03056nas a2200289 4500008004100000022001400041245007700055210006900132260001600201520209900217653002402316653002502340653002602365653002902391653001802420653002202438100002302460700001802483700002002501700002202521700001502543700002002558700002102578700002802599700002202627856011702649 2015 eng d a1387-354700aDifferent behavioural strategies among seven highly invasive ant species0 aDifferent behavioural strategies among seven highly invasive ant cApr-04-20153 a

Ants figure prominently among the worst invasive species because of their enormous ecological and economic impacts. However, it remains to be investigated which species would be behaviourally dominant when confronted with another invasive ant species, should two species be introduced in the same area. In the future, many regions might have suitable environmental conditions for several invasive ant species, as predicted under climate change scenarios. Here, we explored interactions among several highly invasive ant species, which have been shown to have overlapping suitable areas. The aim of this study was to evaluate the performance in interference competition of seven of the world’s worst invasive ant species (Anoplolepis gracilipesParatrechina longicornisMyrmica rubraLinepithema humileLasius neglectusWasmannia auropunctata and Pheidole megacephala). We conducted pairwise confrontations, testing the behaviour of each species against each of the six other species (in total 21 dyadic confrontations). We used single worker confrontations and group interactions of 10 versus 10 individuals to establish a dominance hierarchy among these invasive ant species. We discovered two different behavioural strategies among these invasive ants: three species displayed evasive or indifferent behaviour when individuals or groups were confronted (A. gracilipes, Pa. longicornis, M. rubra), while the four remaining species were highly aggressive during encounters and formed a linear dominance hierarchy. These findings contrast with the widespread view that invasive ants form a homogeneous group of species displaying the ‘invasive syndrome’, which includes generally aggressive behaviour. The dominance hierarchy among the four aggressive species may be used to predict the outcome of future competitive interactions under some circumstances. Yet, the existence of several behavioural strategies renders such a prediction less straightforward.

10aDominance hierarchy10aDominance trade-offs10aDyadic confrontations10aInterference competition10aInvasive ants10aInvasive syndrome1 aBertelsmeier, Cleo1 aAvril, Amaury1 aBlight, Olivier1 aConfais, Amandine1 aDiez, Lise1 aJourdan, Hervé1 aOrivel, Jérôme1 aGermès, Noémie, Saint1 aCourchamp, Franck uhttp://link.springer.com/10.1007/s10530-015-0892-5http://link.springer.com/content/pdf/10.1007/s10530-015-0892-502109nas a2200217 4500008004100000022001400041245004900055210004900104260001600153520139700169653002501566653001901591653002001610653001801630653003201648100002301680700002201703700002701725700002201752856011701774 2014 eng d a0960-311500aWorldwide ant invasions under climate change0 aWorldwide ant invasions under climate change cJul-09-20143 a

Many ants are among the most globally significant invasive species. They have caused the local decline and extinction of a variety of taxa ranging from plants to mammals. They disturb ecosystem processes, decrease agricultural production, damage infrastructure and can be a health hazard for humans. Overall, economic costs caused by invasive ants amount to several billion US $ annually. There is general consensus that the future distributions of invasive species are likely to expand with climate change, however this dogma remains poorly tested. Here we model suitable area globally for 15 of the worst invasive ant species, both currently and with predicted climate change (in 2080), globally, regionally and within the world’s 34 biodiversity hotspots. Surprisingly, the potential distribution of only five species was predicted to increase (up to 35.8 %) with climate change, with most declining by up to 63.3 %. The ant invasion hotspots are predominantly in tropical and subtropical regions of South America, Africa, Asia and Oceanic islands, and particularly correspond with biodiversity hotspots. Contrary to general expectations, climate change and invasive ant species will not systematically act synergistically. However, ant invasions will likely remain as a major global problem, especially where invasion hotspots coincide with biodiversity hotspots.

10abiological invasions10aClimate change10aConsensus model10aInvasive ants10aSpecies distribution models1 aBertelsmeier, Cleo1 aLuque, Gloria, M.1 aHoffmann, Benjamin, D.1 aCourchamp, Franck uhttp://link.springer.com/10.1007/s10531-014-0794-3http://link.springer.com/content/pdf/10.1007/s10531-014-0794-3