Glacial Refugia and Future Habitat Coverage of Selected Dactylorhiza Representatives (Orchidaceae)

Abstract

The intensively discussed taxonomic complexity of the Dactylorhiza genus is probably correlated with its migration history during glaciations and interglacial periods. Previous studies on past processes affecting the current distribution of Dactylorhiza species as well as the history of the polyploid complex formation were based only on molecular data. In the present study the ecological niche modeling (ENM) technique was applied in order to describe the distribution of potential refugia for the selected Dactylorhiza representatives during the Last Glacial Maximum. Additionally, future changes in their potential habitat coverage were measured with regard to three various climatic change scenarios. The maximum entropy method was used to create models of suitable niche distribution. A database of Dactylorhiza localities was prepared on the grounds of information collected from literature and data gathered during field works. Our research indicated that the habitats of majority of the studied taxa will decrease by 2080, except for D. incarnata var. incarnata, for which suitable habitats will increase almost two-fold in the global scale. Moreover, the potential habitats of some taxa are located outside their currently known geographical ranges, e.g. the Aleutian Islands, the western slopes of the Rocky Mountains, Newfoundland, southern Greenland and Iceland. ENM analysis did not confirm that the Balkans, central Europe or central Russia served as the most important refugia for individual representatives of the Dactylorhiza incarnata/maculata complex. Our study rather indicated that the Black Sea coast, southern Apennines and Corsica were the main areas characterized by habitats suitable for most of the taxa.

Fig 1. Localities of D. incarnata var. cruenta (yellow circle), D. incarnata var. incarnata (black square), D. incarnata var. ochroleuca (red square), D. maculata ssp. fuchsii (red circle), D. maculata ssp. maculata (green circle), D. majalis ssp. lapponica (yellow square), D. majalis ssp. majalis (blue circle), and D. majalis ssp. traunsteineri (green square) used in the modeling.

Fig 2. European distribution of the suitable niches of D. majalis ssp. lapponica (A), D. majalis ssp. majalis (B), and D. majalis ssp. traunsteineri (C) within their currently known geographical range in the LGM (PMIP2 based models).

Fig 3. European distribution of the suitable niches of D. incarnata var. cruenta (A), D. incarnata var. incarnata (B), and D. incarnata var. ochroleuca (C) within their currently known geographical range in the LGM (PMIP2 based models).

Fig 4. European distribution of the suitable niches of D. maculata ssp. fuchsii (A) and D. maculata ssp. maculata (B) within their currently known geographical range in the LGM (PMIP2 based models).

Fig 5. Current distribution of suitable niches of D. majalis ssp. lapponica (A), D. majalis ssp. majalis (B), and D. majalis ssp. traunsteineri (C).

Fig 6. Current distribution of suitable niches of D. incarnata var. cruenta (A), D. incarnata var. incarnata (B), and D. incarnata var. ochroleuca (C).

Fig 7. Current distribution of suitable niches of D. maculata ssp. fuchsii (A) and D. maculata ssp. maculata (B).