GENETIC AND BIOCHEMICAL CONSEQUENCES OF POLYPLOIDY IN
            <i>TRAGOPOGON</i>

Roose, Mikeal L.; Gottlieb, L. D.

doi:10.1111/j.1558-5646.1976.tb00963.x

Cited by 269 publications

(202 citation statements)

References 38 publications

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“…The high level of genetic differentiation detected by cDNA-AFLPs between the diploid progenitor species T. dubius and T. pratensis (38.4% in the preliminary study and 35.2% in the extended study) is consistent with previous Tragopogon studies based on allozymes, RAPDs, and chloroplast DNA restriction site data, which showed wide divergence among the T. dubius, T. pratensis, and T. porrifolius genomes (Roose and Gottlieb 1976;Soltis and Soltis 1989;Soltis et al 1995;Cook et al 1998). Recent phylogenetic analyses of Tragopogon using internal and external transcribed spacer sequence data also indicate that T. dubius and T. pratensis are well differentiated, with these two species placed in separate major clades, further attesting to their divergent evolutionary histories (Mavrodiev et al 2005).…”

Section: Discussionsupporting

confidence: 78%

“…Following the introduction of three diploid (2n ¼ 12) species (Tragopogon dubius, T. pratensis, and T. porrifolius) from Europe to western North America during the early 1900s, two allotetraploid species (T. mirus and T. miscellus) formed (Ownbey 1950). The ancestries of both allotetraploids were confirmed through flavonoid, isozymic, and DNA studies (Ownbey andMcCollum 1953, 1954;Brehm and Ownbey 1965;Roose and Gottlieb 1976;Soltis and Soltis 1989;Soltis et al 1995;Cook et al 1998). Molecular data indicate that T. miscellus and T. mirus have formed repeatedly, perhaps as many as 21 and 13 times, respectively, in just the past 80 years (reviewed in Soltis et al 2004).…”

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confidence: 98%

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Evolution and Expression of Homeologous Loci in Tragopogon miscellus (Asteraceae), a Recent and Reciprocally Formed Allopolyploid

et al. 2006

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On both recent and ancient time scales, polyploidy (genome doubling) has been a significant evolutionary force in plants. Here, we examined multiple individuals from reciprocally formed populations of Tragopogon miscellus, an allotetraploid that formed repeatedly within the last 80 years from the diploids T. dubius and T. pratensis. Using cDNA-AFLPs followed by genomic and cDNA cleaved amplified polymorphic sequence (CAPS) analyses, we found differences in the evolution and expression of homeologous loci in T. miscellus. Fragment variation within T. miscellus, possibly attributable to reciprocal formation, comprised 0.6% of the cDNA-AFLP bands. Genomic and cDNA CAPS analyses of 10 candidate genes revealed that only one ''transcript-derived fragment'' (TDF44) showed differential expression of parental homeologs in T. miscellus; the T. pratensis homeolog was preferentially expressed by most polyploids in both populations. Most of the cDNA-AFLP polymorphisms apparently resulted from loss of parental fragments in the polyploids. Importantly, changes at the genomic level have occurred stochastically among individuals within the independently formed populations. Synthetic F 1 hybrids between putative diploid progenitors are additive of their parental genomes, suggesting that polyploidization rather than hybridization induces genomic changes in Tragopogon. P OLYPLOIDY, or genome doubling, has been an important process in many eukaryotic lineages, particularly in flowering plants. Recent genome-level studies have revealed that even the model ''diploid'' plant Arabidopsis thaliana has undergone several rounds of whole-genome duplication (Vision et al. 2000;Blanc et al. 2003;Bowers et al. 2003;Blanc and Wolfe 2004b). Many polyploid plants are allopolyploids, having arisen through hybridization between genetically distinct entities (usually species) and chromosome doubling. This combination of divergent but compatible genomes in allopolyploids may provide a novel substrate for evolutionary processes (Stebbins 1950;Levin 1983;Grant 2002;Osborn et al. 2003). As all genes in allopolyploids are duplicated, a number of possibilities exist for the evolutionary fate of the homeologs (genes duplicated by polyploidy). Theory predicts three potential outcomes for these duplicated genes: (1) both copies are retained and remain functional, (2) one copy retains the original function while the other copy is lost or silenced, or (3) the two copies diverge such that each copy assumes only a part of the original gene function (subfunctionalization) or one copy acquires a new function (neofunctionalization) (Ohno 1970;Lynch and Conery 2000;Prince and Pickett 2002).In recent years, studies of genome evolution and gene expression have been in the foreground of polyploidy research (Leitch and Bennett 1997;Soltis and Soltis 1999;Wendel 2000;Liu and Wendel 2003). Much of this work has been conducted on Arabidopsis (Comai et al. 2000;Lee and Chen 2001), Brassica (Lukens et al. 2004Pires et al. 2004b), and crop plants, such as wheat (Feld...

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Section: Discussionsupporting

confidence: 78%

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confidence: 98%

Evolution and Expression of Homeologous Loci in Tragopogon miscellus (Asteraceae), a Recent and Reciprocally Formed Allopolyploid

et al. 2006

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“…The Hawaiian silversword alliance appears to have descended from an interspecific hybrid between members of two extant North American tarweed lineages (16). Polyploidy, which is believed to be an important avenue for plant species formation (38)(39)(40), may be associated with increases in genetic heterozygosity (41), chromosomal diversification (42), and phenotypic variation (43,44). Gene duplication events, such as those observed under polyploidy, may also result in increased rates of nonsynonymous nucleotide substitutions (45,46).…”

Section: Accelerated Regulatory Gene Evolution and Adaptive Radiationmentioning

confidence: 99%

Accelerated regulatory gene evolution in an adaptive radiation

Barrier

Robichaux

Purugganan

2001

Proc. Natl. Acad. Sci. U.S.A.

183

110

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The disparity between rates of morphological and molecular evolution remains a key paradox in evolutionary genetics. A proposed resolution to this paradox has been the conjecture that morphological evolution proceeds via diversification in regulatory loci, and that phenotypic evolution may correlate better with regulatory gene divergence. This conjecture can be tested by examining rates of regulatory gene evolution in species that display rapid morphological diversification within adaptive radiations. We have isolated homologues to the Arabidopsis APETALA3 (ASAP3͞TM6) and APETALA1 (ASAP1) floral regulatory genes and the CHLOROPHYLL A͞B BINDING PROTEIN9 (ASCAB9) photosynthetic structural gene from species in the Hawaiian silversword alliance, a premier example of plant adaptive radiation. We have compared rates of regulatory and structural gene evolution in the Hawaiian species to those in related species of North American tarweeds. Molecular evolutionary analyses indicate significant increases in nonsynonymous relative to synonymous nucleotide substitution rates in the ASAP3͞TM6 and ASAP1 regulatory genes in the rapidly evolving Hawaiian species. By contrast, no general increase is evident in neutral mutation rates for these loci in the Hawaiian species. An increase in nonsynonymous relative to synonymous nucleotide substitution rate is also evident in the ASCAB9 structural gene in the Hawaiian species, but not to the extent displayed in the regulatory loci. The significantly accelerated rates of regulatory gene evolution in the Hawaiian species may reflect the influence of allopolyploidy or of selection and adaptive divergence. The analyses suggest that accelerated rates of regulatory gene evolution may accompany rapid morphological diversification in adaptive radiations.floral regulatory loci ͉ MADS-box ͉ CAB9 ͉ Hawaiian silversword alliance R ates of morphological evolution are generally not correlated with rates of molecular evolution. This paradoxical observation was highlighted early by Wilson and coworkers (1-3), and subsequent molecular studies in species groups that have undergone recent adaptive radiations, such as African rift lake cichlids (4), columbines (5), and the Hawaiian silversword alliance (6), have documented marked incongruities in rates of morphological and molecular evolution. A proposed resolution to this paradox has been the conjecture that evolutionary changes in regulatory genes, rather than large-scale diversification in structural genes, may be responsible for interspecific variation in organismal morphologies (1)(2)(3)(7)(8)(9). This conjecture is reinforced by molecular developmental studies that indicate that dramatic shifts in organismal structure may arise from mutations at key regulatory loci (7-9). One test of this conjecture is to examine whether there is a significant acceleration in rates of regulatory gene evolution in species that display rapid morphological diversification within adaptive radiations.The Hawaiian silversword alliance (Asteraceae: Heliantheae-Madiinae) is...

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“…Eight percent polyacrylamide gels and Poulik (1957) buffers were used for MDH; 6% and 7% polyacrylamide gels and Roose & Gottlieb (1976) buffers were used for a-GPDH and AMY, respectively. Gels were run at a voltage gradient of 10V/cm until the front line was 9 cm from the origin.…”

Section: Electrophoresismentioning

confidence: 99%

Genetic variability and social structure of colonies in Acromyrmex heyeri and A. striatus (Hymenoptera: Formicidae)

2001

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The breeding structure of both colony and population of social insects can be examined by genetic analysis. Colonies of the leaf-cutting ants Acromyrmex heyeri and A. striatus (Myrmicinae, Attini) were thus analyzed for isoenzyme systems MDH, a-GPDH, and AMY to describe genotype variability and social structure. A total of five loci were investigated (three for amylase and one for each other system). Ninety-seven colonies of A. heyeri and 103 of A. striatus were sampled in different localities in Southern Brazil (State of Rio Grande do Sul). The genotypes found show the occurrence of monogyny and polygyny associated or not with polyandry, which indicates that the social organization is colony-specific. The polygyny and polyandry observed are likely to be responsible for the great genotypic diversity of the colonies. The average inbreeding coefficient per colony was higher in A. striatus than in A. heyeri, which may reflect the different patterns of production of sexual individuals and nuptial flight of those two species.Key words: Attini, genetic polymorphism, breeding structure, leaf-cutter ants. RESUMOVariabilidade genética e estrutura social das colônias de Acromyrmex heyeri e A. striatus (Hymenoptera, Formicidae)A estrutura de cruzamento de colônias e populações de insetos sociais pode ser observada por análise genética. Assim, colônias de formigas cortadeiras Acromyrmex heyeri e A. striatus (Myrmicinae, Attini) foram analisadas para os sistemas isoenzimáticos MDH, a-GPDH e AMY, a fim de descrever sua variabilidade genotípica e estrutura social. Foram investigados cinco locos (três para amilase e um para cada outro sistema), em 97 colônias de A. heyeri e 103 de A. striatus, amostradas em diversas localidades do Rio Grande do Sul. Os genótipos encontrados indicaram a ocorrência de monoginia e poliginia associadas ou não à poliandria, indicando que a organização social é colônia específica. Tanto a poliginia quanto a poliandria são responsáveis pela grande diversidade genotípica das colônias. O coeficiente de endocruzamento médio por colônia foi mais alto em A. striatus do que em A. heyeri e pode refletir os diferentes padrões de produção dos indivíduos sexuados e de vôo nupcial das duas espécies.Palavras-chave: Attini, polimorfismo genético, estrutura de cruzamento, formigas cortadeiras.Braz. J. Biol., 61(4): 667-678 668 DIEHL, E., ARAÚJO, A. M. de and CAVALLI-MOLINA, S.

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GENETIC AND BIOCHEMICAL CONSEQUENCES OF POLYPLOIDY IN TRAGOPOGON

Cited by 269 publications

References 38 publications

Evolution and Expression of Homeologous Loci in Tragopogon miscellus (Asteraceae), a Recent and Reciprocally Formed Allopolyploid

Evolution and Expression of Homeologous Loci in Tragopogon miscellus (Asteraceae), a Recent and Reciprocally Formed Allopolyploid

Accelerated regulatory gene evolution in an adaptive radiation

Genetic variability and social structure of colonies in Acromyrmex heyeri and A. striatus (Hymenoptera: Formicidae)

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