Genetic divergence of climatically marginal populations of Vicia pisiformis on the Scandinavian Peninsula.
Vicia pisiformis L. is a perennial leguminous plant with a main distribution in broadleaved forest-steppes of eastern Europe. The species is classified as endangered (EN) according to the IUCN red-lists in both Norway and Sweden, due to severe fragmentation, small population sizes and continuing population decline. The populations on the Scandinavian Peninsula constitute the northern limit of the species distribution and are mostly restricted to warm stony slopes with predominantly southern aspects. In this study we used the AFLP method, which is a high-resolution genetic fingerprint method. Samples were collected from 22 Scandinavian populations. The overall genetic structure was analysed in an AMOVA, in a Mantel test and through constrained correspondence analysis (CCA). The ordination scores representing non-geographic genetic divergence were extracted from the CCA and analysed in a linear model using habitat variables and population size as explanatory variables. We found (i) a strong geographic structure, (ii) significant genetic divergence between populations, (iii) that this genetic divergence remained significant even after removing the effect of geography in a partial CCA and (iv) that the remaining non-geographic part of genetic divergence (distance from the ordination centre) was associated with aspect, populations with a northern aspect were more genetically divergent. Aspect explains more variation than population size and is the only variable retained in the minimal adequate model. We suggest that local adaptation has caused this divergence from an expected geographical pattern of genetic variation. This explanation is further supported by the association between aspect and specific AFLP fragments.
Jonsson
Magnus
M
Södertörn University College, School of Life Sciences, Huddinge, Sweden. magnus.jonsson@sh.se.
Bertilsson
Maria
M
Ehrlén
Johan
J
Lönn
Mikael
M
D000222:Adaptation, Physiological; D054458:Amplified Fragment Length Polymorphism Analysis; D002980:Climate; D018744:DNA, Plant / Q000235:genetics; D017753:Ecosystem; D014644:Genetic Variation; D005843:Geography; D009664:Norway; D013548:Sweden; D031306:Vicia / Q000235:genetics*
D018744:DNA, Plant