Genetic analysis reveals Finnish Formica fennica populations do not form a separate genetic entity from F. exsecta

Sanja Maria Hakala; Perttu Seppä; Maria Heikkilä; Pekka Punttila; Jouni Sorvari; Heikki Helanterä

doi:10.7717/peerj.6013

Genetic analysis reveals Finnish Formica fennica populations do not form a separate genetic entity from F. exsecta

PeerJ. 2018 Dec 6:6:e6013. doi: 10.7717/peerj.6013. eCollection 2018.

Authors

Sanja Maria Hakala^{1

2}, Perttu Seppä^{1

2}, Maria Heikkilä³, Pekka Punttila⁴, Jouni Sorvari⁵, Heikki Helanterä^{1

2

6}

Affiliations

¹ Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
² Tvärminne Zoological Station, University of Helsinki, Hanko, Finland.
³ Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland.
⁴ Finnish Environment Institute, Helsinki, Finland.
⁵ Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland.
⁶ Ecology and genetics research unit, University of Oulu, Oulu, Finland.

Abstract

Coptoformica Müller, 1923 is a subgenus of Formica Linnaeus, 1758 that consists of c. a dozen species of ants that typically inhabit open grassy habitats and build small nest mounds. The most recent addition to the group is Formica fennica Seifert, 2000. The description was based on morphological characters, but the species status has not been confirmed by molecular methods. In this study, we use thirteen DNA microsatellite markers and a partial mitochondrial COI gene sequence to assess the species status of F. fennica, by comparing the genetic variation among samples identified as F. fennica and six other boreal Formica (Coptoformica) species. Most of the species studied form separate, discontinuous clusters in phylogenetic and spatial analyses with only little intraspecific genetic variation. However, both nuclear and mitochondrial markers fail to separate the species pair F. exsecta Nylander, 1846 and F. fennica despite established morphological differences. The genetic variation within the F. exsecta/fennica group is extensive, but reflects spatial rather than morphological differences. Finnish F. fennica populations studied so far should not be considered a separate species, but merely a morph of F. exsecta.

Keywords: Barcoding; Coptoformica; Hymenoptera; Microsatellites; Species delimitation; Species identification.

Grants and funding

Our work was funded by the Academy of Finland (#140990, #135970, #251337 and #284666), Finnish Cultural Foundation, Kone Foundation, Emil Aaltonen Foundation and Societas pro Fauna et Flora Fennica. NFI ant data collection was funded by the Academy of Finland (#200870 and #114380). There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.