Summary1. The effects of the present biodiversity crisis have been largely focused on the loss of species. However, a missed component of biodiversity loss that often accompanies or even precedes species disappearance is the extinction of ecological interactions. 2. Here, we propose a novel model that (i) relates the diversity of both species and interactions along a gradient of environmental deterioration and (ii) explores how the rate of loss of ecological functions, and consequently of ecosystem services, can be accelerated or restrained depending on how the rate of species loss covaries with the rate of interactions loss. 3. We find that the loss of species and interactions are decoupled, such that ecological interactions are often lost at a higher rate. This implies that the loss of ecological interactions may occur well before species disappearance, affecting species functionality and ecosystems services at a faster rate than species extinctions. We provide a number of empirical case studies illustrating these points. 4. Our approach emphasizes the importance of focusing on species interactions as the major biodiversity component from which the 'health' of ecosystems depends.

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Alien plant species can alter pollinator visitation and, in turn, the sexual reproduction of natives. Using a conventional and a phylogenetically controlled meta-analytical approach on a data set of 40 studies, we evaluated the effect of alien neighbour plant species (aliens) on visitation to and reproduction of native co-flowering focal species (focals), and compared such effect to that of native neighbours (natives). An overall significantly negative effect of aliens on visitation to and reproduction of focals was confirmed. Interestingly, aliens differed from natives in their effect on visitation, but not on reproductive success. The negative effect of aliens on visitation and reproductive success increased at high relative alien plant abundance, but this increase was proportionally lower than the increase in relative plant abundance. Likewise, effect of aliens on visitation and reproductive success was most detrimental when alien and focal species had similar flower symmetry or colour. The phylogenetic relatedness between alien neighbours and focals influenced the reproductive success effect size. Results of the phylogenetic meta-analysis were only partly consistent with those of the conventional meta-analysis, depending on the response variable and on whether we controlled for the phylogeny of neighbour or focal species, which calls for special attention to control for species relatedness in this type of review. This study demonstrates the predominant detrimental impact of alien plants on pollination and reproduction of natives, and highlights the importance of phenotypic similarity to the outcome of the interaction.

Mutualisms structure ecosystems and mediate their functioning. They also enhance invasions of many alien species. Invasions disrupt native mutualisms, often leading to population declines, reduced biodiversity, and altered ecosystem functioning. Focusing on three main types of mutualisms (pollination, seed dispersal, and plant-microbial symbioses) and drawing on examples from different ecosystems and from species-and community-level studies, we review the key mechanisms whereby such positive interactions mediate invasions and are in turn influenced by invasions. High interaction generalization is "the norm" in most systems, allowing alien species to infiltrate recipient communities. We identify traits that influence invasiveness (e.g., selfing capacity in plants, animal behavioral traits) or invasibility (e.g., partner choice in mycorrhizas/rhizobia) through mutualistic interactions. Mutualistic disruptions due to invasions are pervasive, and subsequent cascading effects are also widespread. Ecological networks provide a useful framework for predicting tipping points for community collapse in response to invasions and other synergistic drivers of global change. 89

The time at which a seedling emerges can determine its future success as a plant. Despite the large number of studies that have examined the effect of emergence time on different components of plant fitness (survival, growth, and/or fecundity), the potential evolutionary response to selection on seedling emergence date is still poorly known. In this study, we review 55 of those studies by a random-effects meta-analysis, considering the phylogenetic relatedness among taxa. We test the following hypotheses: (1) early emergence increases seedling survival, growth, and fecundity, (2) early emergence is more advantageous to large-seeded species than to small-seeded ones, as the former can compensate for the lower number of seeds by increasing seedling survival, (3) perennial plants benefit more than annuals from early emergence, as the iteroparity of the former allows them to risk seedling emergence to the best conditions each year, whereas the semelparity of the latter forces them to spread the risk of emergence over time, and (4) the effect of emergence time may depend upon the experimental conditions (field vs. controlled experiments in a greenhouse or laboratory). Our results show that early emergence differentially affects components of plant fitness, with no effect on seedling survival but large benefits to seedling growth and fecundity. Such effects vary depending upon intrinsic factors like seed size or life-form, and also upon methodology (census time and experimental conditions). Large-seeded species gain from emerging early by growing more during their first growing seasons, although they survive and reproduce similarly to small-seeded species. The survival benefit of early emergence is greater in perennial than in annual species, thus supporting hypothesis 3. The relationship between emergence time and seedling growth appears to be stronger under controlled conditions than in the field, probably as a result of the unlimited nutrient and water resources of the former. In field conditions, in contrast, limited resources probably decelerate the growth of early seedlings, precluding the detection of differences between these and late seedlings.

The importance of the first mechanism and the modification of seed coat traits (e.g., permeability of the coat to water and gases) after gut treatment, which changes the capacity of germination and/or the speed at which seeds germinate, were studied. The overall effect of gut treatment on seed germination percentage was significantly positive (mean effect size lnOR=0.29; 95% CI: (0.27-0.31)). A similar value was found when meta-analysis was carried out at the study level (lnOR=0.25; (0.23-0.72)), which avoids pseudo-replication effects. The heterogeneity test of Qt was highly significant (P<0.00001), implying that other variables (predictors) account for some of the variation among studies. It is suggested that seed passage through the gut of a vertebrate can probably break only seed coat dormancy (functional dormancy) and not physiological (internal or embryological) dormancy, as difference in germination rate between ingested and uningested seeds are usually only a few days and more rarely a few weeks.