The EICA‐hypothesis predicts that invading plants adapt to their novel environment by evolving increased performance and reduced resistance in response to the release from natural enemies, and assumes a resource allocation tradeoff among both trait groups as mechanistic basis of this evolutionary change. Using the plant Silene latifolia as a study system, we tested these predictions by investigating whether 1) invasive populations evolved lower resistance and higher performance, 2) this evolutionary change is indeed adaptive, and 3) there is a negative genetic correlation between performance and resistance (i.e. a tradeoff) in native and introduced individuals. Moreover, we sampled eight native and eight invasive populations and determined their population co‐ancestry based on neutral SSR‐markers. We performed controlled crossings to produce five sib‐groups per population and exposed them to increased and reduced levels of enemy attack in a full‐factorial experiment to estimate performance and resistance. With these data, we performed trait‐by‐trait comparisons between ranges with ‘animal models’ that account for population co‐ancestry to quantify the amount of variance in traits explained by non‐adaptive versus adaptive evolution. Moreover, we tested for genetic correlations among performance and resistance traits within sib‐groups. We found significant reductions in resistance and increases in performance in invasive versus native populations, which could largely be attributed to adaptive evolution. While we detected a non‐significant trend towards negative genetic performance × resistance correlations in native populations, invasive populations exhibited both significant and non‐significant positive correlations. In summary, these results do not support a shift of performance and resistance trait values along a tradeoff line in response to enemy release, as predicted by EICA. They rather suggest that the independent evolution of both traits is not constrained by a tradeoff, and that various selective agents (including resource availability) interact in shaping both traits and in weakening negative genetic correlations in the invaded habitat.

Vegetation history in tropical Africa is still to date hardly known and the drivers of population differentiation and speciation processes are little documented. It has often been postulated that population fragmentations following climate changes have played a key role in shaping the geographic distribution patterns of genetic diversity and in driving speciation. Here we analyzed phylogeographic patterns (chloroplast-DNA sequences) within and between eight (sister) species of widespread rainforest herbs and lianas from four genera of Marantaceae (Halopegia, Haumania, Marantochloa, Megaphrynium), searching for concordant patterns across species and concordance with the Pleistocene refuge hypothesis. Using 1146 plastid DNA sequences sampled across African tropical lowland rainforest, particularly in the Lower Guinean (LG) phytogeographic region, we analyzed intra- and interspecific patterns of genetic diversity, endemism and distinctiveness. Intraspecific patterns of haplotype diversity were concordant among most species as well as with the species-level diversity pattern of Marantaceae. Highest values were found in the hilly areas of Cameroon and Gabon. However, the spatial distribution of endemic haplotypes, an indicator for refuge areas in general, was not congruent across species. Each proposed refuge exhibited high values of endemism for one or a few species indicating their potential role as area of retraction for the respective species only. Thus, evolutionary histories seem to be diverse across species. In fact, areas of high diversity might have been both refuge and/or crossing zone of recolonization routes i.e., secondary contact zone. We hypothesize that retraction of species into one or the other refuge happened by chance depending on the species' distribution range at the time of climate deterioration. The idiosyncratic patterns found in Marantaceae species are similar to those found among tropical tree species, especially in southern LG.

Germination is a crucial step for invasive plants to extend their distribution under different environmental conditions in a new range. Therefore, information on germination characteristics of invasive plant species provides invaluable knowledge about the factors which might contribute to the invasion success. Moreover, intra-specific comparisons under controlled conditions will show if different responses between non-native and native populations are caused by evolutionary changes or by phenotypic plasticity towards different environmental influences. This paper focuses on the germination of native and non-native Ulmus pumila populations. We expected that non-native populations would be characterized by their higher final germination percentage and enhanced germination rate, which might indicate an influence due to corresponding climatic conditions. Germination experiments with a moderate and a warm temperature treatment did not reveal significant differences in final germination percentage. However, seeds from the North American non-native range germinated significantly faster than native seeds (p < 0.001). Additionally, mean time to germination in both ranges was significantly negatively correlated with annual precipitation (p = 0.022). At the same time, this relationship is stronger in the native range whereas mean time to germination in nonnative populations seems to be less influenced by climatic conditions. Different germination responses of the North American populations could be caused by a fast evolutionary change mediating a higher tolerance to current climatic conditions in the non-native range. However, our findings could also be caused by artificial selection during the introduction process and extensive NeoBiotaHeidi Hirsch et al. / NeoBiota 15: 53-68 (2012) 54 planting of U. pumila in its non-native range. Nevertheless, we assume that the faster germination rate of non-native populations is one potential explanation for the invasion success of U. pumila in its new range since it might provide a competitive advantage during colonization of new sites.

Inbreeding and enemy infestation are common in plants and can synergistically reduce their performance. This inbreeding ×environment (I × E) interaction may be of particular importance for the success of plant invasions if introduced populations experience a release from attack by natural enemies relative to their native conspecifics. Here, we investigate whether inbreeding affects plant infestation damage, whether inbreeding depression in growth and reproduction is mitigated by enemy release, and whether this effect is more pronounced in invasive than native plant populations. We used the invader Silene latifolia and its natural enemies as a study system. We performed two generations of experimental out‐ and inbreeding within eight native (European) and eight invasive (North American) populations under controlled conditions using field‐collected seeds. Subsequently, we exposed the offspring to an enemy exclusion and inclusion treatment in a common garden in the species’ native range to assess the interactive effects of population origin (range), breeding treatment, and enemy treatment on infestation damage, growth, and reproduction. Inbreeding increased flower and leaf infestation damage in plants from both ranges, but had opposing effects on fruit damage in native versus invasive plants. Inbreeding significantly reduced plant fitness; whereby, inbreeding depression in fruit number was higher in enemy inclusions than exclusions. This effect was equally pronounced in populations from both distribution ranges. Moreover, the magnitude of inbreeding depression in fruit number was lower in invasive than native populations. These results support that inbreeding has the potential to reduce plant defenses in S. latifolia, which magnifies inbreeding depression in the presence of enemies. However, future studies are necessary to further explore whether enemy release in the invaded habitat has actually decreased inbreeding depression and thus facilitated the persistence of inbred founder populations and invasion success.

We compared the seedling growth performance of native and non-native Siberian elm populations in a common greenhouse experiment to gain knowledge about possible changes in life history traits in populations of non-native woody species. Our results showed that non-native Siberian elm populations are characterized by an enhanced early life cycle performance which likely contributes to its invasion success. This study contributes to a better understanding of the still little-known invasion processes of woody non-native species.

37Inbreeding and enemy infestation are common in plants and can synergistically reduce their 38 performance. This inbreeding × environment (I×E) interaction may be of particular 39 importance for the success of plant invasions if introduced populations experience a release 40 from attack by natural enemies relative to their native conspecifics. Using native and invasive 41 plant populations, we investigate whether inbreeding affects infestation damage, whether 42 inbreeding depression in performance is mitigated by enemy release and whether genetic 43 differentiation among native and invasive plants modifies these I×E interactions. We used the 44 plant invader Silene latifolia and its natural enemies as a study system. We performed two 45 generations of experimental out-and inbreeding within eight native (European) and eight 46 invasive (North American) S. latifolia populations under controlled conditions using field-47 collected seeds. Subsequently, we exposed the offspring to an enemy exclusion and 48 inclusion treatment in a common garden in the species' native range to assess the interactive 49 effects of population origin (range), breeding treatment and enemy treatment on infestation 50 damage as well as plant performance. Inbreeding increased flower and leaf infestation 51 damage in plants from both ranges, but had opposing effects on fruit damage in native 52 versus invasive plants. Both inbreeding and enemy infestation had negative effects on plant 53 performance, whereby inbreeding depression in fruit number was higher in enemy inclusions 54 than exclusions in plants from both ranges. Moreover, the magnitude of inbreeding 55 depression in fruit number was lower in invasive than native populations. Our results support 56 that inbreeding increases enemy susceptibility of S. latifolia, which magnifies inbreeding 57 depression in the presence of enemies. Enemy release in the invaded habitat may thus 58 increase the persistence of inbred founder populations and thereby contribute to successful 59 invasion. Moreover, our findings emphasize that genetic differentiation among native and 60 invasive plants can shape the magnitude and even the direction of inbreeding effects. 61 4 Keywords 62 biological invasion, genetic differentiation, genetic paradox, herbivory, purging, white 63 campion 64Understanding the forces that promote or prevent species range expansions remains a 66 challenging goal in ecology (Barrett, 2015). During invasion of a new range, populations can 67