A reexamination of the North American <i>Crepis</i> agamic complex and comparison with the findings of Babcock and Stebbins’ classic biosystematic monograph

Sears, Christopher J.; Whitton, Jeannette

doi:10.3732/ajb.1600057

Cited by 11 publications

(31 citation statements)

References 48 publications

(57 reference statements)

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“…Comparison of flow cytometry estimates of DNA content of standing individuals against known ranges for diploids and polyploids of these taxa (Sears and Whitton ) confirmed that all but one sampled C. atribarba were diploid (2C range: 10.42 –14.53 pg;

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= 13.12 ± 0.38 pg) and that C. barbigera individuals were of high ploidy (~7x–8x; 2C range: 40.83–48.77 pg;

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= 45.32 ± 0.85 pg); a single sample identified as C. atribarba (Fig. A, C = 27.33 pg) was polyploid.…”

Section: Resultsmentioning

confidence: 58%

“…In addition, natural pentaploid individuals were found in a previous census (1:14 individuals; Sears and Whitton 2016) as well as our own (1:24 individuals). We note however that the standing individuals surveyed in both our sample and that of Sears and Whitton (2016) were nonrandom and modest in number, and in our case, we intentionally did not sample individuals with intermediate morphology, so these results should not be taken as an estimate of the frequency of hybrids in the standing population. Nevertheless, the fact that we found hybrids in relatively small censuses indicates that viable hybrids can be formed in this population.…”

Section: Discussionmentioning

confidence: 93%

“…47.8358, Long. ‐120.067; Sears and Whitton ). Fourteen samples from the population were previously characterized using flow cytometry and found to contain diploid individuals of Crepis atribarba subsp.…”

Section: Methodsmentioning

confidence: 99%

“…originalis (henceforth C. atribarba ; seven samples with 2C DNA content of 12.3‐13.9 pg) and high ploidy individuals of C. barbigera (6 individuals inferred to be 7x or 8x, with 2C DNA content of 46.1–52.0 pg). A single individual of C. atribarba had a DNA content consistent with pentaploidy (2C DNA = 32.7; ploidy estimates are based on mean diploid values for each taxon from a broader survey of the agamic complex; Sears ; Sears and Whitton ). Although the samples in the previous analysis were not randomly chosen, they nonetheless suggested that both taxa are common at this site and that most C. atribarba are diploid.…”

Section: Methodsmentioning

confidence: 99%

“…We surveyed the standing population on 20 May 2014 in order to determine the suitability of the site for assessing the effects of asymmetric reproductive interference. We identified individuals as either C. barbigera or C. atribarba and collected leaf samples from a total of 24 individuals in silica gel for subsequent flow cytometric analysis of ploidy, in order to confirm ploidy levels reported from earlier surveys (Sears 2011). At the time of this initial visit, most individuals of C. atribarba had open flowers and buds, while individuals of C. barbigera were not yet flowering.…”

Section: Study Sitementioning

confidence: 99%

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Attack of the clones: reproductive interference between sexuals and asexuals in theCrepisagamic complex

Hersh

Grimm

Whitton

2016

Ecology and Evolution

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Negative reproductive interactions are likely to be strongest between close relatives and may be important in limiting local coexistence. In plants, interspecific pollen flow is common between co‐occurring close relatives and may serve as the key mechanism of reproductive interference. Agamic complexes, systems in which some populations reproduce through asexual seeds (apomixis), while others reproduce sexually, provide an opportunity to examine effects of reproductive interference in limiting coexistence. Apomictic populations experience little or no reproductive interference, because apomictic ovules cannot receive pollen from nearby sexuals. Oppositely, apomicts produce some viable pollen and can exert reproductive interference on sexuals by siring hybrids. In the Crepis agamic complex, sexuals co‐occur less often with other members of the complex, but apomicts appear to freely co‐occur with one another. We identified a mixed population and conducted a crossing experiment between sexual diploid C. atribarba and apomictic polyploid C. barbigera using pollen from sexual diploids and apomictic polyploids. Seed set was high for all treatments, and as predicted, diploid–diploid crosses produced all diploid offspring. Diploid–polyploid crosses, however, produced mainly polyploidy offspring, suggesting that non‐diploid hybrids can be formed when the two taxa meet. Furthermore, a small proportion of seeds produced in open‐pollinated flowers was also polyploid, indicating that polyploid hybrids are produced under natural conditions. Our results provide evidence for asymmetric reproductive interference, with pollen from polyploid apomicts contributing to reduce the recruitment of sexual diploids in subsequent generations. Existing models suggest that these mixed sexual–asexual populations are likely to be transient, eventually leading to eradication of sexual individuals from the population.

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\overset{X}{true}

= 13.12 ± 0.38 pg) and that C. barbigera individuals were of high ploidy (~7x–8x; 2C range: 40.83–48.77 pg;

\overset{X}{true}

= 45.32 ± 0.85 pg); a single sample identified as C. atribarba (Fig. A, C = 27.33 pg) was polyploid.…”

Section: Resultsmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

See 3 more Smart Citations

Attack of the clones: reproductive interference between sexuals and asexuals in theCrepisagamic complex

Hersh

Grimm

Whitton

2016

Ecology and Evolution

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Navigating the Challenges in Apomixis Population Genetics: Insights from Past, Present, and Future Perspectives

Karunarathne,

Reutemann,

James

et al. 2024

Critical Reviews in Plant Sciences

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Asteraceae as a model system for evolutionary studies: from fossils to genomes

Palazzesi

Pellicer

Barreda

et al. 2022

Botanical Journal of the Linnean Society

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With c. 24 700 species (10% of all flowering plants), Asteraceae are one of the largest and most phenotypically diverse angiosperm families, with considerable economic and ecological importance. Asteraceae are distributed worldwide, from nearly polar latitudes all the way to the tropics, and occur across a diverse range of habitats from extreme deserts to swamps and from lowland rainforests to alpine tundra. Altogether, these characteristics make this family an outstanding model system to address a broad range of eco-evolutionary questions. In this review, we summarize recent progress in our understanding of Asteraceae on the basis of joint efforts by specialists in the fields of palaeobotany, cytogenetics, comparative genomics and phylogenomics. We will highlight how these developments are opening up new possibilities for integrating fields and better comprehending evolution beyond Asteraceae.

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A reexamination of the North American Crepis agamic complex and comparison with the findings of Babcock and Stebbins’ classic biosystematic monograph

Cited by 11 publications

References 48 publications

Attack of the clones: reproductive interference between sexuals and asexuals in theCrepisagamic complex

Attack of the clones: reproductive interference between sexuals and asexuals in theCrepisagamic complex

Navigating the Challenges in Apomixis Population Genetics: Insights from Past, Present, and Future Perspectives

Asteraceae as a model system for evolutionary studies: from fossils to genomes

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