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Ledig, F. Thomas; Hodgskiss, Paul D.; Jacob-Cervantes, Virginia

doi:10.1023/a:1015297621884

Cited by 60 publications

(9 citation statements)

References 29 publications

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“…In fact, F in the mature trees at Highline Trailhead was negative, which indicates excess heterozygosity above expectations from random mating. Similar situations have been reported in several conifers (e.g., Plessas and Strauss 1986;Ledig et al 2002), which suggests that selfed progeny were weeded out during stand development and that heterozygotes had a selective advantage. In all three Engelmann spruce populations for which we could measure observed heterozygosity, H o , it was greater in the mature trees than in the embryos (Table 8), although the differences were small and not statistically significant.…”

Section: Mating System and Inbreedingsupporting

confidence: 82%

“…Rates of outcrossing estimated in the endemic spruces of Mexico were generally lower than 70%, and as low as 0% and 15% in two small populations of Chihuahua spruce (Ledig et al 1997(Ledig et al , 2002. In contrast to the Mexican endemics, the rare Serbian spruce (Picea omorika (Panc.)…”

Section: Mating System and Inbreedingmentioning

confidence: 93%

“…All these endemics have small, fragmented populations in North America. Among them, means varied only from 27.0% to 44.2% for P, from 1.4 to 1.5 for A, and from 0.093 to 0.129 for H e (Ledig et al 1997(Ledig et al , 2002(Ledig et al , 2005. Even the three Engelmann spruce populations in which recent bottlenecks were indicated (Table 3), had higher estimates of diversity than the endemic spruces, averaging 70.8% for P, 2.1 for A, and 0.251 for H e .…”

Section: Genetic Diversitymentioning

confidence: 97%

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The structure of genetic diversity in Engelmann spruce and a comparison with blue spruce

2006

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Genetic diversity and genetic structure in Engelmann spruce (Picea engelmannii Parry ex Engelm.) were interpreted with respect to the effects of glacial and interglacial displacement and compared with patterns in blue spruce (Picea pungens Engelm.), which occupies a range well south of the last glacial front. On average, Engelmann spruce populations were polymorphic at 80% of 24 isozyme loci, with 2.4 alleles per locus and expected heterozygosity of 0.255. The respective means for four populations of blue spruce were 42.7%, 1.6 alleles, and 0.138. Of total diversity, 14.7% was among populations in Engelmann spruce and 8.6% in blue spruce. In Engelmann spruce, numbers of alleles increased from south to north. Recent bottlenecks were indicated in the three southernmost populations of Engelmann spruce and in the northernmost population of blue spruce. Cluster analysis divided Engelmann spruce into a northern group and a Southwestern group; however, populations from Utah were distributed among both clusters. Genetic distance was correlated with geographic distance between northern populations but not between Southwestern populations, where drift predominated over gene flow. In two Engelmann spruce populations from Utah, multilocus outcrossing rates were 0.951 (±0.016) and 0.940 (±0.071). At Flys Peak, Arizona, the southernmost location of Engelmann spruce, outcrossing was also high, 0.899 (±0.017). Thus, inbreeding coefficients observed for parental (-0.104 to 0.047) and filial (0.011 to 0.026) generations were low. Although Engelmann spruce seemed genetically robust, the evidence of bottlenecks in the southern extreme of its range suggested future problems in an era of global warming.Résumé : Les auteurs ont interprété la diversité génétique et la structure génétique de l'épinette d'Engelmann (Picea engelmannii Parry ex Engelm.) en relation avec les effets des déplacements glaciaires et interglaciaires, et les ont comparées avec les patrons de l'épinette bleue (Picea pungens Engelm.), qui occupe une région bien au sud du dernier front glaciaire. En moyenne, les populations de l'épinette d'Engelmann sont polymorphes chez 80 % de 24 loci isozymiques, avec 2.4 allèles par locus et une hétérozygocité attendue de 0,255. Ces moyennes respectives, chez quatre populations d'épinette bleue, sont de 42,7 %, 1,6 allèles, et 0,138. De la diversité totale, 14,7 % se retrouve parmi les populations de l'épinette d'Engelmann, et 8,6 % parmi celles de l'épinette bleue. Chez l'épinette d'Engelmann, les nombres d'allèles augmentent du sud au nord. On observe des goulots d'étranglements récents dans les trois populations les plus méridionales de l'épi-nette d'Engelmann et dans la population la plus nordique de l'épinette bleue. L'analyse par regroupement divise l'épinette d'Engelmann en un groupe nordique et un groupe du sud-ouest; cependant les populations de l'Utah sont présentes dans les deux regroupements. La distance génétique est corrélée avec les distances géographiques entre les populations du nord, mais non entre les populatio...

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Section: Mating System and Inbreedingsupporting

confidence: 82%

Section: Mating System and Inbreedingmentioning

confidence: 93%

Section: Genetic Diversitymentioning

confidence: 97%

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The structure of genetic diversity in Engelmann spruce and a comparison with blue spruce

2006

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“…Such source populations may represent themselves or be located close to glacial refugial populations. A similar low genetic differentiation among mountain populations was observed in a few studies for other conifers, e.g., Picea mexicana Martí-nez (Ledig et al 2002) or P. sylvestris (Robledo-Arnuncio et al 2005).…”

Section: Genetic Diversity and Differentiationsupporting

confidence: 84%

Comparison of range-wide chloroplast microsatellite and needle trait variation patterns in Pinus mugo Turra (dwarf mountain pine)

Żukowska¹,

Boratyńska²,

Wachowiak³

2017

iForest

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In this study, range-wide genetic variation was analysed in 553 Pinus mugo Turra (dwarf mountain pine) individuals from 21 locations using 11 chloroplast microsatellites. Our main goal was to assess the spatial distribution of neutral genetic variation. We also used data from a previous study on the morphological variation of needles from 18 stands of P. mugo. In total, 22 needle characteristics were reanalysed and compared to microsatellite data to describe the distribution of morphological variation in the context of neutral genetic variation. We hypothesised that the chloroplast microsatellite and needle trait variation patterns would not entirely overlap. The results indicate the recent divergence of P. mugo populations derived from a formerly larger distribution. We identified 4 genetic and 3 morphological clusters whose spatial distribution overlapped only to some extent. The distribution of genetic variation showed a south-north pattern with signs of admixture in the Alps and Carpathians. Two south-westernmost stands from Italy were evidently isolated from the others. In contrast, morphological variation tended to display a west-east pattern. A separate group based on needle traits was formed mostly by eastern stands and was not observed by microsatellite analysis. In addition, a few needle characteristics significantly correlated with longitude and climate variables. These findings suggest that eastern populations of P. mugo may be of different origin and/or that some needle characteristics may be adaptively important in these locations. The potential roles of past demographic events, phenotypic plasticity and local adaptation in shaping the patterns of genetic and morphological variation in P. mugo are discussed.

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“…Habitat destruction and fragmentation would inevitably result in small and isolated populations [40,41], and increase the risk of population extinction. Today, many natural habitats of T. mongolica around the Yellow River have been destroyed or altered due to human overexploitation.…”

Section: Discussionmentioning

confidence: 99%

Conservation genetics and phylogeography of endangered and endemic shrub Tetraena mongolica (Zygophyllaceae) in Inner Mongolia, China

Hwang

Liu

et al. 2011

BMC Genet

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BackgroundTetraena mongolica (Zygophyllaceae), an endangered endemic species in western Inner Mongolia, China. For endemic species with a limited geographical range and declining populations, historical patterns of demography and hierarchical genetic structure are important for determining population structure, and also provide information for developing effective and sustainable management plans. In this study, we assess genetic variation, population structure, and phylogeography of T. mongolica from eight populations. Furthermore, we evaluate the conservation and management units to provide the information for conservation.ResultsSequence variation and spatial apportionment of the atpB-rbcL noncoding spacer region of the chloroplast DNA were used to reconstruct the phylogeography of T. mongolica. A total of 880 bp was sequenced from eight extant populations throughout the whole range of its distribution. At the cpDNA locus, high levels of genetic differentiation among populations and low levels of genetic variation within populations were detected, indicating that most seed dispersal was restricted within populations.ConclusionsDemographic fluctuations, which led to random losses of genetic polymorphisms from populations, due to frequent flooding of the Yellow River and human disturbance were indicated by the analysis of BEAST skyline plot. Nested clade analysis revealed that restricted gene flow with isolation by distance plus occasional long distance dispersal is the main evolutionary factor affecting the phylogeography and population structure of T. mongolica. For setting a conservation management plan, each population of T. mongolica should be recognized as a conservation unit.

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Cited by 60 publications

References 29 publications

The structure of genetic diversity in Engelmann spruce and a comparison with blue spruce

The structure of genetic diversity in Engelmann spruce and a comparison with blue spruce

Comparison of range-wide chloroplast microsatellite and needle trait variation patterns in Pinus mugo Turra (dwarf mountain pine)

Conservation genetics and phylogeography of endangered and endemic shrub Tetraena mongolica (Zygophyllaceae) in Inner Mongolia, China

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