Hybrid swarms: catalysts for multiple evolutionary events in<i>Senecio</i>in the British Isles

Lowe, Andrew J.; Abbott, Richard J.

doi:10.1080/17550874.2015.1028113

Cited by 9 publications

(9 citation statements)

References 44 publications

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“…However, our genomic analyses suggest that the genetic distinctness of E. micrantha may be a feature of the Fair Isle population rather than the species as a whole. This could be a consequence of regional differentiation caused by strong drift and the local fixation of genomic incompatibilities, local hybridization, or polytopic origins as seen in other polyploids ( Schwarzbach and Rieseberg, 2002 ; Soltis et al., 2004 ; Ainouche et al., 2012 ; Lowe and Abbott, 2015 ).…”

Section: Discussionmentioning

confidence: 99%

Maintenance of Species Differences in Closely Related Tetraploid Parasitic Euphrasia (Orobanchaceae) on an Isolated Island

Becher

Powell

et al. 2020

Plant Communications

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Polyploidy is pervasive in angiosperm evolution and plays important roles in adaptation and speciation. However, polyploid groups are understudied due to complex sequence homology, challenging genome assembly, and taxonomic complexity. Here, we study adaptive divergence in taxonomically complex eyebrights ( Euphrasia ), where recent divergence, phenotypic plasticity, and hybridization blur species boundaries. We focus on three closely related tetraploid species with contrasting ecological preferences that are sympatric on Fair Isle, a small isolated island in the British Isles. Using a common garden experiment, we show a genetic component to the morphological differences present between these species. Using whole-genome sequencing and a novel k-mer approach we call “Tetmer”, we demonstrate that the species are of allopolyploid origin, with a sub-genome divergence of approximately 5%. Using ∼2 million SNPs, we show sub-genome homology across species, with a very low sequence divergence characteristic of recent speciation. This genetic variation is broadly structured by species, with clear divergence of Fair Isle heathland Euphrasia micrantha , while grassland Euphrasia arctica and coastal Euphrasia foulaensis are more closely related. Overall, we show that tetraploid Euphrasia is a system of allopolyploids of postglacial species divergence, where adaptation to novel environments may be conferred by old variants rearranged into new genetic lineages.

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Section: Discussionmentioning

confidence: 99%

Maintenance of Species Differences in Closely Related Tetraploid Parasitic Euphrasia (Orobanchaceae) on an Isolated Island

Becher

Powell

et al. 2020

Plant Communications

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“…) or stabilised introgressants ( e.g . Lowe & Abbott ). Additionally, in many species, hybridisation is associated with changes in ploidy level, either resulting from hybridisation between heteroploid entities or resulting from genome duplications after homoploid hybridisation (Fig.…”

Section: Introductionmentioning

confidence: 99%

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

et al. 2017

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Natural hybridisation and polyploidy are currently recognised as drivers of biodiversity, despite early scepticism about their importance. The Mediterranean region is a biodiversity hotspot where geological and climatic events have created numerous opportunities for speciation through hybridisation and polyploidy. Still, our knowledge on the frequency of these mechanisms in the region is largely limited, despite both phenomena are frequently cited in studies of Mediterranean plants. We reviewed information available from biodiversity and cytogenetic databases to provide the first estimates of hybridisation and polyploidy frequency in the Mediterranean region. We also inspected the most comprehensive modern Mediterranean Flora (Flora iberica) to survey the frequency and taxonomic distribution of hybrids and polyploids in Iberian Peninsula. We found that <6% of Mediterranean plants were hybrids, although a higher frequency was estimated for the Iberian Peninsula (13%). Hybrids were concentrated in few families and in even fewer genera. The overall frequency of polyploidy (36.5%) was comparable with previous estimates in other regions; however our estimates increased when analysing the Iberian Peninsula (48.8%). A surprisingly high incidence of species harbouring two or more ploidy levels was also observed (21.7%). A review of the available literature also showed that the ecological factors driving emergence and establishment of new entities are still poorly studied in the Mediterranean flora, although geographic barriers seem to play a major role in polyploid complexes. Finally, this study reveals several gaps and limitations in our current knowledge about the frequency of hybridisation and polyploidy in the Mediterranean region. The obtained estimates might change in the future with the increasing number of studies; still, rather than setting the complete reality, we hope that this work triggers future studies on hybridisation and polyploidy in the Mediterranean region.

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“…However, our genomic analyses suggest the genetic distinctness of E. micrantha may be a feature of the Fair Isle population rather than the species as a whole. This could be a consequence regional differentiation caused by strong drift and the local fixation of genomic incompatibilities, local hybridisation, or polytopic origins as seen in other polyploids (Schwarzbach and Rieseberg, 2002;Soltis et al, 2004;Ainouche et al, 2012;Lowe and Abbott, 2015).…”

Section: Discussionmentioning

confidence: 99%

Maintenance of species differences in closely related tetraploid parasiticEuphrasia(Orobanchaceae) on an isolated island

Becher

Powell

et al. 2020

Preprint

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Polyploidy is pervasive in angiosperm evolution and plays important roles in adaptation and speciation. However, polyploid groups are understudied due to complex sequence homology, challenging genome assembly, and taxonomic complexity. Here we study adaptive divergence in taxonomically complex eyebrights (Euphrasia), where recent divergence, phenotypic plasticity and hybridisation blur species boundaries. We focus on three closely-related tetraploid species with contrasting ecological preferences, and which are sympatric on Fair Isle, a small isolated island in the British Isles. Using a common garden experiment, we show a genetic component to the morphological differences present between these species. Using whole genome sequencing and a novel k-mer approach, we demonstrate an allopolyploid origin, with sub-genome divergence of approximately 5%. Using ~2 million SNPs we show sub-genome homology across species consistent with a common origin, with very low sequence divergence characteristic of recent speciation. This genetic variation is broadly structured by species, with clear divergence of Fair Isle heathland E. micrantha, while grassland E. arctica and coastal E. foulaensis are more closely related. Overall, we show tetraploid Euphrasia is an allopolyploid system characterised by postglacial species divergence, where adaptation to novel environments may be conferred by old variants rearranged into new genetic lineages.

show abstract

Hybrid swarms: catalysts for multiple evolutionary events inSenecioin the British Isles

Cited by 9 publications

References 44 publications

Maintenance of Species Differences in Closely Related Tetraploid Parasitic Euphrasia (Orobanchaceae) on an Isolated Island

Maintenance of Species Differences in Closely Related Tetraploid Parasitic Euphrasia (Orobanchaceae) on an Isolated Island

How much do we know about the frequency of hybridisation and polyploidy in the Mediterranean region?

Maintenance of species differences in closely related tetraploid parasiticEuphrasia(Orobanchaceae) on an isolated island

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