Phillips Seth, Scheffrahn Rudolf H, Piel Alex, Stewart Fiona, Agbor Anthony, Brazzola Gregory, Tickle Alexander, Sommer Volker, Dieguez Paula, Wessling Erin G, Arandjelovic Mimi, Kühl Hjalmar, Boesch Christophe, Oelze Vicky M
Anthropology Department, University of California Santa Cruz, Santa Cruz, California, United States of America.
Fort Lauderdale Research & Education Center, Davie, Florida, United States of America.
PLoS One. 2021 Feb 10;16(2):e0244685. doi: 10.1371/journal.pone.0244685. eCollection 2021.
Stable isotope analysis is an increasingly used molecular tool to reconstruct the diet and ecology of elusive primates such as unhabituated chimpanzees. The consumption of C4 plant feeding termites by chimpanzees may partly explain the relatively high carbon isotope values reported for some chimpanzee communities. However, the modest availability of termite isotope data as well as the diversity and cryptic ecology of termites potentially consumed by chimpanzees obscures our ability to assess the plausibility of these termites as a C4 resource. Here we report the carbon and nitrogen isotope values from 79 Macrotermes termite samples from six savanna woodland chimpanzee research sites across equatorial Africa. Using mixing models, we estimated the proportion of Macrotermes C4 plant consumption across savanna woodland sites. Additionally, we tested for isotopic differences between termite colonies in different vegetation types and between the social castes within the same colony in a subset of 47 samples from 12 mounds. We found that Macrotermes carbon isotope values were indistinguishable from those of C3 plants. Only 5 to 15% of Macrotermes diets were comprised of C4 plants across sites, suggesting that they cannot be considered a C4 food resource substantially influencing the isotope signatures of consumers. In the Macrotermes subsample, vegetation type and caste were significantly correlated with termite carbon values, but not with nitrogen isotope values. Large Macrotermes soldiers, preferentially consumed by chimpanzees, had comparably low carbon isotope values relative to other termite castes. We conclude that Macrotermes consumption is unlikely to result in high carbon isotope values in either extant chimpanzees or fossil hominins.
稳定同位素分析是一种越来越常用的分子工具，用于重建诸如未习惯化黑猩猩等难以捉摸的灵长类动物的饮食和生态。黑猩猩食用以C4植物为食的白蚁，这可能部分解释了一些黑猩猩群体报告的相对较高的碳同位素值。然而，白蚁同位素数据的可得性有限，以及黑猩猩可能食用的白蚁的多样性和隐秘生态，使我们难以评估这些白蚁作为C4资源的合理性。在此，我们报告了来自赤道非洲六个稀树草原林地黑猩猩研究地点的79个大白蚁样本的碳和氮同位素值。我们使用混合模型估计了稀树草原林地各地点大白蚁对C4植物的消耗比例。此外，我们在来自12个蚁丘的47个样本子集中，测试了不同植被类型的蚁群之间以及同一蚁群内不同社会等级之间的同位素差异。我们发现，大白蚁的碳同位素值与C3植物的碳同位素值没有区别。各地点大白蚁的食物中只有5%至15%由C4植物组成，这表明它们不能被视为对消费者同位素特征有重大影响的C4食物资源。在大白蚁子样本中，植被类型和等级与白蚁的碳值显著相关，但与氮同位素值无关。被黑猩猩优先食用的大型大白蚁兵蚁，其碳同位素值相对于其他白蚁等级较低。我们得出结论，食用大白蚁不太可能导致现存黑猩猩或化石人类的碳同位素值升高。
