Biotic interactions prior to seed dispersal determine recruitment probability of peyote (Lophophora diffusa, Cactaceae), a threatened species pollinator-dependent

Abstract

Seedlings recruitment is key to maintaining populations and depends on diverse biotic interactions and abiotic factors before and after seed dispersal. Cacti recruitment is infrequent and occurs at sporadic pulses associated with rainy years. Furthermore, biotic interactions can limit seeds availability due to scarce or inefficient pollinators, dispersers or to antagonistic interactions with florivores and seed predators, as cactus depend on animals for pollination and dispersal. We identified interactions and traits involved in the regeneration process of Lophophora diffusa, during seven years (2015–21). We assessed floral rewards, pollination rates, intensity of florivory, and seed removal, to estimate the probability of recruitment through seeds, as well as survival and establishment of seedlings in a population located in Queretaro, Mexico. We found that pre-dispersal events reduced recruitment as flower–fruit transition has a low probability. High florivory and low pollinator visitation rate due to low nectar availability decreased seed formation in all years. Seed predation was not limiting recruitment, since most seeds escaped predation. Even so, a low proportion of seeds established as seedlings, possibly due to water limitation or seed dormancy. The interactions with pollinators and florivores decreased ovule–seed transition; once the seeds are formed, there is a high probability of evade predation. Hence, pre-dispersal interactions during flowering determine the availability of seeds, and reduce recruitment in peyote, rather than post-dispersal interactions.