TY  - JOUR
A1  - Menzel, Florian
A1  - Blüthgen, Nico
A1  - Tolasch, Till
A1  - Conrad, Jürgen
A1  - Beifuss, Uwe
A1  - Beuerle, Till
A1  - Schmitt, Thomas
T1  - Crematoenones - a novel substance class exhibited by ants functions as appeasement signal
JF  - Frontiers in Zoology
N2  - Background: Parasitic, commensalistic, and mutualistic guests in social insect colonies often circumvent their hosts' nestmate recognition system to be accepted. These tolerance strategies include chemical mimicry and chemical insignificance. While tolerance strategies have been studied intensively in social parasites, little is known about these mechanisms in non-parasitic interactions. Here, we describe a strategy used in a parabiotic association, i.e. two mutualistic ant species that regularly share a common nest although they have overlapping food niches. One of them, Crematogaster modiglianii, produces an array of cuticular compounds which represent a substance class undescribed in nature so far. They occur in high abundances, which suggests an important function in the ant's association with its partner Camponotus rufifemur. 
Results: We elucidated the structure of one of the main compounds from cuticular extracts using gas chromatography, mass spectrometry, chemical derivatizations and nuclear magnetic resonance spectroscopy (NMR). The compound consists of two fused six-membered rings with two alkyl groups, one of which carries a keto functionality. To our knowledge, this is the first report on the identification of this substance class in nature. We suggest naming the compound crematoenone. In behavioural assays, crematoenones reduced interspecific aggression. Camponotus showed less aggression to allospecific cuticular hydrocarbons when combined with crematoenones. Thus, they function as appeasement substances. However, although the crematoenone composition was highly colony-specific, interspecific recognition was mediated by cuticular hydrocarbons, and not by crematoenones. 
Conclusions: Crematenones enable Crematogaster to evade Camponotus aggression, and thus reduce potential costs from competition with Camponotus. Hence, they seem to be a key factor in the parabiosis, and help Crematogaster to gain a net benefit from the association and thus maintain a mutualistic association over evolutionary time. To our knowledge, putative appeasement substances have been reported only once so far, and never between non-parasitic species. Since most organisms associated with social insects need to overcome their nestmate recognition system, we hypothesize that appeasement substances might play an important role in the evolution and maintenance of other mutualistic associations as well, by allowing organisms to reduce costs from antagonistic behaviour of other species.
KW  - cuticular hydrocarbons
KW  - appeasement substance
KW  - bees
KW  - ecology
KW  - parasitism
KW  - alkyloctahydronaphthalene
KW  - usurpation
KW  - venom
KW  - pheromone
KW  - crematogaster
KW  - parabiotic ants
KW  - Dufours gland
KW  - polyergus rufescens
KW  - formicidae
KW  - interspecific aggression
KW  - nestmate recognition cues
KW  - parabiotic association
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-122595
SN  - 1742-9994
VL  - 10
IS  - 32
ER  - 
TY  - JOUR
A1  - Hartke, Juliane
A1  - Sprenger, Philipp P.
A1  - Sahm, Jacqueline
A1  - Winterberg, Helena
A1  - Orivel, Jérôme
A1  - Baur, Hannes
A1  - Beuerle, Till
A1  - Schmitt, Thomas
A1  - Feldmeyer, Barbara
A1  - Menzel, Florian
T1  - Cuticular hydrocarbons as potential mediators of cryptic species divergence in a mutualistic ant association
JF  - Ecology and Evolution
N2  - Upon advances in sequencing techniques, more and more morphologically identical organisms are identified as cryptic species. Often, mutualistic interactions are proposed as drivers of diversification. Species of the neotropical parabiotic ant association between Crematogaster levior and Camponotus femoratus are known for highly diverse cuticular hydrocarbon (CHC) profiles, which in insects serve as desiccation barrier but also as communication cues. In the present study, we investigated the association of the ants’ CHC profiles with genotypes and morphological traits, and discovered cryptic species pairs in both genera. To assess putative niche differentiation between the cryptic species, we conducted an environmental association study that included various climate variables, canopy cover, and mutualistic plant species. Although mostly sympatric, the two Camponotus species seem to prefer different climate niches. However in the two Crematogaster species, we could not detect any differences in niche preference. The strong differentiation in the CHC profiles may thus suggest a possible role during speciation itself either by inducing assortative mating or by reinforcing sexual selection after the speciation event. We did not detect any further niche differences in the environmental parameters tested. Thus, it remains open how the cryptic species avoid competitive exclusion, with scope for further investigations.
KW  - environmental association
KW  - integrative taxonomy
KW  - niche differentiation
KW  - population structure
KW  - sexual selection
KW  - speciation
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227857
VL  - 9
ER  -