Abstract Background Seed dispersal allows plants to colonize new habitats that has an significant influence on plant distribution and population dynamics. Orchids produce numerous tiny seeds without endosperm, which are considered to be mainly wind-dispersed. Here, we report avian seed dispersal for an early diverging orchid species, Neuwiedia singapureana, which produces fleshy fruits with hard seed coats in the understory of tropical forests. Results Neuwiedia singapureana produced fleshy fruits that turned red in autumn, and birds were confirmed to be the primary seed dispersers. As compared to its sister species, N. veratrifolia with dehiscent capsular fruits, embryos of N. singapureana were larger and enclosed by thickened and lignified seed coats. After passing through the digestive tracts of birds, the seeds still stayed alive, and the walls of seed coat contained several cracks. The germination percentage increased significantly for digested seeds as compared with seeds from intact fruits. Conclusion The thickened and lignified seed coat may protect seeds as they passed through the digestive tracts of birds. Taken together with a recent report of insect-mediated seed dispersal system in the subfamily Apostasioideae, the animal-mediated seed dispersal may be an adaptive mechanism promoting the success of colonization in dark understory habitats.

Phenolic compounds (phenolics) are secondary metabolites ubiquitous across plants. The earliest phenolics are linked to plants' successful transition from an aquatic to a terrestrial environment, serving as protection against damaging ultraviolet (UV) radiation, and as antioxidants to reduce oxidative stress in an atmosphere with an increasingly high O₂:CO₂ ratio. In modern plants, phenolics are best known for the defense against fungal and bacterial pathogens and as antifeedants that deter herbivory. Phenolics also play a role in seed dormancy, delaying germination, and lengthening viability in the seed bank. Many plants' seeds are endozoochorous - dispersed by animals, like birds, who eat and later excrete the seeds. Plants send visual signals to attract birds with UV-sensitive (UVS) vision for pollination and seed dispersal. As fruits ripen, antioxidant activity and phenolic content decrease. The waxy cuticle of fruits increases in UV reflection as phenolic rings, which absorb UV light, degrade. The UV contrast that birds detect may act as an honest signal, indicating nutritional changes in the fruit. However, there is little evidence to support the evolution of UV coloration during ripening being driven by frugivore selection. Antioxidant properties of fruit phenolics may be dually adaptive in plants and avian frugivores.

Seed dispersal is a dynamic process through which diaspores (seeds or seed-bearing fruits) are detached from the mother plant, transported to different sites in the landscape that offer physical protection, competitive advantages, or lower predation risk. A variety of biotic and abiotic factors contribute to seed dispersal processes, resulting in a high diversity of dispersal systems observed in nature. At present, the relationship and classification of seed dispersal processes remain unclear. It is therefore essential to delineate seed dispersal systems and understand their functional traits in relation to ecosystem functioning and diversity, in order to elucidate plant distribution patterns. This review presents an updated synthesis of current knowledge on multiphase seed, reframing diaspora dispersal systems (fruits with seeds) as dynamic networks of transitions rather than discrete events, with particular emphasis on their efficiency and legitimacy. Three operational phases were defined: primary release, secondary transit and deposition, and the filters acting at each stage, including physical abrasion, digestive modification, vector movement, and habitat boundaries. To achieve this purpose, an analysis of 115 bibliographical references was conducted, ensuring the inclusion of seminal works from preceding years. We specifically describe how endozoochory and diploendozoochory can be considered efficient and legitimate dispersal systems for plants, as well as the potential benefits of a triple endozoochory process. Likewise, we propose a network-based framework to model multiphase dispersal, integrating movement ecology, gut retention, and seed condition metrics. This review demonstrates that diaspore dispersal is a multifactorial process associated with intrinsic attributes of the diaspores, their dispersion agents, and their interactions with the environment and proposes a subtype of seed dispersal by endozoochory (triploendozoochory). By highlighting the ecological relevance and conservation implications of multiphase dispersal, this review calls for interdisciplinary research to quantify its contribution to plant connectivity, especially under global change. Recognizing predators, waterbirds, and caching agents' key multiphase vectors reframes their role in ecosystem resilience and restoration.

Despite being abundant in urban gardens, the Canary Islands dragon tree Dracaena draco is close to extinction in the wild. It tends to produce relatively large fruits, which limits the pool of vertebrates that might disperse its seeds. We aimed to shed light on the seed dispersal system of this plant by studying its fruit size in relation to the feeding behavior of its present dispersers, and to discuss on possible differences with the past dispersal system, when large-sized dispersers were abundant. Besides fruit and seed characterization, we performed experiments on seedling emergence (using the characterized seeds), and field observations of the fruit handling behavior of frugivorous birds. Seed removal by granivores beneath and outside the dragon tree canopies was assessed through a field experiment. An additional seedling emergence experiment tested the effect of pulp removal from around the seed (using seeds contained within the fruits and manually depulped seeds). A feeding experiment was carried out with captive individuals of the Canary endemic white-tailed pigeon Columba junoniae—a large frugivore that occasionally consumes D. draco fruits—to test if its gut treatment influences seed viability. Small fruits produced seeds unable to germinate, while most seedling emergence was recorded only for seeds from large fruits. Our observations suggest that the only passerine species able to swallow large fruits is the medium-size passerine Turdus merula, whereas small passer