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Summary: The ecological and evolutionary processes shaping community structure and functions of microbial symbionts are known to be scale‐dependent. Nonetheless, understanding how the relative importance of these processes changes across spatial scales, and deciphering the hierarchical metacommunity structure of fungal endophytes has proven challenging.We investigated metacommunities of endophytic fungi within leaves of an invasive plant (Alternanthera philoxeroides) across wide latitudinal transects both in its native (Argentina) and introduced (China) ranges to test whether metacommunities of fungal endophytes were structured by different drivers at different spatial scales.We found Clementsian structures with seven discrete compartments (distinctive groups of fungal species with coincident distribution ranges), which coincided with the distribution of major watersheds. Metacommunity compartments were explicitly demarcated at three spatial scales, that is, the between‐continent, between‐compartment, and within‐compartment scales. At larger spatial scales, local environmental conditions (climate, soil, and host plant traits) were replaced by other geographical factors as principal determinants of metacommunity structure of fungal endophytes and community diversity–function relationships.Our results reveal novel insights into the scale dependency of diversity and functions of fungal endophytes, which are likely similar for plant symbionts. These findings can potentially improve our understanding of the global patterns of fungal diversity. [ABSTRACT FROM AUTHOR]

There is conflicting evidence from studies on the fitness consequences of plant kin interactions, suggesting that kinship is not the only important factor in determining the outcome of kin interaction.Here, we tested whether density‐dependent kin interactions have evolved from competition to cooperation by kin selection of reduced shade avoidance responses following the introduction of an invasive plant. We measured how plants respond to kin neighbours (the same accession) and simulated vegetation shade (lower PPFD and R:FR ratio treatments using transparent green plastic filters) and determine whether shade avoidance responses affect the outcome of kin interactions using five native (Argentina) and five invasive (USA) accessions of Alternanthera philoxeroides.Our results showed that invasive accessions exhibited constant stem elongation but increased total biomass as canopy density increased, while native accessions exhibited the opposite. Furthermore, invasive accessions reduced stem elongation, but increased biomass and defence allocation in response to an experimental treatment causing a low R:FR ratio, while native accessions exhibited the opposite.Synthesis. Our results support the hypothesis that kin selection against shade avoidance may effectively promote the evolution of density‐dependent kin cooperation. This suggests that kin selection pressures may play a more important role in fine‐tuning plant shade avoidance responses than generally thought. Kin selection against selfish shade avoidance behaviour and release from negative density‐dependent regulation provides a new mechanism to explain plant invasion success for future studies. [ABSTRACT FROM AUTHOR]