Differential foraging preferences on seed size by rodents result in higher dispersal success of medium‐sized seeds

Abstract

Rodent preference for scatter-hoarding large seeds has been widely considered to favor the evolution of large seeds. Previous studies supporting this conclusion were primarily based on observations at earlier stages of seed dispersal, or on a limited sample of successfully established seedlings. Because seed dispersal comprises multiple dispersal stages, we hypothesized that differential foraging preference on seed size by animal dispersers at different dispersal stages would ultimately result in medium-sized seeds having the highest dispersal success rates. In this study, by tracking a large number of seeds for 5 yr, we investigated the effects of seed size on seed fates from seed removal to seedling establishment of a dominant plant Pittosporopsis kerrii (Icacinaceae) dispersed by scatter-hoarding rodents in tropical forest in southwest China. We found that small seeds had a lower survival rate at the early dispersal stage where more small seeds were predated at seed stations and after removal; large seeds had a lower survival rate at the late dispersal stage, more large seeds were recovered, predated after being cached, or larder-hoarded. Medium-sized seeds experienced the highest dispersal success. Our study suggests that differential foraging preferences by scatter-hoarding rodents at different stages of seed dispersal could result in conflicting selective pressures on seed size and higher dispersal success of medium-sized seeds.

Land‐use change and the ecological consequences of personality in small mammals

“…Our results also suggest that less anxious mice (i.e., those who show moderate levels of grooming in the open‐field test, indicating the ability to cope with stress) disperse seeds at farther distances than do more anxious mice (grooming behaviours are discussed in Table ). Because previous research suggests relationships between the size/quality of seeds and dispersal distance (Xiao et al ; Cao et al ; Wang & Corlett ), we tested for this effect during our model selection process, but we found no evidence for this. Regardless, these results suggest that the populations of mice in shelterwood forest are less anxious and show better coping than those in reference forest and therefore are dispersing seeds at farther distances than those in reference forest (Table ).…”

Deciphering seed dispersal decisions: Size, not tannin content, drives seed fate and survival in a tropical forest

“…, Cao et al. ). There is much conflicting evidence regarding how the trait of seed size affects the behavior of seed‐storing rodents.…”

“…, Cao et al. ). Seed‐eating rodents commonly eat and kill small seeds immediately but prefer to hoard larger seeds.…”

“…Ultimately, large cached seeds are more often relocated and consumed by hoarding animals than seeds of intermediate sizes, which are forgotten, resulting in effective incidental dispersal (Cao et al. ). In our study, medium‐sized seeds were hoarded at intermediate levels compared to small seeds, which were hoarded rarely, and large seeds, which were cached very often.…”

Prescribed fire and partial overstory removal alter an acorn–rodent conditional mutualism

“…The smallest and largest 15% of acorns were discarded to minimize the influence of acorn size on dispersal behavior (Cao et al. ). Mass of acorns presented was 5.7 ± 1.7 g after removal of caps.…”