group of arctic–alpine species must not be mixed up with boreo-montane species,
which have a somewhat similar distribution, but are confined to the montane and
subalpine forests in the mountains and to the boreal forest belt in the North (Schmitt
2009); furthermore, these elements are also found in the forests of the lower
European mountain ranges without an alpine belt. Similar differences exist between
alpine disjunct and montane disjunct species. As boreo-montane and montane
disjunct species are not true high mountain elements, they are not addressed in this
chapter.
3.2 Different Genetic Lineages Within High
Mountain Systems
Following the picture of an island archipelago of high mountain systems in the
‘European Sea of Lowlands’, the Alps are the largest ‘island’, or even a ‘continent’
surrounded by other mountain ‘islands’. As such, the Alps harbour a large number
of endemic high mountain species, some of them distributed throughout these
mountains, others with rather narrow distributions in some parts of the Alps, with
many of these distributions located in the south-western or south-eastern Alps
(Varga and Schmitt 2008). Although some of these geographically restricted
endemics are genetically impoverished (e.g. Erebia sudetica inalpina; Haubrich
and Schmitt 2007), perhaps as a result of constantly low numbers of individuals and
the hereby resulting genetic bottlenecks, others are genetically even more diverse
than their lowland relatives (e.g. Coenonympha darwiniana, C. macromma;
Schmitt and Besold 2010). This high genetic diversity might be the consequence of
simple uphill—downhill shifts within one region as conditions changed from
interglacial to glacial and vice versa without major genetic bottlenecks.
In most cases, more widely distributed Alpine species comprise several genetic
lineages, which can be ‘translated’ into several centres of differentiation, i.e. refugia
that later served as centres of dispersal. The classic pattern, repeated with little
variation in numerous plant and animal species (e.g. Schönswetter et al. 2002,
2003a, b, 2004a; Stehlik et al. 2002a; Tribsch et al. 2002; Margraf et al. 2007;
Thiel-Egenter et al. 2009), is of four genetic groups localised in the south-western,
western, central and eastern Alps (Fig. 3.2a). This pattern is assumed to have
evolved in four glacial refugia in the lower and thus unglaciated parts of the
south-western Alps, south of the western and central Alps as well as east of the
eastern Alps, i.e. in southern peripheral refugia. Some species show a pattern of
fewer refugia, with just an eastern and a western genetic group (Fig. 3.2b), and thus
only two centres of survival (e.g. Pauls et al. 2006; Haubrich and Schmitt 2007;
Schmitt and Haubrich 2008). However, some species even had peripheral refugia
north of the Alps (e.g. Erebia epiphron; Schmitt et al. 2006) or survived (additionally or even exclusively) on nunataks (i.e. ice-free areas surrounded by the
Alpine glaciers), as proven for several plant species (e.g. Stehlik et al. 2001, 2002b;
Holderegger et al. 2002; Stehlik 2002).
3 Molecular Biogeography of the High Mountain Systems …
65
which have a somewhat similar distribution, but are confined to the montane and
subalpine forests in the mountains and to the boreal forest belt in the North (Schmitt
2009); furthermore, these elements are also found in the forests of the lower
European mountain ranges without an alpine belt. Similar differences exist between
alpine disjunct and montane disjunct species. As boreo-montane and montane
disjunct species are not true high mountain elements, they are not addressed in this
chapter.
3.2 Different Genetic Lineages Within High
Mountain Systems
Following the picture of an island archipelago of high mountain systems in the
‘European Sea of Lowlands’, the Alps are the largest ‘island’, or even a ‘continent’
surrounded by other mountain ‘islands’. As such, the Alps harbour a large number
of endemic high mountain species, some of them distributed throughout these
mountains, others with rather narrow distributions in some parts of the Alps, with
many of these distributions located in the south-western or south-eastern Alps
(Varga and Schmitt 2008). Although some of these geographically restricted
endemics are genetically impoverished (e.g. Erebia sudetica inalpina; Haubrich
and Schmitt 2007), perhaps as a result of constantly low numbers of individuals and
the hereby resulting genetic bottlenecks, others are genetically even more diverse
than their lowland relatives (e.g. Coenonympha darwiniana, C. macromma;
Schmitt and Besold 2010). This high genetic diversity might be the consequence of
simple uphill—downhill shifts within one region as conditions changed from
interglacial to glacial and vice versa without major genetic bottlenecks.
In most cases, more widely distributed Alpine species comprise several genetic
lineages, which can be ‘translated’ into several centres of differentiation, i.e. refugia
that later served as centres of dispersal. The classic pattern, repeated with little
variation in numerous plant and animal species (e.g. Schönswetter et al. 2002,
2003a, b, 2004a; Stehlik et al. 2002a; Tribsch et al. 2002; Margraf et al. 2007;
Thiel-Egenter et al. 2009), is of four genetic groups localised in the south-western,
western, central and eastern Alps (Fig. 3.2a). This pattern is assumed to have
evolved in four glacial refugia in the lower and thus unglaciated parts of the
south-western Alps, south of the western and central Alps as well as east of the
eastern Alps, i.e. in southern peripheral refugia. Some species show a pattern of
fewer refugia, with just an eastern and a western genetic group (Fig. 3.2b), and thus
only two centres of survival (e.g. Pauls et al. 2006; Haubrich and Schmitt 2007;
Schmitt and Haubrich 2008). However, some species even had peripheral refugia
north of the Alps (e.g. Erebia epiphron; Schmitt et al. 2006) or survived (additionally or even exclusively) on nunataks (i.e. ice-free areas surrounded by the
Alpine glaciers), as proven for several plant species (e.g. Stehlik et al. 2001, 2002b;
Holderegger et al. 2002; Stehlik 2002).
3 Molecular Biogeography of the High Mountain Systems …
65