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  - Leifso, A.
A1  - MacDougall, A. S.
A1  - Husband, B.
A1  - Hierro, J. L.
A1  - Köchy, Martin
A1  - Pärtel, M.
A1  - Peltzer, D. A.
T1  - Expansion of a globally pervasive grass occurs without substantial trait differences between home and away populations
JF  - Oecologia
N2  - The global expansion of species beyond their ancestral ranges can derive from mechanisms that are trait-based (e.g., post-establishment evolved differences compared to home populations) or circumstantial (e.g., propagule pressure, with no trait-based differences). These mechanisms can be difficult to distinguish following establishment, but each makes unique predictions regarding trait similarity between ancestral ('home') and introduced ('away') populations. Here, we tested for trait-based population differences across four continents for the globally distributed grass Dactylis glomerata, to assess the possible role of trait evolution in its worldwide expansion. We used a common-environment glasshouse experiment to quantify trait differences among home and away populations, and the potential relevance of these differences for competitive interactions. Few significant trait differences were found among continents, suggesting minimal change during global expansion. All populations were polyploids, with similar foliar carbon:nitrogen ratios (a proxy for defense), chlorophyll content, and biomass. Emergence time and growth rate favored home populations, resulting in their competitive superiority over away populations. Small but significant trait differences among away populations suggest different introductory histories or local adaptive responses following establishment. In summary, the worldwide distribution of this species appears to have arisen from its pre-adapted traits promoting growth, and its repeated introduction with cultivation and intense propagule pressure. Global expansion can thus occur without substantial shifts in growth, reproduction, or defense. Rather than focusing strictly on the invader, invasion success may also derive from the traits found (or lacking) in the recipient community and from environmental context including human disturbance.
KW  - Invasion ecology
KW  - Common-environment trial
KW  - Competition
KW  - Plant functional traits
KW  - Orchard grass
Y1  - 2012
U6  - https://doi.org/10.1007/s00442-012-2370-4
SN  - 0029-8549
VL  - 170
IS  - 4
SP  - 1123
EP  - 1132
PB  - Springer
CY  - New York
ER  -