Behind coexistence: The role of regenerative niche divergence in the invasion of multiple confamilial woody species

Premise Multispecies invasions raise questions about the mechanisms enabling coexistence. Differences in regenerative niche requirements may reduce competition and facilitate coinvasion in related species with similar life forms, phenology, and habitat ranges. We expected closely related woody invaders to differ in germination phenology and seedling stress tolerance during early life stages. Methods We compared the regenerative niche requirements of four confamilial non‐native shrubs ( Pyracantha angustifolia , Pyracantha atalantoides , Cotoneaster franchetii , and Cotoneaster glaucophyllus ), using seeds from a single invaded site where they co‐occur in the Córdoba Mountains, Argentina. We evaluated germination and seedling establishment using germination chambers and greenhouse conditions. We assessed germination responses to alternating temperatures, light sensitivity, seed mass, and dormancy, and seedling performance under varying light and water levels. Results While all species shared the same optimal germination temperature under an alternating regime of 25°C during the day and 15°C at night, they differed in seed mass, final germination percentage, germination temperature range and speed, and dormancy‐breaking treatments. High germination of P. angustifolia contrasted with seed dormancy of the other species. Seedlings varied in performance and functional traits related to resource acquisition and use. In stressful conditions, Cotoneaster species outperformed Pyracantha , especially under low light. Conclusions Differences in germination phenology and seedling tolerance to water stress and low light suggest potential niche differentiation across irradiance and water gradients. These interspecific differences among coinvasive species may influence establishment sites, leading to spatial segregation and facilitating coexistence in multispecies‐invaded ecosystems.