Patterns and Levels of Genetic Variation in Great Basin Bristlecone Pine, Pinus longaeva

Hiebert, Ronald D.; Hamrick, J. L.

doi:10.2307/2408339

Cited by 47 publications

(38 citation statements)

References 6 publications

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“…Although species have been described (particularly in subsection Balfourianae) in which individual longevity could reach thousands of years, it is more common within the range from tens of years to a few hundred years. Longevity could be one of the causes of the data observed, like the level of expected heterozygosity estimated for P. longaeva (0.340, Hiebert & Hamrick 1983).…”

Section: Constancy In Heterozygosity Among Speciesmentioning

confidence: 95%

Comparative genetic structure in pines: evolutionary and conservation consequences

Delgado

Cuenca

Escalante

et al. 2002

Rev. chil. hist. nat.

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Pines have been the focus of several studies that estimate population genetic parameters using both allozymes and chloroplast single sequence repeats (SSRs). Also, the genus has also been recently studied using molecular systematics so that we now have a more clear understanding of their evolutionary history. With this background we studied comparatively the genetic structure in pines. Expected heterozygosity is particularly constant with a 99 % confidence interval between 0.19 and 0.23 in species that have been studied until now using allozymes. There is a significant proportion of species (9/41) that show high population differentiation estimates (F ST = or larger than 0.15) and five of these have large and wingless seeds probably associated with low densities, bird dispersal mechanisms and resistance to water stress. These species include the North American pinyon pines. Outcrossing rates are also constant among species from both subgenus Pinus and subgenus Strobus, which probably reflects a selective limit to the amount of deleterious alleles that can be maintained in pine species and this also affects inbreeding levels. We also explored the data published using microsatellites in pines and conclude that these markers uncover a higher proportion of variation and genetic differentiation as expected and that the evolutionary models that are used to derive the population genetic structure estimators should take into account other sources of mutation (point mutations, larger insertions and or deletions and duplications) to better understand the comparative applications of these molecular markers.

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Section: Constancy In Heterozygosity Among Speciesmentioning

confidence: 95%

Comparative genetic structure in pines: evolutionary and conservation consequences

Delgado

Cuenca

Escalante

et al. 2002

Rev. chil. hist. nat.

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show abstract

“…Nei's (1975) genetic distance has been the most widely used parameter of population differentiation for forest trees (e.g. Guries & Ledig, 1982;Wheeler & Guries, 1982;Hiebert & Hamrick, 1983) and its use here is appropriate for comparison with other studies. A problem with this parameter is its relative ' Trace [Tr (BW^')] is the sum of the diagonal elements of the matrix product of the between-group sums of squares and cross-products matrix (B) and the inverse of the within-group sums of squares and crossproducts matrix (W^').…”

Section: Population Differentiationmentioning

confidence: 99%

Caledonian Scots Pine: Origins and Genetic Structure

1986

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SUMMARYMonoterpene and isozyme loci, used as markers to study the genetic structure of Scots pine {Pinus sylvestris L.) native to Scotland, showed that the endemic populations are not genetically impoverished, in spite of severe contraction in range and numbers as a result of both natural and anthropogenic causes. On the contrary, variability in the relict populations is almost the highest of any plant species studied, with average heterozygosities of 0-33 for monoterpenes (five loci) and 0-30 for isozymes (16 loci). The overwhelming proportion of this variability (> 95 "") was within populations, even though significant differences in gene frequencies of many individual loci existed among populations. Multiple-locus comparison of gene frequencies among populations, resolved by canonical variate analysis, showed no coherent geographic pattern of differences from population to population or region to region, with one major exception: certain populations in northwestern Scotland (Wester Ross) were distinct from all others and each other. The pattern of variability of the biochemical markers was consistent with that of metrical and physiological traits reported in the literature. These traits, in turn, show relatively little genetic affinity between eonteniporary Scottish and continetital European populations. The genetic evidence, together with the anomalous distribution of pine pollen in the British Isles during the Holocene, suggests that the Caledonian race of Scots pine originated endemically from more tban one refugium after the last glaciation.

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“…As a result, C. balansae maintained higher levels of genetic variation that most other long-lived and outcrossed perennials. For example, the mean variation within populations of C. balansae Hs = 0.579 was higher than the mean values of 0.328, 0.465 and 0.289 for Liatris cylindracea, Pinus longgaeva and P. ponderosa, respectively [25,26,27]. C. balansae also maintained higher level of genetic diversity than the species Gleditsia triacanthos with similar life history traits (dioecy and insect pollination) 0.255 [28] and Panicum maximum 0.381 [29].…”

Section: Discussionmentioning

confidence: 94%

Effects of Habitat Fragmentation on Genetic Diversity in Cycas Balansae (Cycadaceae)

Tâm¹,

Trang²,

Giang³

et al. 2017

AJSTD

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Habitat fragmentation is a serious threat to species survival. In Vietnam, Cycas balansae has been considered as threatened species because of the reduction and fragmentation of its habitats and over-exploitation. We assessed genetic variability and the pattern of population structure among six populations sampled in four provinces: Hoa Binh, Ha Nam, Ninh Binh and Quang Ninh. Polyacrylamide gel electrophoresis was performed on leaf tissues from 152 individuals representing 6 populations of C. balansae. Six of twelve enzyme systems were used to estimate genetic diversity at population and species levels. Eleven loci were examined. The allozyme data showed high levels of genetic diversity within all populations, ranging from 0.538 in Ba Sao to 0.628 in Tan Dan (average 0.576). The maintenance of high levels of expected heterozygosity (average 0.571) and low in observed heterozygosity (average 0.347) might be related to great heterozygote deficiency and increased frequencies of rare alleles. Genetic differentiation among populations was low (Dst = 0.036 and Gst = 0.064), indicating high level of gene flow (Nm = 3.22). Isolation by geographical distance was observed, however, no significant relationship between genetic distances and geographical distances was recorded. Our studies suggest small population sizes of cycads brought about by fragmentation of its habitats, over-exploitation, and increasing number of inbred individuals within populations.

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Patterns and Levels of Genetic Variation in Great Basin Bristlecone Pine, Pinus longaeva

Cited by 47 publications

References 6 publications

Comparative genetic structure in pines: evolutionary and conservation consequences

Comparative genetic structure in pines: evolutionary and conservation consequences

Caledonian Scots Pine: Origins and Genetic Structure

Effects of Habitat Fragmentation on Genetic Diversity in Cycas Balansae (Cycadaceae)

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