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Review— Evolution and Phylogeny. Lecture 6b. Determining a Phylogenetic Tree—1. Based on shared characters (traits) Internal or external Major derived characters ( synapomorphies )—large scale relationships

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Review— Evolution and Phylogeny


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determining a phylogenetic tree 1
Determining a Phylogenetic Tree—1
  • Based on shared characters (traits)
    • Internal or external
  • Major derived characters (synapomorphies)—large scale relationships
    • Examples: physostomus vs. physoclistous, ctenoid scales, thoracic pelvic fins
determining a phylogenetic tree 11
Determining a Phylogenetic Tree—1
  • Secondarily derived traits—fine scale relationships
    • Typically many traits are examined
      • Meristic counts and anatomical features
determining a phylogenetic tree 2
Determining a Phylogenetic Tree—2
  • Fossil record often used to determine ancestral origins of major lineages
determining a phylogenetic tree 3
Determining a Phylogenetic Tree—3
  • Gene sequencing and DNA fingerprinting commonly used to determine relationships
  • Molecular clocks—Genes used to determine when major branch points occur
    • Technique uses specific genes known to evolve at a constant rate
      • No selection pressure
      • Genetic drift
determining a phylogenetic tree 31
Determining a Phylogenetic Tree—3
  • Molecular clocks must be calibrated—example
    • Branching point for birds and mammals  310 mya
      • Extensive fossil record
    • Hypothesis: all mammals are equally different from any bird species, at this gene site
slide9

Class Actinopterygii

Class Sarcopterygii

SublassNeopterygii

SublassChondrostei

Teleosts

Order

Lepisosteiformes

Tetrapods

Lungfish

Coelacanth

Gars

Sturgeons

primitive fishes phylogeny
Primitive Fishes Phylogeny

Fish-like form

Osmoregulation

True teeth

Jaws

Swim bladder

Teleosts

Gars

Lamprey

Conodonts

Placoderms

Hagfish

Chondrostei

Sarcopterygii

Tunicates

Chondrichthyes

First fishes

teleostei
Teleostei
  • Originated 215 mya
  • > 26,000 species
  • Adaptations of jaws, fins, swim bladder, & skeleton
  • All possess_____ or ______ scales,mobile maxilla bone, & ________ caudal fin
    • Scales overlap like shingles  greater flexibility
phylogeny teleostei

Detached maxilla,

cycloid/ctenoid

scales, homocercal tail

Phylogeny—teleostei

Leptocephalus larvae

Weberianossicles

Physoclistous swim bladder

Tetraodontiformes

Perciformes

Pleuronectiformes

Atherinomorpha

Gars

Protacanthopterygii

Ostariophysi

Clupeomorpha

Elopomorpha

cladogram teleostei jaws
Cladogram—teleosteiJaws

Protrusiblepremaxilla

Tetraodontiformes

Perciformes

Pleuronectiformes

Atherinomorpha

Gars

Protacanthopterygii

Ostariophysi

Clupeomorpha

Elopomorpha

teleost evolution jaws feeding
Teleost Evolution: jaws & feeding

Bowfin—non-teleost fish

Premaxilla bone

Maxilla bone

synapomorphy jaw morphology 1
Synapomorphy—jaw morphology #1
  • Protrusible jaw
  • Posterior connection of maxilla bone freed
      • Swings forward
  • Benefits?
synapomorphy jaw morphology 2
Synapomorphy—jaw morphology #2
  • Pipette mouth—premaxillary bone also freed
    • Structure slides along groove over skull
  • http://www.xromm.org/projects/fish-feeding
pipette mouth advantage
Pipette mouth advantage
  • Increased suction power; more focused
    • Tradeoff  gape reduction
    • Ideal for small prey
  • Attack speed also 
    • Suction not always produced
    • LMB almost 2x

Gape & protrusion (mm)

Flow speed (m/s)

pharyngeal teeth
Pharyngeal teeth
  • Protrusion of jaws has tradeoff
    • Maxillary bone not toothed in advanced forms
  • Pharyngeal teeth well developed in many teleosts
    • Gill arches, tongue, bones on roof of mouth
moray eel pharyngeal jaws
Moray eel—pharyngeal jaws
  • Eels have weak suction power
    • Swallowing prey more difficult
  • Modified anterior gill arches
    • Project forward to draw prey in
herbivorous teleosts
Herbivorous teleosts
  • Almost all non-teleosts are carnivorous
  • Most herbivorous teleosts in freshwater or on coral reefs
    • Feed on algae or aquatic plants
    • Many temperate species are omnivorous
herbivorous teleosts1
Herbivorous teleosts
  • Plants  thick cell walls made of cellulose
    • How do mammals overcome this?
  • Herbivores have pharyngeal mills or gizzards
  • Highly acidic stomachs & long intestines
    • High intake, low assimilation
phylogeny teleostei paired fin placement and function
Phylogeny—teleosteiPaired fin placement and function

Pectoral fins

placed higher

Pelvic fins thoracic

Tetraodontiformes

Perciformes

Pleuronectiformes

Atherinomorpha

Gars

Protacanthopterygii

Ostariophysi

Clupeomorpha

Elopomorpha

synapomorphies paired fin placement
Synapomorphies—paired fin placement

More primitive  pectorals ventral to gills; horizontal

  • Paired fins for stabilization & braking, no spines
  • Derived pectorals behind gills &vertical; pelvics thoracic
    • Pectorals maneuvering & thurst
    • Pelvic fins  braking & stabilization
      • Defense
cladogram teleostei dorsal fin
Cladogram—teleosteiDorsal fin

Two dorsal fins

Tetraodontiformes

Perciformes

Pleuronectiformes

Atherinomorpha

Gars

Protacanthopterygii

Ostariophysi

Clupeomorpha

Elopomorpha

synapomorphy dorsal fin
Synapomorphy—Dorsal fin

More primitive  single, only soft-rays, less articulating

  • Prevents rolling

More advanced  Two fins

  • Anterior fin spinous and retractable
    • Function—
  • Posterior fin soft rays, articulating
    • Function—
bone reduction occurred throughout teleost evolution
Bone reduction occurred throughout teleost evolution
  • Vertebrate reduction— > 60 in elopomorpha < 30 in advanced forms
  • Reduction in vertebral accessories (ribs)
  • Fewer bones in skull and tail
  • Scales reduced in size and thickness
phylogeny teleostei1
Phylogeny—teleostei

Tetraodontiformes

Perciformes

Pleuronectiformes

Atherinomorpha

Gars

Protacanthopterygii

Ostariophysi

Clupeomorpha

Elopomorpha

tetraodontiformes four teeth
Tetraodontiformes—four teeth
  • Most derived and recently evolved group
    • Originated 65 mya
    • 360 living species—mostly marine
tetraodontiformes
Tetraodontiformes
  • Many bones fused or lost
      • 16 vertebrae
      • Premaxilla and maxillary fused
      • Pelvic fins lost
  • Scales modified into small spines or ossicles, or bony plates
tetraodontiformes1
Tetraodontiformes

Many have adapted to previously unoccupied niches

  • Diet of sponges, sea urchin, coral, jellyfish
  • Some eat benthic or pelagic invertebrates

Fin swimmers—types?

tetraodontiformes leatherjackets
Tetraodontiformes—Leatherjackets

Triggerfish and filefish—leatherjackets

  • Make noise grinding teeth or drumming swim bladder with pectoral spine-bone
  • Locking dorsal spine
  • Eyes move independent

Humuhumu………..

“the fish that sews with a needle and grunts like a pig

tetraodontiformes puffers
Tetraodontiformes—Puffers

Puffers—fill stomach to puff up  3x volume

    • Stomach may  volume 100x
    • Causes spines to erect—diodontidae
  • Freshwater species
  • Viscera and eyes are toxic
    • 2nd most toxic vertebrate

Fugu anyone?

tetraodontiformes mola
Tetraodontiformes—Mola

Four species

  • Molamolaweigh > 4000 lbs.
  • > 300 million eggs in larger sunfishlow ________
    • Highest among vertebrates
  • Much of skeleton cartilaginous—secondarily derived
  • Feed on abundant jellyfish
  • Common bycatch on driftnet and longline fisheries

http://www.youtube.com/watch?v=U60obmWODLQ

Slender Mola