Genetic structure of red wood ant (Formica rufa group)
Project Number: CH-3440
| molecular biology|
Formic rufa group
Abstract Dis. Christian Bernasconi 2009:
Mound building red wood ants (species of the Formica rufa group) belong to one of the most studied groups of ants in Europe and have fundamental roles and positive effects in forested habitats of the northern hemisphere. In addition, they are considered among the most promising bioindicators of forest ecosystems. Because of their importance, these ants are protected by law in many European countries, including Switzerland. However, despite this protection, they are included on the red list of threatened species edited by the International Union for Conservation of Nature (IUCN) and on the red list of some particular countries like Switzerland. Because of their similar morphology and a high intraspecific variability, the morphological identification of these species can be quite complicated. In addition, they are sometimes able to hybridize or to form mixed colonies. Consequently, the taxonomy of this group of ants has been much debated during the past decades. Based on a phylogenetic study, today the group is considered to count six species in Europe: F. rufa, F. polyctena, F. lugubris, F. paralugubris, F. aquilonia and F. pratensis. Nevertheless, the taxonomy of the group is often neglected mainly due to the lack of reliable and easy to use identification methods.
Considering the importance of correct species assessment in conservation biology, in this study we want to disentangle the taxonomical difficulties within the Formica rufa group and to clarify the diversity of these protected ants, by using an integrative approach.
We first analyzed the distribution of the sibling species F. lugubris and F. paralugubris in the Italian Alps by collecting new samples on the field and by examining one of the major red wood ant collections, which is deposited at the University of Pavia, Italy. After that, we developed a molecular tool based on mitochondrial DNA, which provides a reliable and easy-to-use technique for the identification of F. lugubris and F. paralugubris. Afterwards, we extended the use of molecular markers for species identification to the whole F. rufa group and made a microsatellite analysis. Results confirm that molecular markers are consistent tools for species identification and that the six known species represent six different genetic pools. In addition, genetic data highlighted the existence of a new cryptic species in the Swiss Alps, called Formica lugubris-X.
The presence of a new species can have a great influence on future conservation plans in favour of these protected ants and consequently for forested habitats. We therefore completed molecular data by behavioural (pupae recognition) and chemical analyses based on sex pheromones of the entire F. rufa group. Both approaches are in accordance to genetic results and confirm that F. lugubris-X really represents a new cryptic species of red wood ant within the Swiss National Park (Eastern Swiss Alps).
Results obtained in this study have a great importance in terms of biodiversity. Moreover, they provide important taxonomical information, reliable tools for species identifications and future perspectives for a consequent conservation of red wood ant species.
Due to their importance in forest ecosystems, wood ants (Formica rufa group) are protected in many European countries. At present time, the Formica rufa group includes six species: F. rufa, F. polyctena, F. lugubris, F. paralugubris, F. aquilonia and F. pratensis. However, because of their morphological similarity and ability to hybridize, species identification can be very tough and the taxonomy of the group has always been controversial.
Due to the lack of clear morphological criteria for species identification, we're now investigating the suitability of genetic markers (mitochondrial DNA and microsatellites) as new discriminative tool to distinguish between F. aquilonia, F. lugubris and F. paralugubris, three species that often coexist in the same forests within the Alps.
Situation in teh Swiss National Park
During 2005 and 2006 we collected workers from several nests of F. lugubris and F. aquilonia in Val Minger, allowing us to make interspecific and intraspecific comparisons with other Formica samples collected in Champlönch and in Buffalora during previous researches (Bernasconi 2002, Maeder 2006).
Preliminary results show that all F. aquilonia nests share the same genetic characteristics within the park and that they are clearly separated from F. lugubris nests. This suggests that genetic markers could be a powerful tool for species identification at a local scale. Nevertheless, when comparing F. lugubris nests within the park, we observed that all nests of these species share the same genetic profile, with the exception of individuals collected in Val Minger.
This interesting result could be explained by hybridization of F. lugubris with F. paralugubris and/or F. aquilonia in Val Minger, or could indicate the existence of a cryptic species.
For a better understanding of these phenomena, we would need to collect and analyze F. lugubris, F. aquilonia and F. paralugubris samples within the other valleys of the Park. Sampling will be conducted along the trails (see Devenoges, 1999 for details) by collecting ants on nests present within a band of about 20m from each side of a pathway. In order to get powerful results, all the main pathways within the park should be inspected. This would be really helpful to improve knowledge of these protected species.
Bernasconi Christian (2009): Integrative taxonomy of the Frmica rufa group (Hymenoptera: Formicidae). Dis. Uni Lausanne 2009
Last update: 3/20/18
Source of data: ProClim- Research InfoSystem (1993-2020)
Update the data of project: CH-3440