Transcript Vertebrate Diversity

Vertebrate Diversity
Chapter 34
Chordate Phylogeny
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
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
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
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, RBC’s with
hemoglobin, and kidneys
Myxini
 Cartilaginous skull without jaws
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or vertebrae
Muscles against notocord for
movement
Small brain, eyes, ears, nasal
opening, and tooth-like
formations of keratin
Bottom dwelling scavengers
Slime glands
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
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
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
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
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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
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
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
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
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
Class Amphibia
 Salamanders and newts
 Some entirely aquatic, others on land or
throughout life
 On land use side-to-side motion
 Frogs and toads
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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
‘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
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
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
Snakes
 Force for movement from bending against objects to move
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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
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 β-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
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
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
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
Eutherians
 Longer pregnancy
 Embryonic development completed in uterus
 Nurtured by placenta
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)
Prosimians
 Lemurs
 Only in Madagascar
 Evolved in isolation
Ring-tailed lemur
 Primarily nocturnal
 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
 Monkeys (not monphyletic)
 Active during the day and live in social
bands
 Forelimbs about equal length as
hindlimbs
 New world
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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)
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 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
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
Humans didn’t evolve in a direct path. Dead end
groups broke off and ended in extinction; except
for us.