Intra-tooth stable isotope analysis reveals seasonal dietary variability and niche partitioning among bushpigs/red...

How animals respond to seasonal resource availability has profound implications for their dietary flexibility and realized ecological niches. We sought to understand seasonal dietary niche partitioning in extant African suids using intra-tooth stable isotope analysis of enamel. We collected enamel samples from canines of red river hogs/bushpigs (Potamochoerus spp.) and third molars of warthogs (Phacochoerus spp.) in 3 different regions of central and eastern Africa. We analyzed multiple samples from each tooth and used variations in stable carbon and oxygen isotope ratios (δ¹³C and δ¹⁸O) and covariances between them to infer seasonal dietary changes. We found that most Phacochoerus display C₄-dominated diets, while most Potamochoerus display C₃-dominated diets. Phacochoerus and Potamochoerus that co-occur in the same region display no overlap in intra-tooth δ¹³C, which suggests dietary niche partitioning. They also show diverging δ¹³C values as the dry seasons progress and converging δ¹³C values during the peak of the rainy seasons, which suggests a greater dietary niche separation during the dry seasons when resources are scarce than during the rainy season. We found statistically significant cross-correlations between intra-tooth δ¹³C and δ¹⁸O in most specimens. We also observed a temporal lag between δ¹³C and δ¹⁸O in some specimens. This study demonstrates that intra-tooth stable isotope analysis is a promising approach to investigate seasonal dietary niche variation. However, large inter-individual variations in δ¹⁸O at certain localities can be challenging to interpret. Future studies that expand the intra-tooth stable isotope surveys or include controlled feeding experiments will improve its application in ecological studies.