title: Genetic structure in a fragmented Northern Hemisphere rainforest: large effective sizes and high connectivity among populations of the epiphytic lichen Lobaria pulmonaria.
abstract: An extraordinary diversity of epiphytic lichens is found in the boreal rainforest of central Norway, the highest-latitude rainforest in the world. These rainforest relicts are located in ravine systems, and clear cutting has increased the distance between remaining patches. We hypothesized that the relatively small lichen populations in the remaining forest stands have suffered a depletion of genetic diversity through bottlenecks and founder events. To test this hypothesis, we assessed genetic diversity and structure in the populations of the tripartite lichen Lobaria pulmonaria using eight SSR loci. We sampled thalli growing on Picea abies branches and propagules deposited in snow at three localities. Contrary to expectations, we found high genetic diversity in lichen and snow samples, and high effective sizes of the studied populations. Also, limited genetic differentiation between populations, high historical migration rates, and a high proportion of first generation immigrants were estimated, implying high connectivity across distances <30km. Almost all genetic variation was attributed to variation within sites; spatial genetic structures within populations were absent or appeared on small scales (5-10m). The high genetic diversity in the remaining old boreal rainforests shows that even relict forest patches might be suitable for conservation of genetic diversity.
authors.affiliation: Department of Biology, Faculty of Natural Science and Technology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. olga.hilmo@bio.ntnu.no
authors.forename: Olga
authors.initials: O
authors.lastname: Hilmo
authors.forename: Sverre
authors.initials: S
authors.lastname: Lundemo
authors.forename: Håkon
authors.initials: H
authors.lastname: Holien
authors.forename: Kirsti
authors.initials: K
authors.lastname: Stengrundet
authors.forename: Hans K
authors.initials: HK
authors.lastname: Stenøien
mesh_terms: D000483:Alleles; D051456:Gene Flow; D014644:Genetic Variation; D005828:Genetics, Population; D008011:Lichens / Q000235:genetics*; D018895:Microsatellite Repeats; D009664:Norway; D028222:Picea; D011156:Population Density; D012914:Snow; D014197:Trees