Allozyme frequencies in New Jersey and North Carolina populations of Atlantic white‐cedar, <i>Chamaecyparis thyoides</i> (Cupressaceae)

Kuser, John E.; Meagher, Thomas R.; Sheely, Deborah L.; White, Adam

doi:10.2307/2446615

Cited by 13 publications

(10 citation statements)

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“…Allelic diversity in the New England and Maritime region was a highly monomorphic subset of the genetic diversity observed in the Atlantic Coastal Plain populations of C. glabra. Similar patterns of reduced genetic variation resulting from putative postglacial range expansion also were observed in Pinus (Cwynar and MacDonald, 1987;Parker et al, 1997) and Chamaecyparis (Kuser et al, 1997). Based on our data, we propose that C. glabra migrated to the New England and Maritime region via an Atlantic coastal route.…”

supporting

confidence: 78%

“…Previous research also demonstrated that the potential for hybridization and polyploidy was influenced greatly by ecohistorical factors, such as the pronounced geoclimatic changes and subsequent plant migrations during the Quaternary Period (Ehrendorfer, 1959;Stebbins, 1971). In eastern North America, the repeated expansion, contraction, fragmentation, and amalgamation of species' ranges during the Pleistocene and Holocene epochs, which began two million years ago (Cain, 1944;Holt and Paterson, 1970;Jacobs, Werth, and Guttman, 1984 court and Delcourt, 1987;Delcourt, 1991), undoubtedly resulted in new contacts between previously isolated populations Kuser et al, 1997), increased the probability of interlineage hybridization and introgression Parker et al, 1997), and led to extinctions of progenitor taxa (Werth, 1991).…”

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confidence: 99%

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Polyploid evolution and biogeography inChelone(Scrophulariaceae): morphological and isozyme evidence

Nelson

Elisens

1999

American J of Botany

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Chelone is a genus of perennial herbs comprising three diploid species (C. cuthbertii, C. glabra, and C. lyonii) and a fourth species (C. obliqua) that occurs as tetraploid and hexaploid races. To assess patterns of isozyme and morphological variation, and to test hypotheses of hybridization and allopolyploidy, we analyzed variation among 16 isozyme loci from 61 populations and 16 morphological characters from 33 populations representing all taxa and ploidy levels. Based on morphological analyses using clustering (unweighted pair group method using an arithmetic average) and ordination (principal components analysis and canonical variance analysis) methods, we recognize three diploid species without infraspecific taxa. Polyploids in the C. obliqua complex were most similar morphologically to diploid populations of C. glabra and C. lyonii. Patterns of isozyme variation among polyploids, which included fixed heterozygosity and recombinant profiles of alleles present in diploids, suggested polytopic origins of tetraploids and hexaploids. Our data indicate independent origins of polyploids in or near the southern Blue Ridge, Interior Highlands and Plains, and Atlantic Coastal Plain regions from progenitors most similar to C. glabra and C. lyonii. Extant tetraploids were not implicated in evolution of hexaploids, and plants similar to C. cuthbertii appeared unlikely as diploid progenitors for polyploids. We propose multiple differentiation and hybridization/polyploidization cycles in different geographic regions to explain the pattern of allopatry and inferred polytopic origins among polyploids.

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supporting

confidence: 78%

mentioning

confidence: 99%

Polyploid evolution and biogeography inChelone(Scrophulariaceae): morphological and isozyme evidence

Nelson

Elisens

1999

American J of Botany

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“…In several studies, patterns of genetic variation along the geographical range of tree species using isozymes have been explained by Pleistocene environmental changes ( Fowler & Morris, 1977; Cwynar & MacDonald, 1987; Sherman‐Broyles et al. , 1992 ; Zabinski, 1992; Kuser et al. , 1997 ; Parker et al.…”

Section: Introductionmentioning

confidence: 99%

“…Genetic markers such as isozymes have been used to locate glacial refugia and to trace migration routes after glacial retreat of Northern Hemisphere plant taxa yielding comparable results to those gathered from the pollen record (Wheeler & Guries, 1982). In several studies, patterns of genetic variation along the geographical range of tree species using isozymes have been explained by Pleistocene environmental changes (Fowler & Morris, 1977;Cwynar & MacDonald, 1987;Sherman-Broyles et al, 1992;Zabinski, 1992;Kuser et al , 1997;Parker et al , 1997).…”

Section: Introductionmentioning

confidence: 99%

Isozyme variation and recent biogeographical history of the long‐lived conifer Fitzroya cupressoides

Premoli

Kitzberger

Veblen

2000

Journal of Biogeography

143

138

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Aim Palaeoenvironmental records of Pleistocene glaciation and associated vegetation changes in Patagonia have led to the hypothesis that during the last glacial maximum (LGM) tree species survived locally in favourable habitats. If present populations originated from spread from only one refugium, such as an ice‐free area of coastal Chile (Single Refugium hypothesis), we would expect that eastern populations would be genetically depauperate and highly similar to western populations. In contrast, if the ice cap was not complete and tree species persisted in forest patches on both slopes of the Andes (Multiple Refugia hypothesis), we would expect a greater degree of genetic divergence between populations either on opposite sides of the Cordillera (Cordillera Effect scenario) or towards its present‐day southern distributional limit where the ice sheet reached its maximum coverage (Extent‐of‐the‐Ice scenario). Location We tested this refugia hypothesis using patterns of isozyme variation in populations sampled over the entire modern range of the endemic conifer Fitzroya cupressoides (Mol.) Johnst. (Cupressaceae) in temperate South America. Methods Fresh foliage was collected from twenty‐four populations and analysed by horizontal electrophoresis on starch gels. Results Twenty‐one putative loci were reliably scored and 52% were polymorphic in at least one population. Populations from the eastern slope of the Andes were genetically more variable than those from the western slope; the former had a greater mean number of alleles per locus, a larger total number of alleles and rare alleles, and higher polymorphism. Genetic identities within western populations were greater than within eastern populations. Discriminant analyses using allelic frequencies of different grouping schedules of populations were non significant when testing for the Single Refugium hypothesis whereas significant results were obtained for the Multiple Refugia hypothesis. Main conclusions Our results indicate that present Fitzroya populations are the result of spreading from at least two, but possibly more, glacial refugia located in Coastal Chile and on the southern flanks of the Andes in Argentina.

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“…Thus, geographical distribution of genetic variation can provide an alternative source of information on past events which in turn is independent from the fossil record (Cwynar & MacDonald, 1987;Lagercrantz & Ryman, 1990;Schnable et al , 1993;Kuser et al , 1997;Ledig, 2000;among others). Thus, geographical distribution of genetic variation can provide an alternative source of information on past events which in turn is independent from the fossil record (Cwynar & MacDonald, 1987;Lagercrantz & Ryman, 1990;Schnable et al , 1993;Kuser et al , 1997;Ledig, 2000;among others).…”

Section: Introductionmentioning

confidence: 99%

Patterns of isozyme variation as indicators of biogeographic history in Pilgerodendron uviferum (D. Don) Florín

Premoli¹,

Souto²,

Rovere³

et al. 2002

Diversity and Distributions

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The effects of Pleistocene glaciations on the genetic characteristics of the most austral conifer in the world, Pilgerodendron uviferum , were analysed with specific reference to the hypothesis that the species persisted locally in ice-free areas in temperate South America. It was expected that genetic variation would decrease with latitude, given that ice fields were larger in southern Patagonia and thus refugia were probably located towards the northern distributional limit of the species as suggested by the fossil record. In addition, an increase in among-population genetic divergence was expected with increasing distance to putative glacial refugia. We examined the relationship between location and within-population variability indices of 20 Pilgerodendron populations derived from isozyme analyses. We analysed possible refugia hypotheses by the distribution of allele frequencies using multivariate discriminant analysis. The degree of genetic differentiation with geographical distance between all population pairs was investigated by Mantel tests. Results indicated that Pilgerodendron populations are highly monomorphic, probably reflecting past population bottlenecks and reduced gene flow. Southernmost populations tend to be the least genetically variable and were therefore probably more affected by glacial activity than northern ones. Populations located outside ice limits seem to have been isolated during the glacial period. The presence of centres of genetic diversity, together with the lack of a significant correlation between genetic and geographical distances and the absence of geographical patterns of allelic frequencies at most analysed alleles, may indicate that Pilgerodendron did not advance southward after the last glaciation from a unique northern refugium, but spread from several surviving populations in ice-free areas in Patagonia instead.

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Allozyme frequencies in New Jersey and North Carolina populations of Atlantic white‐cedar, Chamaecyparis thyoides (Cupressaceae)

Cited by 13 publications

References 13 publications

Polyploid evolution and biogeography inChelone(Scrophulariaceae): morphological and isozyme evidence

Polyploid evolution and biogeography inChelone(Scrophulariaceae): morphological and isozyme evidence

Isozyme variation and recent biogeographical history of the long‐lived conifer Fitzroya cupressoides

Patterns of isozyme variation as indicators of biogeographic history in Pilgerodendron uviferum (D. Don) Florín

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