Transcript Evolution of Vertebrates

Evolution of Vertebrates
Chapter 19
Chordate Characteristics
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Dorsal, hollow nerve cords
Notocord between GI tract and nerve cord
Pharyngeal slits
Post-anal tail
Phylum Chordata
Subphylum Cephalochordata
Subphylum Urochordata
• Tunicates or Sea squirts
• Lancets
• Substrate causes metamorphosis • All 4 characteristics present
– Larva: all 4 characteristics & motile
– Adult: slits only & sessile
• Mucus aids filter feeding
– Swollen tip of nerve cord
• Mucus for filter feeding
• Shows segmentation
Development of Vertebrates
Emphasizes (in blue) characteristics of vertebrate evolution
Should refer back to with each Class
Class Agnatha (Jawless fish)
Craniates, no jaws, and notochord as main support
Hagfishes
• Weak vision, developed touch
and smell (habitat)
• Enter prey through openings
or create holes
• Can knot body or secrete
slime
Lampreys
 Beginnings of vertebrae
 Larvae are suspension
feeders that live in stream
sediment
 Fish parasites
 Problematic in Great Lakes
from St. Lawrence Seaway
Class Chondricthyes (Cartilaginous fishes)
Craniates, jaws, and cartilage vertebrae as main support
 Lateral line system to detect changes in water pressure
and vibrations
 No operculum or swim bladder
 Clades
 Sharks
 Most are predators with powerful jaws (largest are filter feeders)
 Detect prey muscle movement through electrosensors on their
head
 Sharp vision, keen smell, and streamlined bodies
 Stingrays and skates
 Suspension feeders
 Dorsoventrally flattened with eyes on top of head
 Barbed tails with venom glands (not skates)
Class Osteichthyes (Bony fishes)
Craniates, jaws, and bony skeleton as main support
• Calcium phosphate mineralized cartilage
• Flattened scales covered in mucus = reduces drag
• Operculum , protective flap covering the gills
– Can breathe without swimming, contrast to most sharks
• Swim bladder keeps them afloat
• Two dorsal fins, paired pectoral and pelvic fins (one
bone)
• Clades
– Ray-finned fishes
– Lobe-finned fishes
• Coelacanth, lungfishes, and tetrapods
Evolution of Tetrapods
• Lobe fins seem homologous
to limbs
– Digits to create ground force
• Early development of lunglike structures
• Sense organs from water to
land
• Fossils show fused girdles
and head/neck separation
– Fish with necks
Class Amphibia
Tetrapods with 2 pairs of limbs
 Damp habitats so skin stays moist
 Skin has poison glands and coloration for defense
 Distribution limited by vulnerability to dehydration
 Ectothermic = metabolism doesn’t make heat must absorb
 Clades
 Salamanders and newts
 Walk side to side
 Caecilians
 legless
 Frogs
 Most adult life on land, but lay eggs in water
 Metamorphosis from tadpole (fish characteristics) to adult frog
Class Reptilia
Tetrapods with terrestrial egg (amniotes)
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Eggs develop in fluid-filled amniotic sacs protected by a leathery shell
Skin with scales and waterproofed by keratin
Rib cage helps ventilate lungs
Ectothermic
– Small dinosaurs may have been endothermic, using metabolism
• Clades
– Turtles and tortoises
• Shell and vertebrae are fused
– Lizards and snakes
• Snakes likely lost legs due to burrowing nature; can detach jaws
• Lizards can detach tail, moveable eyelids, and external ear openings
– Crocodilians
• Most time in water with nostrils out
• Advanced behavior resembles birds and mammals
Class Aves
Feathered reptiles adapted to flight
• Lightened body structure
– No teeth, tail with few vertebrae, feather shafts hollow, and
honeycombed bones
• Feathers of keratin provide lift and maneuverability
– Wings resemble air foils with large breast muscles
• Basis for classification
– Courtship and insulation role too
• High metabolism = energy for flight and endothermic
• Highly efficient circulatory system, lungs, and vision
• Complex behavior, both sexes incubate hard shelled eggs
and feed
Class Mammalia
• Hair (keratin) and mammary glands
– Hair to insulate and increase size (goose bumps)
– Milk to nurture young
• Efficient respiratory and circulatory systems for high
metabolism
– Endothermic
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Large brain and long parental care
Differentiation of teeth for variety of foods
One evolution from reptiles (current view)
3 lineages
– Offspring are hatched or birthed (loss of the egg)
Monotremes
• Egg-laying mammals
– No nipples, milk sucked from
glands on belly
• Only in Australia and
New Guinea
• 2 existing members
– Duck-billed platypus (1)
– Spiny anteaters (4)
Marsupials
• Higher metabolic rates
and nipples
• Birth live young
– Complete development
while nursing in external
pouch
– No direct yolk sac/amnion
connection
• Most live in Australia and
New Zealand
– Opossums only ones in
North America
Eutherians (Placental Animals)
• Longer gestation = fully developed live young
– Nurtured by a placenta
• Placenta nurtures by nutrient diffusion between mother’s and embryo’s
blood
• Many resemble marsupials  convergent evolution
Order Primate Phylogeny
Order Primates
• Limber joints, 5 digits, flexible thumb and big toe
– Aids grasping and manipulation behaviors
– Adapted for arboreal (tree-dwelling) life
• Flat nails, not claws
• Reduced olfaction, increased vision
– Smaller noses, but larger forward facing eyes
• Smaller litter size, longer gestation, increased
maternal care
• Fewer specialized teeth
– 2 incisors, 1 canine, 3 premolars, and 3 molars in each
quadrant
• 2 taxonomic arrangements (generally)
Prosimians
• Lemurs
– Only in Madagascar
– Primarily nocturnal
– Most social
• Lorises
– Africa and southern Asia
– All nocturnal
• Tarsiers
Loris
– Specialized for vertical climbing and leaping
– Southeast Asia and Indonesia
– Diet is almost completely animal matter
Tarsier
Anthropoids
• Fully opposable thumb
• Monkeys
– Active during the day and live in
social bands
– Fore- and hindlimbs about equal
length
– New world
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Central and South America
Nostrils wide open and far apart
Long prehensile tail
E.g spider monkeys and tamarins
– Old world
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Africa and Asia
Lack prehensile tail
Nostrils open downward
E.g macaque, baboons, and rhesus
• Hominoids (Apes)
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
Hominoid (Ape) Divisions
• Gibbons
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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
Hominoid (Ape) 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
Vertebrate Diversity Review
List characteristics
responsible for each
branch point (a-i)