Biodiversity dynamics and ecological cascading in logged tropical forests of the Guiana Shield - Consequences and perspectives for amphibian communities in anthropogenically altered ecosystems
Final Report Abstract
The search for patterns in the composition and diversity of species and the assessment of the relative roles of present and historic processes that generate these patterns is a central problem in community and macroecology. Within the scope of a rigorously standardised and quasi-experimental pre-post logging study framework (BioDEC Guiana), we investigated whether and how anthropogenic habitat alteration, here selective logging, affects community assembly and diversity patterns in complex tropical amphibian communities. We found that actual changes in amphibian diversity between pristine and selectively logged areas are quite complex. The trait composition of local amphibian assemblages is the result of an inter-play between evolutionary processes linked to environmental templets and unique processes of environmental filtering (e.g. through logging). There is a significant phylogenetic component that contributes to present day species-trait–habitat relations and therefore influences the assembly of local assemblages. However, ecological processes, such as environmental trait filtering likewise contribute to the trait assembly process and thereby ultimately determine observed species assemblages. Integrating trait–habitat links into analyses of biological assemblages can thus enhance the predictive power and general application of species assembly rules in community and macroecology, particularly when phylogenetic comparative methods are simultaneously applied. However, in order to predict trait composition based on habitat templets, trait–habitat links cannot be assumed to be universal but have to be established individually prior to model building. Among the traits that are functionally important to the ecosystem (effect traits), feeding guild membership or trophic position are important components in amphibian trait assemblages. We found adult anuran assemblages to exhibit an unexpectedly distinct trophic structure. Yet trophic guilds do not always correspond to particular evolutionary lineages indicating convergent trait evolution under similar constraints. The occurrence of both response and effect traits in local assemblages was not exclusively determined by a single filter factor (selective logging). Logging was also found to interact with other drivers, most prominently with climatic extreme events. These interactions have the potential to dramatically alter general diversity patterns but were found to result in counterintuitive patterns. Whether interactions between different drivers can be detected and whether these are positive, negative, or neutral depends crucially on the spatial and temporal scale of the study and how respective diversity component investigated are being weighted in analyses. These results underline that understanding responses of different facets of biodiversity to multiple drivers operating at different scales and in systems exhibiting differing dynamics, creates challenges in predicting future responses to global environmental change that can only be met in longer-term, crossscale, and quasi experimental studies in real-world settings. Results of the project have been published in scientific journals and key elements have been prepared in media reports, review articles, and a TV documentary for the general public (documentary accessible through the following links: www.3sat.de/page/?source=/nano/umwelt/158552/index.html, or www.br.de/themen/wissen/froesche-guyana-oekosystem100.html).
Publications
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(2011) Assessing the molecular phylogeny of a near extinct group of vertebrates: the Neotropical harlequin frogs (Bufonidae; Atelopus). Systematics and Biodiversity 9: 45-57
Lötters, S, van der Meijden, A, Coloma, L.A., Boistel, R, Coetes, P,Ernst, R, Lehr, E, Veith, M
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(2011) New records and geographic distribution map of Adenomera heyeri Boistel, de Massary and Angulo 2006 (Anura, Leptodactylidae). Check List 7(5):601-605
Fouquet, A., Dewynter, M., Gaucher, P., Blanc, M., Marty, C., Rodrigues, M.T., Ernst, R.
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(2011) Species diversity of Hyalinobatrachium glassfrogs (Amphibia: Centrolenidae) from the Guiana Shield, with the description of two new species. Zootaxa 3132: 1–55
Castroviejo-Fisher, S., Vilà, C., Ayarzagüena, J., Blanc, M., Ernst, R.
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(2012) Common ancestry or environmental trait filters: cross-continental comparisons of traithabitat relationships in tropical anuran amphibian assemblages. Global Ecology and Biogeography. 21: 704-715
Ernst, R., Keller, A., Landburg,G., Grafe, T.U., Linsenmair,K.E., Rödel, M.-O., Dziock, F.
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(2013) A third microendemic to the Iwokrama Mountains of central Guyana: a new "cryptic" species of Allobates Zimmerman and Zimmerman, 1988 (Anura: Aromobatidae). Organisms Diversity and Evolution
Kok, P.J.R., Hölting, M., Ernst, R.
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(2013) Systematics of spiny-backed treefrogs (Hylidae: Osteocephalus): an Amazonian puzzle. Zoologica Scripta
Jungfer, K.-H., Faivovich, J., Padial, J. M., Castroviejo-Fisher, S., Lyra, M.L., Berneck, B.V.M., Iglesias, P.P., Kok, P. J. R., MacCulloch, R. D., Rodrigues, M. T., Verdade, V. K., Torres Gastello, C. P., Chaparro, J. C., Valdujo, P. H., Reichle, S., Moravec, J., Gvoždík, V., Gagliardi-Urrutia, G., Ernst, R., De la Riva, I., Means, D. B., Lima, A. P., Señaris, J. C., Wheeler, W. C., Haddad, C. F. B.
