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Chumová Z, Monier Z, Šemberová K, Havlíčková E, Euston-Brown D, Muasya AM, Bergh NG, Trávníček P. Diploid and tetraploid cytotypes of the flagship Cape species Dicerothamnus rhinocerotis (Asteraceae): variation in distribution, ecological niche, morphology and genetics. Ann Bot 2024; 133:851-870. [PMID: 37410810 PMCID: PMC11082512 DOI: 10.1093/aob/mcad084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/04/2023] [Indexed: 07/08/2023]
Abstract
BACKGROUND AND AIMS The Greater Cape Floristic Region is one of the world's biodiversity hotspots and is considered poor in polyploids. To test this assumption, ploidy variation was investigated in a widespread Cape shrub, Dicerothamnus rhinocerotis (renosterbos, Asteraceae). The aim was to elucidate the cytotype distribution and population composition across the species range, and to assess differences in morphology, environmental niches and genetics. METHODS Ploidy level and genome size were determined via flow cytometry and cytotype assignment was confirmed by chromosome counting. Restriction site-associated DNA sequencing (RADseq) analyses were used to infer genetic relationships. Cytotype climatic and environmental niches were compared using a range of environmental layers and a soil model, while morphological differences were examined using multivariate methods. KEY RESULTS The survey of 171 populations and 2370 individuals showed that the species comprises diploid and tetraploid cytotypes, no intermediates and only 16.8 % of mixed populations. Mean 2C values were 1.80-2.06 pg for diploids and 3.48-3.80 pg for tetraploids, with very similar monoploid genome sizes. Intra-cytotype variation showed a significant positive correlation with altitude and longitude in both cytotypes and with latitude in diploids. Although niches of both cytotypes were highly equivalent and similar, their optima and breadth were shifted due to differences mainly in isothermality and available water capacity. Morphometric analyses showed significant differences in the leaves and corolla traits, the number of florets per capitulum, and cypsela dimensions between the two cytotypes. Genetic analyses revealed four groups, three of them including both cytotypes. CONCLUSIONS Dicerothamnus rhinocerotis includes two distinct cytotypes that are genetically similar. While tetraploids arise several times independently within different genetic groups, morphological and ecological differences are evident between cytotypes. Our results open up new avenues for questions regarding the importance of ploidy in the megadiverse Cape flora, and exemplify the need for population-based studies focused on ploidy variation.
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Affiliation(s)
- Zuzana Chumová
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
| | - Zafar Monier
- Bolus Herbarium, Department of Biological Sciences, University of Cape Town, Cape Town, 7707, South Africa
| | - Kristýna Šemberová
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
| | - Eliška Havlíčková
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
- Department of Botany, Faculty of Science, Charles University, Benátská 2, Prague, 120 00, Czech Republic
| | | | - A Muthama Muasya
- Bolus Herbarium, Department of Biological Sciences, University of Cape Town, Cape Town, 7707, South Africa
| | - Nicola G Bergh
- Bolus Herbarium, Department of Biological Sciences, University of Cape Town, Cape Town, 7707, South Africa
- The Compton Herbarium, Kirstenbosch National Botanical Gardens, Cape Town, 7735, South Africa
| | - Pavel Trávníček
- Institute of Botany of the Czech Academy of Sciences, Zámek 1, Průhonice, 252 43, Czech Republic
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Blanco-Gavaldà C, Galbany-Casals M, Susanna A, Andrés-Sánchez S, Bayer RJ, Brochmann C, Cron GV, Bergh NG, Garcia-Jacas N, Gizaw A, Kandziora M, Kolář F, López-Alvarado J, Leliaert F, Letsara R, Moreyra LD, Razafimandimbison SG, Schmickl R, Roquet C. Repeatedly Northwards and Upwards: Southern African Grasslands Fuel the Colonization of the African Sky Islands in Helichrysum (Compositae). Plants (Basel) 2023; 12:plants12112213. [PMID: 37299192 DOI: 10.3390/plants12112213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/17/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023]
Abstract
The Afromontane and Afroalpine areas constitute some of the main biodiversity hotspots of Africa. They are particularly rich in plant endemics, but the biogeographic origins and evolutionary processes leading to this outstanding diversity are poorly understood. We performed phylogenomic and biogeographic analyses of one of the most species-rich plant genera in these mountains, Helichrysum (Compositae-Gnaphalieae). Most previous studies have focused on Afroalpine elements of Eurasian origin, and the southern African origin of Helichrysum provides an interesting counterexample. We obtained a comprehensive nuclear dataset from 304 species (≈50% of the genus) using target-enrichment with the Compositae1061 probe set. Summary-coalescent and concatenation approaches combined with paralog recovery yielded congruent, well-resolved phylogenies. Ancestral range estimations revealed that Helichrysum originated in arid southern Africa, whereas the southern African grasslands were the source of most lineages that dispersed within and outside Africa. Colonization of the tropical Afromontane and Afroalpine areas occurred repeatedly throughout the Miocene-Pliocene. This timing coincides with mountain uplift and the onset of glacial cycles, which together may have facilitated both speciation and intermountain gene flow, contributing to the evolution of the Afroalpine flora.
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Affiliation(s)
- Carme Blanco-Gavaldà
- Systematics and Evolution of Vascular Plants-Associated Unit to CSIC by IBB, Department of Animal Biology, Plant Biology and Ecology, Faculty of Biosciences, Autonomous University of Barcelona, ES-08193 Bellaterra, Spain
| | - Mercè Galbany-Casals
- Systematics and Evolution of Vascular Plants-Associated Unit to CSIC by IBB, Department of Animal Biology, Plant Biology and Ecology, Faculty of Biosciences, Autonomous University of Barcelona, ES-08193 Bellaterra, Spain
| | - Alfonso Susanna
- Botanic Institute of Barcelona (IBB), CSIC-Ajuntament de Barcelona, Pg. Migdia s/n, ES-08038 Barcelona, Spain
| | - Santiago Andrés-Sánchez
- Department of Botany and Plant Physiology and Plant DNA Biobank, DNA National Bank, University of Salamanca, Edificio I+D+i, Espejo St., ES-37007 Salamanca, Spain
| | - Randall J Bayer
- Department of Biological Sciences, Center for Biodiversity, University of Memphis, Memphis, TN 38152, USA
| | - Christian Brochmann
- Natural History Museum, University of Oslo, P.O. Box 1172, NO-0318 Oslo, Norway
| | - Glynis V Cron
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag 3, Johannesburg 2050, South Africa
| | - Nicola G Bergh
- Foundational Biodiversity Science, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Newlands, Cape Town 7735, South Africa
| | - Núria Garcia-Jacas
- Botanic Institute of Barcelona (IBB), CSIC-Ajuntament de Barcelona, Pg. Migdia s/n, ES-08038 Barcelona, Spain
| | - Abel Gizaw
- Natural History Museum, University of Oslo, P.O. Box 1172, NO-0318 Oslo, Norway
- Department of Plant Biology and Biodiversity Management, Addis Ababa University, Addis Ababa P.O. Box 3434, Ethiopia
| | - Martha Kandziora
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801 Prague, Czech Republic
| | - Filip Kolář
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801 Prague, Czech Republic
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-25243 Průhonice, Czech Republic
| | - Javier López-Alvarado
- Systematics and Evolution of Vascular Plants-Associated Unit to CSIC by IBB, Department of Animal Biology, Plant Biology and Ecology, Faculty of Biosciences, Autonomous University of Barcelona, ES-08193 Bellaterra, Spain
| | | | - Rokiman Letsara
- Herbarium of the Parc Botanique et Zoologique of Tsimbazaza (PBZT), Antananarivo 3G9G+V6C, Madagascar
| | - Lucía D Moreyra
- Botanic Institute of Barcelona (IBB), CSIC-Ajuntament de Barcelona, Pg. Migdia s/n, ES-08038 Barcelona, Spain
| | | | - Roswitha Schmickl
- Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-12801 Prague, Czech Republic
- Institute of Botany, Academy of Sciences of the Czech Republic, CZ-25243 Průhonice, Czech Republic
| | - Cristina Roquet
- Systematics and Evolution of Vascular Plants-Associated Unit to CSIC by IBB, Department of Animal Biology, Plant Biology and Ecology, Faculty of Biosciences, Autonomous University of Barcelona, ES-08193 Bellaterra, Spain
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Kemp JE, Bergh NG, Soares M, Ellis AG. Dominant pollinators drive non-random community assembly and shared flower colour patterns in daisy communities. Ann Bot 2019; 123:277-288. [PMID: 29992277 PMCID: PMC6344215 DOI: 10.1093/aob/mcy126] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/13/2018] [Indexed: 05/20/2023]
Abstract
Background and Aims As most plants rely on pollination for persistence in communities, pollination interactions should be important determinants of plant community assembly. Here, trait and phylogenetic null modelling approaches were combined with pollinator interaction networks to elucidate the processes structuring flower colour assembly patterns in Asteraceae communities in Namaqualand, South Africa. Methods Plant species were assigned to flower colour pattern categories (CPCs) that incorporate the complexity of the bulls-eye colour pattern, using pollinator vision models. Null models were used to assess whether daisy communities exhibit clustering (driven by filtering, facilitation or convergence) or overdispersion (driven by competitive exclusion or character displacement) of CPCs. Next, flower visitor networks were constructed for communities with non-random CPC assembly to confirm the functional role of pollinators in determining floral trait assembly. Key Results Plant species are unevenly distributed across CPCs, the majority of which are not phylogenetically conserved, suggesting that certain CPCs have a selective advantage. Clustering of CPCs in communities is more frequent than overdispersion, and this does not reflect non-random phylogenetic assembly. In most communities at least one CPC is overrepresented relative to null assemblages. Interaction networks show that each community has a single dominant pollinator that strongly interacts with the overrepresented CPC, suggesting a role for pollinator preferences in driving clustered assembly of CPCs within daisy communities. Conclusion This novel approach, which demonstrates non-random assembly of complex flower colour patterns and corroborates their functional association with particular pollinators, provides strong evidence that pollinators influence plant community assembly. Results suggest that in some community contexts the benefits of pollinator sharing outweigh the costs of heterospecific pollen transfer, generating clustered assembly. They also challenge the perception of generalized pollination in daisies, suggesting instead that complex daisy colour patterns represent a pollination syndrome trait linked to specific fly pollinators.
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Affiliation(s)
- Jurene E Kemp
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
| | - Nicola G Bergh
- The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Newlands, Cape Town, South Africa
- The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Muri Soares
- The Bolus Herbarium, Department of Biological Sciences, H.W. Pearson Building, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Allan G Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland, South Africa
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Verboom GA, Bergh NG, Haiden SA, Hoffmann V, Britton MN. Topography as a driver of diversification in the Cape Floristic Region of South Africa. New Phytol 2015; 207:368-376. [PMID: 25708902 DOI: 10.1111/nph.13342] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 01/22/2015] [Indexed: 06/04/2023]
Abstract
The rugged topography of the Cape Floristic Region (CFR), South Africa, is frequently invoked to explain the spectacular radiation of the Cape flora, but the mechanisms involved remain unclear. Where recent authors emphasize the importance of elevation gradients as stimuli for ecological speciation, earlier workers stressed the role of topography as an isolating mechanism, particularly in montane lineages. Using six Cape plant lineages, we tested whether elevation niches are phylogenetically conserved. We then assessed whether high-elevation species are more consistently range-restricted than low-elevation species, and whether high-elevation sisters show stronger range exclusivity (allopatry) and weaker ecological and phenotypic differentiation, suggestive of nonecological speciation. Elevation niches tend to be phylogenetically conserved. Also, high-elevation species are more consistently range-restricted than low-elevation species, potentially explaining the generally stronger range exclusivity of high-elevation sisters. While the high-elevation zone is less homogeneous ecologically, more data are required to demonstrate that high-elevation sister species show generally weaker ecological and phenotypic differentiation. Topographic complexity promotes geographical isolation at high elevations, thereby providing opportunities for nonecological, vicariant speciation. While recognizing the need for additional data, we suggest that the upland and lowland floras of the CFR may differ with regard to predominant speciation mode.
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Affiliation(s)
- G Anthony Verboom
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, Private Bag, 7701, Rondebosch, South Africa
| | - Nicola G Bergh
- Compton Herbarium, South African National Biodiversity Institute, Private Bag X7, 7735, Claremont, South Africa
| | - Sarah A Haiden
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, Private Bag, 7701, Rondebosch, South Africa
| | - Vera Hoffmann
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, Private Bag, 7701, Rondebosch, South Africa
| | - Matthew N Britton
- Bolus Herbarium and Department of Biological Sciences, University of Cape Town, Private Bag, 7701, Rondebosch, South Africa
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Bentley J, Verboom GA, Bergh NG. Erosive processes after tectonic uplift stimulate vicariant and adaptive speciation: evolution in an Afrotemperate-endemic paper daisy genus. BMC Evol Biol 2014; 14:27. [PMID: 24524661 PMCID: PMC3927823 DOI: 10.1186/1471-2148-14-27] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 02/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The role of tectonic uplift in stimulating speciation in South Africa's only alpine zone, the Drakensberg, has not been explicitly examined. Tectonic processes may influence speciation both through the creation of novel habitats and by physically isolating plant populations. We use the Afrotemperate endemic daisy genus Macowania to explore the timing and mode (geographic versus adaptive) of speciation in this region. Between sister species pairs we expect high morphological divergence where speciation has happened in sympatry (adaptive) while with geographic (vicariant) speciation we may expect to find less morphological divergence and a greater degree of allopatry. A dated molecular phylogenetic hypothesis for Macowania elucidates species' relationships and is used to address the potential impact of uplift on diversification. Morphological divergence of a small sample of reproductive and vegetative characters, used as a proxy for adaptive divergence, is measured against species' range distributions to estimate mode of speciation across two subclades in the genus. RESULTS The Macowania crown age is consistent with the hypothesis of post-uplift diversification, and we find evidence for both vicariant and adaptive speciation between the two subclades within Macowania. Both subclades exhibit strong signals of range allopatry, suggesting that geographic isolation was important in speciation. One subclade, associated with dry, rocky environments at high altitudes, shows very little morphological and ecological differentiation but high range allopatry. The other subclade occupies a greater variety of habitats and exhibits far greater morphological differentiation, but contains species with overlapping distribution ranges. CONCLUSIONS Species in Macowania are likely to have diversified in response to tectonic uplift, and we invoke uplift and uplift-mediated erosion as the main drivers of speciation. The greater relative morphological divergence in sympatric species of Macowania indicates that speciation in the non-sympatric taxa may not have required obvious adaptive differences, implying that simple geographic isolation was the driving force for speciation ('neutral speciation').
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Bergh NG, Verboom GA. Anomalous capitulum structure and monoecy may confer flexibility in sex allocation and life history evolution in the Ifloga lineage of paper daisies (Compositae: Gnaphalieae). Am J Bot 2011; 98:1113-1127. [PMID: 21700801 DOI: 10.3732/ajb.1000457] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PREMISE OF THE STUDY Evolutionary significance of the Compositae capitulum and variation in its structure is poorly understood, although it may permit flexibility in sexual expression. Optimal sex ratio differs with life-history and reproductive strategy. We explore how the genus Ifloga and related members of southern African Gnaphalieae achieved different sex ratios, and the associations of these ratios with annual and perennial life history. METHODS Sex allocation was measured using the male to female ratio (M/F), a novel approximator of the pollen to ovule ratio (P/O). Life-history (annuality/perenniality), capitulum structure, capitular sexual system, and M/F were reconstructed on time-proportional phylogenies. Trait associations were examined using phylogenetically independent contrasts (PICs). KEY RESULTS Annual taxa have strongly female-biased capitula, as measured by M/F, and either gynomonoecious or monoecious sexual systems, while perennials have equal or male-biased capitula that are hermaphroditic or monoecious. These results are largely supported by PIC analysis. Different sexual systems afford differing flexibility in sex allocation, with hermaphrodites having the least, and monoecious taxa the greatest, range in M/F. Within Ifloga, the anomalous capitulum evolved in an annual, gynomonoecious ancestor, followed by two independent gains of monoecy. Two subsequent gains of perenniality occurred within a monoecious sublineage. CONCLUSIONS Different life histories have divergent sex allocation optima and are strongly associated with different sexual systems in gnaphalioid daisies. An anomalous capitulum structure in Ifloga may have facilitated the evolution of monoecy, which in turn may be linked to the evolution of life-history diversity in the genus.
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Affiliation(s)
- Nicola G Bergh
- The Compton Herbarium, Kirstenbosch Research Centre, South African National Biodiversity Institute, Private Bag X7, Newlands, Cape Town 7735, South Africa.
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Bergh NG, Peter Linder H. Cape diversification and repeated out-of-southern-Africa dispersal in paper daisies (Asteraceae–Gnaphalieae). Mol Phylogenet Evol 2009; 51:5-18. [DOI: 10.1016/j.ympev.2008.09.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2008] [Revised: 06/24/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
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