Plants with extrafloral nectaries share indirect defenses and shape the local arboreal ant community.

Associational resistance (AR) is a positive interaction in which a plant suffers less herbivore damage due to its association with a protective plant. Here, we evaluated whether plants with extra-floral nectaries (EFNs) can share indirect defenses with neighboring plants. We sampled 45 individuals of an EFN-bearing liana (Smilax polyantha) and recorded whether their support species had EFNs. In S. polyantha, we measured foliar herbivory and flower and fruit production. We examined the ant species composition and visitation of S. polyantha and whether they changed according to the supporting plant type (with or without EFNs). We experimentally determined whether S. polyantha supplemented with artificial nectaries could share indirect defenses with defenseless neighboring plants. Support plants with EFNs indirectly benefited S. polyantha by sharing mutualistic ant species. Smilax polyantha supported by plants with EFNs had a more specific ant species composition, a higher number of visiting ants and ant species richness, and exhibited nearly 3 times less foliar herbivory. However, we did not observe differences in fruit production between the two groups of S. polyantha. Finally, we observed that S. polyantha with artificial nectaries increased ant visitation on neighboring plants 2.5 times. We provide evidence that interspecific neighbors with EFNs can experience reciprocal benefits by sharing indirect defenses. Such local effects might escalate and affect the structure of plant communities.

Polyploidy and high environmental tolerance increase the invasive success of plants.

Ploidy level and genome size (GS) could affect the invasive capacity of plants, although these parameters can be contradictory. While small GS seems to favor dispersion, polyploidy-which increases the GS-also seems to favor it. Using a phylogenetic path analysis, we evaluated the effects of both factors on the environmental tolerance and invasive success of plants. We selected 99 invasive plant species from public online databases and gathered information about invasive capacity (number of non-original countries in which each species occurs), tolerance to environmental factors, ploidy level, and GS. The invasive capacity varied depending on the ploidy level and tolerance to environmental factors. Polyploids and species with increased tolerance to elevated temperatures and rainfall values exhibited high invasive capacity. We found no evidence that GS affects the invasive capacity of plants. We suggest that the genetic variability provided by polyploidization has a positive impact on plant competitiveness, which may ultimately lead to an increased ability to colonize new environments. In a global warming scenario, integrative approaches using phenotypic, genetic, epigenetic, and ecological traits should be a productive route to unveil the aspects of invasive plants.