Stritih Nataša, Žunič Kosi Alenka
National Institute of Biology, Department of Organisms and Ecosystems Research, Ljubljana, Slovenia.
PLoS One. 2017 Nov 7;12(11):e0187512. doi: 10.1371/journal.pone.0187512. eCollection 2017.
In animal contests, communicating aggressive motivation is most often mediated by visual or acoustic signals, while chemical signals are not expected to serve such a function since they are less able to be modulated by the sender during the changing behavioral context. We describe a rare example of ephemeral olfactory signals in terrestrial animals, signals that are emitted via protrusive scent glands in male cave crickets Troglophilus neglectus (Orthoptera, Rhaphidophoridae) to reflect the state of the signaler's aggression. We correlate the intensity of behaviorally expressed aggression of the individuals in dyadic contests with the frequency and extent of their gland tissue protrusion, the latter serving as an indication of the amount of released odor. We detected large amounts of odor release during brief gland protrusions, and the absence of its release during gland retraction. Males protruded the glands during and after encountering a rival, with the degree of protrusion increasing with the intensity of the signalers' aggression. During the encounters, the degree of gland protrusion increased most strongly with the occurrence of the elevated body posture, directly preceding the attack. This degree was significantly higher in encounter winners than in losers displaying such posture, suggesting the highly important role of the released odor for contest resolution. After the encounters, glands were protruded almost exclusively by winners, apparently announcing victory. We tested for the function of the olfactory signals also directly, by preventing gland tissue protrusion in symmetric and asymmetric treatments of the contestants. Treating only the dominant individuals decreased the percentage of encounters they won by over 60%, while treating both contestants elicited a significant increase in the frequency and duration of fights. During contests, the olfactory signals of T. neglectus apparently function as a highly effective threat, which prevents maximal contest escalation and decreases the conflict-related costs.
在动物争斗中，传达攻击动机通常是通过视觉或听觉信号来介导的，而化学信号则被认为不具备这样的功能，因为在不断变化的行为情境中，发送者对化学信号的调节能力较弱。我们描述了一个陆生动物中短暂嗅觉信号的罕见例子，即雄性疏忽洞蟋（直翅目，裂蟋科）通过突出的气味腺发出信号，以反映信号发出者的攻击状态。我们将二元争斗中个体行为表达的攻击强度与它们腺体组织突出的频率和程度相关联，后者可作为释放气味量的指标。我们检测到在腺体短暂突出时会释放大量气味，而在腺体缩回时则没有气味释放。雄性在遇到对手期间和之后会突出腺体，突出程度随着信号发出者攻击强度的增加而增加。在争斗过程中，腺体突出程度随着攻击前身体姿势的升高而增加最为强烈。在表现出这种姿势的争斗中，获胜者的腺体突出程度明显高于失败者，这表明释放的气味在争斗结果中起着至关重要的作用。争斗结束后，几乎只有获胜者会突出腺体，显然是在宣告胜利。我们还通过在对称和不对称处理的参赛者中阻止腺体组织突出，直接测试了嗅觉信号的功能。仅处理占主导地位的个体，会使它们赢得争斗的百分比降低超过60%，而同时处理双方参赛者则会导致争斗频率和持续时间显著增加。在争斗过程中，疏忽洞蟋的嗅觉信号显然起到了高效威胁的作用，它能防止争斗升级到最大限度，并降低与冲突相关的成本。
