Genetic introgression as a potential to widen a species’ niche: Insights from alpine Carex curvula Milica Nenadic Study organism Carex curvula •  •  •  •  •  dominant sedge of most alpine grasslands clonal long-lived protogynous wind-pollinated & primarily out-crossing 2 taxa (subspecies) C. curvula subsp. curvula ~> Cc C. curvula subsp. rosae ~> Cr base-rich substrates acidic substrates •  Spatial distribution does not overlap •  Cc and Cr populations close => interbreeding •  Morphologicaly intermediate individuals obsereved and are fertile Main objectives: 1.  Are morphological and ecological variation correlated with genetic differentiation? 2.  Do ecologically marginal populations of each tacon exhibit particular multilocus genotype when compared to population of optimal habitats? Methods Genetic analysis Sampled: 18 populations on Alps + 1 Cc population on Pyrenees 8-10 individuals per population (total: 177) AFLP markers ⇒  between population genetic distances (Nei) ⇒  F statistics Niche investigation •  Determine niche for each taxa •  Discriminate between optimal and marginal habitats •  1300 vegetation relevés (plots) species list six local-scale environmental variables coinertia analasys taken from: Dray S., Chessel D., Thioulouse J. (2003). Co=inertia analysus and the linking of ecological data tables. Ecology, 84(11), pp. 3078-3089 Results Niche investigation results Genetic analysis results opt marg Cc Cr Pyrenees Cc • Fst • diagnostic markers • Nei’s genetic distance Genome integrity of each taxon is maintained even if populations are very close (<1 km distance) Conclusions Single origin for Cc and Cr •  Morphological and ecological variation in C. curvula populations strongly correlated with genetic differentiation •  Genetic relatedness between Cc and Cr independent of geographical distance (Unknown initial reproduction barrier) Cross-pollination between Cc and Cr is likely widespread dominant sp. wind pollen dispersal sympatric over large areas Maintenance of genetic differentiation: 1.  2.  Habitat specialization => change in phenology Lower hybrid fitness in typical habitats Marginal populations might result from genetic introgression between Cc and Cr morphologically intermediate hybrids “non-typical” AFLP phenotypes western and middle parts of the Alps Hybridization and introgression are sources of genetic variation and are shaping species distribution along gradients!