TY - JOUR A1 - Dammhahn, Melanie A1 - Randriamoria, Toky M. A1 - Goodman, Steven M. T1 - Broad and flexible stable isotope niches in invasive non-native Rattus spp. in anthropogenic and natural habitats of central eastern Madagascar JF - BMC ecology N2 - Background: Rodents of the genus Rattus are among the most pervasive and successful invasive species, causing major vicissitudes in native ecological communities. A broad and flexible generalist diet has been suggested as key to the invasion success of Rattus spp. Here, we use an indirect approach to better understand foraging niche width, plasticity, and overlap within and between introduced Rattus spp. in anthropogenic habitats and natural humid forests of Madagascar. Results: Based on stable carbon and nitrogen isotope values measured in hair samples of 589 individual rodents, we found that Rattus rattus had an extremely wide foraging niche, encompassing the isotopic space covered by a complete endemic forest-dwelling Malagasy small mammal community. Comparisons of Bayesian standard ellipses, as well as (multivariate) mixed-modeling analyses, revealed that the stable isotope niche of R. rattus tended to change seasonally and differed between natural forests and anthropogenic habitats, indicating plasticity in feeding niches. In co-occurrence, R. rattus and Rattus norvegicus partitioned feeding niches. Isotopic mismatch of signatures of individual R. rattus and the habitat in which they were captured, indicate frequent dispersal movements for this species between natural forest and anthropogenic habitats. Conclusions: Since R. rattus are known to transmit a number of zoonoses, potentially affecting communities of endemic small mammals, as well as humans, these movements presumably increase transmission potential. Our results suggest that due to their generalist diet and potential movement between natural forest and anthropogenic habitats, Rattus spp. might affect native forest-dependent Malagasy rodents as competitors, predators, and disease vectors. The combination of these effects helps explain the invasion success of Rattus spp. and the detrimental effects of this genus on the endemic Malagasy rodent fauna. KW - Bayesian standard ellipse KW - Coexistence KW - Habitat use KW - Humid forest KW - Invasion ecology KW - Invasive species KW - Rattus rattus KW - Rattus norvegicus KW - Rodents KW - Fur KW - Stable carbon isotope KW - Stable nitrogen isotope Y1 - 2017 U6 - https://doi.org/10.1186/s12898-017-0125-0 SN - 1472-6785 VL - 17 PB - BioMed Central CY - London ER - TY - JOUR A1 - Synodinos, Alexios D. A1 - Tietjen, Britta A1 - Jeltsch, Florian T1 - Facilitation in drylands: Modeling a neglected driver of savanna dynamics JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - Our current understanding regarding the functioning of the savanna ecosystem describes savannas as either competition- or disturbance-dependent. Within this generalized view, the role and importance of facilitation have been mostly neglected. This study presents a mathematical model of savannas with coupled soil moisture-vegetation dynamics, which includes interspecific competition and environmental disturbance. We find that there exist environmental and climatic conditions where grass facilitation toward trees plays an important role in supporting tree cover and by extension preserving the savanna biome. We, therefore, argue that our theoretical results in combination with the first empirical studies on the subject should stimulate further research into the role of facilitation in the savanna ecosystem, particularly when analyzing the impact of past and projected climatic changes on it. (C) 2015 Elsevier B.V. All rights reserved. KW - Ecohydrological modeling KW - ODE model KW - Coexistence KW - Biome shifts KW - Fire KW - Grazing Y1 - 2015 U6 - https://doi.org/10.1016/j.ecolmodel.2015.02.015 SN - 0304-3800 SN - 1872-7026 VL - 304 SP - 11 EP - 21 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Liesenjohann, Monique A1 - Liesenjohann, Thilo A1 - Trebaticka, Lenka A1 - Haapakoski, Marko A1 - Sundell, Janne A1 - Ylonen, Hannu A1 - Eccard, Jana T1 - From interference to predation type and effects of direct interspecific interactions of small mammals JF - Behavioral ecology and sociobiology N2 - Indirect exploitative competition, direct interference and predation are important interactions affecting species coexistence. These interaction types may overlap and vary with the season and life-history state of individuals. We studied effects of competition and potential nest predation by common shrews (Sorex araneus) on lactating bank voles (Myodes glareolus) in two seasons. The species coexist and may interact aggressively. Additionally, shrews can prey on nestling voles. We studied bank vole mothers' spatial and temporal adaptations to shrew presence during summer and autumn. Further, we focused on fitness costs, e.g. decreased offspring survival, which bank voles may experience in the presence of shrews. In summer, interference with shrews decreased the voles' home ranges and they spent more time outside the nest, but there were no effects on offspring survival. In autumn, we found decreased offspring survival in enclosures with shrews, potentially due to nest predation by shrews or by increased competition between species. Our results indicate a shift between interaction types depending on seasonal constraints. In summer, voles and shrews seem to interact mainly by interference, whereas resource competition and/or nest predation by shrews gain importance in autumn. Different food availability, changing environmental conditions and the energetic constraints in voles and shrews later in the year may be the reasons for the varying combinations of interaction types and their increasing effects on the inclusive fitness of bank voles. Our study provides evidence for the need of studies combining life history with behavioural measurements and seasonal constraints. KW - Nest predation KW - Interspecific interaction KW - Coexistence KW - Interference KW - Small mammals KW - Voles KW - Shrews Y1 - 2011 U6 - https://doi.org/10.1007/s00265-011-1217-z SN - 0340-5443 VL - 65 IS - 11 SP - 2079 EP - 2089 PB - Springer CY - New York ER - TY - JOUR A1 - Seifan, Merav A1 - Seifan, Tal A1 - Jeltsch, Florian A1 - Tielboerger, Katja T1 - Combined disturbances and the role of their spatial and temporal properties in shaping community structure JF - Perspectives in plant ecology, evolution and systematics N2 - Disturbances are characteristic for many ecosystems. However, we still lack generalizations concerning their role in shaping communities, particularly when disturbances co-occur. To study such effects, we used a novel modeling approach that is unrestricted by a priori tradeoffs among specific plant traits, except for those generated by allocation principles. Thus, trait combinations were emergent properties associated with biotic and abiotic constraints. Specifically, we asked which traits dominate under specific disturbance regimes, whether single and combined disturbance regimes promote similar trait tradeoffs and how complex disturbance regimes affect species richness and functional diversity. Overall, disturbances' temporal properties governed the outcome of combined disturbances and were a stronger assortative force than spatial disturbance properties: low temporal predictability decreased seed-dispersability and dormancy, but increased competitive ability and disturbance tolerance. Evidence for tradeoffs between different colonization modes and between dormancy and disturbance tolerance were found, while surprisingly, the widely accepted colonization-competition tradeoff was not generated. Diversity was highest at intermediate disturbance intensity, but decreased monotonically with increasing unpredictability. In accordance with our results, future models should avoid restrictive assumptions about tradeoffs to generate robust and more general predictions about the role of disturbances for community dynamics. KW - Intermediate disturbance hypothesis KW - Coexistence KW - Environmental heterogeneity KW - Competition-colonization KW - Plant community KW - Individual-based model Y1 - 2012 U6 - https://doi.org/10.1016/j.ppees.2011.11.003 SN - 1433-8319 VL - 14 IS - 3 SP - 217 EP - 229 PB - Elsevier CY - Jena ER -