3/4/2014
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 frogs LEPTODACTYLINAE – BUFONIDAE –“true toads” HYLINAE –tree frogs CENTROLINIDAE “glass frogs” DENDROBATIDAE “poison dart frogs”
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RANIDAE
Rana forrei
Eleutherodactylus minimus
E. coqui
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Bufonidae
Bufo marinus
Agalychnis spurrelli
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Centrolenidae
Sachatamia ilex
DENDROBATIDAE
Dendrobates azureus (Suriname)
Oophaga pumilio
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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 ponds Streams Constructed basins Tree holes and epiphytes
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Eggs laid in a nest:
Foam nest
Folded leaf nest
Edalorhina perezi, from Ecuador.
Anurans of Costa Rica Eggs 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 are globally threatened (1896 species) • >50% species in trouble! • 165 species believed extinct • 130 possibly extinct • >43% of species declining in population (<1% increasing) • 500 species –threats cannot be mitigated rapidly enough and need ex‐situ intervention
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Habitat Destruction
• e.g. Massif de la Hotte, Haiti – last remaining cloud forest in Haiti
• 13 amphibian species!
• Rapid habitat destruction through charcoal production, slash & burn
• Generally, populations tend to decline more slowly than in enigmatic declines
Enigmatic Losses
1966 –1987 ~ 1500 individuals
1988 –10 individuals
1989 –1 individual
Bufo periglenes
~ 1500m
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Interacting threats: climate change and disease • Between the 1980s and 1990s, two‐thirds of the 110 known Harlequin Atelopus species became Extinct
• Chytrid fungus has been suggested as the prime suspect
• Unexpected altitudinal patterns in Atelopus extinctions –is temperature important?
Xenopus laevis
Human chorionic gonadotropin
12 3/4/2014
Chytridiomycosis – an emerging disease • Caused by Batrachochytrium dendrobatidis fungus • First detected in African clawed frog Xenopus spp. ‐ exported around world • Causes extremely high mortality in some spp. • Fungus invades skin – affecting water uptake and respiration? • Spores persist in soil and water • Optimum temperatures = 17‐ 25 degrees but more pathogenic at lower temps
Interacting threats: climate change and disease
• But why suddenly it has having such impact?
• Working synergistically with climate change –the chytridthermal‐ optimum‐hypothesis
• Temperatures in highlands are shifting towards growth optimum of Chytrid fungus • i.e. increased cloud cover = cooler days and warmer Nights
• Fungal outbreaks causing mass mortality events
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The mountain chicken Leptodactylus fallax
• Endemic to Dominica and Montserrat
• Chytrid fungus arrived in Dominica c. 2002
• Action to prevent introduction to Montserrat
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