Amphibian Diversity What are Amphibians?

21 Pages·2013·9.5 MB·English

Topic 6: Amphibian Diversity What are Amphibians?
(cid:1) What are amphibians?
(cid:1) What are the three major amphibian clades?
(cid:1) The Amphibia
(cid:1) What are some trends in amphibian is a diverse
clade, with
evolution? many
__________
groups
(cid:1) * Introduction to the biology of each clade:
(cid:1) Extant (crown)
(cid:2) Gymnophiona amphibians
make up the
(cid:2) Urodela ____________
(cid:2) Anura
Benton 1997, Fig 4.21
What are Amphibians? What are Amphibians?
(cid:1) Synapomorphies (cid:1) Synapomorphies
(cid:2) Pedicellate, bicuspid teeth (cid:2) Skin with _________ and ________
(cid:2) Ear with stapes and operculum glands
(cid:2) Green rod receptor cells in eyes
(cid:1) Lost in Gymnophiona
(cid:2) Short, straight ________ that do not
encircle the body
(cid:2) Reduction of skull bones via
__________________
(cid:2) Metamorphosis is unique among
tetrapods but plesiomorphic
Pough et al 2004, Fig 2-5 Pough et al 2004, Fig 2-6
Paedomorphosis Paedomorphosis
(cid:1) Paedo ~ child (Gr), morph ~ form (Gr)
(cid:1) A type of heterochrony, which is a _______________ (cid:1) Paedomorphosis is
_______________________ prevalent in the _______
(cid:1) The retention of juvenile (child-like) characteristics
into adulthood/sexual maturity (cid:2) Retention of gills in adult
(cid:1) Non-herp example: axolotl
(cid:2) Relative hairlessness and upright face of humans
(cid:2) Missing late-developing
bones
(cid:2) Large orbits –form early
during development
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What are the three major amphibian clades? What are the three major amphibian clades?
(cid:1) Lissamphibia
(cid:2) Many synapomorphies
(cid:2) ~5,300 extant species
(cid:1)More than Mammalia
(cid:2) Three Major clades
(cid:1)______________: 167 spp
(cid:1)______________: 516 spp
(cid:1)___________: ~4,800 spp
Photos: KP Bergmann, Pough et al. Fig 3-8 Photos: KP Bergmann, Pough et al. Fig 3-8
Major Trends in Lissamphibian Evolution Gymnophiona
(cid:1) Gymnophiona are caecilians
(cid:1) Body ____________ (cid:2) Highly derived
and limb reduction
(cid:2) Strange morphology
(cid:2) Elongate and limbless
Gymnophiona
Urodela
Microsaur
Body ____________
and stiffening
Anura
Pough et al 2004, Fig 3-8
Gymnophiona – General Features Gymnophiona - Synapomorphies
(cid:1) Elongate bodies
(cid:1) Annulated bodies
(cid:1) ____________, terrestrial, or aquatic (cid:2) Annulus–Ring L.
(cid:2) Aquatic habits are derived (cid:2) Homologous with ______________ in Urodela
(cid:1) Many structures are reduced Male Typhlonectes
(cloaca)
(cid:2) ___________
(cid:2) Limbs
(cid:2) __________ reduced or absent
Typhlonectes Pough et al 2004, Fig 3-8
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Gymnophiona - Synapomorphies Gymnophiona - Synapomorphies
(cid:1) _______________ reduced or absent
(cid:2) Associated with body elongation
(cid:1) _________________ (cid:2) This is the same side lung as is reduced in snakes
(cid:2) Involved in chemoreception (cid:2) Gymnophiona includes the largest lungless tetrapod (Typhlonectes)
(cid:2) Contains glands, ducts, and muscles
(cid:2) Located between eyes and nostrils (cid:1) Why would caecilians be less reliant on their lungs than snakes?
(cid:1)Its position is phylogenetically informative
(cid:2) Protrusible from the skull
Tentacle
nostril foramen orbit
Pough et al 2004, Fig 3-9
Gymnophiona - Synapomorphies Gymnophiona - Reproduction
(cid:1) _________________
(cid:1) Internal fertilization
(cid:2) A projection of skin from the cloaca in males
(cid:2) What is the intromittent organ called?
(cid:2) Used as an intromittent organ
(cid:2) (cid:3)_______________ fertilization
(cid:1) ~70% oviparous, rest are viviparous
Male T(cylpohalcoan)ectes (cid:1) ______________ species
(cid:2) Eggs can be aquatic or terrestrial
(cid:2) When terrestrial, there is parental care
(cid:1) ______________ species
(cid:2) Young are nourished by secretions from oviduct
(cid:2) After birth, mother’s skin produces edible secretions
Typhlonectes
(mating)
Gymnophiona – Scales?
(cid:1) Deep scales in dermis
(cid:2) Only in some species –not a synapomorphy
(cid:2) Only amphibians with scales
(cid:2) surrounded by poison and mucous glands
Pough et al 2004, Fig 3-10
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Gymnophiona - Synapomorphies
(cid:1) Fusion of bones in skull
(cid:2) Skulls are highly ossified and bones are closely associated
(cid:2) Very solid, akinetic structure
(cid:2) Fusion into os basaleand maxilopalatine
Pough et al 2004, Fig 3-9
Gymnophiona - Synapomorphies
Three types of amphibian skulls
______________ ______________ ______________
• Temporal region • Skull is • Skull is
open intermediate completely roofed
• Anura & Urodela • Gymniophiona • Gymnophiona
Pough et al 2004, Fig 2-6, 3-9
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Gymnophiona - Fossoriality
(cid:1) Caecilians have many adaptations to a fossorial existence
(cid:1) Non-fossorial forms are derived
(cid:1) What are some of these adaptations?
http://digimorph.org/specimens/Dermophis_mexicanus/
Adaptations for fossoriality
(cid:1) ______________________
(cid:1) ______________________
(cid:1) ______________________
(cid:1) ______________________
(cid:1) ______________________
(cid:1) ______________________ is a result of a
fossorial existence
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Gymnophiona –Diversity & Phylogeny Gymnophiona - Distribution
(cid:1) Northern S. America
(cid:1) 6 major clades
(cid:1) Central Africa
(cid:2) Don’t worry about
their names (cid:1) SE Asia
(cid:2) 33 genera, 167 spp.
(cid:2) 109 spp. Are
“Caeciliidae”, a
paraphyletic group
(cid:1) Not a lot known
about most of these
animals
Pough et al 2004, Fig 3-12 Pough et al 2004, Fig 3-13
Three Major Clades Urodela
(cid:1) Salamanders and newts
Photos: KP Bergmann, Pough et al. Fig 3-8 Pough et al 2004, Fig 3-2, 3-5
Urodela Urodela - Synapomorphies
(cid:1) Urodela –refers to crown group salamanders
(cid:1) Many obscure
(cid:1) _________________ –refers to stem group osteological
synapomorphies
(cid:2) Fusion of some bones in
digits I and II
(cid:1) What species would be included in the (cid:2) Operculum is fused to
Caudata that are excluded from the Urodela? the ear capsule
(cid:2) Quadratojugals are
absent
(cid:2) 2ndCeratobranchial
bone is lost at
metamorphosis
Duellman & Trueb 1994, Fig. 13.1
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Urodela – General features
(cid:1) Most species have a
generalized
morphology:
(cid:2) Four limbs
(cid:2) ______________
(cid:2) Long tail
(cid:2) ______________
(cid:1) Some trends towards
limb reduction and
body elongation
(Sirenidae,
Amphiumidae)
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Urodela – Defense Urodela – Other Information
(cid:1) Many behavioral anti-
predator adaptations (cid:1) Large _____________
(cid:2) Largest among
vertebrates
(cid:2) _________________
(cid:2) Cells are large to
contain all the DNA
(cid:1) Paedomorphosis is
common
(cid:2) In some species, all
adults retain larval
characters
(cid:2) In others, only some
adults retain larval
characters
Echinotriton chinhaiensis © Max Sparreboom Duellman and Trueb, 1986
Urodela – Phylogeny & Diversity Urodela – Sirenidae
(cid:1) 10 major clades
(cid:1) 4 species in SE USA (cid:1) Paedomorphic features
(cid:1) 516 species (cid:2) No ______________
(cid:1) ______________ lineage (cid:2) External gills
(cid:1) Phylogeny (cid:1) ___________ & limb reduced (cid:2) Roned tuhcee fdr onnutm libmebrs of toes
controversial (cid:1) Fully ______________
(cid:2) Reanalysis of rRNA (cid:1) Prey on insects, crayfish, worms
and morphological (cid:1) Oviparous –lay eggs
data
(cid:2) Uncertainty of (cid:1) Synapomorphies
position of Sirenidae (cid:2) No pelvic girdle or hind limbs
(cid:1)Basal vs. near (cid:2) Kpreermatainxiizlleadr yb eteaekt hreplaces
Proteidae (cid:2) Non-pedicellate teeth
Pough et al. 2004, Fig 3-1 Pough et al. 2004, Fig 3-2a
Urodela – Cryptobranchoidea Urodela – Cryptobranchidae
(cid:1) Includes (cid:1) 3 species in Japan, China, and (cid:1) Synapomorphies
(cid:2) Cryptobranchidae Eastern USA (cid:2) Lack eye lids
(cid:2) Hynobiidae (cid:2) Hellbender (cid:2) One set of _________
(cid:2) These are
(cid:1) SSiasltaemr aton droidea (cid:1) Hanadv eh e_a_d_s________ bodies (cid:2) p*a*eLdaotemraolr spkhiinc ftoralditss
(cid:1) Synapomorphies (cid:1) _____________
(cid:2) _____________ ribs (cid:1) Largest –up to 1.8 m!
(cid:2) _________ that secrete (cid:1) Males make nests and guard
into cloaca nests
(cid:2) Fusion of some hyoid (cid:1) Live in cold mountain streams
bones
(cid:1) Rely on _______________
respiration (skin folds)
Pough et al. 2004, Fig 3-1 © Dr. Eric J. Routman
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Urodela – Salamandroidea Urodela – Amphiumidae
(cid:1) 3 species in SE USA
(cid:1) Includes all other (cid:1) Elongate and limb-reduced
Urodela (cid:2) Have remnants of all 4 limbs
(cid:1) Paedomorphic
(cid:1) Synapomorphy (cid:2) Lack eyelids
(cid:2) Females have a (cid:2) Have gill slits (but lack external
________________, gills –distinguish from Sirenids © John White
which stores sperm
after insemination (cid:1) Aquatic ________________
(cid:2) Vertebrates and inverts
(cid:2) Powerful, muscular jaws
(cid:1) Oviparous
(cid:1) Large –up to over a meter
Pough et al. 2004, Fig 3-1 Duellman & Trueb 1994, Fig. 13-6
Urodela –
Plethodontidae Urodela – Plethodontidae
(cid:1) Only salamanders to
radiate in ___________
(cid:1) Diverse: 360 species
(cid:1) Highly variable
(cid:1) Coastal western USA
(cid:2) Subterranean, aquatic,
(cid:1) Eastern USA terrestrial and arboreal
(cid:1) Mexico to Brazil (cid:2) Life history varied
(cid:1) Italy
(cid:1) Some forms with webbed
feet, prehensile tails
(cid:1) Often small
Pough et al. 2004, Fig 3-7 Pough et al. 2004, Fig 3-5
Urodela – Plethodontidae Urodela – Proteidae
(cid:1) 6 species in E USA & Balkans
(cid:1) 5 species in Massachusetts (cid:1) Aquatic –large permanent
(cid:2) Including Plethodon cinereus bodies of water
Proteus anguinus
(cid:1) Large –up to 45 cm
(cid:1) Synapomorphies
(cid:1) Synapomorphies (cid:2) No _________________
(cid:2) ________________ (cutaneous (cid:2) External gills and gill slits
respiration) (paedomorphic)
(cid:2) __________________________ (cid:2) 2n=38 (other Urodela have
(cid:2) Lacrimals & pterygoids absent 30 chromosomes)
(cid:2) No operculum
Photos: PJB, Stebbins and Cohen 1995, Fig 7-2 Pough et al. 2004, Fig 3-2d
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Urodela – Salamandridae Urodela – Salamandridae
(cid:1) 62 species (cid:1) Many species _____________
(cid:1) Coastal USA and Canada (cid:1) Includes “____________”
(cid:1) Europe & Northern Africa (cid:1) Some have rugose skin
(cid:1) China & Japan (cid:1) Unken reflex for defense
(cid:1) Tetrodotoxins
(cid:1) Massachusets species:
Nothophthalmus viridescens
(cid:1) Complex life cycle
(cid:2) Metamorphosis 1: Larva to Eft
(cid:2) Metamorphosis 2: Eft to Adult
(cid:2) Aquatic (cid:3)terrestrial (cid:3)aquatic
Pough et al. 2004, Fig 3-3 Photos © PJB, H Greene
Urodela – Ambystomatidae
(cid:1) 30 species in N. America
(cid:1) Robust body
(cid:1) Some terrestrial, some aquatic
(cid:1) ___________ is paedomorphic
(cid:1) Some hybridize and are
unisexual and parthenogenetic
(cid:2) Variable ploidy level
(cid:1) Four species in Massachusetts
Pough et al. 2004, Fig 3-2e
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