ZOO 4910 Lecture Notes - Lecture 3: Branchial Arch, Cyclostomata, Craniate
2 May 2018
School
Department
Course
Professor
Key innovations led to immense adaptive radiation in fish
•
Within fish, diversity (and convergent evolution) can be used to
explain mechanism
•
Evolution of early tetrapods was a result of innovations and
possible plasticity
•
When examining a trait/behaviour/species/taxa…
Novel/Derived Characters --> Adaptation --> Environment
Retention of Ancestral Characters --> Phylogenetic Inertia --> History
Cyclostome monophyly
1.
Cyclostome paraphyly
2.
Grouping Fish: two competing hypotheses
Myxinomorphi (hagfishes) -class: Myxini
•
Petromyzontomorphi (lampreys) -class: Petromyzontida
•
Classes: Chondrichthyes (sharks, rays), Sarcopterygii
(lobe-fins, lung fish), Actinopterygii (ray-finned fish)
○
Gnathostoma
•
Superclasses of Living Fish:
~70 spp in two major genera
•
No jaws, fins or image forming eyes (circadian organs only)
•
Cartilaginous skull (Craniata) but no vertebrae
•
Hagfish:
~40 spp in two major genera
•
No jaws, fins are dorsal and unpaired, eyes are image forming
•
Cartilaginous skull (Craniata) and vertebrae (Vertebrata)
•
Lamprey:
*amount of diversity can vary among groups and over time within
groups -see slide!
Food filters were modified to form gills
•
First gill arch became upper and lower jaws
•
Second gill arch moves forward to brace jaws
•
Evolution of the Jaw from Pharyngeal Arches:
*early jawed fishes has two sets of paired fine for increased accuracy
of movement
*see slide
Jaws were a major diversification, indicative of key innovation and
adaptive radiation
Holocephali (chimeras)
•
More than 360 spp
!
Jaws not attached to skull
!
Vision, chemoreception, electroreception
!
No swim bladder -use liver and motion to stay
buoyant
!
Great diversity of teeth for various food sources
!
Outer enamel and inner dentine with pulp
□
Scales are placoid with spines pointing
backwards
□
Strength of teeth differ between species
□
Shark teeth & Scales:
!
Body surfaces -have broader shorter scales
□
Fins -have narrower & longer scales; more
streamline contours
□
Phenotypic plasticity in growth:
!
Whale shark -14m
□
Dwarf Latern shark -15cm
□
Large disparity in size:
!
Convergent evolution -feeding basket like mouths
!
Galeomorpha & Squalomorpha (sharks)
○
Batoidea (rays, skates)
○
Elasmobranchii:
•
Modern Cartilaginous Fishes (Chondrichthyes)
Sarcopterygii (lobe-finned) -coelacanth, lungfishes, tetrapods
•
Actinopterygii (ray-finned) -all other bony fishes
•
Appeared in the Triassic
○
Origin may have been freshwater or marine
○
Evolution of swim bladder, specializations of swimming
mode
○
Specialization of jaws played a major role in
diversification
○
Teleostei:
•
Cyprinidae -carps and minnows
○
Gobiidae -gobies
○
There is a large diversity of fish in East African rift
lakes -many adaptive radiations
○
Ambush predators
!
Pursuit predators
!
Molluscivores
!
Scale-scrapers
!
Plankton feeders
!
Crevice feeders
!
Ectoparasite cleaners
!
Trophic specializations in Malawi cichlids:
○
Specializations for fish-eating, scale-eating and
algae-eating fish
!
Cichlid tooth morphologies:
○
This is why cichlids are so flexible
!
Cichlids have throat jaws towards the back of the mouth
and separate mouth jaws
○
Males aggressively defend territories (up to 18
months)
!
In rock-dwelling species, males are larger and more
colourful along a broad spectrum, from UV to long
wavelengths
!
In sand-dwelling species, males construct elaborate
"bowers" in the sand to attract females
!
Female colouration is so drab that specific
identification can be taxonomically challenging
!
Communication -sexual selection
○
Specious families, multiple life-history stages, and immense
plasticity:
•
Bony Fishes (Osteichthyes)
Stage 1 -Habitat
•
Stage 2 -Morphology
•
Stage 3 -Communication
•
Stages of Vertebrate Evolutionary Radiation:
First appeared in the Middle Devonian (410 mya)
○
Thought extinct since the Cretaceous, but first specimen
was caught in 1938
○
Two living species
○
Living sacropterygian "fishes" -coelacanth
•
First one discovered: Acanthostega gunnari
○
Ventastega
!
Acanthostega
!
Ichthyostega
!
Tulerpeton
!
There is a fossil gap of intermediate forms
○
There is homology of the Euthenopteron fin bones to the
tetrapod limb
○
375 mya
!
Primarily aquatic
!
Limbs intermediate between lobe-finned fishes and
Acanthostega
!
Tiktaalik roseae
○
Eusthenopteron -pectoral fin
!
Tiktaalik -transitional foot-like structure
!
Ichthyostega -hind limb
!
Evolution of the limb:
○
A Canadian discovery filled in the fossil gap with late
Devonian lobe-finned fish and amphibious tetrapods
○
Frogfish, coelacanth, mudskipper
!
The transition to land evolved via independent evolution
of "walking" on fins
○
From fins to limbs, the first tetrapods moved onto land
•
Sarcopterygian and the Origin of Tetrapods
*together they
are Agnatha
(cyclostomata)
Diversity of Fish and Early Tetrapods
Friday,*September* 15,*2017
12:34*PM
Key innovations led to immense adaptive radiation in fish
•
Within fish, diversity (and convergent evolution) can be used to
explain mechanism
•
Evolution of early tetrapods was a result of innovations and
possible plasticity
•
When examining a trait/behaviour/species/taxa…
Novel/Derived Characters --> Adaptation --> Environment
Retention of Ancestral Characters --> Phylogenetic Inertia --> History
Cyclostome monophyly1.
Cyclostome paraphyly2.
Grouping Fish: two competing hypotheses
Myxinomorphi (hagfishes) -class: Myxini
•
Petromyzontomorphi (lampreys) -class: Petromyzontida
•
Classes: Chondrichthyes (sharks, rays), Sarcopterygii
(lobe-fins, lung fish), Actinopterygii (ray-finned fish)
○
Gnathostoma
•
Superclasses of Living Fish:
~70 spp in two major genera
•
No jaws, fins or image forming eyes (circadian organs only)
•
Cartilaginous skull (Craniata) but no vertebrae
•
Hagfish:
~40 spp in two major genera
•
No jaws, fins are dorsal and unpaired, eyes are image forming
•
Cartilaginous skull (Craniata) and vertebrae (Vertebrata)
•
Lamprey:
*amount of diversity can vary among groups and over time within
groups -see slide!
Food filters were modified to form gills
•
First gill arch became upper and lower jaws
•
Second gill arch moves forward to brace jaws
•
Evolution of the Jaw from Pharyngeal Arches:
*early jawed fishes has two sets of paired fine for increased accuracy
of movement
*see slide
Jaws were a major diversification, indicative of key innovation and
adaptive radiation
Holocephali (chimeras)
•
More than 360 spp
!
Jaws not attached to skull
!
Vision, chemoreception, electroreception
!
No swim bladder -use liver and motion to stay
buoyant
!
Great diversity of teeth for various food sources
!
Outer enamel and inner dentine with pulp
□
Scales are placoid with spines pointing
backwards
□
Strength of teeth differ between species
□
Shark teeth & Scales:
!
Body surfaces -have broader shorter scales
□
Fins -have narrower & longer scales; more
streamline contours
□
Phenotypic plasticity in growth:
!
Whale shark -14m
□
Dwarf Latern shark -15cm
□
Large disparity in size:
!
Convergent evolution -feeding basket like mouths
!
Galeomorpha & Squalomorpha (sharks)
○
Batoidea (rays, skates)
○
Elasmobranchii:
•
Modern Cartilaginous Fishes (Chondrichthyes)
Sarcopterygii (lobe-finned) -coelacanth, lungfishes, tetrapods
•
Actinopterygii (ray-finned) -all other bony fishes
•
Appeared in the Triassic
○
Origin may have been freshwater or marine
○
Evolution of swim bladder, specializations of swimming
mode
○
Specialization of jaws played a major role in
diversification
○
Teleostei:
•
Cyprinidae -carps and minnows
○
Gobiidae -gobies
○
There is a large diversity of fish in East African rift
lakes -many adaptive radiations
○
Ambush predators
!
Pursuit predators
!
Molluscivores
!
Scale-scrapers
!
Plankton feeders
!
Crevice feeders
!
Ectoparasite cleaners
!
Trophic specializations in Malawi cichlids:
○
Specializations for fish-eating, scale-eating and
algae-eating fish
!
Cichlid tooth morphologies:
○
This is why cichlids are so flexible
!
Cichlids have throat jaws towards the back of the mouth
and separate mouth jaws
○
Males aggressively defend territories (up to 18
months)
!
In rock-dwelling species, males are larger and more
colourful along a broad spectrum, from UV to long
wavelengths
!
In sand-dwelling species, males construct elaborate
"bowers" in the sand to attract females
!
Female colouration is so drab that specific
identification can be taxonomically challenging
!
Communication -sexual selection
○
Specious families, multiple life-history stages, and immense
plasticity:
•
Bony Fishes (Osteichthyes)
Stage 1 -Habitat
•
Stage 2 -Morphology
•
Stage 3 -Communication
•
Stages of Vertebrate Evolutionary Radiation:
First appeared in the Middle Devonian (410 mya)
○
Thought extinct since the Cretaceous, but first specimen
was caught in 1938
○
Two living species
○
Living sacropterygian "fishes" -coelacanth
•
First one discovered: Acanthostega gunnari
○
Ventastega
!
Acanthostega
!
Ichthyostega
!
Tulerpeton
!
There is a fossil gap of intermediate forms
○
There is homology of the Euthenopteron fin bones to the
tetrapod limb
○
375 mya
!
Primarily aquatic
!
Limbs intermediate between lobe-finned fishes and
Acanthostega
!
Tiktaalik roseae
○
Eusthenopteron -pectoral fin
!
Tiktaalik -transitional foot-like structure
!
Ichthyostega -hind limb
!
Evolution of the limb:
○
A Canadian discovery filled in the fossil gap with late
Devonian lobe-finned fish and amphibious tetrapods
○
Frogfish, coelacanth, mudskipper
!
The transition to land evolved via independent evolution
of "walking" on fins
○
From fins to limbs, the first tetrapods moved onto land
•
Sarcopterygian and the Origin of Tetrapods
*together they
are Agnatha
(cyclostomata)
Diversity of Fish and Early Tetrapods
Friday,*September* 15,*2017 12:34*PM
Document Summary
Key innovations led to immense adaptive radiation in fish. Within fish, diversity (and convergent evolution) can be used to explain mechanism. Evolution of early tetrapods was a result of innovations and possible plasticity. Retention of ancestral characters --> phylogenetic inertia --> history. Classes: chondrichthyes (sharks, rays), sarcopterygii (lobe-fins, lung fish), actinopterygii (ray-finned fish) No jaws, fins or image forming eyes (circadian organs only) No jaws, fins are dorsal and unpaired, eyes are image forming. *amount of diversity can vary among groups and over time within groups - see slide! First gill arch became upper and lower jaws. Second gill arch moves forward to brace jaws. *early jawed fishes has two sets of paired fine for increased accuracy of movement. Jaws were a major diversification, indicative of key innovation and adaptive radiation. No swim bladder - use liver and motion to stay buoyant. Great diversity of teeth for various food sources. Fins - have narrower & longer scales; more streamline contours.
