Weaving a Tangled Web: Divergent and Reticulate Speciation in &lt;I&gt;Boechera fendleri&lt;/I&gt; sensu lato (Brassicaceae: Boechereae)

Alexander, Patrick J.; Windham, Michael D.; Beck, James B.; Al‐Shehbaz, Ihsan A.; Allphin, Loreen; Bailey, C. Donovan

doi:10.1600/036364415x688745

Cited by 21 publications

(51 citation statements)

References 42 publications

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“…The genus Boechera (Böcher's rock cress, formerly Arabis , Brassicaceae) is a member of the tribe Boechereae (127 species in nine genera, Al‐Shehbaz, ) distributed throughout North America and Greenland (Koch et al ., , ; Kiefer et al ., ). The genus with 110 species is monophyletic (Alexander et al ., ), has a basic chromosome number x = 7 (Koch et al ., ), and is characterized by diploid sexual (2 n = 2x = 14), as well as diploid, aneuploid, and mostly triploid (2 n = 3x = 21) apomictic forms (Böcher, ; Schranz et al ., ; Alexander et al ., ). Extensive morphological variations and corresponding problematic taxonomy of the genus are due to rampant hybridization among diploid species resulting in the origin of apomictic diploid and aneuploid hybrids.…”

Section: Introductionmentioning

confidence: 97%

“…Extensive morphological variations and corresponding problematic taxonomy of the genus are due to rampant hybridization among diploid species resulting in the origin of apomictic diploid and aneuploid hybrids. Triploids have arisen multiple times through hybridization between sexual and apomictic diploid species (Alexander et al ., ) as geographically and genetically distinct populations (Sharbel and Mitchell‐Olds, ; Sharbel et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes

et al. 2015

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SUMMARYChromosome rearrangements may result in both decrease and increase of chromosome numbers. Here we have used comparative chromosome painting (CCP) to reconstruct the pathways of descending and ascending dysploidy in the genus Boechera (tribe Boechereae, Brassicaceae). We describe the origin and structure of three Boechera genomes and establish the origin of the previously described aberrant Het and Del chromosomes found in Boechera apomicts with euploid (2n = 14) and aneuploid (2n = 15) chromosome number. CCP analysis allowed us to reconstruct the origin of seven chromosomes in sexual B. stricta and apomictic B. divaricarpa from the ancestral karyotype (n = 8) of Brassicaceae lineage I. Whereas three chromosomes (BS4, BS6, and BS7) retained their ancestral structure, five chromosomes were reshuffled by reciprocal translocations to form chromosomes BS1-BS3 and BS5. The reduction of the chromosome number (from x = 8 to x = 7) was accomplished through the inactivation of a paleocentromere on chromosome BS5. In apomictic 2n = 14 plants, CCP identifies the largely heterochromatic chromosome (Het) being one of the BS1 homologues with the expansion of pericentromeric heterochromatin. In apomictic B. polyantha (2n = 15), the Het has undergone a centric fission resulting in two smaller chromosomes -the submetacentric Het 0 and telocentric Del. Here we show that new chromosomes can be formed by a centric fission and can be fixed in populations due to the apomictic mode of reproduction.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes

et al. 2015

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“…Given these results suggesting elevated heterozygosity, combined with previous results from the Boechera genus [18,25], we hypothesized that apomicts would be hybrids, where B . spatifolia represented one of the parental genotypes.…”

Section: Resultsmentioning

confidence: 87%

Mutation Accumulation in an Asexual Relative of Arabidopsis

et al. 2017

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Asexual populations experience weaker responses to natural selection, which causes deleterious mutations to accumulate over time. Additionally, stochastic loss of individuals free of deleterious mutations can lead to an irreversible increase in mutational load in asexuals (the “click” in Muller’s Ratchet). Here we report on the genomic divergence and distribution of mutations across eight sympatric pairs of sexual and apomictic (asexual) Boechera (Brassicaceae) genotypes. We show that apomicts harbor a greater number of derived mutations than sympatric sexual genotypes. Furthermore, in phylogenetically constrained sites that are subject to contemporary purifying selection, the ancestral, conserved allele is more likely to be retained in sexuals than apomicts. These results indicate that apomictic lineages accumulate mutations at otherwise conserved sites more often than sexuals, and support the conclusion that deleterious mutation accumulation can be a powerful force in the evolution of asexual higher plants.

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“…In a phylogenetic analysis incorporating data from the nuclear pistillata locus, different clone sequences from this sample associated with gracilipes , perennans and texana , respectively (13). STRUCTURE analysis of the microsatellite data available at the time for this taxon revealed admixture proportions averaging 25% gracilipes , 37% perennans and 23% texana , with a lesser contribution attributed to fendleri .…”

Section: Resultsmentioning

confidence: 99%

Boechera microsatellite website: an online portal for species identification and determination of hybrid parentage

Rushworth

Beck

et al. 2017

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Boechera (Brassicaceae) has many features to recommend it as a model genus for ecological and evolutionary research, including species richness, ecological diversity, experimental tractability and close phylogenetic proximity to Arabidopsis. However, efforts to realize the full potential of this model system have been thwarted by the frequent inability of researchers to identify their samples and place them in a broader evolutionary context. Here we present the Boechera Microsatellite Website (BMW), a portal that archives over 55 000 microsatellite allele calls from 4471 specimens (including 133 nomenclatural types). The portal includes analytical tools that utilize data from 15 microsatellite loci as a highly effective DNA barcoding system. The BMW facilitates the accurate identification of Boechera samples and the investigation of reticulate evolution among the ±83 sexual diploid taxa in the genus, thereby greatly enhancing Boechera’s potential as a model system. Database URL: http://sites.biology.duke.edu/windhamlab/

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Weaving a Tangled Web: Divergent and Reticulate Speciation in <I>Boechera fendleri</I> sensu lato (Brassicaceae: Boechereae)

Cited by 21 publications

References 42 publications

Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes

Karyotype evolution in apomictic Boechera and the origin of the aberrant chromosomes

Mutation Accumulation in an Asexual Relative of Arabidopsis

Boechera microsatellite website: an online portal for species identification and determination of hybrid parentage

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