Spatial discontinuity of mountain systems and genetic structure of alpine plants: the Alps-Carpathians disjunction in a comparative phylogeographical context

Aim In mountain areas, geographical isolation and history of mountain
systems are believed to be among the most important factors which
determine population distribution and connectivity. In this study we
address the importance of discontinuity among mountain systems for
intraspecific genetic structure by investigating whether the geographical
disjunction between the Alps and the Carpathians (and the related habitat
gap) is the primary factor that shapes the genetic structure of the
high-mountain plant populations. We compare the large-scale genetic
structure of alpine plants from these two parts of the European Alpine
System concerning the location of the main genetic split in the studied
species, large-scale patterns of phylogeographical lineages and potential
factors influencing their distribution. Location The Alps and the
Carpathians Taxon 22 alpine/subalpine vascular plant species Methods We
performed Bayesian population structure analysis on genome-wide genotyping
(AFLP) data and reconstructed relationships between individuals and
populations using the PCoA and Neighbour Joining. We also performed AMOVA
to estimate the contribution of genetic variation among regions. Based on
these analyses, we examined the location of primary and lower-level
phylogeographical breaks. Results A clear primary genetic split between
the Alps and the Carpathians was observed in three species (14% of studied
species). In seventeen species (77%) we identified other genetic patterns
or, in some cases, we did not observe any geographical pattern (two
species, 9%). We found no specific pattern of biological traits that are
correlated with genetic split between the Alps and the Carpathians.
Conclusions The geographical gap between the Alps and the Carpathians is
not a primary factor in shaping the genetic structure of the regional
high-mountain flora as it aligns with a first-rank phylogeographic break
in a minority of species. The genetic division between the Alps and the
Carpathians appears mostly at higher K values, showing that internal
complexity of these large mountain systems plays a no less important role.
Several patterns of large-scale distribution of intraspecific lineages
were detected, including connections between the Carpathians and the
nearest Eastern Alps but also historical links of the Carpathians with
Southern and Western Alps through latitudinally extended genetic groups.