The gut microbiota is a critical component in the life history of animals, particularly in the interactions between herbivores and plants. Phytophagous insects that feed on oak leaves face the challenge of detoxifying high-level tannins. Although the intestinal microbial community plays a key role in improving detoxification, it is not yet known where and how insects acquire the key tannin-degrading bacteria. Here, we tracked the source of tannin-degrading bacteria in the guts of Nothomyllocerus illitus Reitter, a major pest weevil that primarily consumes oak leaves, using 16S rDNA sequencing of gut microbiota, isolation and culture of bacteria, determination of tannin degradation activity of bacteria, as well as tracing fluorescently labeled bacteria. Our study showed that Bacillus, Acinetobacter, and Enterobacter represent the core bacterial genera involved in tannin degradation within the intestinal tract of N. illitus. Our findings provide strong evidence that N. illitus acquires these tannin-degrading bacteria from the oak phyllosphere rather than from the soil microbiome. The successful colonization of fluorescently labeled Bacillus and Acinetobacter in the weevil gut confirms that these bacteria empower N. illitus to degrade toxic tannins, enabling the weevil to thrive on oak leaves despite the presence of high concentrations of defensive chemicals, such as tannins.

The leaf-height-seed (LHS) plant ecology strategy scheme posits that functional traits such as leaf size, stem height and seed mass play a key role in life history of plants. Although many studies have explored the LHS scheme across plant species, to our knowledge, no study has so far linked functional trait patterns across different plant clades. Here, we first explored the LHS scheme of several plant clades, i.e., palms, other monocots, dicots and gymnosperms, to understand how potential forces drive variation of plant functional traits. We showed that phylogeny constrains plant functional traits and appears to be the most decisive factor that controls variation in seed mass irrespective of plant clades. Apart from phylogeny, a majority of variation in seed mass was explained by leaf size in palms clade, whereas by plant height in other monocots and dicots. Neither leaf size nor plant height well explained variation in seed mass of gymnosperms clade. Our study strongly suggests that different plant clades exhibit distinct LHS schemes, paving a new avenue for better understanding evolution and correlation between functional traits across sets of plant species.

Although the leaf-height-seed (LHS) scheme states that plant height and leaf area are closely correlated with seed mass; phylogeny, genome size, growth form, and leaf N may also explain variations in seed mass. Till now, there has been little information on the relative contributions of these factors. We compiled data consisting of 1071 plant species from the literature to quantify the relationships between seed mass, explanatory variables and phylogeny. Strong phylogenetic signals of these explanatory variables reflected inherited ancestral traits of the plant species. Without controlling phylogeny, growth form and leaf N are associated with seed mass. However, this association disappeared when accounting for phylogeny. Plant height, leaf area, and genome size showed consistent positive relationship with seed mass irrespective of phylogeny. Using partial R2s, phylogeny explained 50.89% of the variance in seed mass, much more than plant height, leaf area, genome size, leaf N, and growth form explaining only 7.39%, 0.58%, 1.85%, 0.06% and 0.09%, respectively. Our study is the first to disentangle the contributions of phylogeny and plant attributes to the variance in seed mass, providing a novel avenue for better understanding variation in traits across plant species.

In general, it is accepted that gap formation significantly affects the placement of scatter-hoarded seeds by small rodents, but the effects of different forest gap sizes on the seed-eating and scatter-hoarding behaviors of small rodents remain unclear. Thus, we examined the effects of a closed canopy forest, forest edge, and gaps with different sizes on the spatial dispersal of Quercus variabilis acorns and cache placement by small rodents using coded plastic tags in the Taihang Mountains, China. The seeds were removed rapidly and there were significant differences in the seed-eating and caching strategies between the stand types. We found that Q. variabilis acorns were usually eaten after being removed from the closed canopy forest and forest edges. By contrast, the Q. variabilis acorns in the forest gap stands were more likely to be scatter hoarded. The dispersal distances of Q. variabilis acorns were significantly longer in the forest gap plots compared with the closed canopy and forest edge plots. However, the proportions of scatter-hoarded seeds did not increase significantly as the gap size increased. In small-scale oak reforestation projects or research, creating small gaps to promote rodent-mediated seed dispersal may effectively accelerate forest recovery and successional processes.

In general, it is accepted that gap formation significantly affects the placement of scatter-hoarded seeds by small rodents, but the effects of different forest gap sizes on the seed-eating and scatter-hoarding behaviors of small rodents remain unclear. Thus, we examined the effects of a closed canopy forest, forest edge, and gaps with different sizes on the spatial dispersal of Quercus variabilis acorns and cache placement by small rodents using coded plastic tags in the Taihang Mountains, China. The seeds were removed rapidly and there were significant differences in the seed-eating and caching strategies between the stand types. We found that Q. variabilis acorns were usually eaten after being removed from the closed canopy forest and forest edges. By contrast, the Q. variabilis acorns in the forest gap stands were more likely to be scatter hoarded. The dispersal distances of Q. variabilis acorns were significantly longer in the forest gap plots compared with the closed canopy and forest edge plots. However, the proportions of scatter-hoarded seeds did not increase significantly as the gap size increased. In small-scale oak reforestation projects or research, creating small gaps to promote rodent-mediated seed dispersal may effectively accelerate forest recovery and successional processes.