Table 1.

Overview of the congeneric pairs of mid- and high-elevation species included in our study with their main range limits in the literature having only been given in terms of altitudinal zonations as defined for the European Alps by Lauber and Wagner (2001) and Aeschiman et al. (2004): ‘colline’ = 300–900 m; ‘montane’ = 900–1500 m; ‘subalpine’ = 1600–2300 m; ‘alpine’ = 2300–3000 m; ‘mid-elevation’ species mainly ranged from the colline to the lower montane zones, while ‘high-elevation’ species mainly ranged from the subalpine to the alpine zones

Family	Mid-elevation species	High-elevation species
Lamiaceae	Acinos arvensis (Lam.) Dandy	Acinos alpinus (L.) Moench
	colline–montane	subalpine
Poaceae	Anthoxanthum odoratum L.	Anthoxanthum alpinum Löve
	colline–alpine	subalpine–alpine
Fabaceae	Anthyllis vulneraria ssp. vulneraria L. s.l.	Anthyllis vulneraria ssp. alpéstris Schult
	colline–montane	subalpine–alpine
Brassicaceae	Arabis hirsuta L.	Arabis alpina L. s.l.
	colline–montane	montane–alpine
Campanulaceae	Campanula rotundifolia L.	Campanula scheuchzeri Vill.
	Colline–subalpine	subalpine–alpine
Asteraceae	Centaurea scabiosa L. s.l.	Centaurea montana L.
	colline–montane	montane–subalpine
Caryophyllaceae	Dianthus deltoides L.	Dianthus sylvestris Wulfen
	colline–montane	colline–subalpine
Rosaceae	Geum urbanum L.	Geum montanum L.
	colline–montane	subalpine–alpine
Fabaceae	Lotus corniculatus L.	Lotus alpinus Ramond
	colline–subalpine	alpine
Fabaceae	Onobrychis viccifolia Scop.	Onobrychis montana DC.
	colline–montane	subalpine
Poaceae	Phleum phleoides (L.) Karsten	Phleum alpinum L.
	colline–montane	subalpine–alpine
Plantaginaceae	Plantago lanceolata L.	Plantago alpina L.
	colline–subalpine	subalpine–alpine
Caryophyllaceae	Silene vulgaris ssp. vulgaris (Moench) Garcke s.l.	Silene vulgaris ssp. glareosa (Jord.) Marsd.-Jon & Turill
	colline–subalpine	alpine
Fabaceae	Trifolium pratense ssp. pratense L.	Trifolium pratense ssp. nivale (Koch)
	colline–subalpine	alpine