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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 )
Amphibian Classification
Caudata ( 300 sp )
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Amphibian Classification
Anura (~ 2500 sp)
28 families, 361 genera
Anurans of Costa Rica
(Important families only)
RANIDAE – true frogsLEPTODACTYLINAE –BUFONIDAE – “true toads”HYLINAE – tree frogsCENTROLINIDAE “glass frogs”DENDROBATIDAE “poison dart frogs”
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Rana forrei
RANIDAE
Eleutherodactylus minimus
E. coqui
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Bufonidae
Bufo marinus
Agalychnis spurrelli
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Centrolenidae
Sachatamia ilex
Dendrobates azureus(Suriname)
Oophaga pumilio
DENDROBATIDAE
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Anurans of Costa Rica
Much ecological segregation is at the larval stage.
Where are the eggs laid?
How/where do the tadpoles feed?
Eggs laid in water:
Open pondsStreamsConstructed basinsTree holes and epiphytes
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Eggs laid in a nest:
Foam nest
Folded leaf nest
Edalorhina perezi, from Ecuador.
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
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• 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
Enigmatic Losses
Bufo periglenes
1966 – 1987 ~ 1500 individuals
1988 – 10 individuals
1989 – 1 individual
~ 1500m
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Interacting threats: climate changeand disease• Between the 1980s and1990s, two‐thirds of the110 known HarlequinAtelopus species becameExtinct
• Chytrid fungus has beensuggested as the primesuspect
• Unexpected altitudinalpatterns in Atelopusextinctions – istemperature important?
Xenopus laevis
Human chorionic gonadotropin
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Chytridiomycosis – an emergingdisease• 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
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