Geographic variation and dispersal history in Fennoscandian populations of two forest herbs

Tyler, Torbjörn; Prentice, Honor C.; Widén, Björn

doi:10.1007/s006060200054

Cited by 26 publications

(21 citation statements)

References 54 publications

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“…This pattern is congruent with a situation where genetic drift in small populations, initial founder events, and rare but highly leptokurtic long-distance dispersal are the most important factors shaping the geographic structure of genetic variation. Similar (lack of) patterns have been found in other widespread woodland plants (Tyler et al 2002;Tyler 2002a) but appear to be rare among other studied plant species. However, most studies hitherto undertaken have concentrated either on forest trees, which generally have extremely efficient gene flow with pollen, or on rare and threatened species with highly disjunct distributions.…”

Section: Discussionsupporting

confidence: 84%

“…Protocols for extraction, starch gel electrophoresis, and staining follow Tyler et al (2002). Eight enzyme systems with a total of 14 polymorphic loci were analysed: three loci of PGI (EC 5.3.1.9), two loci of each of AAT (EC 2.6.1.1), DIA (EC 1.6.99), TPI (EC 5.3.1.1), SKD (EC 1.1.1.25), IDH (EC 1.1.1.42), and PGM (EC 5.4.2.2), and one locus of 6PGD (EC 1.1.1.44).…”

Section: Enzyme Electrophoresismentioning

confidence: 99%

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Geographic structure of genetic variation in the widespread woodland grassMilium effusumL. A comparison between two regions with contrasting history and geomorphology

Tyler

2002

Genome

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Allozyme variation in the forest grass Milium effusum L. was studied in 21-23 populations within each of two equally sized densely sampled areas in northern and southern Sweden. In addition, 25 populations from other parts of Eurasia were studied for comparison. The structure of variation was analysed with both diversity statistics and measures based on allelic richness at a standardised sample size. The species was found to be highly variable, but no clear geographic patterns in the distribution of alleles or in overall genetic differentiation were found, either within the two regions or within the whole sample. Thus, no inferences about the direction of postglacial migration could be made. Obviously, migration and gene flow must have taken place in a manner capable of randomising the distribution of alleles. However, there were clear differences in levels and structuring of the variation between the two regions. Levels of variation, both in terms of genetic diversity and allelic richness, were lower in northern Sweden as compared with southern Sweden. In contrast, different measures of geographic structure all showed higher levels of population differentiation in the northern region. This is interpreted as due to different geomorphological conditions in the two regions, creating a relatively continuous habitat and gene flow in the southern region as compared with the northern region where the species, although common, is confined to narrow and mutually isolated corridors in the landscape.Key words: Milium effusum, allozymes, geographic differentiation, population fragmentation, allelic richness.Résumé : La variation alloenzymatique chez la graminée forestière Milium effusum L. a été étudiée chez 21-23 populations au sein de deux régions situées dans le Nord et le Sud de la Suède, les deux régions étant de taille semblable et ayant fait l'objet d'un échantillonnage important. De plus, 25 populations situées dans d'autres régions d'Eurasie ont été étudiées pour fins de comparaison. La structure de la variation a été analysée tant à l'aide de statistiques estimant la diversité q'à l'aide de mesures basées sur la richesse allélique au sein d'échantillons de même taille. Cette espèce s'est avérée très variable, mais aucune répartition géographique claire des allèles ou en matière de différenciation géné-tique n'a été observée, pas plus au sein des deux régions que pour l'ensemble de l'échantillon. Ainsi, aucune inférence quant à la direction de la migration post-glaciaire n'a pu être faite. Évidemment, de la migration et des échanges de gènes ont dû avoir lieu de façon à randomiser la distribution des allèles. Cependant, il y avait des différences claires quant au niveau et à la structuration de la variation entre les deux régions. La variation, tant en termes de diversité génétique que de richesse allélique, était plus faible dans le Nord de la Suède que dans le Sud. Par contre diverses mesures de la structure géographique ont montré un plus grand degré de différenciation de la population dans la région ...

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Section: Discussionsupporting

confidence: 84%

Section: Enzyme Electrophoresismentioning

confidence: 99%

Geographic structure of genetic variation in the widespread woodland grassMilium effusumL. A comparison between two regions with contrasting history and geomorphology

Tyler

2002

Genome

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“…F IS increases with latitude, but is not related to population size in Nordic S. nutans. High F IS values may result from selfing, inbreeding, restricted pollen and/or seed dispersal, clonality and/or the spatial effects of selection in different habitats (Linhart & Premoli, 1994;Berg & Hamrick, 1997;Tyler et al, 2002;Van Rossum et al, 2002). In contrast to the high values of F IS in Nordic S. nutans, mean (over populations) F IS values that are near to Hardy-Weinberg equilibrium have been reported for the silicicolous and calcicolous ecotypes (-0.009 and 0.023, respectively) of S. nutans in Belgium (Van Rossum et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

“…Most such studies have focused either on large-scale geographical patterns and postglacial immigration (e.g. Nordal & Jonsell, 1998;Nyberg Berglund & Westerbergh, 2001;Malm & Prentice, 2002;Tyler, Prentice & Widén, 2002) or on the effects of recent population processes on levels of genetic variation within populations (Lammi, Siikamäki & Mustajävi, 1999). The contributions of both recent population processes and of immigration history to the present structure of genetic variation in Nordic species are examined by Rosquist & Prentice (2000) and Schiemann, Tyler & Widén (2000).…”

Section: Introductionmentioning

confidence: 99%

Structure of allozyme variation in Nordic Silene nutans (Caryophyllaceae): population size, geographical position and immigration history

Rossum

Prentice

2004

Biological Journal of the Linnean Society

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We investigated allozyme variation in 34 populations of the perennial herb Silene nutans from Sweden and northern Finland, areas that were ice-covered during the last (Weichselian) glaciation. The present geographical structure of genetic variation in S. nutans in Sweden and northern Finland appears to have been mainly shaped by ancient historical processes. Patterns of variation in allele frequencies suggest two major postglacial immigration routes into Sweden, with populations entering the area from both the south and the east and forming a contact zone with admixed populations in central Sweden. While estimates of within-population genetic diversity and allelic richness are significantly correlated with present population size and geographical position (latitude), population size is not correlated with latitude. Low genetic diversity in the northern populations is more likely to have resulted from ancient stochastic events during the process of immigration than from recent population fragmentation. F IS values are high and increase with latitude. Evidence of recent bottlenecks was detected in several southern Swedish populations: these can be interpreted in terms of population fragmentation as a result of anthropogenic disturbance. Soil pH is uncorrelated with population size and position.

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“…As an outstanding feature, they typically demonstrated levels of genetic diversity in the glacial refugia that were higher than in the unglaciated, newly founded areas (Comes and Kadereit 1998), presumably due to repeated founder events during the range expansion (Ibrahim et al 1996). In addition, despite the paucity of paleobotanical records, forest herbs have also shown the patterns of genetic diversity predicted based on vegetational migration following the last glaciation (Soltis et al 1997;Broyles 1998;Tyler 2002;Tyler et al 2002;Griffin andBarrett 2004a, 2004b). Although there are some exceptions (Ford et al 1998;Schiemann et al 2000), it is reasonable to consider that forest herbs probably experienced a similar migration history with tree species.…”

Section: Introductionmentioning

confidence: 95%

Allozyme Diversity and Geographical Differentiation ofParasenecio adenostyloides(Asteraceae), an Endemic Forest Herb in Japan

Nakagawa

2008

International Journal of Plant Sciences

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In this study, allozyme variation at 15 putative loci was analyzed in 11 populations of Parasenecio adenostyloides (Asteraceae), a perennial herb endemic to Shikoku and Honshu, Japan. This species occurs mainly in the understory of subalpine coniferous forests and shows an islandlike pattern of geographical distribution. Genetic variation at the species level (P ¼ 73:3, mean number of alleles per locus A ð Þ ¼ 4:00, expected heterozygosity H E ð Þ ¼ 0:237) and at the population level (percentage of polymorphic loci ½P ¼ 42:4, A ¼ 2:05, H E ¼ 0:173) was considerably higher than the means for other short-lived perennial herbs and endemic species. A moderate but significant genetic differentiation was observed among the populations (G ST ¼ 0:179). The distribution of genetic variation showed an evident geographical pattern. In addition to the pattern of isolation by distance, a genetic distance phenogram and a principal components analysis based on allele frequencies roughly supported three clusters of the populations in central Honshu, northern Honshu, and Shikoku. In particular, two isolated populations in Shikoku were also characterized by remarkably lower genetic variation than those in Honshu, possibly resulting from strong genetic drift associated with their isolated distribution. This geographical structure of genetic variation was not in accord with the predictions based on migration history of subalpine coniferous forest in Japan, and it exemplified the importance of geographical isolation in establishing the genetic structure of P. adenostyloides.

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Geographic variation and dispersal history in Fennoscandian populations of two forest herbs

Cited by 26 publications

References 54 publications

Geographic structure of genetic variation in the widespread woodland grassMilium effusumL. A comparison between two regions with contrasting history and geomorphology

Geographic structure of genetic variation in the widespread woodland grassMilium effusumL. A comparison between two regions with contrasting history and geomorphology

Structure of allozyme variation in Nordic Silene nutans (Caryophyllaceae): population size, geographical position and immigration history

Allozyme Diversity and Geographical Differentiation ofParasenecio adenostyloides(Asteraceae), an Endemic Forest Herb in Japan

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