International Union for the Study of Social Insects (IUSSI2018), August 5-10, 2018 in Guarujá, Brazil.

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Desiccation resistance and climate adaptation: Conserved cuticular hydrocarbon signatures in invasive Argentine ant super colonies over vast geographic distances

Author(s):
Jan Martin Buellesbach, Jan Martin Buellesbach , Brian A. Whyte , Kelsey Scheckel , Elizabeth I. Cash , Joshua D. Gibson , Neil D. Tsutsui
Institution(s):
Department of Environmental Science, Policy & Management, UC Berkeley, USA; Department of Environmental Science, Policy & Management, UC Berkeley, USA ; Department of Environmental Science, Policy & Management, UC Berkeley, USA ; Department of Environmental Science, Policy & Management, UC Berkeley, USA ; Department of Environmental Science, Policy & Management, UC Berkeley, USA ; Department of Environmental Science, Policy & Management, UC Berkeley, USA ; Department of Environmental Science, Policy & Management, UC Berkeley, USA
Cuticular hydrocarbons (CHC), the dominant fraction of the insects’ epicuticle, form the basis for a wide array of different chemical signaling systems while primarily functioning as desiccation barrier. In eusocial insects, CHC have been shown to be the main mediators of nestmate recognition, with CHC profile uniformity appearing to be the main factor for maintaining colony identity. In our study system, the unicolonial Argentine ant Linepithema humile, a recent unparalleled invasive expansion has led to cooperation between vast super colonies spanning hundreds to thousands of miles, whose individual colony members retain the capability to recognize each other as nestmates. CHC uniformity as basis for this vastly extended nestmate recognition behavior would largely conflict with the CHC desiccation barrier function, which is expected to display considerable flexibility while adapting to the fundamentally different environmental conditions these populations encounter in their expanded range. To shed light on these seemingly contradictory selective pressures, we attempt to decipher the particular CHC profile properties enabling constant nestmate recognition over vast geographical distances in relation to the more flexible CHC profile variations ensuring desiccation resistance despite considerable environmental fluctuations. Correlations with environmental factors and desiccation survival rates revealed a certain number of specific CHC compounds which apparently allow for the vast flexibility in adaption to a wide range of different habitats. In contrast, we found that the conserved colony-specific CHC signatures clearly override the more flexible CHC patterns correlated with environmental flexibility, delivering intriguing first hints at the hierarchy of CHC functionality integrating both desiccation resistance and the maintenance of a common, unambiguous and universally accepted chemical language.
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