Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.
PLoS One. 2013;8(2):e56492. doi: 10.1371/journal.pone.0056492. Epub 2013 Feb 22.
Social organisms rank among the most abundant and ecologically dominant species on Earth, in part due to exclusive recognition systems that allow cooperators to be distinguished from exploiters. Exploiters, such as social parasites, manipulate their hosts' recognition systems, whereas cooperators are expected to minimize interference with their partner's recognition abilities. Despite our wealth of knowledge about recognition in single-species social nests, less is known of the recognition systems in multi-species nests, particularly involving cooperators. One uncommon type of nesting symbiosis, called parabiosis, involves two species of ants sharing a nest and foraging trails in ostensible cooperation. Here, we investigated recognition cues (cuticular hydrocarbons) and recognition behaviors in the parabiotic mixed-species ant nests of Camponotus femoratus and Crematogaster levior in North-Eastern Amazonia. We found two sympatric, cryptic Cr. levior chemotypes in the population, with one type in each parabiotic colony. Although they share a nest, very few hydrocarbons were shared between Ca. femoratus and either Cr. levior chemotype. The Ca. femoratus hydrocarbons were also unusually long-chained branched alkenes and dienes, compounds not commonly found amongst ants. Despite minimal overlap in hydrocarbon profile, there was evidence of potential interspecific nestmate recognition -Cr. levior ants were more aggressive toward Ca. femoratus non-nestmates than Ca. femoratus nestmates. In contrast to the prediction that sharing a nest could weaken conspecific recognition, each parabiotic species also maintains its own aggressive recognition behaviors to exclude conspecific non-nestmates. This suggests that, despite cohabitation, parabiotic ants maintain their own species-specific colony odors and recognition mechanisms. It is possible that such social symbioses are enabled by the two species each using their own separate recognition cues, and that interspecific nestmate recognition may enable this multi-species cooperative nesting.
社会性生物是地球上最为丰富和生态优势明显的物种之一，部分原因是它们拥有独特的识别系统，使合作者与剥削者能够区分开来。剥削者，如社会寄生虫，会操纵宿主的识别系统，而合作者则被期望最大限度地减少对其伴侣识别能力的干扰。尽管我们对单一种群社会巢穴中的识别有了丰富的认识，但对多物种巢穴中的识别系统，特别是涉及合作者的识别系统，了解得较少。一种不常见的筑巢共生关系，称为并殖现象，涉及两种蚂蚁共享一个巢穴和觅食路径，表面上是合作关系。在这里，我们调查了巴西东北部亚马孙地区 Camponotus femoratus 和 Crematogaster levior 的并殖混合物种蚁巢中的识别线索（表皮碳氢化合物）和识别行为。我们在该种群中发现了两种同域、隐生的 Cr. levior 化学型，每一个并殖群体中都有一种。尽管它们共享一个巢穴，但 Ca. femoratus 和任何一种 Cr. levior 化学型之间共享的碳氢化合物非常少。Ca. femoratus 的碳氢化合物也异常长链支链烯和二烯，这些化合物在蚂蚁中并不常见。尽管碳氢化合物图谱的重叠很少，但有证据表明存在潜在的种间巢内识别——Cr. levior 蚂蚁对 Ca. femoratus 非巢内伙伴比对 Ca. femoratus 巢内伙伴更具攻击性。与共享巢穴可能会削弱同种识别的预测相反，每种并殖物种也维持其自身的攻击性识别行为，以排斥同种非巢内伙伴。这表明，尽管共生共存，但是并殖蚂蚁仍然保持其自身特定物种的群体气味和识别机制。可能是由于两种物种各自使用自己独立的识别线索，使得这种社会性共生得以实现，并且种间巢内识别可能使这种多物种合作筑巢成为可能。
