Cultivated walnut trees showed earlier but not final advantage over its wild relatives in competing for seed dispersers

Abstract

Little is known about seeding regeneration of cultivated trees compared to wild relatives in areas where seed dispersers are shared. Here, we investigated the differences in seed fates of cultivated walnut (Juglans regia) and wild Manchurian walnut (Juglans mandshurica) trees under rodent predation and dispersal. J. regia seeds have higher nutritional value (large size, mass and kernel mass) and lower mechanical defensiveness (thin endocarp) than J. mandshurica seeds. We tracked seeds of J. regia and J. mandshurica under both enclosure and field conditions to assess differences in competing for seed dispersers of the two co-occurring tree species of the same genus. We found that rodents preferred to harvest, eat and scatter-hoard seeds of J. regia as compared to those of J. mandshurica. Seeds of J. regia were removed and scatter-hoarded faster than those of J. mandshurica. Caches of J. regia were more likely to be rediscovered by rodents than those of J. mandshurica. These results suggest that J. regia showed earlier dispersal fitness but not the ultimate dispersal fitness over J. mandshurica in seeding regeneration under rodent mediation, implying that J. regia has little effect on seeding regeneration of J. mandshurica in the field. The effects of seed traits on seed dispersal fitness may vary at different dispersal stages under animal mediation.

Interspecific synchrony of seed rain shapes rodent‐mediated indirect seed–seed interactions of sympatric tree species in a subtropical forest

“…Seed fate is critical for achieving plant population regeneration during seed dispersal (Vander Wall 2001;Jansen et al 2004;Zhang et al 2017). In general, the more seeds that are scatter-hoarded by seed hoarders, the better the seed germination and the establishment of seedlings are (Wang et al 2014;Zhang et al 2016a).…”

Seed density affects post‐dispersal seed predation: evidence from a seed removal experiment of 62 species

“…Granivorous rodents are important seed predators and are ubiquitous in almost every ecosystem (Moles et al 2003;Zhang et al 2017;Dittel & Vander Wall 2018). Many studies have examined density-dependent effects on post-dispersal seed predation by rodents, but the results of these studies remain controversial, as studies have shown positive (Baraibar et al 2012;Pardini et al 2017) and negative density-dependent patterns (Romo et al 2004;Daedlow et al 2014) and density-independent results (Lott et al 1995;von Allmen et al 2004;Haught & Myster 2008;Rosin & Poulsen 2018).…”

Responses of seedling growth and survival to post‐germination cotyledon removal: An investigation among seven oak species

“…The dispersal and establishment of seeds are regarded as one of the most vulnerable and limiting stages in the plant life cycle (Chen, Tomlinson, Cao, & Wang, ; Janzen, ; Zhang, Chu, & Zhang, 2017a; Urgoiti, Muñoz, Espelta, & Bonal, ). Successful seed survival and seedling establishment are often threatened by a variety of biotic and abiotic factors (Bogdziewicz et al, ; Canelo, Gaytán, Gonzálezbornay, & Bonal, ; Gómez, Puerta‐Piñero, & Schupp, ; Hou, Yi, Yang, & Liu, ; Wallertz & Petersson, ; Zhang, Wang, Liu, & Yi, 2017b).…”