Stefan Lötters

Bio: Stefan Lötters is an academic researcher. The author has contributed to research in topics: Atelopus flavescens. The author has an hindex of 1, co-authored 1 publications receiving 7 citations.

Is there a chance for conservation breeding? Ex situ management, reproduction, and early life stages of the Harlequin toad Atelopus flavescens Duméril & Bibron, 1841 (Amphibia: Anura: Bufonidae)

Abstract: We report on our experiences with the captive management and ex situ reproduction of the Harlequin toad from Suriname (Atelopus flavescens ) at the amphibian breeding unit of the Cologne Zoo. Egg deposition was stimulated by maintaining A. flavescens in a drier environment followed by a period of intensive irrigation. Here we provide for the first time an overview of the larval development from oviposition to metamorphosis, including diagnostic morphological char- acters according to Gosner. Eggs were arranged in strings and attached to the substrate below the water surface. Larvae hatched about five days after egg deposition and the characteristic abdomi- nal suctorial disc developed about two days later (stages 20-21). Tadpoles are gastromyzophorous and were observed rasping algae. The average time for larval development to stage 41 was 100-130 days. Larval development appears to be dependent on water temperature with faster development at higher temperatures. Concerning color pattern in adults, we observed a slight sexual dimorphism and we were able to recognize individuals due to a constant color pattern. However, color was ob- served to slightly change over time.

Amphibians and conservation breeding programmes: do all threatened amphibians belong on the ark?

Abstract: Amphibians are facing an extinction crisis, and conservation breeding pro- grammes are a tool used to prevent imminent species extinctions. Compared to mammals and birds, amphibians are considered ideal candidates for these programmes due to their small body size and low space requirements, high fecundity, applicability of reproductive technologies, short generation time, lack of parental care, hard wired behaviour, low maintenance requirements, relative cost effectiveness of such programmes, the success of several amphibian conservation breeding programmes and because captive husbandry capacity exists. Superficially, these reasons appear sound and conservation breeding has improved the conservation status of several amphibian species, however it is impossible to make generalisations about the biology or geo-political context of an entire class. Many threatened amphibian species fail to meet criteria that are commonly cited as reasons why amphibians are suitable for conservation breeding programmes. There are also limitations associated with maintaining populations of amphibians in the zoo and private sectors, and these could potentially undermine the success of conservation breeding programmes and reintroductions. We recommend that species that have been assessed as high priorities for ex situ conservation action are subsequently individually reassessed to determine their suitability for inclusion in conservation breeding programmes. The limitations and risks of maintaining ex situ populations of amphibians need to be considered from the outset and, where possible, mitigated. This should improve programme success rates and ensure that the limited funds dedicated to ex situ amphibian conservation are allocated to projects which have the greatest chance of success.

Fine‐scale habitat heterogeneity explains the local distribution of two Amazonian frog species of concern for conservation

Abstract: To test the hypothesis that subtle differences in abiotic requirements can result in almost total spatial segregation, we sampled two species of diurnal frogs, Atelopus spumarius and Allobates sumtuosus, in a primary forest reserve in central Brazilian Amazonia. We conducted visual and acoustic surveys on three occasions over 2 months, in 40 streamside (riparian) plots distributed throughout the reserve's two major drainage basins, using a grid system that covers 64 km2. On average, drainages differed in the pH of stream water and the number of connected and isolated streamside pools. Differences in abiotic characteristics of drainages were associated with the spatial distribution of frog species. The occurrence and density of Allobates sumtuosus was negatively related to stream pH and discharge and positively related to the number of isolated pools in plots. The occurrence and density of Atelopus spumarius was associated with streams with high discharge and pH near neutral. These results indicate that although very large reserves will probably contain sufficient landscape heterogeneity to accommodate different species of diurnal frogs, due to strongly patchy distributions, in situ studies using fine-scale species-distribution models will be necessary to assess the adequacy of small reserves in Amazonia that cover hundreds of square kilometers or less for the conservation of some anuran species.

Not every drought is bad: quantifying reproductive effort in the harlequin frog Atelopus laetissimus (Anura: Bufonidae)

Abstract: Atelopus laetissimus is an endemic and threatened harlequin frog from the high mountain forests of Sierra Nevada de Santa Marta, Colombia. Knowledge of its reproductive biology is essential for understanding the intraspecific interactions that can help the conservation of Atelopus species. We quantified the energy, measured in body weight, invested by males and females of A. laetissimus for reproduction, and how this energetic investment is related to the survival of individuals and rainfall conditions in habitats during two years (2014 and 2015). Our results show plasticity in terms of reproductive phenology linked to rainfall with short- and long-duration breeding strategies. The first year of this study, 2014, had a precipitation level in accordance with the annual averages at the area. During this time frogs exhibit a short breeding period. Contrary to 2014, 2015 was a year with little precipitation, below the annual averages, which probably facilitated the females’ quick spawning in the creek...

Structural and Heterochronic Variations During the Early Ontogeny in Toads (Anura: Bufonidae)

Abstract: In recent decades, a renewed interest in comparative studies of embryonic ontogeny in anurans is taking place. Toad embryos are often employed as model organisms, and scarce attention has been put on interspecific variations. In this work we analyze the development of transient embryonic and larval structures in 21 species in five genera of Bufonidae. These species vary in their ovipositional mode and the type of environments where the embryos and tadpoles develop, including ponds, streams, and axils of leaves of terrestrial or epiphytic plants. Comparative anatomical studies and sequence heterochrony analyses show that primary morphological variations occur in the morphology at the tail-bud stage, the arrangement and development of the external gills, adhesive gland type and division timing, growth of the dorsal hatching gland on the head, configuration of the oral disc, emergence and development of the hind limbs, and presence of the abdominal sucker. Some of these transformations are best ex...