Lecture 21- Amphibians Flashcards
What is the proportion of vertebrates are amphibians in Australia?
10%
-they are monophyletic, one origin (unlike reptiles= they are polyphyletic)
What are the topics we do?
- Amphibian history and relationships within the vertebrates
* Amphibian groups worldwide vs Oz • Australian frog groups & characteristics • Life cycles • Frog declines
What are the amphibians? (evolution, limbs, where they live, ecto or endothermic)
• First vertebrate group to exploit the terrestrial environment
• Limbs (tetrapods) & lungs: terrestrial life
• Still dependent on moist environments - adults have highly permeable skin
- most sp. require water for reproduction (some exceptions) - eggs without shells
• Ectothermic
What are the three orders of Amphibia?
1.order Anura - frogs & toads 2.order Caudata- newts & salamanders order 3.Gymnophiona - caecilians (legless)
What is the only group of amphibians in Australia?
-Order Anura - only group of amphibians in Australia
• 21 families worldwide
• 5 families native to Australia
What are the four division of frogs?
- Limnodynastidae=limnodynastid frogs
- Myobatrachidae=southern frogs 3.Hylidae=treefrogs 4.Microhylidae=tiny tree frogs/narrow-mouthed frogs
- Ranidae=true frogs
Where are there many frogs in Australia?
-in the north
How many species are there in Limnodynastidae in Australia?
-40 spp.
-8 Genera
-Widespread distribution in Australia
(used to be in Myobatrachidae)
What are the characteristics of Limnodynastidae?
- All 40 species in Australia
- Extensive adaptive radiation in Australia
- Wide range of ecological and developmental specialisations
- Variety of life history patterns
- Most are burrowing or terrestrial, none are arboreal
What is the Pobblebok (Banjo frog)?
- Very common in south- eastern Australia
- Range of habitats
- Burrows
- Very distinctive “bonk” call – chorus sounds like a banjo
How many species are there in many Myobatrachidae in Australia?
- 88 spp.
- 13 Genera
- Widespread distribution in Australia
What are the characteristics of Myobatrachidae?
• All 88 species in Australia
• Extensive adaptive radiation
• Wide range of morphological, ecological and developmental specialisations
• Variety of life history patterns – from fully aquatic to fully terrestrial
• Burrowing and terrestrial
-Gondwanan
What is the turtle frog like?
-Turtle frog Myobatrachus gouldii
•Strictly terrestrial – no aquatic phase in life cycle
• Often found in termite mounds or in burrows
-belong to Myobatrachidae
How many species are the in the Hylidae?
- 73 spp.
- 3 Genera
- Widespread in Australia
What are the characteristics of Hylidae?
• Worldwide, but most in Australia and S. America • 73 species (3 genera) in Australia:
Litoria, Cyclorana & Nyctimystes
• Widespread & successful in Australia
• Typical water-dependent reproduction
• Morphological, physiological & behavioural adaptations to extreme environments
– arid zones – rainforests
What is the Magnificent tree frog?
- Magnificent tree frog Litoria splendida
- Discs/pads on ends of toes
What is special about the Hylidae species Cyclorana?
-Some hylids evolved into a life far from the forests
Water-holding frog
Cyclorana platycephala
How many species are there of Microhylidae in Australia?
-18 spp.
- 2 Genera
Distribution limited
What are the characteristics of Microhylidae?
- 18 species (2 genera): Sphenophryne & Cophixalus
* Tropical northern Australia • Small, from 1 – 3 cm: hard to find unless calling • Direct development
What are the nursery frogs?
-Cophixalus species
• Lay clutch in moist soil under rocks, leaf litter • Eggs coated with anti-fungal agent • Male guards eggs • Tadpole develops inside egg, froglet hatches out • Restricted distributions, some species very rare
How many Ranids are there in Australia?
1 spp. 1 Genus
What are the characteristics of Ranidae?
- Most successful family worldwide
* Only one species/genus in Australia: Rana daemeli (wood or water frog)
What is the most damaging introduced frog species?
-Cane toad Rhinella (Bufo) marinus
• Family Bufonidae • Introduced to Australia in
1935 to ‘control’ cane beetles
• Highly fecund: up to 25000 eggs/spawn
• Range expansion ~ 50km/yr – arrived in Kakadu NP 2001
• Poisonous glands: major problem for native wildlife
How far did the cane toads already get?
-Have now crossed the NT/WA border
What are the characteristics of cane toads?
- the big glands behind a cane toad’s eyes release a poisonous milky liquid when the toad feels threatened
- cane toad skin is dry and warty, rather than moist and slippery like many native frogs and usually in dull brownish colours
- cane toad feet don’t gave suckers on the end of the toes
- cane toads have very distinctive bony rodges over their eyes. These ridges meet in the middle
- the call of a male toad is like a high-pitched purr, a bit like a telephone dial tone
- adult cane toads are heavily built and average from 100mm to 150mm
What Australian frog families are Gondwanan?
1: Limnodynatidae 2:Myobatrachidae
3: Hylidae
What Australian frog families are from Asia?
Microhylidae and Ranidae
What Australian frog family is introduced?
Bufonidae
What gender does the calling in frogs?
• Only males call: for mate attraction & announcement of territory
• Frogs have selective hearing!
-important in reproduction
What is the frog life generally dependent on?
- water
- usually egg to tadpole and undergo metamorphosis= frog
What is the life cycle like in Hylidae?
- typical frog pattern; lay eggs in water and tadpoles develop in water, non- foamy egg mass
What is the life cycle like in Myobatrachidae?
- wide variety of reproductive patterns: from water-dependent to water-independent
How many reproductive modes are there in frogs?
Ten reproductive modes:
tendency towards independence from free water for larval development
What are the reproductive strategies of Myobatrachidae?
- eggs or eggs in water+ foam or eggs on land, and on land+foam= all of these have tadpoles in water
- can also have direct development (no feeding stage) where eggs are on land, on land and buried, brood pouches or in stomach
What are the reproductive strategies in Hylidae?
-can have eggs in water or on land with tadpoles in water
What is the reproductive strategy of the Ranidae?
-eggs in water and tadpoles in water
What is the reproductive strategy in Microhylidae?
-direct development, no feeding stage with eggs on land
What families have mode I: eggs in water, non-foamy egg mass, tadpoles in water?
-Hylidae, Myobatrachidae, Ranidae
What families have mode II: eggs in water, foamy egg mass, tadpoles in water?
Myobatrachidae
What families have mode III: eggs on land, in burrow or vegetation with tadpoles in water?
Hylidae and Myobatrachidae
What families have mode IV: eggs in a foamy mass in burrow with tadpoles in water?
Myobatrachidae
What families have modes V, VI and VII: direct development without a feeding stage, hatches from capsule/ foamy and /or nest?
Myobatrachidae, Microhylidae
What families have mode VIII: direct development without a feeding stage, eggs deep under soil (up to 1.2m) intra-capsular development?
Myobatrachidae
What families have mode IX: direct development without a feeding stage, male carries larvae in brood pouches?
Myobatrachidae
What families have mode X: direct development without a feeding stage, female carries larvae in stomach?
Myobatrachidae
What are the extremes of water independence and parental care in frogs?
Myobatrachid frogs:
• Assa darlingtoni “marupsial frog”; males carry developing tadpoles in brood pouches. Very small distribution: NSW-Qld. border
• Reobatrachus spp. – gastric-brooding frogs from Queensland rainforests
How does Assa darlingtoni develop?
- adult and eggs
- 11.5 days: male + embryos
- embryo enter pouch
- 62 days= emerging froglets
What is the northern gastric brooding frog?
(Rheobatrachus vitellinus): last seen in the wild 1985
What is the conservation status of frogs?
- Sudden, dramatic decline in frog numbers in many countries – commenced late 1970s
- Frog declines noted throughout Australia, mostly QLD, NSW, VIC.
- Australia: 27 species endangered, rare or presumed extinct
- Are declines caused by humans or a natural phenomenon?
Why have frog populations been declining?
• Climate change? - elevated temperatures: water loss
• Habitat loss and fragmentation? - e.g. effects of timber harvesting on spotted
tree frog in Vic.
• Disease? - chytrid fungus
Summary:
• Only one order: Anura
(Frogs) in Australia
• Wide diversity within that order – 3 families Gondwanan origins – 2 families Asian origins – 1 family introduced by Europeans
• Diversity in reproductive patterns • Global declines of frogs
