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Topic 6: Amphibian Diversity
� What are amphibians?
� What are the three major amphibian clades?
� What are some trends in amphibian evolution?
� * Introduction to the biology of each clade:
� Gymnophiona
� Urodela
� Anura
� The Amphibia is a diverse clade, with many __________ groups
� Extant (crown) amphibians make up the ____________
What are Amphibians?
Benton 1997, Fig 4.21
What are Amphibians?
� Synapomorphies
� Pedicellate, bicuspid teeth
� Ear with stapes and operculum
Pough et al 2004, Fig 2-5
What are Amphibians?
Pough et al 2004, Fig 2-6
� Synapomorphies
� Skin with _________ and ________ glands
� Green rod receptor cells in eyes
� Lost in Gymnophiona
� Short, straight ________ that do not encircle the body
� Reduction of skull bones via __________________
� Metamorphosis is unique among tetrapods but plesiomorphic
Paedomorphosis
� Paedo ~ child (Gr), morph ~ form (Gr)
� A type of heterochrony, which is a _______________ _______________________
� The retention of juvenile (child-like) characteristics into adulthood/sexual maturity
� Non-herp example:
� Relative hairlessness and upright face of humans
Paedomorphosis
� Paedomorphosis is prevalent in the _______
� Retention of gills in adult axolotl
� Missing late-developing bones
� Large orbits – form early during development
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What are the three major amphibian clades?
� Lissamphibia
� Many synapomorphies
� ~5,300 extant species
� More than Mammalia
� Three Major clades
� ______________: 167 spp
� ______________: 516 spp
� ___________: ~4,800 spp
Photos: KP Bergmann, Pough et al. Fig 3-8 Photos: KP Bergmann, Pough et al. Fig 3-8
What are the three major amphibian clades?
Major Trends in Lissamphibian Evolution
Body ____________ and stiffening
Microsaur
Anura
Urodela
Gymnophiona
� Body ____________ and limb reduction
Gymnophiona
� Gymnophiona are caecilians
� Highly derived
� Strange morphology
� Elongate and limbless
Pough et al 2004, Fig 3-8
Gymnophiona – General Features
� Elongate bodies
� ____________, terrestrial, or aquatic
� Aquatic habits are derived
� Many structures are reduced
� ___________
� Limbs
� __________ reduced or absent
Male Typhlonectes(cloaca)
Typhlonectes
Gymnophiona - Synapomorphies
� Annulated bodies
� Annulus – Ring L.
� Homologous with ______________ in Urodela
Pough et al 2004, Fig 3-8
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Gymnophiona - Synapomorphies
� _________________
� Involved in chemoreception
� Contains glands, ducts, and muscles
� Located between eyes and nostrils
� Its position is phylogenetically informative
� Protrusible from the skull
nostril orbitTentacle foramen
Pough et al 2004, Fig 3-9
Gymnophiona - Synapomorphies� _______________ reduced or absent
� Associated with body elongation
� This is the same side lung as is reduced in snakes
� Gymnophiona includes the largest lungless tetrapod (Typhlonectes)
� Why would caecilians be less reliant on their lungs than snakes?
Gymnophiona - Synapomorphies
� _________________
� A projection of skin from the cloaca in males
� Used as an intromittent organ
� � _______________ fertilization
Typhlonectes(mating)
Male Typhlonectes(cloaca)
Gymnophiona - Reproduction
� Internal fertilization
� What is the intromittent organ called?
� ~70% oviparous, rest are viviparous
� ______________ species
� Eggs can be aquatic or terrestrial
� When terrestrial, there is parental care
� ______________ species
� Young are nourished by secretions from oviduct
� After birth, mother’s skin produces edible secretions
Gymnophiona – Scales?
� Deep scales in dermis
� Only in some species – not a synapomorphy
� Only amphibians with scales
� surrounded by poison and mucous glands
Pough et al 2004, Fig 3-10
1
Gymnophiona - Synapomorphies� Fusion of bones in skull
� Skulls are highly ossified and bones are closely associated
� Very solid, akinetic structure
� Fusion into os basale and maxilopalatine
Pough et al 2004, Fig 3-9
Gymnophiona - Synapomorphies
Three types of amphibian skulls
______________
• Temporal region open
• Anura & Urodela
______________
• Skull is completely roofed
• Gymnophiona
______________
• Skull is intermediate
• Gymniophiona
Pough et al 2004, Fig 2-6, 3-9
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Gymnophiona - Fossoriality
� Caecilians have many adaptations to a fossorial existence
� Non-fossorial forms are derived
� What are some of these adaptations?
http://digimorph.org/specimens/Dermophis_mexicanus/
Adaptations for fossoriality
� ______________________
� ______________________
� ______________________
� ______________________
� ______________________
� ______________________ is a result of a fossorial existence
1
Gymnophiona – Diversity & Phylogeny
� 6 major clades
� Don’t worry about their names
� 33 genera, 167 spp.
� 109 spp. Are “Caeciliidae”, a paraphyletic group
� Not a lot known about most of these animals
Pough et al 2004, Fig 3-12
Gymnophiona - Distribution
Pough et al 2004, Fig 3-13
� Northern S. America
� Central Africa
� SE Asia
Three Major Clades
Photos: KP Bergmann, Pough et al. Fig 3-8
Urodela
� Salamanders and newts
Pough et al 2004, Fig 3-2, 3-5
Urodela
� Urodela – refers to crown group salamanders
� _________________ – refers to stem group
� What species would be included in the Caudata that are excluded from the Urodela?
Urodela - Synapomorphies
� Many obscure osteological synapomorphies� Fusion of some bones in digits I and II
� Operculum is fused to the ear capsule
� Quadratojugals are absent
� 2nd Ceratobranchial bone is lost at metamorphosis
Duellman & Trueb 1994, Fig. 13.1
2
Urodela – General features
� Most species have a generalized morphology:� Four limbs
� ______________
� Long tail
� ______________
� Some trends towards limb reduction and body elongation (Sirenidae, Amphiumidae)
Ambystoma californiense
Urodela – General features
� Most species are terrestrial
� Some arboreal, some aquatic
� All rely on water for reproduction
� Have mucous & poison glands
� Glands also produce ________________
� ___________ glands are used in courtship
Stebbins and Cohen, 1995, Fig. 17.3
Urodela – Reproduction
� Often have elaborate courtship rituals
� Most have internal fertilization
� Use a ______________
� No intromittent organ
� Larval stage as well as direct development (Plethodontindae) are common
Duellman and Trueb, 1986
female
male
Urodela – Reproduction
� Larvae similar to adults (compared to other amphibians)
� Larvae have external gills and slits
� How are these larvae adapted to their habitats?
Stebbin & Cohn 1995, Fig 17.16
Pond Dweller
Stream Dweller
Terrestrial Direct – Developer
Pond Dweller
1
Urodela – Defense
� Many behavioral anti-predator adaptations
� _________________
Echinotriton chinhaiensis © Max Sparreboom Duellman and Trueb, 1986
Urodela – Other Information
� Large _____________� Largest among vertebrates
� Cells are large to contain all the DNA
� Paedomorphosis is common� In some species, all adults retain larval characters
� In others, only some adults retain larval characters
Urodela – Phylogeny & Diversity
� 10 major clades
� 516 species
� Phylogeny controversial
� Reanalysis of rRNA and morphological data
� Uncertainty of position of Sirenidae
� Basal vs. near Proteidae
Pough et al. 2004, Fig 3-1
Urodela – Sirenidae
� 4 species in SE USA
� ______________ lineage
� ___________ & limb reduced
� Fully ______________
� Prey on insects, crayfish, worms
� Oviparous – lay eggs
� Synapomorphies
� No pelvic girdle or hind limbs
� Keratinized beak replaces premaxillary teeth
� Non-pedicellate teeth
Pough et al. 2004, Fig 3-2a
� Paedomorphic features
� No ______________
� External gills
� Reduced number of toes on the front limbs
Urodela – Cryptobranchoidea
� Includes� Cryptobranchidae
� Hynobiidae
� Sister to Salamandroidea
� Synapomorphies� _____________ ribs
� _________ that secrete into cloaca
� Fusion of some hyoid bones
Pough et al. 2004, Fig 3-1
Urodela – Cryptobranchidae
� 3 species in Japan, China, and Eastern USA
� Hellbender
� Have ___________ bodies and heads
� _____________
� Largest – up to 1.8 m!
� Males make nests and guard nests
� Live in cold mountain streams
� Rely on _______________ respiration (skin folds)
� Synapomorphies
� Lack eye lids
� One set of _________
� These are paedomorphic traits
� **Lateral skin folds
© Dr. Eric J. Routman
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Urodela – Salamandroidea
� Includes all other Urodela
� Synapomorphy
� Females have a ________________, which stores sperm after insemination
Pough et al. 2004, Fig 3-1
Urodela – Amphiumidae
� 3 species in SE USA
� Elongate and limb-reduced� Have remnants of all 4 limbs
� Paedomorphic� Lack eyelids� Have gill slits (but lack external
gills – distinguish from Sirenids
� Aquatic ________________� Vertebrates and inverts� Powerful, muscular jaws
� Oviparous
� Large – up to over a meter
© John White
Duellman & Trueb 1994, Fig. 13-6
Urodela –
Plethodontidae
� Diverse: 360 species
� Coastal western USA
� Eastern USA
� Mexico to Brazil
� Italy
Pough et al. 2004, Fig 3-7
Urodela – Plethodontidae
� Only salamanders to radiate in ___________
� Highly variable
� Subterranean, aquatic, terrestrial and arboreal
� Life history varied
� Some forms with webbed feet, prehensile tails
� Often small
Pough et al. 2004, Fig 3-5
Urodela – Plethodontidae
� 5 species in Massachusetts
� Including Plethodon cinereus
� Synapomorphies
� ________________ (cutaneous respiration)
� __________________________
� Lacrimals & pterygoids absent
� No operculum
Photos: PJB, Stebbins and Cohen 1995, Fig 7-2
Urodela – Proteidae
� 6 species in E USA & Balkans
� Aquatic – large permanent bodies of water
� Large – up to 45 cm
� Synapomorphies
� No _________________
� External gills and gill slits (paedomorphic)
� 2n=38 (other Urodela have 30 chromosomes)
Pough et al. 2004, Fig 3-2d
Proteus anguinus
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Urodela – Salamandridae
� 62 species
� Coastal USA and Canada
� Europe & Northern Africa
� China & Japan
Pough et al. 2004, Fig 3-3
Urodela – Salamandridae
� Many species _____________
� Includes “____________”
� Some have rugose skin
� Unken reflex for defense
� Tetrodotoxins
� Massachusets species: Nothophthalmus viridescens
� Complex life cycle
� Metamorphosis 1: Larva to Eft
� Metamorphosis 2: Eft to Adult
� Aquatic � terrestrial � aquatic
Photos © PJB, H Greene
Urodela – Ambystomatidae
� 30 species in N. America
� Robust body
� Some terrestrial, some aquatic
� ___________ is paedomorphic
� Some hybridize and are unisexual and parthenogenetic
� Variable ploidy level
� Four species in Massachusetts
Pough et al. 2004, Fig 3-2e
Clades of Urodela Covered in Lecture Clade #
spp Distribution Synapomorphies Habitat Paedo-
morphic? Other Notes
- Sirenidae
CRYPTO-BRANCHOIDEA
- Cryptobranchidae
SALAMANDROIDEA
- Amphiumidae
- Plethodontidae
- Proteidae
- Salamanridae
- Ambystomatidae
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Three Major Clades
Photos: KP Bergmann, Pough et al. Fig 3-8
Anura
Pough et al. 2004, PJB
Anura
� Anura – Crown group frogs
� _____________ – Stem group frogs, so includes fossil forms as well
� Anura is our focus in this course
Anura
� Evolved in the Cretaceous
� Triadibatrachus is sister group to Anura, from Lower Triassic
� ~12 presacral vertebrae instead of 8-9
� Had a ________________, composed of _________________
Pough et al. 2004, Fig. 3-19
Anuran Synapomorphies
Pough et al 2004, Fig 3-14
� _________ presacral vertebrae
� ________________
� Hindlimbs > Forelimbs
� ______________ bone: Ulna & radius fused
� ______________ bone: Tibia & fibula fused
� Elongate ankles
� Fused bones in skull
� How are these adaptations for jumping?
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Anura – Specialized Jumpers
� Adaptations?
� 9 presacral vertebrae
� Urostyle
� Hindlimbs > Forelimbs
� Ulna & radius fused
� Tibia & fibula fused
� Elongate ankles
� Fused bones in skull
� What they do
Anura – Specialized Jumpers
Zug et al. 2001, Fig 2.10
� Fusion and reduction of skull
� _____________
� Also, ribs are reduced or lost
� Lightens body
� Allows vertebrae to be more _________
� Less protection of organs
Caecilian
Salamander
Frog
1
Anura – Specialized Jumpers
© National Geographic, B Lavies
� Jumping likely originated as ______________________
� Today, most frogs are specialized jumpers
� Jump as a form of ________________
� Many are not very good at walking
� Hind limbs too long
� Body not flexible
Anura – Specialized Jumpers?
© KP Bergmann
� Exceptions:
� Heavy horned frogs
� Short limbed toads (Bufonidae)
� Some aquatic specialists (Pipa, Xenopus)
� All of these can still jump, but not well
� Rely more on walking or swimming
Anura – Skin
© PJB, KP Bergmann
� The skin of frogs serves many important functions
� ___________________
� Water balance
� ___________________
� Reproduction
� ___________________
� Defense
Anura – Skin
Stebbins & Cohen 1995, Fig. 2.1
� Mucous Glands
� Mucous glands
� prevent dehydration
� ____________ glands
� Localized to nuptual pads
� Sticky – good grip
� Sexually dimorphic
� Poison/granular Glands
� Toxic or noxious secretions
� Defensive
Anura – Skin
Stebbins & Cohen 1995, Fig. 2.2
� __________________
� Give pigmentation
� Xanthophores
� Red & Yellow
� Just beneath epidermis
� Iridiophores
� Silver, grey
� Deeper than xanthophores
� Melanophores
� Black
� Deepest
� Under hormonal control
Anura – Skin
� All amphibians use cutaneous respiration to some degree
� Why is this important to Plethodontids?
� Some species have epidermal elaborations
� Increased _________________
� Increased _________________
� Rely on water being abundant
� Hairy Frog (Trichobatrachus) �
� Compare to Hellbender
Stebbins & Cohen 1995, Fig. 3.5
2
Anura – Reproduction
� Diverse reproductive strategies
� Sound production
� Primary mode of ____________
� Primarily males, calling for mates
� Used in:
� ________________
� Territory defense
� ________________
Anura – Reproduction
� ______________
� L. = embrace, hug
� 3 Types:
� Inguinal
� Axillary
� Cephalic
� Eggs are:
� Generally deposited in water
� Deposited on land
� Suspended (arboreal)
© KP Bergmann; Stebbins and Cohen, 1995
Anura – Reproduction
� Parental care
� Common
� Varied
Stebbins & Cohen 1995, Fig. 18.2, 18.4
Darwin Frog – Young in vocal sacs
Egg guarding
Brood guarding
Anura – Reproduction
� Tadpoles and adults are very distinct
� Tadpole
� Generally ______________ (algae)
� Some are carnivores, some are __________________
� Some do not feed
� Adults
� ____________ (insectivores)
� Modifications to gut, jaws, limbs, body shape, tail
Stebbins & Cohen 1995, Fig. 1.2
Anura – Phylogeny and Diversity
� 29 major lineages
� ~4,800 species
� Have radiated extensively in the _______________
� Account for the majority of Lissamphibian diversity
� Major clades are characterized mainly by:
� Skull & vertebral characters
� _______________ morphology
� Limb muscles
� _______________ type See next �
Anura – Phylogeny and Diversity
Pough et al. 2004, Fig 3-20
� Yikes! What a monster!
Note: Poor resolution among derived groups
3
Anura – Phylogeny
and Diversity
Pough et al. 2004, Fig 3-20
� More basal frogs are better resolved
� Successive sister groups to the Pipanura (5)
� Ascaphidae*
� Leiopelmatidae
� Bombinatoridae*
� Discoglossidae
* CoveredNeobatrachia
Anura - Ascaphidae
� 1 species in NW USA, SW Canada
� “Tailed frog”
� Tail is extension of __________, used in _________________
� Inhabit high energy streams (fast)
� Do not call
� Lack _____________
http://www.digimorph.org/
Anura - Bombinatoridae
� 10 species
� Europe, E China, Korea, Philippines
� Bombina – Fire-bellied toads
� Toxic, ____________
� Use Unken reflex
� Synapomorphies are a number of skull characteristics
Bombina orientalis
Anura – Mesobatrachia
Pough et al. 2004, Fig 3-20
� Next most basal clade (6)
� Includes:
� Pipidae*
� Rhinophrynidae
� Megalophrydae
� Pelodytidae
� Pelobatidae*
� Synapomorphies:
� Skull and hyoid characters (don’t need to know them)
Anura – Pelobatidae� 11 species� USA, Mexico, Europe� 1 MA speices: Scaphiopus holbrookii
� Spadefoot toads
� ______________ are keratinized metatarsal tubercles for digging
� ______________
� Often enlarged parotid glands (convergent with Bufonidae)
� Adapted to dry habitats:� Aestivate� Explosive breeders� Fast development (egg to
metamorphosis in ~8 days)
Anura – Pipidae
� 30 species
� Amazon, sub-saharan Africa
� _____________
� Dorsoventrally compressed
� _______________________
� Eggs develop in swollen skin of female’s back
� Xenopus a model species
� Synapomorphies:� Non-pedicellate teeth
� No tongue
� ______________________
© P Corasaro; Pough et al. 2004, Fig 3-23f
4
Anura – Phylogeny
and Diversity
Pough et al. 2004, Fig 3-20
� More derived groups are “Bufonoidea” and Ranoidea
� “Bufonoidea” are probably paraphyletic
� Together, they make up Neobatrachia (10)
Anura – Bufonidae
� ~450 species
� Cosmopolitan, except Sahara, Australia, Papua New Guinea, and extreme north
Pough et al. 2004, Fig 3-27
Anura – Bufonidae
� ______________
� Walk and hop
� Short legs
� Includes cane toad, Bufo marinus, introduced to Australia
� Synapomorphies:
� No teeth
� _______________ glands
� Bidder’s organ (rudimentary ovaries on male’s testes)
� 2 MA species: Anaxyrus americanus & A. fowleri
Anura – “Hylidae”
� 835 species
� Americas, Europe, Middle East, China, Japan, Papua NG, Australia
Pough et al. 2004, Fig 3-27
Anura – “Hylidae”
� 2 MA species
� Mainly arboreal
� _______________ on digits
� Claw shaped terminal phalanges
� Have radiated mainly in Neotropics
� Phyllomedusa have lipid glands and use a wiping behavior to spread lipids on the body to prevent desiccation �
Photos PJB
Anura – “Leptodactylidae”
� >1,100 spp.
� South America, Middle America, Caribbean
� No synapomorphies
� Very diverse
� Includes most species rich vertebrate genus� Eleutherodactylus >700
species!
� Also includes Ceratophrys, horned frogs
© J Milmoe, KP Bergmann
5
Anura – Myobatrachidae
� 122 species
� Australia & PNG
� 2 spp with female ________________
� 1 sp with male inguinal pouches for young
� Synapomorphies are sperm characteristics
Pough et al. 2004, Fig 3-21
Anura – Phylogeny and Diversity
Pough et al. 2004, Fig 3-17, 3-20
� Ranoidea is monophyletic
� Synapomorphies have to do with pectoral girdle
Anura – “Ranidae”
� >600 spp
� Cosmopolitan, except islands, Sahara, Australia, extreme North & South
� Another paraphyletic group with no synapomorphies
� Highly variable
� 5 MA species, including Bullfrog & Leopard Frog
Anura – Dendrobatidae
� 205 species
� Central America, N. half of S. America
� Use __________ amplexus
� Carry larvae – parental care
� Aposematic and highly toxic
� Poison is dietary (ants, millipedes)
� __________ and terrestrial
� Synapomorphy: Dermal scutes on dorsal surface of fingers
PJB; Pough et al. 2004, Fig 3-28c
Anura – Mantellidae
� 140 species
� Madagascar
� Defined solely by ______________________
� Primarily terrestrial, small
� _________________ coloration
� Lipophilic skin alkaloids (convergent with Dendrobatids)
� Ecologically diverse
Pough et al. 2004, Fig 3-30e,f
Anura – Rhacophoridae
� 300 species
� Central Africa, SE Asia, Japan
Pough et al. 2004, Fig 3-22
Rhacophoridae
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Anura – Rhacophoridae
� Mostly arboreal
� Enlarged toe pads
� Some are _________, with large membranes between digits
� Some with foam nests and communal nests
� Primarily muscle synapomorphies
Photo © T Laman
Clades of Anura Covered in Lecture Clade #
Spp Distribution Synapomorphies Habitat Other Notes
- Ascaphidae
- Bombinatoridae
MESOBATRACHIA
- Pelobatidae
- Pipidae
BUFONOIDEA
- Bufonidae
- “Hylidae”
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