Mixed colonies and hybridisation of Messor harvester ant species (Hymenoptera: Formicidae)

Steiner, Florian, Seifert, Bernhard, Grasso, Donato A, Le Moli, Francesco, Arthofer, Wolfgang, Stauffer, Christian, Crozier, Ross, and Schlck-Steiner, Birgit C (2011) Mixed colonies and hybridisation of Messor harvester ant species (Hymenoptera: Formicidae). Organisms, Diversity & Evolution, 11 (2). pp. 107-134.

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Abstract

The Mediterranean harvester ant species Messor minor, M. cf. wasmanni, and M. capitatus can co-occur in the same habitat. In Italian populations, we encountered colonies that contained workers from more than one species as identified via standard morphology, as well as colonies with workers that appeared to be morphologically intermediate between species. This unusual finding required further analysis. We analysed such colonies using microsatellites, mitochondrial DNA and refined morphometrics, and a simple inference key for the colony-level interpretation of data from the three sources combined. We infer that Messor minor and M. cf. wasmanni engage in bidirectional interspecific gene flow. Hybrids between these two species are inferred to produce fertile offspring, which would indicate that barriers to hybridisation do not exist or can be completely overcome. This is unexpected, given that they are non-sister species and broadly sympatric in nature. Our findings also indicate the possible occurrence of hybrid-hybrid crosses, a phenomenon rarely observed in ants. We cautiously interpret the data at hand as in support of the interspecific gene flow considerably shaping the genetic makeup of populations, raising the question about a potential adaptive value of this hybridisation. Messor capitatus mixes with hybrids of the other two species, but we found no indication of hybridisation involving this species. We discuss various hypotheses on the causations of colony mixing and hybridisation in the three Messor species at the proximate and ultimate level.

Item ID: 21252
Item Type: Article (Refereed Research - C1)
Keywords: hybridisation; bidirectional interspecific gene flow; non-sister species; inference key
ISSN: 1439-6092
Funders: Australian Research Council DP0665890, Austrian Science Fund J2639-B17, Austrian Science Fund J2642-B17
Date Deposited: 26 Mar 2012 04:38
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060201 Behavioural Ecology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified @ 100%
Citation Count from Web of Science Web of Science 2
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