Does Large Genome Size Limit Speciation in Endemic Island Floras?

Kapralov, Maxim V.; Filatov, Dmitry A.

doi:10.1155/2011/458684

Cited by 12 publications

(15 citation statements)

References 38 publications

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“…crassifolius. Notwithstanding, while the reduction of GS observed here is in line with the current view that larger GSs might limit speciation in island floras (Kapralov & Filatov, 2011), it remains to be demonstrated whether the increase in number of rDNA loci has been relevant for the colonisation and subsequent explosive radiation of Cheirolophus in the Canary and Madeira archipelagos. Chromosome numbers in bold are those that are new or reassessed/confirmed in this study.…”

Section: Discussionsupporting

confidence: 87%

“…-There is growing evidence that oceanic island colonisations tend to involve species with smaller GSs than their continen tal counterparts (e.g., Cheirolophus, Garnatje & al., 2007;Schiedea, Kapralov & al., 2009; Veronica L., Meudt & al., 2015). Indeed, this trend is seen even at the level of whole floras (e.g., in Macaronesia, Suda & al., 2003;2005; in Marquesas, Macaronesian and Hawaiian islands, Kapralov & Filatov, 2011). It has also been observed that genera of oceanic island floras that undergo species radiations have significantly smaller GSs than nonradiating genera (e.g., in Canarian flora, Pérez de Paz & CaujapéCastells, 2013).…”

Section: Discussionmentioning

confidence: 98%

“…However, other aspects of plant evolution, including the role of genomic (including cytogenetic) traits are also starting to receive increased at tention, and these are contributing significant and valuable new insights into plant radiations (e.g., Pachycladon Hook.f., Mandakova & al., 2010;Schiedea Cham. & Schltdl., Kapralov & al., 2009;Kapralov & Filatov, 2011). Cheirolophus is the only genus of subtribe Centaureinae to have undergone a radiation in Macaronesia.…”

Section: Cytogenetic Insights Into An Oceanic Island Radiationmentioning

confidence: 99%

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Cytogenetic insights into an oceanic island radiation: The dramatic evolution of pre‐existing traits in Cheirolophus (Asteraceae: Cardueae: Centaureinae)

Hidalgo

Vitales

Vallès

et al. 2017

TAXON

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The genus Cheirolophus constitutes one of the most striking cases of species radiation in Macaronesia, where it di versified into a lineage of ca. 20 endemic species at a rate that is amongst the fastest reported for oceanic islands. Whilst the cytogenetic dynamics of many of the Macaronesian Cheirolophus species have been comparatively well studied, an overall vision of chromosome and genome evolution has been hampered by the lack of data for the earliestdiverging species, Ch. crassifolius. In this study, we have completed the cytogenetic survey of Cheirolophus to investigate how different cytogenetic traits may have contributed to the dramatic radiation of the genus in Macaronesia. We provide new cytogenetic data (i.e., chromosome counts, genome size estimates and physical mapping of 35S rDNA loci) for several key species, including Ch. crassifolius, and then model trait evolution within a phylogenetic context. Our results reveal a trend of genome downsizing accompanied by a dramatic increase in number of 35S rDNA loci which started early in the evolutionary history of the genus, before its radiation in Macaronesia. It is notable that the increasing number of 35S rDNA loci has not been driven by polyploidisation, in contrast to the more typical trend observed in many angiosperms. In addition, the number of 35S rDNA loci was observed to negatively correlate with genome size, which is also very unusual in angiosperms. It is suggested that nonhomologous and unequal homologous recombination are the most likely mechanisms to explain these observations and we discuss whether the unique genomic architectures of Cheirolophus could have predisposed the genus to its successful and rapid speciation in Macaronesia.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 98%

Section: Cytogenetic Insights Into An Oceanic Island Radiationmentioning

confidence: 99%

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Cytogenetic insights into an oceanic island radiation: The dramatic evolution of pre‐existing traits in Cheirolophus (Asteraceae: Cardueae: Centaureinae)

Hidalgo

Vitales

Vallès

et al. 2017

TAXON

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“…range from 0.73 to 3.19 pg, including some of the highest values in the genus, but with 1Cx‐values ranging from 0.24 to 0.52 pg (2.2‐fold variation), including some of the lowest. The low 1Cx‐values found in subgenus Pseudoveronica (the only insular radiation in the genus) are in line with studies showing that insular endemic radiations in the Canary, Hawaiian and Marquesas Islands have smaller genome sizes relative to the mainland flora (Suda, Kyncl & Jarolímová, ; Kapralov & Filatov, ). The extent to which the New Zealand endemic flora follows this pattern is unknown, as phylogenetic studies of genome size are lacking, and indeed very few (< 10%) native angiosperms have had their genome sizes estimated.…”

Section: Discussionsupporting

confidence: 82%

Is genome downsizing associated with diversification in polyploid lineages ofVeronica?

et al. 2015

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The study of genome size evolution in a phylogenetic context in related polyploid and diploid lineages can help us to understand the advantages and disadvantages of genome size changes and their effect on diversification. Here, we contribute 199 new DNA sequences and a nearly threefold increase in genome size estimates in polyploid and diploid Veronica (Plantaginaceae) (to 128 species, c. 30% of the genus) to provide a comprehensive baseline to explore the effect of genome size changes. We reconstructed internal transcribed spacer (ITS) and trnL‐trnL‐trnF phylogenetic trees and performed phylogenetic generalized least squares (PGLS), ancestral character state reconstruction, molecular dating and diversification analyses. Veronica 1C‐values range from 0.26 to 3.19 pg. Life history is significantly correlated with 1C‐value, whereas ploidy and chromosome number are strongly correlated with both 1C‐ and 1Cx‐values. The estimated ancestral Veronica 1Cx‐value is 0.65 pg, with significant genome downsizing in the polyploid Southern Hemisphere subgenus Pseudoveronica and two Northern Hemisphere subgenera, and significant genome upsizing in two diploid subgenera. These genomic downsizing events are accompanied by increased diversification rates, but a ‘core shift’ was only detected in the rate of subgenus Pseudoveronica. Polyploidy is important in the evolution of the genus, and a link between genome downsizing and polyploid diversification and species radiations is hypothesized. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 243–266.

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“…Although the concept of the LGCH was originally framed using interspecific genome size comparisons, intraspecific comparisons better control for phylogenetic differences among taxonomic groups. Furthermore, the LGCH has not been explicitly tested using manipulative experiments (but see Kapralov and Filatov 2011, Carta and Peruzzi 2016 for correlative studies) and has never been tested at the intraspecific level.…”

Section: Introductionmentioning

confidence: 99%

Plant genome size influences stress tolerance of invasive and native plants via plasticity

et al. 2020

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Citation: Meyerson, L. A., P. Py sek, M. Lu canov a, S. Wigginton, C.-T. Tran, and J. T. Cronin. 2020. Plant genome size influences stress tolerance of invasive and native plants via plasticity. Ecosphere 11(5):Abstract. Plant genome size influences the functional relationships between cellular and whole-plant physiology, but we know little about its importance to plant tolerance of environmental stressors and how it contributes to range limits and invasion success. We used native and invasive lineages of a wetland plant to provide the first experimental test of the Large Genome Constraint Hypothesis (LGCH)-that plants with large genomes are less tolerant of environmental stress and less plastic under stress gradients than plants with small genomes. We predicted that populations with larger genomes would have a lower tolerance and less plasticity to a stress gradient than populations with smaller genomes. In replicated experiments in northern and southern climates in the United States, we subjected plants from 35 populations varying in genome size and lineage to two salinity treatments. We measured traits associated with growth, physiology, nutrition, defense, and plasticity. Using AICc model selection, we found all plant traits, except stomatal conductance, were influenced by environmental stressors and genome size. Increasing salinity was stressful to plants and affected most plant traits. Notably, biomass in the high-salinity treatment was 3.0 and 4.9 times lower for the invasive and native lineages, respectively. Plants in the warmer southern greenhouse had higher biomass, stomate density, stomatal conductance, leaf toughness, and lower aboveground percentage of N and total phenolics than in the northern greenhouse. Moreover, responses to the salinity gradient were generally much stronger in the southern than northern greenhouse. Aboveground biomass increased significantly with genome size for the invasive lineage (43% across genome sizes) but not for the native. For 8 of 20 lineage trait comparisons, greenhouse location 9 genome size interaction was also significant. Interestingly, the slope of the relationship between genome size and trait means was in the opposite direction for some traits between the gardens providing mixed support for LGCH. Finally, for 30% of the comparisons, plasticity was significantly related to genome size-for some plant traits, the relationship was positive, and in others, it was negative. Overall, we found mixed support for LGCH and for the first time found that genome size is associated with plasticity, a trait widely regarded as important to invasion success.

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Does Large Genome Size Limit Speciation in Endemic Island Floras?

Cited by 12 publications

References 38 publications

Cytogenetic insights into an oceanic island radiation: The dramatic evolution of pre‐existing traits in Cheirolophus (Asteraceae: Cardueae: Centaureinae)

Cytogenetic insights into an oceanic island radiation: The dramatic evolution of pre‐existing traits in Cheirolophus (Asteraceae: Cardueae: Centaureinae)

Is genome downsizing associated with diversification in polyploid lineages ofVeronica?

Plant genome size influences stress tolerance of invasive and native plants via plasticity

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