Spatial and temporal patterns of richness and abundance in the anuran assemblage of an artificial water reservoir from the semiarid central region of Argentina (original) (raw)
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Biodiversity and Conservation, 2002
The species composition, reproductive ecology, and patterns of activitywere determined for an anuran assemblage of an area of subtropical montaneforest in northwest Argentina. Twenty-four species were recorded at ParqueNacional Calilegua, Province of Jujuy. This study reflects a 75% increase in thenumber of species reported in previous surveys. Most species inhabiting the parkare mainly from adjacent Chacoan regions and only six taxa are known to beendemic from montane forest areas. Most species are aquatic breeders, and theabsence of many forest reproductive modes is noticeable. Although baselineinformation to compare former community composition was lacking, comparisonsbased on museum specimens revealed no evidence of local population extinctions.Immediate intensive monitoring is needed to quantitatively address amphibianpopulation fluctuations and to examine the effectiveness of present-day montaneforest protection. Although long-term population monitoring and documentation ofspecies declines is lacking, I propose a list of seven species of conservationconcern in order to assist and promote future monitoring programs.
Anuran amphibians dynamics in an intermittent pond in southern Brazil
Small wetlands are particularly important habitats for amphibians due to their close dependence on these habitats for their critical life-story functions. The constant degradation of wetland systems has been considered as one of the main causes for the declining of the anuran population observed around the world, including in southern Brazil. The objective of this study was to analyze the richness, abundance, and composition of the amphibian assemblage in a small pond associated to a floodplain system in a Neotropical region in Southern Brazil over a year. A total of 19 amphibian samplings were carried out over a year (from September 2004 to August 2005), and the survey was made in five transects (30 x 2 m) distributed at random along the studied pond. A total of 17 anuran species distributed in six families (Bufonidae, Cycloramphidae, Hylidae, Leiuperidae, Leptodactylidae, and Microhylidae) were observed. The Hylidae family represented 35.3% of the total species, and 22.0% of the total individuals observed over the studied period. Rhinella fernandezae was the most abundant species, representing 24.7% of the all collected individuals. The amphibian richness and abundance did not show any variation during the study period and between phases with and without superface water. However, the anuran composition changed between periods with surface water and without surface water. Air temperature and rainfall did not influence the amphibian richness and abundance. The high diversity and abundance of the anuran observed (17 species and 332 individuals) point to the need to include small wetlands in the biodiversity conservation programs in Southern Brazil, mainly when 90% have already disappeared due to anthropic activities. But these results should serve as hypotheses for long-term investigations in a larger area.
The increase in urban land as well as the continuous increment of road network experienced by littoral zones contributes to the loss, degradation and isolation of both terrestrial and aquatic habitats in which amphibians spend the different stages of their life cycle. The aim of this study is to explain the relationship between the characteristics of seventeen seasonal ponds located in the Atlantic littoral of Cádiz province (SW Spain), the land uses in their watershed, the road network, and the diversity of amphibian species. Our results show that amphibian richness is higher in larger ponds with longer hydroperiods, surrounded by forest and scrubland, and away from the nearest road. Roads, and in particular secondary roads, have a great and negative impact on amphibian richness because the shorter the distance between the pond and the road was, the fewer breeding species were found. From the data obtained in this study we have classified the ponds according to their status of conservation. This classification demonstrates that 94% of the studied ponds require immediate measures to be taken in order to reduce the negative impact of habitat fragmentation caused by roads. Finally, in order to maintain healthy amphibian populations at the long term, forests and scrublands surrounding ponds must be protected, and connectivity among ponds, as well as with the terrestrial habitats in the vicinity, must be ensured. Preventing amphibians from road kills during their migration movements can be achieved by means of constructing underpasses and tunnels in hot spots. Basic and Applied Herpetology 00 (0000) 00-00.
Basic and Applied Herpetology, 2015
The increase in urban land and the continuous increment of road network experienced by littoral zones contribute to the loss, degradation and isolation of both terrestrial and aquatic habitats in which amphibians spend the different stages of their life cycle. The aim of this study is to explain the relationship between the characteristics of 17 seasonal ponds located in the Atlantic littoral of Cádiz province (SW Spain), the land uses in their surroundings, the road network, and the diversity of amphibian species. Our results show that amphibian richness is higher in larger ponds with longer hydroperiods, surrounded by forest and scrubland, and away from the nearest road. Roads, and in particular secondary roads, have a great and negative impact on amphibian richness because the shorter the distance between the pond and the road was, the fewer breeding species were found. From the data obtained in this study, we have classified the ponds according to their status of conservation. This classification demonstrates that 94% of the studied ponds require immediate measures to be taken in order to reduce the negative impact of habitat fragmentation caused by roads. Finally, in order to maintain healthy amphibian populations at the long term, forests and scrublands surrounding ponds must be protected, and connectivity among ponds, as well as with the terrestrial habitats in the vicinity, must be ensured. Preventing amphibians from road kills during their migration movements can be achieved by means of constructing underpasses and tunnels in hot spots.
Journal of Threatened Taxa, 2019
We present an assessment on composition, diversity and structure of amphibians in three zones along an elevation gradient (2,400–3,000 m) in the Central Cordillera of Colombia. For this purpose, we carried out two field trips in November 2014 and February 2015, covering rainy and dry seasons, respectively. Diurnal (08:00–12:00 h) and nocturnal (18:00–22:00 h) visual encounter surveys were made without spatial restrictions. The diversity for each zone (alpha) and for the entire landscape (gamma) was evaluated by the effective number of species, and the structure of the communities was analyzed by range-abundance curves. The inequality factor for each of the sampling zones was also calculated. A total of 15 species belonging to seven genera and three families were recorded, all of the order Anura. Craugastoridae with 11 species (73.3% of richness) and Pristimantis (eight species) were the most diverse family and genus, respectively. The average alpha diversity per zone was 6.6 effective species, with zone A being the most diverse with eight species. In terms of beta diversity we found 2.5 effective communities at the landscape level, and differences between zones are given by the rare species, while the most abundant ones (e.g., Pristimantis uranobates) are shared between them. It is presumed that the greater diversity of zone A is due to the lower elevation and better state of conservation if compared to the other two zones. Of the total species recorded, three are threatened with extinction: Endangered (Hypodactylus latens, Osornophryne percrassa), and Critically Endangered (Niceforonia adenobrachia). The finding of three yet undescribed species is highlighted.
Composition of amphibian assemblages in agroecosystems from the central region of Argentina
The anuran diversity, abundance, richness and evenness were examined in agroecosystems from the central region of Argentina, area that was greatly altered by agricultural activities. Relationships with climatic characteristics were also analyzed. To capture anurans, pitfall trap transects were established. A total of 561 amphibians of seven species, belonging to four families (Bufonidae, Leiuperidae, Cycloramphidae, and Leptodactylidae) were recorded. Stepwise multiple linear regressions showed strong positive association between both species richness and anuran abundance with habitat variables as rainfall and rain-day. The anuran richness observed in the studied areas is similar to other sites with level of alteration comparable, but the anuran richness and abundance observed here is lower compared with the records of anuran species for the region before agricultural development. Thus, these results have suggested that amphibians may be particularly affected by habitat modification and degradation due to agricultural activities in the central region of Argentina, and it may be contributing to regression of their diversity and richness.
The distribution of amphibians is affected by abiotic and biotic factors, availability of resources and the characteristics of reproductive sites. In particular, reproductive activity of aquatic-breeding anurans that inhabit tropical dry areas is affected by rainfall, which determines the availability and quality of reproductive sites. In this study, we analyzed the spatial and temporal distribution of anurans with indirect development in a tropical dry forest in Western Mexico, during two rainy seasons (July 10-October 4, 2013, and June 26-September 26, 2014). We collected data on the occupancy and reproductive activity of 15 species in four temporary streams, and evaluated their relationship with precipitation, humidity and temperature. We determined richness, abundance and diversity of species in each stream; we also identified differences in the reproductive strategies and microhabitats used by the species. The most abundant species were: Tlalocohyla smithii and Exerodonta smaragdina, whereas the least abundant were Leptodactylus melanonotus and Incilius mazatlanen-sis. Species richness, abundance and reproductive activity peaked alongside the stream with the greatest number of breeding sites (e.g. pools). We found temporal segregation in the occupancy and reproductive activity of species in all streams which were mainly associated with precipitation. However, occupancy and reproductive activity of some species overlapped up to four weeks during part of the breeding season. Most species used specific substrates for particular reproductive activities (e.g. oviposition), but used a range of microhabitats (leaf-litter, water, rocks, branches, leaves, logs, etc.) for others (e.g. calling). We discuss these behavioral differences as factors that facilitate coexistence of species in this environment in the rainy season. Rev. Biol. Trop. 65 (3): 1082-1094. Epub 2017 September 01.