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3/3/2015
1
Professor Donald McFarlane
Tropical Amphibians
Amphibian Classification
Gymnophiona (caecilians, legless amphibians) 160 sp
Caudata (previously Urodela — salamanders, newts) 300 sp
Anura (frogs, toads) ~ 5000 sp
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Amphibian Classification
Gymnophiona (~ 160 sp )Caecilians
Amphibian Classification
Caudata ( 300 sp )
Salamanders and newts
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Amphibian Classification
Anura (~ 2500 sp)
28 families, 361 genera
Frogs and Toads
Anurans of Costa Rica
(Important families only)
RANIDAE – true frogsELEUTHERODACTYLINAELEPTODACTYLINAE – “thin toed frogs”BUFONIDAE – “true toads”HYLINAE – tree frogsCENTROLINIDAE “glass frogs”DENDROBATIDAE “poison dart frogs”
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Lithobates vaillanti
RANIDAE
Leptodactylussavagei)
Leptodactylinae
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Eleutherodactylus minimus E. coqui
Eleutherodactylidae
Bufonidae
Bufo marinus
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Agalychnis spurrelli
Centrolenidae
Sachatamia ilex
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Dendrobates azureus(Suriname)
Oophaga pumilio
DENDROBATIDAE
Anurans of Costa Rica
Much ecological segregation is at the larval stage.
Where are the eggs laid?
How/where do the tadpoles feed?
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Eggs laid in water:
Open pondsStreamsConstructed basinsTree holes and epiphytes
Eggs laid in a nest:
Foam nest
Folded leaf nest
Edalorhina perezi, from Ecuador.
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Anurans of Costa RicaEggs laid out of water, on leaves:
Tadpoles drop into water
Eggs hatch into froglets
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Eggs carried by adults
Ranitomyer reticulata
Dendrobates pumilio
• 32% amphibians areglobally threatened (1896species)• >50% species in trouble!• 165 species believedextinct• 130 possibly extinct• >43% of species decliningin population (<1%increasing)• 500 species – threatscannot be mitigated rapidlyenough and need ex‐situintervention
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HabitatDestruction
• e.g. Massif de la Hotte, Haiti – last remaining cloud forest in Haiti
• 13 amphibian species!
• Rapid habitat destructionthrough charcoalproduction, slash & burn
• Generally, populationstend to decline moreslowly than in enigmaticdeclines
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Enigmatic Losses
Bufo periglenes
1966 – 1987 ~ 1500 individuals
1988 – 10 individuals
1989 – 1 individual
~ 1500m
Interacting threats: climate changeand disease• Between the 1980s and1990s, two‐thirds of the110 known HarlequinAtelopus species becameExtinct
• Chytrid fungus has beenidentified as the primesuspect
• Unexpected altitudinalpatterns in Atelopusextinctions – istemperature important?
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Chytridiomycosis – an emerging
disease• Caused by Batrachochytriumdendrobatidis fungus• First detected in Africanclawed frog Xenopus spp. ‐exported around world• Causes extremely highmortality in some spp.• Fungus invades skin –affecting water uptake andrespiration?• Spores persist in soil andwater• Optimum temperatures = 17‐25 degrees but morepathogenic at lower temps
Xenopus laevis
Human chorionic gonadotropin
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Chytrid spread – Central America
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Interacting threats: climate changeand disease
• But why suddenly it hashaving such impact?
• Working synergistically withclimate change – the chytridthermal‐optimum‐hypothesis
• Temperatures in highlandsare shifting towards growthoptimum of Chytrid fungus• i.e. increased cloud cover =cooler days and warmernights
• Fungal outbreaks causingmass mortality events
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• Endemic to Dominica andMontserrat
• Chytrid fungus arrived inDominica c. 2002
• Action to prevent introductionto Montserrat
The mountain chickenLeptodactylus fallax