to
  vertebral discs
• Dorsal hollow nerve cord
• Roll of ectoderm that is unique to chordates
  becomes CNS
• Pharyngeal slits or clefts
• Series of pouches along the pharynx that open to
  the outside of the body
• Filter feeding in invertebrates and gas exchange
  in vertebrates
• Muscular, post-anal tail
• Reduced in many species
• Propels many aquatic species

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Subphylum Cephalochordata

• Lancelets have a bladelike shape
• Retain all 4 characteristics of chordates as
  adults
• Filter feeders
• Gas exchange across body
• Muscles for movement in and out of sand

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Subphylum Urochordata

• Tunicates or sea squirts
• Short larval stage is a motile bilateraterian
  with all chordate characteristics
• Lasts until suitable substrate found when
  metamorphosis occurs
• Adult is sessile with degenerated NS, resorbed
  notocord and tail
• Suspension feeders

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Craniates

• Chordates with a head containing a brain at
  anterior end of nerve cord, eyes and sensory
  organs
• Neural crest distinguishes craniates from other
  chordates
• Collection of cells near closing neural tube in
  developing embryos
• Cells give rise to teeth, bones of skull, facial
  dermis, and neurons
• Pharyngeal slits into gill slits which allow
  sucking food and gas exchange
• Higher metabolism, extensive muscles, 2 chamber
  heart, RBCs with hemoglobin, and kidneys

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Myxini

• Cartilaginous skull without jaws or vertebrae
• Muscles against notocord for movement
• Small brain, eyes, ears, nasal opening, and
  tooth-like formations of keratin
• Bottom dwelling scavengers
• Slime glands

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Vertebrates

• More extensive skull
• Backbone of vertebrae
• Encloses spinal cord and replaces notocord
  function
• Skeletons evolved initially as unmineralized
  cartilage
• First structures were dental elements
• Allowed animals to become scavengers and
  predators
• Aquatic species developed dorsal, ventral, and
  anal fins to provide steering control
• More efficient means of gas exchange

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Lampreys

• Parasites clamp on with jawless mouth and bore
  into fish to suck blood
• Larvae is freshwater filter feeder
• Some feed as larvae only before reproducing and
  dying
• Cartilaginous skeleton with no collagen in its
  matrix
• Notocord is main axial structure surrounded by
  cartilage
• Dorsal projections partially enclosing nerve cord

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Gnathostomes

• Jawed animals that are aided by teeth to grip and
  slice food
• Evolved from skeletal rods that supported
  anterior gill slits
• Forebrain enlargement associated with enhanced
  vision and smell
• Lateral line system
• Organs form rows on either side of body and sense
  vibrations in water
• Paired fins and tail enhance swimming after prey

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Class Chondrichthyans

• Endokeleton composed of cartilage and Ca
• Bone traces in scales, teeth, and vertebrae
  surfaces
• Sharks
• Swift, but unagile awimmers
• Bouyancy from oil stored in liver, but must stay
  swimming
• Continually replace teeth as lost
• Spiral valve increases SA of digestive tract
• Enhanced senses
• Internal fertilization of eggs
• Oviparous lay eggs in protective cases that
  hatch outside mother
• Ovoviviparous retain fertilized eggs in
  oviducts, nourished by yolk
• Viviparous develop in uterus provide nutrients
  through a placenta
• Rays

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Class Osteichthyans

• Ossified endoskeleton with matrix of calcium
  phosphate
• Gills for gas exchange, protected by an operculum
• Buoyancy from a swim bladder, or air sac, with
  gas exchange to control rise and fall
• Skin covered by bony scales
• Skin glands secrete mucus to skin to reduce drag
• Most species are oviparous
• Reproduce by external fertilization after female
  sheds eggs

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Actinopterygii

• Ray-finned fishes
• Modified for maneuvering and defense
• Originated in fresh water and spread to seas
• Salmon and trout between salt and fresh water
• Human source of protein

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Sarcopterygii

• Lobe-fin fishes
• Muscle surrounds rod-shaped bones
• For swimming and walking across underwater
  substrate
• Coelacanths still survive
• Previously thought extinct
• Lungfishes
• Surface to breathe, but gills for gas exchange
• Tetrapods

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Tetrapods

• Limbs that support weight on land
• Digits on feet to create forces with ground
• Head separated from neck
• 1 vertebrae allowed up and down, 2 allowed side
  to side
• Pelvic girdle fused to backbone to transfer leg
  forces to body
• Pharyngeal slits become ears and glands

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Class Amphibia

• Salamanders and newts
• Some entirely aquatic, others on land or
  throughout life
• On land use side-to-side motion
• Frogs and toads
• Hind legs to jump
• Insects and prey caught with tongue
• Skin glands secrete mucous for protection
• Color variations as warnings or camouflage
• Caecilian
• Legless and nearly blind
• Absence of legs are secondary adaptations

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Amphibians

• Life on land and water
• Herbivorous tadpole is the larval stage of frogs
• Has gills, lateral line system, and long finned
  tail no legs
• Metamorphosis into a carnivorous adult
• Develops legs, lungs, external ear drums, and a
  digestive system lost gills and lateral line
  system
• Salamander and caecilian larvae resemble adult
  and both stages carnivorous
• Necessary for skin to stay moist for gas exchange
• External fertilization in frogs
• Eggs laid in moist environments to prevent
  desiccation
• Oviparous and viviparous species
• Complex social behavior, ectothermic, cloaca, and
  3-chambered heart

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Amniotes

• Amniotic egg with 4 membranes
• Develop from tissue layers growing from embryo
• Allows embryonic development on land
• Eggs with shells
• Differs in birds and reptiles
• Mammals develop embryo without egg inside female
• Rib cage helps ventilate lungs
• Abandon skin breathing and conserve water

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Class Reptilia

• Scales of keratin to protect from desiccation and
  abrasion
• Eggs on land after internal fertilization
• Viviparous
• Ectotherms use heat absorbing behavior instead
  of metabolism to regulate body temperature
• Turtles
• Box-like shields fused to vertebrae, clavicles,
  and ribs
• Neck retraction is horizontal or vertical
• Incubation temperature can determine sex
• Crocodilians
• 4 chambered hearts and developed kidneys for
  excretion
• Lizards
• Often carnivorous

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Snakes

• Force for movement from bending against objects
  to move forward
• Lack ears, but sensitive to ground vibrations
• Infrared detection
• All carnivorous with teeth for griping and/or
  injecting venom
• Jacobs organ
• Flexible airway, loosely articulated jaw, and
  elastic skin to swallow prey

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Class Aves

• Features adapted for flight
• Lack urinary bladders, females with 1 ovary,
  reduced gonads in both sexes except in breeding
  season, lightened bones, and toothless
• Feathers are ß-keratin (modified scales) arranged
  into airfoils
• Some adapted for soaring others require constant
  flapping
• Flightless birds are missing sternal keel and
  developed muscles
• Enhanced hunting and scavenging, protection, and
  food resource attainment
• Energetically expensive
• Endothermic animals with layers of fat to provide
  insulation
• Efficient respiratory and circulatory system with
  4-chambered heart
• Acute vision and muscle control with larger brain
• Complex behavioral displays, often related to
  breeding
• Internal fertilization via cloacal kiss
• Brooding keeps eggs warm

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Class Mammalia

• Mammary glands and hair
• Endothermic with high metabolic rates
• Efficient respiratory and circulatory system with
  4-chambered heart
• Diaphragm to help ventilate lungs
• Larger brains and differentiated teeth
• 3 lineages
• Monotremes are egg-laying
• Marsupials have a pouch
• Eutherians are placental mammals

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Monotremes

• Only in Australia and New Guinea
• 1 species of platypus
• 4 species of echidnas (spiny anteaters)
• Lay eggs, but produce milk and have hair
• No nipples, milk from glands at belly that young
  suck

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Marsupials

• Higher metabolic rates and nipples
• Give birth to live young
• Born early and complete development while nursing
  in pouch
• Most live in Australia
• Opossums only ones in North America

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Eutherians

• Longer pregnancy
• Embryonic development completed in uterus
• Nurtured by placenta

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Order Primates

• Opposable thumb and big toe
• Aids grasping and manipulation behaviors
• Adapted for arboreal (tree-dwelling) life
• Flat nails and not claws
• Reduced olfaction, but increased reliance on
  vision
• Smaller noses, but larger eyes in front close
  together
• Smaller litter size, longer gestation, increased
  maternal care
• Fewer teeth, but specialized
• 2 incisors, 1 canine, 3 premolars, and 3 molars
  in each quadrant
• 2 taxonomic arrangements (generally)

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Prosimians

• Lemurs
• Only in Madagascar
• Evolved in isolation
• Primarily nocturnal
• Lorises
• Africa and southern Asia
• All nocturnal
• Tarsiers
• Specialized for vertical climbing and leaping
• Southeast Asia and Indonesia
• Diet is almost completely animal matter

Ring-tailed lemur
Loris
Tarsier
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Anthropoids

• Monkeys (not monphyletic)
• Active during the day and live in social
• bands
• Forelimbs about equal length as
• hindlimbs
• New world
• All arboreal
• Central and South America
• Nostrils wide open and far apart
• Long prehensile tail-specialized for grasping
• tree limbs
• Old world
• Ground dwelling and arboreal
• Africa and Asia
• Lack prehensile tail
• Nostrils open downward
• Hominoids (Apes)

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Hominoids (Apes)

• Lack tails
• Long arms and short legs
• Mainly vegetarians
• Humans are omnivorous, eating plants and animals
• More flexible
• Larger brain relative to body size
• High degree of social organization
• 5 divisions

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Hominoid Divisions

• Gibbons
• 9 species all in Southeast Asia
• Only entirely arboreal apes
• Smallest, lightest and most acrobatic
• Monogamous for life
• Orangutan
• Solitary species in rain forests of Sumatra and
  Borneo
• Largest arboreal mammal, occasionally move on
  ground
• Gorillas
• Largest ape found only in African rainforests
• Live in groups of up to 20
• Stand upright, walk on 4 legs with knuckles on
  the ground

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Hominoid Divisions (cont.)

• Chimpanzees (and bonoboos)
• Knuckle walkers
• Tropical Africa
• Behavior closely mirrors humans
• Make simple tools
• Respond to mirrors
• Can learn human sign language
• Humans
• Bipedal, larger brain, capable of language,
  thought, and complex tools

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Humans didnt evolve in a direct path. Dead end
groups broke off and ended in extinction except
for us.