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Estévez Manso Galán L, Antonetti M, Ibañez AC, Sérsic AN, Cocucci AA. Phenotypic selection patterns in a hybrid zone between two Calceolaria species with contrasting pollinators: insights from field surveys and fitness assessments. New Phytol 2024. [PMID: 38655668 DOI: 10.1111/nph.19775] [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: 02/07/2024] [Accepted: 04/04/2024] [Indexed: 04/26/2024]
Abstract
Hybrid zones provide natural experimental settings to test hypotheses about species divergence. We concentrated on a hybrid swarm in which oil-collecting bees and flower-pecking birds act as pollinators of two Calceolaria species. We asked whether both pollinators contributed to flower divergence by differentially promoting prezygotic fitness at the phenotypic extremes that represent parentals. We studied pollinator-mediated selection on phenotypic traits critical in plant-pollinator mechanical interaction, namely plant height, reward-to-stigma distance, and flower shape. We utilised the quantity and quality of pollen deposited as fitness measures and distinguished between the contribution of the two pollinator types. Results showed uni- and bivariate disruptive selection for most traits through pollen grains deposited by both pollinators. Bird-mediated fitness favoured low plants with a long reward-to-stigma distance and a straight corolla, while bee-mediated fitness favoured tall plants with a short reward-to-stigma distance and curved corolla. In addition, stabilising selection at one end of the phenotypic range showed a bird-mediated reproductive asymmetry within the swarm. The disruptive pattern was countered, albeit weakly, by hybrids receiving higher-quality pollen on the stigmas. Results suggest that pollinator-mediated selection promotes divergence of integrated flower phenotypes mechanically adjusted either to bees or birds underscoring the importance of pollinator specialisation in diversification.
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Affiliation(s)
- Lucía Estévez Manso Galán
- Laboratorio de Ecología Evolutiva - Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfield, 1611(X5016GCA), Córdoba, Argentina
| | - Marco Antonetti
- Laboratorio de Ecología Evolutiva - Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfield, 1611(X5016GCA), Córdoba, Argentina
| | - Ana C Ibañez
- Laboratorio de Ecología Evolutiva - Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfield, 1611(X5016GCA), Córdoba, Argentina
| | - Alicia N Sérsic
- Laboratorio de Ecología Evolutiva - Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfield, 1611(X5016GCA), Córdoba, Argentina
| | - Andrea A Cocucci
- Laboratorio de Ecología Evolutiva - Biología Floral, Instituto Multidisciplinario de Biología Vegetal (IMBIV), CONICET-Universidad Nacional de Córdoba, Av. Vélez Sarsfield, 1611(X5016GCA), Córdoba, Argentina
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Pfeilsticker TR, Jones RC, Steane DA, Harrison PA, Vaillancourt RE, Potts BM. Expansion of the rare Eucalyptus risdonii under climate change through hybridization with a closely related species despite hybrid inferiority. Ann Bot 2022; 129:1-14. [PMID: 34351372 PMCID: PMC8752398 DOI: 10.1093/aob/mcab103] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [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: 04/27/2021] [Accepted: 08/04/2021] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIMS Hybridization is increasingly recognized as an integral part of the dynamics of species range expansion and contraction. Thus, it is important to understand the reproductive barriers between co-occurring species. Extending previous studies that argued that the rare Eucalyptus risdonii was expanding into the range of the surrounding E. amygdalina by both seed and pollen dispersal, we here investigate the long-term fitness of both species and their hybrids and whether expansion is continuing. METHODS We assessed the survival of phenotypes representing a continuum between the two pure species in a natural hybrid swarm after 29 years, along with seedling recruitment. The performance of pure species as well as of artificial and natural hybrids was also assessed over 28 years in a common garden trial. KEY RESULTS In the hybrid zone, E. amygdalina adults showed greater mortality than E. risdonii, and the current seedling cohort is still dominated by E. risdonii phenotypes. Morphologically intermediate individuals appeared to be the least fit. Similar results were observed after growing artificial first-generation and natural hybrids alongside pure species families in a common garden trial. Here, the survival, reproduction, health and growth of the intermediate hybrids were significantly less than those of either pure species, consistent with hybrid inferiority, although this did not manifest until later reproductive ages. Among the variable progeny of natural intermediate hybrids, the most E. risdonii-like phenotypes were the most fit. CONCLUSIONS This study contributes to the increasing number of reports of hybrid inferiority in Eucalyptus, suggesting that post-zygotic barriers contribute to the maintenance of species integrity even between closely related species. However, with fitness rapidly recovered following backcrossing, it is argued that hybridization can still be an important evolutionary process, in the present case appearing to contribute to the range expansion of the rare E. risdonii in response to climate change.
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Affiliation(s)
- T R Pfeilsticker
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
| | - R C Jones
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
| | - D A Steane
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
| | - P A Harrison
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
| | - R E Vaillancourt
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
| | - B M Potts
- School of Natural Sciences and ARC Training Centre for Forest Value, University of Tasmania, Hobart, Australia
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Baker HK, Hankins DC, Shurin JB. Introgressive hybridization erodes morphological divergence between lentic and lotic habitats in an endangered minnow. Ecol Evol 2021; 11:13593-13600. [PMID: 34646492 PMCID: PMC8495819 DOI: 10.1002/ece3.8086] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 08/16/2021] [Indexed: 11/24/2022] Open
Abstract
Introgressive hybridization may erode phenotypic divergence along environmental gradients, collapsing locally adapted populations into a hybrid swarm. Alternatively, introgression may promote phenotypic divergence by providing variation on which natural selection can act. In freshwater fishes, water flow often selects for divergent morphological traits in lake versus stream habitats. We tested the effects of introgression on lake-stream morphological divergence in the minnow Owens Tui Chub (Siphateles bicolor snyderi), which has been rendered endangered by introgession from the introduced Lahontan Tui Chub (Siphateles bicolor obesa). Using geometric morphometric analysis of 457 individual Tui Chub from thirteen populations, we found that both native and introgressing parent taxa exhibited divergent body and caudal fin shapes in lake versus stream habitats, but their trajectories of divergence were distinct. In contrast, introgressed populations exhibited intermediate body and caudal fin shapes that were not differentiated by habitat type, indicating that introgression has eroded phenotypic divergence along the lentic-lotic gradient throughout the historic range of the Owens Tui Chub. Individuals within hybrid populations were less morphologically variable than those within parent populations, suggesting hybrid adaptation to selective agents other than water flow or loss of variance by drift.
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Affiliation(s)
- Henry K. Baker
- Section of Ecology, Behavior, and EvolutionUniversity of California San DiegoLa JollaCAUSA
| | - Danielle C. Hankins
- Section of Ecology, Behavior, and EvolutionUniversity of California San DiegoLa JollaCAUSA
| | - Jonathan B. Shurin
- Section of Ecology, Behavior, and EvolutionUniversity of California San DiegoLa JollaCAUSA
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Morgan-Richards M, Vilcot M, Trewick SA. Lack of assortative mating might explain reduced phenotypic differentiation where two grasshopper species meet. J Evol Biol 2021; 35:509-519. [PMID: 34091960 PMCID: PMC9290589 DOI: 10.1111/jeb.13879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 04/20/2021] [Accepted: 06/01/2021] [Indexed: 01/12/2023]
Abstract
Hybridization is an evolutionary process with wide‐ranging potential outcomes, from providing populations with important genetic variation for adaptation to being a substantial fitness cost leading to extinction. Here, we focussed on putative hybridization between two morphologically distinct species of New Zealand grasshopper. We collected Phaulacridium marginale and Phaulacridium otagoense specimens from a region where mitochondrial introgression had been detected and where their habitat has been modified by introduced mammals eating the natural vegetation and by the colonization of many non‐native plant species. In contrast to observations in the 1970s, our sampling of wild pairs of grasshoppers in copula provided no evidence of assortative mating with respect to species. Geometric morphometrics on pronotum shape of individuals from areas of sympatry detected phenotypically intermediate specimens (putative hybrids), and the distribution of phenotypes in most areas of sympatry was found to be unimodal. These results suggest that hybridization associated with anthropogenic habitat changes has led to these closely related species forming a hybrid swarm, with random mating. Without evidence of hybrid disadvantage, we suggest a novel hybrid lineage might eventually result from the merging of these two species.
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Affiliation(s)
| | - Maurine Vilcot
- Wildlife & Ecology, Massey University, Palmerston North, New Zealand
| | - Steven A Trewick
- Wildlife & Ecology, Massey University, Palmerston North, New Zealand
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Svardal H, Quah FX, Malinsky M, Ngatunga BP, Miska EA, Salzburger W, Genner MJ, Turner GF, Durbin R. Ancestral Hybridization Facilitated Species Diversification in the Lake Malawi Cichlid Fish Adaptive Radiation. Mol Biol Evol 2020; 37:1100-1113. [PMID: 31821500 PMCID: PMC7086168 DOI: 10.1093/molbev/msz294] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The adaptive radiation of cichlid fishes in East African Lake Malawi encompasses over 500 species that are believed to have evolved within the last 800,000 years from a common founder population. It has been proposed that hybridization between ancestral lineages can provide the genetic raw material to fuel such exceptionally high diversification rates, and evidence for this has recently been presented for the Lake Victoria region cichlid superflock. Here, we report that Lake Malawi cichlid genomes also show evidence of hybridization between two lineages that split 3-4 Ma, today represented by Lake Victoria cichlids and the riverine Astatotilapia sp. "ruaha blue." The two ancestries in Malawi cichlid genomes are present in large blocks of several kilobases, but there is little variation in this pattern between Malawi cichlid species, suggesting that the large-scale mosaic structure of the genomes was largely established prior to the radiation. Nevertheless, tens of thousands of polymorphic variants apparently derived from the hybridization are interspersed in the genomes. These loci show a striking excess of differentiation across ecological subgroups in the Lake Malawi cichlid assemblage, and parental alleles sort differentially into benthic and pelagic Malawi cichlid lineages, consistent with strong differential selection on these loci during species divergence. Furthermore, these loci are enriched for genes involved in immune response and vision, including opsin genes previously identified as important for speciation. Our results reinforce the role of ancestral hybridization in explosive diversification by demonstrating its significance in one of the largest recent vertebrate adaptive radiations.
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Affiliation(s)
- Hannes Svardal
- Department of Biology, University of Antwerp, Antwerp, Belgium
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Wellcome Sanger Institute, Hinxton, United Kingdom
- Naturalis Biodiversity Center, Leiden, The Netherlands
| | | | - Milan Malinsky
- Zoological Institute, University of Basel, Basel, Switzerland
| | | | - Eric A Miska
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Wellcome Sanger Institute, Hinxton, United Kingdom
- Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | | | - Martin J Genner
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - George F Turner
- School of Biological Sciences, Bangor University, Bangor, United Kingdom
| | - Richard Durbin
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Wellcome Sanger Institute, Hinxton, United Kingdom
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Slager DL, Epperly KL, Ha RR, Rohwer S, Wood C, Van Hemert C, Klicka J. Cryptic and extensive hybridization between ancient lineages of American crows. Mol Ecol 2020; 29:956-969. [PMID: 32034818 DOI: 10.1111/mec.15377] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/30/2019] [Accepted: 02/05/2020] [Indexed: 01/02/2023]
Abstract
Most species and therefore most hybrid zones have historically been defined using phenotypic characters. However, both speciation and hybridization can occur with negligible morphological differentiation. Recently developed genomic tools provide the means to better understand cryptic speciation and hybridization. The Northwestern Crow (Corvus caurinus) and American Crow (Corvus brachyrhynchos) are continuously distributed sister taxa that lack reliable traditional characters for identification. In this first population genomic study of Northwestern and American crows, we use genomic SNPs (nuDNA) and mtDNA to investigate the degree of genetic differentiation between these crows and the extent to which they may hybridize. Our results indicate that American and Northwestern crows have distinct evolutionary histories, supported by two nuDNA ancestry clusters and two 1.1%-divergent mtDNA clades dating to the late Pleistocene, when glacial advances may have isolated crow populations in separate refugia. We document extensive hybridization, with geographic overlap of mtDNA clades and admixture of nuDNA across >900 km of western Washington and western British Columbia. This broad hybrid zone consists of late-generation hybrids and backcrosses, but not recent (e.g., F1) hybrids. Nuclear DNA and mtDNA clines had concordant widths and were both centred in southwestern British Columbia, farther north than previously postulated. Overall, our results suggest a history of reticulate evolution in American and Northwestern crows, perhaps due to recurring neutral expansion(s) from Pleistocene glacial refugia followed by lineage fusion(s). However, we do not rule out a contributing role for more recent potential drivers of hybridization, such as expansion into human-modified habitats.
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Affiliation(s)
- David L Slager
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Kevin L Epperly
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Renee R Ha
- Department of Psychology, University of Washington, Seattle, WA, USA
| | - Sievert Rohwer
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
| | - Chris Wood
- Burke Museum of Natural History and Culture, Seattle, WA, USA
| | | | - John Klicka
- Department of Biology, University of Washington, Seattle, WA, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
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Knutson AE, Tracy JL, Ritzi C, Moran PJ, Royer T, Deloach CJ. Establishment, Hybridization, Dispersal, Impact, and Decline of Diorhabda spp. (Coleoptera: Chrysomelidae) Released for Biological Control of Tamarisk in Texas and New Mexico. Environ Entomol 2019; 48:1297-1316. [PMID: 31603984 DOI: 10.1093/ee/nvz107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 05/16/2019] [Indexed: 06/10/2023]
Abstract
Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from 2003 to 2010 for biological control of tamarisk (Tamarix spp.): Mediterranean tamarisk beetles, D. elongata (Brullé) from Greece, also established in New Mexico; subtropical tamarisk beetles, D. sublineata (Lucas) from Tunisia; and larger tamarisk beetles, D. carinata (Faldermann) from Uzbekistan. More than one million tamarisk beetles were released at 99 sites. Species establishment success ranged from 52 to 83%. All three species now co-occur in New Mexico with the northern tamarisk beetles, D. carinulata (Desbrochers). A phenotypic hybrid scoring system was developed to assess Diorhabda phenotype distributions and character mixing in hybrid zones. Widespread field populations of bispecific hybrid phenotypes for D. carinata/D. elongata and D. sublineata/D. elongata rapidly appeared following contact of parental species. Initial distributions and dispersal of Diorhabda spp. and hybrids are mapped for Texas, New Mexico, Oklahoma, and Kansas, where they produced large-scale tamarisk defoliation and localized dieback for 3-4 yr. However, populations subsequently severely declined, now producing only isolated defoliation and allowing tamarisk to recover. Diorhabda sublineata and D. elongata temporarily produced nontarget spillover defoliation of ornamental athel, Tamarix aphylla (L.) Karst, along the Rio Grande. Hybrid phenotypes were generally bimodally distributed, indicating some degree of reproductive isolation. Additional diagnostic phenotypic characters in males allowed more precise hybrid scoring. Character mixing in some hybrid populations approached or reached that of a hybrid swarm. The significance of hybridization for tamarisk biocontrol is discussed.
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Affiliation(s)
- Allen E Knutson
- Texas A&M AgriLife Extension, Department of Entomology, Texas A&M AgriLife Research and Extension Center, Dallas, TX
| | - James L Tracy
- Knowledge Engineering Laboratory, Department of Entomology, Texas A&M University, TAMU, College Station, TX
| | - Chris Ritzi
- Biology, Geology, and Physical Sciences Department, Sul Ross State University, Alpine, TX
| | - Patrick J Moran
- USDA Agricultural Research Service, Invasive Species and Pollinator Health, Albany, CA
| | - Tom Royer
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK
| | - C Jack Deloach
- USDA Agricultural Research Service (Retired), Austin, TX
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Tihon E, Imamura H, Dujardin JC, Van Den Abbeele J, Van den Broeck F. Discovery and genomic analyses of hybridization between divergent lineages of Trypanosoma congolense, causative agent of Animal African Trypanosomiasis. Mol Ecol 2017; 26:6524-6538. [PMID: 28752916 DOI: 10.1111/mec.14271] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 05/24/2017] [Accepted: 06/28/2017] [Indexed: 12/19/2022]
Abstract
Hybrid populations and introgressive hybridization remain poorly documented in pathogenic micro-organisms, as such that genetic exchange has been argued to play a minor role in their evolution. Recent work demonstrated the existence of hybrid microsatellite profiles in Trypanosoma congolense, a parasitic protozoan with detrimental effects on livestock productivity in sub-Saharan Africa. Here, we present the first population genomic study of T. congolense, revealing a remarkable number of single nucleotide polymorphisms (SNPs), small insertions/deletions (indels) and gene deletions among 56 parasite genomes from ten African countries. One group of parasites from Zambia was particularly diverse, displaying a substantial number of heterozygous SNP and indel sites compared to T. congolense parasites from the nine other sub-Saharan countries. Genomewide 5-kb phylogenetic analyses based on phased SNP data revealed that these parasites were the product of hybridization between phylogenetically distinct T. congolense lineages. Other parasites within the same region in Zambia presented a mosaic of haplotypic ancestry and genetic variability, indicating that hybrid parasites persisted and recombined beyond the initial hybridization event. Our observations challenge traditional views of trypanosome population biology and encourage future research on the role of hybridization in spreading genes for drug resistance, pathogenicity and virulence.
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Affiliation(s)
- Eliane Tihon
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Hideo Imamura
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jean-Claude Dujardin
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jan Van Den Abbeele
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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Yan LJ, Burgess KS, Milne R, Fu CN, Li DZ, Gao LM. Asymmetrical natural hybridization varies among hybrid swarms between two diploid Rhododendron species. Ann Bot 2017; 120:51-61. [PMID: 28444136 PMCID: PMC5737508 DOI: 10.1093/aob/mcx039] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [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: 11/09/2016] [Accepted: 03/14/2017] [Indexed: 05/23/2023]
Abstract
Background and Aims The extent to which hybridization leads to gene flow between plant species depends on the structure of hybrid populations. However, if this varies between locations, species barriers might prove permeable in some locations but not in others. To assess possible variation in hybrid population structure, the magnitude and direction of natural hybridization between two Chinese endemic species, Rhododendron spiciferum and Rhododendron spinuliferum , were evaluated. Methods Thirteen nuclear microsatellite markers were employed to characterize 566 individuals collected from 15 non-allopatric populations and nine allopatric parental populations. Chloroplast DNA (cpDNA) sequences were obtained from a subset of samples. Genetic structure and direction of gene flow was determined using a combination of STRUCTURE and NEWHYBRIDS analysis. Key Results Nuclear analysis revealed that parental taxa formed two genetically distinct clusters and hybrids shared the genetic background of both parents and did not form a separate genetic lineage. Overall, hybrid swarms were dominated by early- and later-generation hybrids, with a significantly higher proportion of hybrids (59·6 %) possessing >50 % R. spiciferum-like nuclear germplasm. The cpDNA analysis further indicated that a significantly greater proportion of hybrids (61·1 %) possessed the R. spiciferum cpDNA haplotype. Conclusions Gene flow between R. spiciferum and R. spinuliferum was found to be bidirectional in 14 of the 15 hybrid swarms and asymmetrical in six hybrid swarms. Asymmetrical gene flow was evident for only nuclear DNA (nDNA) in two populations, for only cpDNA in three populations, and for both nDNA and cpDNA in one population. Collectively, the variation in genetic structure found among the 15 hybrid swarms suggests that introgression rather than hybrid speciation is a more likely outcome of hybridization between these hybridizing taxa.
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Affiliation(s)
- Li-Jun Yan
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- College of Vocational and Technical Education, Yunnan Normal University, Kunming 650092, China
| | - Kevin S. Burgess
- Department of Biology, College of Letters & Sciences, Columbus State University, University System of Georgia, 163A LeNoir Hall, Columbus, GA 31907-5645, USA
| | - Richard Milne
- Institute of Molecular Plant Sciences, University of Edinburgh, King’s Buildings, Edinburgh EH9 3JH, UK
| | - Chao-Nan Fu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - De-Zhu Li
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lian-Ming Gao
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
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Leroy T, Caffier V, Celton JM, Anger N, Durel CE, Lemaire C, Le Cam B. When virulence originates from nonagricultural hosts: evolutionary and epidemiological consequences of introgressions following secondary contacts in Venturia inaequalis. New Phytol 2016; 210:1443-1452. [PMID: 26853715 DOI: 10.1111/nph.13873] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [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: 09/30/2015] [Accepted: 12/21/2015] [Indexed: 06/05/2023]
Abstract
In pathogens, introgressions through secondary contacts between divergent populations from agricultural and nonagricultural disease reservoirs are expected to have crucial evolutionary and epidemiological implications. Despite the importance of this question for disease management, experimental demonstrations of these implications remain scarce. Recently, we identified a virulent population of the apple scab pathogen Venturia inaequalis that migrated from nonagricultural hosts to European domestic apple orchards. Here, we investigated the occurrence of gene flow between agricultural and nonagricultural populations sampled in two orchards, and thereafter its consequences on the pathogenicity of hybrids. Population genetic structure and demographic inferences based on the genotypes of 104 strains revealed a high amount of gene flow between the two populations in one orchard. In this site, mating between populations was made possible by the presence of a common host. Our results revealed an invasion of the virulent trait in the agricultural population; a main direction of introgression in hybrids from the agricultural to nonagricultural genetic backgrounds; and a population of hybrids with transgressive traits. We demonstrate a secondary contact with gene flow between divergent populations of pathogens. Our findings highlight evolutionary and epidemiological changes in pathogens and have concrete implications for sustainable disease management.
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Affiliation(s)
- Thibault Leroy
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Valérie Caffier
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Jean-Marc Celton
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Nicolas Anger
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Charles-Eric Durel
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Christophe Lemaire
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
| | - Bruno Le Cam
- INRA, ACO, Université d'Angers - UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), SFR4207 QUASAV, PRES LUNAM, Beaucouze, France
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Dejaco T, Gassner M, Arthofer W, Schlick-Steiner BC, Steiner FM. Taxonomist's Nightmare … Evolutionist's Delight : An Integrative Approach Resolves Species Limits in Jumping Bristletails Despite Widespread Hybridization and Parthenogenesis. Syst Biol 2016; 65:947-974. [PMID: 26869489 PMCID: PMC5066060 DOI: 10.1093/sysbio/syw003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/26/2015] [Accepted: 01/14/2016] [Indexed: 11/13/2022] Open
Abstract
Accurate species delimitation is fundamental to biology. Traditionally, species were delimited based on morphological characters, sometimes leading to taxonomic uncertainty in morphologically conserved taxa. Recently, multiple taxonomically challenging cases have benefited from integrative taxonomy-an approach that highlights congruence among different disciplines and invokes evolutionary explanations for incongruence, acknowledging that different methods can mirror different stages of the speciation continuum. Here, we used a cohesive protocol for integrative taxonomy to revise species limits in 20 nominal species and 4 morphospecies of an ancestrally wingless insect group, the jumping bristletail genus Machilis from the European Eastern Alps. Even though morphologically conserved, several small-scale endemic species have been described from the Eastern Alps based on variation in hypodermal pigmentation patterns-a highly questionable character. As valuable as these endemics are for conservation, they have never been verified by alternative methods. Using traditional morphometrics, mitochondrial DNA, ribosomal DNA, and amplified fragment-length polymorphism markers, we identify six nominal species as taxonomic junior synonyms (Machilis alpicola Janetschek, 1953 syn. n. under M. vagans Wygodzinsky, 1941; M. ladensis Janetschek, 1950 syn. n., M. robusta Wygodzinsky, 1941 syn. n., and M. vicina Wygodzinsky, 1941 syn. n. under M. inermis Wygodzinsky, 1941; M. aleamaculata Wygodzinsky, 1941 syn. n. under M. montana Wygodzinsky, 1941; M. pulchra Janetschek, 1950 syn. n. under M. helleri Verhoeff, 1910) and describe two new species (Machilis cryptoglacialis sp. n. and Machilis albida sp. n.), one uncovered from morphological crypsis and one never sampled before. Building on numerous cases of incongruence among data sources, we further shed light on complex evolutionary histories including hybrid speciation, historical and recent hybridization, and ongoing speciation. We hypothesize that an inherent affinity to hybridization, combined with parallel switches to parthenogenesis and repeated postglacial colonization events may have boosted endemicity in Eastern Alpine Machilis We thus emphasize the importance of integrative taxonomy for rigorous species delimitation and its implication for evolutionary research and conservation in taxonomically challenging taxa.
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Affiliation(s)
- Thomas Dejaco
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria .,Museum of Nature South Tyrol, Bindergasse 1, 39100 Bozen/Bolzano, Italy
| | - Melitta Gassner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Wolfgang Arthofer
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Birgit C Schlick-Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - Florian M Steiner
- Molecular Ecology Group, Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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Kwan YS, Ko MH, Won YJ. Genomic replacement of native Cobitis lutheri with introduced C. tetralineata through a hybrid swarm following the artificial connection of river systems. Ecol Evol 2014; 4:1451-65. [PMID: 24834340 PMCID: PMC4020703 DOI: 10.1002/ece3.1027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 02/09/2014] [Accepted: 02/18/2014] [Indexed: 11/07/2022] Open
Abstract
River connections via artificial canals will bring about secondary contacts between previously isolated fish species. Here, we present a genetic consequence of such a secondary contact between Cobitis fish species, C. lutheri in the Dongjin River, and C. tetralineata in the Seomjin River in Korea. The construction of water canals about 80 years ago has unidirectionally introduced C. tetralineata into the native habitat of C. lutheri, and then these species have hybridized in the main stream section of the Dongjin River. According to the divergence population genetic analyses of DNA sequence data, the two species diverged about 3.3 million years ago, which is interestingly coincident with the unprecedented paleoceanographic change that caused isolations of the paleo-river systems in northeast Asia due to sea-level changes around the late Pliocene. Multilocus genotypic data of nine microsatellites and three nuclear loci revealed an extensively admixed structure in the hybrid zone with a high proportion of various post-F1 hybrids. Surprisingly, pure native C. lutheri was absent in the hybrid zone in contrast to the 7% of pure C. tetralineata. Such a biased proportion must have resulted from the dominant influence of continually introducing C. tetralineata on the native C. lutheri which has no supply of natives from other tributaries to the hybrid zone due to numerous low-head dams. In addition, mating experiments indicated that there is no discernible reproductive isolation between them. All the results suggest that the gene pool of native C. lutheri is being rapidly replaced by that of continually introducing C. tetralineata through a hybrid swarm for the last 80 years, which will ultimately lead to the genomic extinction of natives in this hybrid zone.
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Affiliation(s)
- Ye-Seul Kwan
- Division of EcoScience, Ewha Womans University52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea
| | - Myeong-Hun Ko
- Division of EcoScience, Ewha Womans University52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea
| | - Yong-Jin Won
- Division of EcoScience, Ewha Womans University52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea
- Department of Life Science, Ewha Womans University52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea
- Correspondence Yong-Jin Won, Division of EcoScience and Department of Life Science, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, Korea. Tel: +82 2 3277 4471; Fax: +82 2 3277 4514; E-mail:
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