The Evergreen Toad, Incilius coniferus, was found perching in groups near the breeding site, sugg... more The Evergreen Toad, Incilius coniferus, was found perching in groups near the breeding site, suggesting that this rarely observed behavior can serve as an antidepredatory strategy.
We describe five new species of lungless salamanders (Plethodontidae) from high mountain habitats... more We describe five new species of lungless salamanders (Plethodontidae) from high mountain habitats along the border betweenCosta Rica and Panama: Bolitoglossa splendida, Bolitoglossa aureogularis, Bolitoglossa kamuk, Nototriton matama, andOedipina nimaso. We also present phylogenetic hypotheses for the new taxa (with the exception of the Oedipina) and their rel-atives based on mitochondrial DNA sequence data. The new species were discovered on a series of expeditions to remote areas (primarily over 1000 m elevation) of the Cordillera de Talamanca, Costa Rica.
We report data on the density, phenology, and biomass of Craugastor underwoodi from Parque Nacion... more We report data on the density, phenology, and biomass of Craugastor underwoodi from Parque Nacional Tapantí (PNT) obtained in 1994–95, and from Estación Biológica Río Macho (EBRM) in 2012–13. We sampled large frogs and froglets using transects of defined width along Sendero La Oropéndola (SLO) at PNT, and quadratic sampling in an old-growth forest (OF) and a secondary forest (SF) at EBRM. In both areas we found large frogs and froglets active day and night throughout the year. The density of large frogs differed slightly between SLO (0.98 ± 0.78 ind/ha) and EBRM (OF = 0.39 ± 0.19 ind/ha; SF = 0.13 ± 0.20 ind/ha), but was similar in froglets between SLO (0.24 ± 0.18 ind/ha) and EBRM (OF = 0.29 ± 0.23 ind/ha; SF = 0.23 ± 0.22 ind/ha). The estimated biomass in EBRM was 54.73 ± 46.30 g/ha for large frogs and 7.29 ± 2.58 g/ha for froglets. We found the density values much lower than those reported for C. bransfordii, a sister species found in the Costa Rican lowlands; however, the values...
Extreme climatic events such as the El Nino Southern Oscillation profoundly affect many plants an... more Extreme climatic events such as the El Nino Southern Oscillation profoundly affect many plants and animals, including amphibians, which are strongly negatively affected by drought conditions. How amphibians respond to exceptionally high precipitation as observed in La Nina events, however, remains unclear. We document the correlation between the exceedingly wet 2010-2012 La Nina and community-level changes in a leaf litter frog assemblage in Costa Rica. Relative abundances of species shifted, diversity and plot occupancy decreased, and community composition became homogenized with the onset of La Nina. These aspects remained altered for over 20 months but rebounded to pre-La Nina levels after approximately 12 months. We hypothesize that complex ecological cascades associated with excess moisture caused short-term declines in abundances of species and associated changes in community structure. If additional stressors such as disease or habitat loss are not co-occurring, frog communities can rapidly recover to pre-disturbance levels following severe climatic events.
... In an intense study between 1982 and 1983 nearly all species known historically to this site ... more ... In an intense study between 1982 and 1983 nearly all species known historically to this site were present (Clark, 1988); no dramatic changes have occurred since then (Bolaños and Chaves, unpublished data), as they have in higher elevations. ...
Proceedings of the National Academy of Sciences, 2007
Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibi... more Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibian species are globally threatened, and over 120 species have likely suffered global extinction since 1980. Most alarmingly, many rapid declines and extinctions are occurring in pristine sites lacking obvious adverse effects of human activities. The causes of these “enigmatic” declines remain highly contested. Still, lack of long-term data on amphibian populations severely limits our understanding of the distribution of amphibian declines, and therefore the ultimate causes of these declines. Here, we identify a systematic community-wide decline in populations of terrestrial amphibians at La Selva Biological Station, a protected old-growth lowland rainforest in lower Central America. We use data collected over 35 years to show that population density of all species of terrestrial amphibians has declined by ≈75% since 1970, and we show identical trends for all species of common reptiles. T...
Biological communities are experiencing rapid shifts of composition in Neotropical ecosystems due... more Biological communities are experiencing rapid shifts of composition in Neotropical ecosystems due to several factors causing population declines. However, emerging evidence has provided insights on the adaptive potential of multiple species to respond to illnesses and environmental pressures. In Costa Rica, the decline of amphibian populations is a remarkable example of these changes. Here we provide evidence of variation in the amphibian richness of a premontane forest of San Ramón (Costa Rica) across a ~30 year period. We also quantified changes in the composition and abundance of the leaf-litter frog community occurring in the same premontane forest, by comparing diversity data with a difference of ~18 years. We evaluated the similarity of species richness from 1980s to 2010s based on several sources, and the dissimilarity of species diversity in the site comparing 28 standardized surveys from 1994-1995 and 2011-2012. We compared the relative abundance of some frogs that inhabit ...
Amphibians around the world are declining from threats that cannot currently be mitigated, making... more Amphibians around the world are declining from threats that cannot currently be mitigated, making it impossible to safeguard some species in their natural habitats. Amphibians in the mountainous neotropics are one example where severe diseaserelated declines prompted calls for the establishment of captive assurance colonies to avoid extinctions. We surveyed experts in Panamanian amphibians to determine the probability of avoiding chytridiomycosis-related extinctions using captive breeding programs. We ranked Panamanian amphibian species by perceived susceptibility to chytridiomycosis, then calculated the likelihood of avoiding extinction as the product of three probabilities, which include (1) finding sufficient founder animals, (2) successfully breeding these species in captivity and (3) becoming extinct in the wild. The likelihood of finding enough animals to create a captive founding population was low for many rare species, especially for salamanders and caecilians. It was also low for frogs which were once regularly encountered, but have already disappeared including Atelopus chiriquiensis, Craugastor emcelae, C. obesus, C. punctariolus, C. rhyacobatrachus, Ecnomiohyla rabborum, Isthmohyla calypsa and Oophaga speciosa. Our results indicate that captive breeding could improve the odds of avoiding extinction for species that have severely declined or are likely to decline due to chytridiomycosis including Atelopus certus, A. glyphus, A. limosus, A. varius, A. zeteki, Anotheca spinosa, Gastrotheca cornuta, Agalychnis lemur and Hemiphractus fasciatus. Priority species that experts predicted were highly susceptible to chytridiomycosis that might also benefit from ex situ management include Craugastor tabasarae, C. azueroensis, C. evanesco, Strabomantis bufoniformis and Colostethus panamansis. In spite of high levels of uncertainty, this expert assessment approach allowed us to refine our priorities for captive amphibian programs in Panama and identify priority conservation actions with a clearer understanding of the probability of success.
Although the sea turtles have long been familiar and even iconic to marine biologists, many aspec... more Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle's (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal sp...
The Evergreen Toad, Incilius coniferus, was found perching in groups near the breeding site, sugg... more The Evergreen Toad, Incilius coniferus, was found perching in groups near the breeding site, suggesting that this rarely observed behavior can serve as an antidepredatory strategy.
We describe five new species of lungless salamanders (Plethodontidae) from high mountain habitats... more We describe five new species of lungless salamanders (Plethodontidae) from high mountain habitats along the border betweenCosta Rica and Panama: Bolitoglossa splendida, Bolitoglossa aureogularis, Bolitoglossa kamuk, Nototriton matama, andOedipina nimaso. We also present phylogenetic hypotheses for the new taxa (with the exception of the Oedipina) and their rel-atives based on mitochondrial DNA sequence data. The new species were discovered on a series of expeditions to remote areas (primarily over 1000 m elevation) of the Cordillera de Talamanca, Costa Rica.
We report data on the density, phenology, and biomass of Craugastor underwoodi from Parque Nacion... more We report data on the density, phenology, and biomass of Craugastor underwoodi from Parque Nacional Tapantí (PNT) obtained in 1994–95, and from Estación Biológica Río Macho (EBRM) in 2012–13. We sampled large frogs and froglets using transects of defined width along Sendero La Oropéndola (SLO) at PNT, and quadratic sampling in an old-growth forest (OF) and a secondary forest (SF) at EBRM. In both areas we found large frogs and froglets active day and night throughout the year. The density of large frogs differed slightly between SLO (0.98 ± 0.78 ind/ha) and EBRM (OF = 0.39 ± 0.19 ind/ha; SF = 0.13 ± 0.20 ind/ha), but was similar in froglets between SLO (0.24 ± 0.18 ind/ha) and EBRM (OF = 0.29 ± 0.23 ind/ha; SF = 0.23 ± 0.22 ind/ha). The estimated biomass in EBRM was 54.73 ± 46.30 g/ha for large frogs and 7.29 ± 2.58 g/ha for froglets. We found the density values much lower than those reported for C. bransfordii, a sister species found in the Costa Rican lowlands; however, the values...
Extreme climatic events such as the El Nino Southern Oscillation profoundly affect many plants an... more Extreme climatic events such as the El Nino Southern Oscillation profoundly affect many plants and animals, including amphibians, which are strongly negatively affected by drought conditions. How amphibians respond to exceptionally high precipitation as observed in La Nina events, however, remains unclear. We document the correlation between the exceedingly wet 2010-2012 La Nina and community-level changes in a leaf litter frog assemblage in Costa Rica. Relative abundances of species shifted, diversity and plot occupancy decreased, and community composition became homogenized with the onset of La Nina. These aspects remained altered for over 20 months but rebounded to pre-La Nina levels after approximately 12 months. We hypothesize that complex ecological cascades associated with excess moisture caused short-term declines in abundances of species and associated changes in community structure. If additional stressors such as disease or habitat loss are not co-occurring, frog communities can rapidly recover to pre-disturbance levels following severe climatic events.
... In an intense study between 1982 and 1983 nearly all species known historically to this site ... more ... In an intense study between 1982 and 1983 nearly all species known historically to this site were present (Clark, 1988); no dramatic changes have occurred since then (Bolaños and Chaves, unpublished data), as they have in higher elevations. ...
Proceedings of the National Academy of Sciences, 2007
Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibi... more Amphibians stand at the forefront of a global biodiversity crisis. More than one-third of amphibian species are globally threatened, and over 120 species have likely suffered global extinction since 1980. Most alarmingly, many rapid declines and extinctions are occurring in pristine sites lacking obvious adverse effects of human activities. The causes of these “enigmatic” declines remain highly contested. Still, lack of long-term data on amphibian populations severely limits our understanding of the distribution of amphibian declines, and therefore the ultimate causes of these declines. Here, we identify a systematic community-wide decline in populations of terrestrial amphibians at La Selva Biological Station, a protected old-growth lowland rainforest in lower Central America. We use data collected over 35 years to show that population density of all species of terrestrial amphibians has declined by ≈75% since 1970, and we show identical trends for all species of common reptiles. T...
Biological communities are experiencing rapid shifts of composition in Neotropical ecosystems due... more Biological communities are experiencing rapid shifts of composition in Neotropical ecosystems due to several factors causing population declines. However, emerging evidence has provided insights on the adaptive potential of multiple species to respond to illnesses and environmental pressures. In Costa Rica, the decline of amphibian populations is a remarkable example of these changes. Here we provide evidence of variation in the amphibian richness of a premontane forest of San Ramón (Costa Rica) across a ~30 year period. We also quantified changes in the composition and abundance of the leaf-litter frog community occurring in the same premontane forest, by comparing diversity data with a difference of ~18 years. We evaluated the similarity of species richness from 1980s to 2010s based on several sources, and the dissimilarity of species diversity in the site comparing 28 standardized surveys from 1994-1995 and 2011-2012. We compared the relative abundance of some frogs that inhabit ...
Amphibians around the world are declining from threats that cannot currently be mitigated, making... more Amphibians around the world are declining from threats that cannot currently be mitigated, making it impossible to safeguard some species in their natural habitats. Amphibians in the mountainous neotropics are one example where severe diseaserelated declines prompted calls for the establishment of captive assurance colonies to avoid extinctions. We surveyed experts in Panamanian amphibians to determine the probability of avoiding chytridiomycosis-related extinctions using captive breeding programs. We ranked Panamanian amphibian species by perceived susceptibility to chytridiomycosis, then calculated the likelihood of avoiding extinction as the product of three probabilities, which include (1) finding sufficient founder animals, (2) successfully breeding these species in captivity and (3) becoming extinct in the wild. The likelihood of finding enough animals to create a captive founding population was low for many rare species, especially for salamanders and caecilians. It was also low for frogs which were once regularly encountered, but have already disappeared including Atelopus chiriquiensis, Craugastor emcelae, C. obesus, C. punctariolus, C. rhyacobatrachus, Ecnomiohyla rabborum, Isthmohyla calypsa and Oophaga speciosa. Our results indicate that captive breeding could improve the odds of avoiding extinction for species that have severely declined or are likely to decline due to chytridiomycosis including Atelopus certus, A. glyphus, A. limosus, A. varius, A. zeteki, Anotheca spinosa, Gastrotheca cornuta, Agalychnis lemur and Hemiphractus fasciatus. Priority species that experts predicted were highly susceptible to chytridiomycosis that might also benefit from ex situ management include Craugastor tabasarae, C. azueroensis, C. evanesco, Strabomantis bufoniformis and Colostethus panamansis. In spite of high levels of uncertainty, this expert assessment approach allowed us to refine our priorities for captive amphibian programs in Panama and identify priority conservation actions with a clearer understanding of the probability of success.
Although the sea turtles have long been familiar and even iconic to marine biologists, many aspec... more Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle's (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal sp...
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