# Functional Traits Shape Seed–Rodent Interactions in a Subtropical Forest: Insights From Individual‐Based Tracking With Double‐Duplex PIT Tagging

## TL;DR

This study shows how seed and rodent size traits influence interactions in a subtropical forest, using a new tracking method to reveal how different species behave based on size.

## Contribution

The study introduces a novel double-duplex PIT tagging technique to track individual-level seed-rodent interactions with high precision.

## Key findings

- Larger rodents prefer large seeds, while smaller rodents favor small seeds.
- Size-related behaviors influence mutualistic and predatory interactions in seed-rodent systems.
- Interspecific pilfering rates vary between rodent species and seed types.

## Abstract

Functional traits of plants and animals play a pivotal role in shaping mutualistic or predatory interactions within plant–animal systems, directly regulating the structure and function of forest ecosystems. Yet, the outcomes of multispecies interactions—particularly in seed–rodent systems—remain inadequately resolved, largely because traditional methods fail to track individual‐level interactions and seed fates with sufficient precision. To address this gap, we applied a novel double‐duplex passive integrated transponder (PIT) tagging technique to investigate the fates of seeds from four sympatric tree species (with distinct seed traits) when exploited by two sympatric rodent species (with contrasting body sizes) in a subtropical forest of Southwest China from 2018 to 2019. Our results revealed that rodent body size and seed size are key determinants of seed fates. The larger rat
Niviventer confucianus
scatter‐hoarded and consumed seeds of all four trees, with a significant preference for large‐sized seeds of
Quercus variabilis
and Lithocarpus harlandii. In contrast, the smaller mouse
Apodemus draco
did not hoard the large‐sized seeds of L. harlandii and showed a significant preference for small‐sized seeds of Camellia oleifera. Additionally,
N. confucianus
exhibited a higher interspecific pilfering rate on seeds of
C. oleifera
and L. harlandii than
A. draco
. Our study highlights the significant role of size traits in shaping the mutualistic or predatory interactions in seed–rodent systems and demonstrates the utility of individual‐based tracking in disentangling complex species interactions.

Using double‐duplex PIT tagging, this study examines how seed and rodent size traits shape interactions between four tree species and two‐rodent species in a subtropical forest, finding larger rodents prefer large seeds, whereas smaller ones favor small seeds, with size‐related behaviors structuring mutualism‐predation balances. These results highlight the role of functional trait diversity in ecological interactions and demonstrate the utility of individual‐level tracking for disentangling complex species relationships.