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Zhang Z, Li J, Suddee S, Bouamanivong S, Averyanov LV, Gale SW. Exploring island syndromes: Variable matrix permeability in Phalaenopsis pulcherrima (Orchidaceae), a specialist lithophyte of tropical Asian inselbergs. FRONTIERS IN PLANT SCIENCE 2023; 14:1097113. [PMID: 36890904 PMCID: PMC9986494 DOI: 10.3389/fpls.2023.1097113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 01/19/2023] [Indexed: 06/18/2023]
Abstract
INTRODUCTION Plants confined to island-like habitats are hypothesised to possess a suite of functional traits that promote on-spot persistence and recruitment, but this may come at the cost of broad-based colonising potential. Ecological functions that define this island syndrome are expected to generate a characteristic genetic signature. Here we examine genetic structuring in the orchid Phalaenopsis pulcherrima, a specialist lithophyte of tropical Asian inselbergs, both at the scale of individual outcrops and across much of its range in Indochina and on Hainan Island, to infer patterns of gene flow in the context of an exploration of island syndrome traits. METHODS We sampled 323 individuals occurring in 20 populations on 15 widely scattered inselbergs, and quantified genetic diversity, isolation-by-distance and genetic structuring using 14 microsatellite markers. To incorporate a temporal dimension, we inferred historical demography and estimated direction of gene flow using Bayesian approaches. RESULTS We uncovered high genotypic diversity, high heterozygosity and low rates of inbreeding, as well as strong evidence for the occurrence of two genetic clusters, one comprising the populations of Hainan Island and the other those of mainland Indochina. Connectivity was greater within, rather than between the two clusters, with the former unequivocally supported as ancestral. DISCUSSION Despite a strong capacity for on-spot persistence conferred by clonality, incomplete self-sterility and an ability to utilize multiple magnet species for pollination, our data reveal that P. pulcherrima also possesses traits that promote landscape-scale gene flow, including deceptive pollination and wind-borne seed dispersal, generating an ecological profile that neither fully conforms to, nor fully contradicts, a putative island syndrome. A terrestrial matrix is shown to be significantly more permeable than open water, with the direction of historic gene flow indicating that island populations can serve as refugia for postglacial colonisation of continental landmasses by effective dispersers.
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Affiliation(s)
- Zhe Zhang
- Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants (Hainan University), Ministry of Education, College of Forestry, Hainan University, Haikou, China
- Key Laboratory of Germplasm Resources of Tropical Special Ornamental Plants of Hainan Province, College of Forestry, Hainan University, Haikou, China
| | - Jihong Li
- Flora Conservation Department, Kadoorie Farm & Botanic Garden, Tai Po, Hong Kong, China
| | - Somran Suddee
- Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Chatuchak, Bangkok, Thailand
| | - Somsanith Bouamanivong
- Biotechnology and Ecology Institute, Ministry of Science and Technology, Vientiane, Laos
| | - Leonid V. Averyanov
- Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, Russia
| | - Stephan W. Gale
- Flora Conservation Department, Kadoorie Farm & Botanic Garden, Tai Po, Hong Kong, China
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Andriamihaja CF, Ramarosandratana AV, Grisoni M, Jeannoda VH, Besse P. Drivers of population divergence and species differentiation in a recent group of indigenous orchids ( Vanilla spp.) in Madagascar. Ecol Evol 2021; 11:2681-2700. [PMID: 33767829 PMCID: PMC7981232 DOI: 10.1002/ece3.7224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/16/2020] [Accepted: 12/22/2020] [Indexed: 11/21/2022] Open
Abstract
With over 25,000 species, orchids are among families with remarkable high rate of diversification. Since Darwin's time, major advances attributed the exceptional diversity of orchids to plant-pollinator interactions. However, unraveling the processes and factors that determine the phenotypic and genotypic variation of natural orchid populations remains a challenge. Here, we assessed genetic population structure and floral differentiation in recently diverged leafless Vanilla species in a world biodiversity hotspot, Madagascar, using seven microsatellite loci and 26 morphometric variables. Additionally, analyses were performed to test for the occurrence of any patterns of isolation by distance, isolation by environment, and isolation by adaptation and to detect possible physical barriers that might have caused genetic discontinuities between populations. Positive inbreeding coefficients detected in 22 populations were probably due to the presence of null alleles, geitonogamy and/or some admixture (sympatric species). In contrast, the only high-altitude population showed an important rate of clonality leading to heterozygote excess. Genetic diversity was maximum in western populations, suggesting a postglacial colonization to the north and south. Clustering analyses identified seven genetic groups characterized by specific floral traits that matched five botanical descriptions in the literature. A contribution of montane refugia and river barriers on population differentiation was detected. We also detected combined effects of IBD/IBE and IBE/IBA on genetic differentiation and suggested this pattern is more likely determined by ecological isolation, although pollinator-mediated divergent selection could not be ruled out for some of the species. Overall, this study provides further insights on speciation in orchids, a group for which Madagascar shows one of the world's highest level of endemism and confirms the importance of the peculiar biogeography of the island in shaping species differentiation.
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Affiliation(s)
- Cathucia F. Andriamihaja
- Université de la RéunionUMR PVBMTSt PierreFrance
- Department of Plant Biology and EcologyUniversity of AntananarivoAntananarivoMadagascar
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Taylor A, Weigelt P, König C, Zotz G, Kreft H. Island disharmony revisited using orchids as a model group. THE NEW PHYTOLOGIST 2019; 223:597-606. [PMID: 30848492 DOI: 10.1111/nph.15776] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 02/18/2019] [Indexed: 05/28/2023]
Abstract
One central concept in island biology is that island assemblages form subsets of the mainland species pool, being disproportionately rich or poor in certain taxonomic groups. This unbalanced composition, termed 'disharmony', is generally explained using a taxon-centred approach, linking the over- or under-representation of taxa to their colonisation abilities. However, islands may also harbour 'functionally' disharmonic flora, being disproportionately rich or poor in species with certain traits, which may offer greater insights into the processes driving island colonisation. Here, we use orchids as a model to illustrate key processes involved in the formation of functionally disharmonic island floras, including filtering effects (for example biotic interactions), and speciation. Our synthesis is based on a comprehensive orchid dataset of 27 637 species and combines both a literature review and simple exploratory analyses to show that orchids are significantly under-represented on islands relative to mainland regions and that insular orchids display shifts in functional traits, from the shortening of nectar spurs to facilitate ornithophily to changes in colour associated with generalist insect pollinators. We highlight that taxa are simply coarse proxies and that we need to consider species traits and interactions to gain a full understanding of the processes constraining plant assembly on islands.
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Affiliation(s)
- Amanda Taylor
- Biodiversity, Macroecology & Biogeography, Faculty for Forest Sciences and Forest Ecology, University of Goettingen, Büsgenweg 1, Göttingen, 37077, Germany
| | - Patrick Weigelt
- Biodiversity, Macroecology & Biogeography, Faculty for Forest Sciences and Forest Ecology, University of Goettingen, Büsgenweg 1, Göttingen, 37077, Germany
| | - Christian König
- Biodiversity, Macroecology & Biogeography, Faculty for Forest Sciences and Forest Ecology, University of Goettingen, Büsgenweg 1, Göttingen, 37077, Germany
| | - Gerhard Zotz
- Institute of Biology and Environmental Sciences, University of Oldenburg, Ammerländer Heerstrasse 114, Oldenburg, 26129, Germany
| | - Holger Kreft
- Biodiversity, Macroecology & Biogeography, Faculty for Forest Sciences and Forest Ecology, University of Goettingen, Büsgenweg 1, Göttingen, 37077, Germany
- Centre of Biodiversity and Sustainable Land Use (CBL), University of Goettingen, Büsgenweg 1, Göttingen, 37077, Germany
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Garot E, Joët T, Combes MC, Lashermes P. Genetic diversity and population divergences of an indigenous tree (Coffea mauritiana) in Reunion Island: role of climatic and geographical factors. Heredity (Edinb) 2019; 122:833-847. [PMID: 30478354 PMCID: PMC6781115 DOI: 10.1038/s41437-018-0168-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 11/09/2018] [Indexed: 01/23/2023] Open
Abstract
Oceanic islands are commonly considered as natural laboratories for studies on evolution and speciation. The evolutionary specificities of islands associated with species biology provide unique scenarios to study the role of geography and climate in driving population divergence. However, few studies have addressed this subject in small oceanic islands with heterogeneous climates. Being widely distributed in Reunion Island forest, Coffea mauritiana represents an interesting model case for investigating patterns of within-island differentiation at small spatial scale. In this study, we examined the genetic diversity and population divergences of C. mauritiana using SNP markers obtained from 323 individuals across 34 locations in Reunion Island. Using redundancy analysis, we further evaluated the contribution of geographic and climatic factors to shaping genetic divergence among populations. Genetic diversity analyses revealed that accessions clustered according to the source population, with further grouping in regional clusters. Genetic relationships among the regional clusters underlined a recent process of expansion in the form of step-by-step colonization on both sides of the island. Divergence among source populations was mostly driven by the joint effect of geographic distance and climatic heterogeneity. The pattern of isolation-by-geography was in accordance with the dispersal characteristics of the species, while isolation-by-environment was mostly explained by the heterogeneous rainfall patterns, probably associated with an asynchronous flowering among populations. These findings advance our knowledge on the patterns of genetic diversity and factors of population differentiation of species native to Reunion Island, and will also usefully guide forest management for conservation.
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Affiliation(s)
- Edith Garot
- IRD, University of Montpellier, DIADE, Montpellier, France
| | - Thierry Joët
- IRD, University of Montpellier, DIADE, Montpellier, France
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Hollenbeck CM, Portnoy DS, Gold JR. Evolution of population structure in an estuarine-dependent marine fish. Ecol Evol 2019; 9:3141-3152. [PMID: 30962887 PMCID: PMC6434539 DOI: 10.1002/ece3.4936] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 12/19/2018] [Accepted: 01/07/2019] [Indexed: 01/06/2023] Open
Abstract
Restriction site-associated DNA (RAD) sequencing was used to characterize neutral and adaptive genetic variation among geographic samples of red drum, Sciaenops ocellatus, an estuarine-dependent fish found in coastal waters along the southeastern coast of the United States (Atlantic) and the northern Gulf of Mexico (Gulf). Analyses of neutral and outlier loci revealed three genetically distinct regional clusters: one in the Atlantic and two in the northern Gulf. Divergence in neutral loci indicated gradual genetic change and followed a linear pattern of isolation by distance. Divergence in outlier loci was at least an order of magnitude greater than divergence in neutral loci, and divergence between the regions in the Gulf was twice that of divergence between other regions. Discordance in patterns of genetic divergence between outlier and neutral loci is consistent with the hypothesis that the former reflects adaptive responses to environmental factors that vary on regional scales, while the latter largely reflects drift processes. Differences in basic habitat, initiated by glacial retreat and perpetuated by contemporary oceanic and atmospheric forces interacting with the geomorphology of the northern Gulf, followed by selection, appear to have led to reduced gene flow among red drum across the northern Gulf, reinforcing differences accrued during isolation and resulting in continued divergence across the genome. This same dynamic also may pertain to other coastal or nearshore fishes (18 species in 14 families) where genetically or morphologically defined sister taxa occur in the three regions.
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Affiliation(s)
- Christopher M. Hollenbeck
- Marine Genomics Laboratory, Department of Life SciencesTexas A&M University ‐ Corpus ChristiCorpus ChristiTexas
- Present address:
Scottish Oceans InstituteUniversity of St. AndrewsSt. Andrews, FifeUK
| | - David S. Portnoy
- Marine Genomics Laboratory, Department of Life SciencesTexas A&M University ‐ Corpus ChristiCorpus ChristiTexas
| | - John R. Gold
- Marine Genomics Laboratory, Department of Life SciencesTexas A&M University ‐ Corpus ChristiCorpus ChristiTexas
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Deschepper P, Brys R, Fortuna MA, Jacquemyn H. Analysis of spatial genetic variation reveals genetic divergence among populations of Primula veris associated to contrasting habitats. Sci Rep 2017; 7:8847. [PMID: 28821787 PMCID: PMC5562905 DOI: 10.1038/s41598-017-09154-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/24/2017] [Indexed: 12/01/2022] Open
Abstract
Genetic divergence by environment is a process whereby selection causes the formation of gene flow barriers between populations adapting to contrasting environments and is often considered to be the onset of speciation. Nevertheless, the extent to which genetic differentiation by environment on small spatial scales can be detected by means of neutral markers is still subject to debate. Previous research on the perennial herb Primula veris has shown that plants from grassland and forest habitats showed pronounced differences in phenology and flower morphology, suggesting limited gene flow between habitats. To test this hypothesis, we sampled 33 populations of P. veris consisting of forest and grassland patches and used clustering techniques and network analyses to identify sets of populations that are more connected to each other than to other sets of populations and estimated the timing of divergence. Our results showed that spatial genetic variation had a significantly modular structure and consisted of four well-defined modules that almost perfectly coincided with habitat features. Genetic divergence was estimated to have occurred about 114 generations ago, coinciding with historic major changes in the landscape. Overall, these results illustrate how populations adapting to different environments become structured genetically within landscapes on small spatial scales.
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Affiliation(s)
- Pablo Deschepper
- Division of Plant Ecology and Systematics, Biology Department, University of Leuven, Leuven, Belgium.
| | - Rein Brys
- Research Institute for Forest and Nature, Gaverstraat 4, B-9500, Geraardsbergen, Belgium
| | - Miguel A Fortuna
- Department of Evolutionary Biology and Environmental Studies. University of Zurich, Zurich, Switzerland
| | - Hans Jacquemyn
- Division of Plant Ecology and Systematics, Biology Department, University of Leuven, Leuven, Belgium
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Termignoni-García F, Jaramillo-Correa JP, Chablé-Santos J, Liu M, Shultz AJ, Edwards SV, Escalante-Pliego P. Genomic footprints of adaptation in a cooperatively breeding tropical bird across a vegetation gradient. Mol Ecol 2017; 26:4483-4496. [DOI: 10.1111/mec.14224] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 05/06/2017] [Accepted: 06/12/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Flavia Termignoni-García
- Department of Zoology; National Collection of Birds (CNAV); Institute of Biology; Universidad Nacional Autónoma de México; CdMx México
| | - Juan P. Jaramillo-Correa
- Department of Evolutionary Ecology; Institute of Ecology; Universidad Nacional Autónoma de México; CdMx México
| | - Juan Chablé-Santos
- Department of Zoology; Facultad de Medicina Veterinaria y Zootecnia; Universidad Autónoma de Yucatán; Yucatán México
| | - Mark Liu
- Biodiversity Research Center; Academia Sinica; Taipei Nankang Taiwan
| | - Allison J. Shultz
- Department of Organismic and Evolutionary Biology (OEB); Harvard University; Cambridge MA USA
| | - Scott V. Edwards
- Department of Organismic and Evolutionary Biology (OEB); Harvard University; Cambridge MA USA
| | - Patricia Escalante-Pliego
- Department of Zoology; National Collection of Birds (CNAV); Institute of Biology; Universidad Nacional Autónoma de México; CdMx México
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Andriananjamanantsoa HN, Engberg S, Louis EE, Brouillet L. Diversification of Angraecum (Orchidaceae, Vandeae) in Madagascar: Revised Phylogeny Reveals Species Accumulation through Time Rather than Rapid Radiation. PLoS One 2016; 11:e0163194. [PMID: 27669569 PMCID: PMC5036805 DOI: 10.1371/journal.pone.0163194] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 09/06/2016] [Indexed: 11/19/2022] Open
Abstract
Angraecum is the largest genus of subtribe Angraecinae (Orchidaceae) with about 221 species. Madagascar is the center of the diversity for the genus with ca. 142 species, of which 90% are endemic. The great morphological diversity associated with species diversification in the genus on the island of Madagascar offers valuable insights for macroevolutionary studies. Phylogenies of the Angraecinae have been published but a lack of taxon and character sampling and their limited taxonomic resolution limit their uses for macroevolutionary studies. We present a new phylogeny of Angraecum based on chloroplast sequence data (matk, rps16, trnL), nuclear ribosomal (ITS2) and 39 morphological characters from 194 Angraecinae species of which 69 were newly sampled. Using this phylogeny, we evaluated the monophyly of the sections of Angraecum as defined by Garay and investigated the patterns of species diversification within the genus. We used maximum parsimony and bayesian analyses to generate phylogenetic trees and dated divergence times of the phylogeny. We analyzed diversification patterns within Angraecinae and Angraecum with an emphasis on four floral characters (flower color, flower size, labellum position, spur length) using macroevolutionary models to evaluate which characters or character states are associated with speciation rates, and inferred ancestral states of these characters. The phylogenetic analysis showed the polyphyly of Angraecum sensu lato and of all Angraecum sections except sect. Hadrangis, and that morphology can be consistent with the phylogeny. It appeared that the characters (flower color, flower size, spur length) formerly used by many authors to delineate Angraecum groups were insufficient to do so. However, the newly described character, position of the labellum (uppermost and lowermost), was the main character delimiting clades within a monophyletic Angraecum sensu stricto. This character also appeared to be associated with speciation rates in Angraecum. The macroevolutionary model-based phylogeny failed to detect shifts in diversification that could be associated directly with morphological diversification. Diversification in Angraecum resulted from gradual species accumulation through time rather than from rapid radiation, a diversification pattern often encountered in tropical rain forests.
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Affiliation(s)
| | - Shannon Engberg
- Omaha’s Henry Doorly Zoo and Aquarium, Omaha, Nebraska, United States of America
| | - Edward E. Louis
- Omaha’s Henry Doorly Zoo and Aquarium, Omaha, Nebraska, United States of America
| | - Luc Brouillet
- Département de sciences biologiques, Université de Montréal, Montréal, Québec, Canada
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Blambert L, Mallet B, Humeau L, Pailler T. Reproductive patterns, genetic diversity and inbreeding depression in two closely related Jumellea species with contrasting patterns of commonness and distribution. ANNALS OF BOTANY 2016; 118:93-103. [PMID: 26944785 PMCID: PMC4934390 DOI: 10.1093/aob/mcw014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 09/11/2015] [Accepted: 11/13/2015] [Indexed: 05/23/2023]
Abstract
BACKGROUNDS AND AIMS Theory predicts that the long-term persistence of plant populations exposed to size reduction can be threatened by a loss of genetic diversity and increased inbreeding. However, several life-history and ecological traits can influence the response to population size reduction. The reproductive patterns, levels of genetic diversity and magnitude of inbreeding depression of the rare and fragmented Jumellea fragrans and of its widespread congener J. rossii were studied. The aim was to evaluate the effects of over-collection and fragmentation on J. fragrans and to enhance our knowledge of the biology and ecology of the two species, used for their aromatic and medicinal properties on Réunion. METHODS Hand pollination experiments were conducted to determine the breeding system and to evaluate the potential for inbreeding depression in both species. Nuclear microsatellite markers were used to investigate selfing rates and levels of genetic diversity. KEY RESULTS Jumellea rossii revealed a mixed-mating system, and inbreeding depression at the germination stage (δ = 0·66). Levels of genetic diversity were relatively high [allelic richness (AR) = 8·575 and expected heterozygosity (He) = 0·673]. In J. fragrans, selfing rates suggest a mainly outcrossing mating system. Genetic diversity was lower than in J. rossii, but not yet critically low (AR = 4·983 and He = 0·492), probably because of the mainly outcrossing mating system and the relatively high density of individuals in the studied population. Jumellea fragrans did not show inbreeding depression, and it is hypothesized that the population had progressively purged its genetic load during successive fragmentation events. CONCLUSIONS Even if the persistence of the J. fragrans population is not threatened in the short term, its genetic diversity has probably been reduced by fragmentation and over-collection. In situ conservation actions for J. fragrans and ex situ cultivation of both species are recommended in order to meet the demand of local people.
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Affiliation(s)
- Laury Blambert
- UMR Peuplements Végétaux et Bio-agresseurs en Milieu Tropical, Université de la Réunion, Ile de La Réunion, 15 Avenue René Cassin, CS 92003, 97744 Saint-Denis Cedex 9, Réunion, France
| | - Bertrand Mallet
- UMR Peuplements Végétaux et Bio-agresseurs en Milieu Tropical, Université de la Réunion, Ile de La Réunion, 15 Avenue René Cassin, CS 92003, 97744 Saint-Denis Cedex 9, Réunion, France
| | - Laurence Humeau
- UMR Peuplements Végétaux et Bio-agresseurs en Milieu Tropical, Université de la Réunion, Ile de La Réunion, 15 Avenue René Cassin, CS 92003, 97744 Saint-Denis Cedex 9, Réunion, France
| | - Thierry Pailler
- UMR Peuplements Végétaux et Bio-agresseurs en Milieu Tropical, Université de la Réunion, Ile de La Réunion, 15 Avenue René Cassin, CS 92003, 97744 Saint-Denis Cedex 9, Réunion, France
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Jaros U, Fischer GA, Pailler T, Comes HP. Spatial patterns of AFLP diversity in Bulbophyllum occultum (Orchidaceae) indicate long-term refugial isolation in Madagascar and long-distance colonization effects in La Réunion. Heredity (Edinb) 2016; 116:434-46. [PMID: 26883184 DOI: 10.1038/hdy.2016.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 10/21/2015] [Accepted: 12/15/2015] [Indexed: 01/30/2023] Open
Abstract
Bulbophyllum occultum, an epiphytic orchid mainly distributed in the rainforests of (north)eastern Madagascar and La Réunion, represents an interesting model case for testing the effects of anthropogenic vs historical (e.g., climate induced) habitat isolation and long-distance colonization on the genetic structure of plant species with disjunct distributions in the Madagascan region. To this aim, we surveyed amplified fragment length polymorphisms (AFLPs) across 13 populations in Madagascar and nine in La Réunion (206 individuals in total). We found overall high levels of population subdivision (Φ(PT)=0.387) and low within-population diversity (H(E), range: 0.026-0.124), indicating non-equilibrium conditions in a mainly selfing species. There was no impact of recent deforestation (Madagascar) or habitat disturbance (La Réunion) detectable on AFLP diversity. K-means clustering and BARRIER analyses identified multiple gene pools and several genetic breaks, both within and among islands. Inter-island levels of population genetic diversity and subdivision were similar, whereby inter-individual divergence in flower colour explained a significant part of gene pool divergence in La Réunion. Our results suggest that (i) B. occultum persisted across multiple isolated ('refugial') regions along the eastern rainforest corridor of Madagascar over recent climatic cycles and (ii) populations in La Réunion arose from either single or few independent introductions from Madagascar. High selfing rates and sufficient time for genetic drift likely promoted unexpectedly high population genetic and phenotypic (flower colour) differentiation in La Réunion. Overall, this study highlights a strong imprint of history on the genetic structure of a low-gene-dispersing epiphytic orchid from the Madagascan region.
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Affiliation(s)
- U Jaros
- Department of Ecology and Evolution, University of Salzburg, Salzburg, Austria
| | - G A Fischer
- Kadoorie Farm and Botanic Garden Corporation, Tai Po, N.T., Hong Kong, SAR
| | - T Pailler
- UMR CIRAD-université de La Réunion. Peuplements Végétaux et Bioagresseurs en Milieu Tropical, Le Tampon, Réunion, France
| | - H P Comes
- Department of Ecology and Evolution, University of Salzburg, Salzburg, Austria
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Chambers SM, Emery NC. Population differentiation and countergradient variation throughout the geographic range in the fern gametophyte Vittaria appalachiana. AMERICAN JOURNAL OF BOTANY 2016; 103:86-98. [PMID: 26758887 DOI: 10.3732/ajb.1500077] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 05/29/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Theory predicts that limited gene flow between populations will promote population differentiation, and experimental studies have found that differentiation is often explained by local adaptation in sexually reproducing angiosperms. However, few experiments have examined the drivers of differentiation among populations in asexual land plants with limited dispersal potential. Here, we evaluated the role of temperature in driving population differentiation in an asexual, obligate gametophyte fern species. METHODS We reciprocally transplanted Vittaria appalachiana gametophytes among six populations that spanned the species' geographic range in the Appalachian Mountains and Plateau. Temperature, survival, and senescence rates were measured for 1 year. KEY RESULTS Populations had significantly different fitness responses to different sites, consistent with the hypothesis that populations have differentiated across the species' range. There was some evidence for local adaptation in marginal populations and for countergradient selection favoring particularly robust genotypes at the northern range edge. Most populations had relatively high fitness at the site with the most stable temperature conditions and were negatively affected by decreasing minimum temperatures. CONCLUSIONS Populations of Vittaria appalachiana exhibit highly variable responses to transplantation across the species' range, and only a small subset of these responses are due to local adaptation. Differences in daily minimum temperature explain some variation in fitness, but other site-specific factors also have significant impacts on transplant fitness. These results indicate that asexual, patchily distributed species with limited dispersal may exhibit population-specific responses to global climate change that have not been elucidated by empirical work focused on sexually reproducing angiosperms.
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Affiliation(s)
- Sally M Chambers
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA, 47907
| | - Nancy C Emery
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, USA, 47907 Department of Ecology and Evolutionary Biology, UCB 334, University of Colorado, Boulder, Colorado, 80309-0334 USA
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Harter DEV, Thiv M, Weig A, Jentsch A, Beierkuhnlein C. Spatial and ecological population genetic structures within two island-endemic Aeonium species of different niche width. Ecol Evol 2015; 5:4327-44. [PMID: 26664682 PMCID: PMC4667834 DOI: 10.1002/ece3.1682] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 07/13/2015] [Accepted: 07/22/2015] [Indexed: 01/21/2023] Open
Abstract
The Crassulacean genus Aeonium is a well-known example for plant species radiation on oceanic archipelagos. However, while allopatric speciation among islands is documented for this genus, the role of intra-island speciation due to population divergence by topographical isolation or ecological heterogeneity has not yet been addressed. The aim of this study was to investigate intraspecific genetic structures and to identify spatial and ecological drivers of genetic population differentiation on the island scale. We analyzed inter simple sequence repeat variation within two island-endemic Aeonium species of La Palma: one widespread generalist that covers a large variety of different habitat types (Ae. davidbramwellii) and one narrow ecological specialist (Ae. nobile), in order to assess evolutionary potentials on this island. Gene pool differentiation and genetic diversity patterns were associated with major landscape structures in both species, with phylogeographic implications. However, overall levels of genetic differentiation were low. For the generalist species, outlier loci detection and loci-environment correlation approaches indicated moderate signatures of divergent selection pressures linked to temperature and precipitation variables, while the specialist species missed such patterns. Our data point to incipient differentiation among populations, emphasizing that ecological heterogeneity and topographical structuring within the small scales of an island can foster evolutionary processes. Very likely, such processes have contributed to the radiation of Aeonium on the Canary Islands. There is also support for different evolutionary mechanisms between generalist and specialist species.
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Affiliation(s)
| | - Mike Thiv
- State Museum of Natural History StuttgartStuttgartGermany
| | - Alfons Weig
- DNA Analytics and EcoinformaticsBayCEERUniversity of BayreuthBayreuthGermany
| | - Anke Jentsch
- Disturbance EcologyBayCEERUniversity of BayreuthBayreuthGermany
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Tsai CC, Chou CH, Wang HV, Ko YZ, Chiang TY, Chiang YC. Biogeography of the Phalaenopsis amabilis species complex inferred from nuclear and plastid DNAs. BMC PLANT BIOLOGY 2015; 15:202. [PMID: 26276316 PMCID: PMC4537552 DOI: 10.1186/s12870-015-0560-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 06/17/2015] [Indexed: 05/24/2023]
Abstract
BACKGROUND Phalaenopsis is one of the important commercial orchids in the world. Members of the P. amabilis species complex represent invaluable germplasm for the breeding program. However, the phylogeny of the P. amabilis species complex is still uncertain. The Phalaenopsis amabilis species complex (Orchidaceae) consists of subspecies amabilis, moluccana, and rosenstromii of P. amabilis, as well as P. aphrodite ssp. aphrodite, P. ap. ssp. formosana, and P. sanderiana. The aims of this study were to reconstruct the phylogeny and biogeographcial patterns of the species complex using Neighbor Joining (NJ), Maxinum Parsimony (MP), Bayesian Evolutionary Analysis Sampling Trees (BEAST) and Reconstruct Ancestral State in Phylogenies (RASP) analyses based on sequences of internal transcribed spacers 1 and 2 from the nuclear ribosomal DNA and the trnH-psbA spacer from the plastid DNA. RESULTS A pattern of vicariance, dispersal, and vicariance + dispersal among disjunctly distributed taxa was uncovered based on RASP analysis. Although two subspecies of P. aphrodite could not be differentiated from each other in dispersal state, they were distinct from P. amabilis and P. sanderiana. Within P. amabilis, three subspecies were separated phylogenetically, in agreement with the vicariance or vicariance + dispersal scenario, with geographic subdivision along Huxley's, Wallace's and Lydekker's Lines. Molecular dating revealed such subdivisions among taxa of P. amabilis complex dating back to the late Pleistocene. Population-dynamic analyses using a Bayesian skyline plot suggested that the species complex experienced an in situ range expansion and population concentration during the late Last Glacial Maximum (LGM). CONCLUSIONS Taxa of the P. amabilis complex with disjunct distributions were differentiated due to vicariance or vicariance + dispersal, with events likely occurring in the late Pleistocene. Demographic growth associated with the climatic oscillations in the Würm glacial period followed the species splits. Nevertheless, a subsequent population slowdown occurred in the late LGM due to extinction of regional populations. The reduction of suitable habitats resulted in geographic fragmenttation of the remaining taxa.
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Affiliation(s)
- Chi-Chu Tsai
- Crop Improvement Division, Kaohsiung District Agricultural Improvement Station, Pingtung, 900, Taiwan.
- Graduate Institute of Biotechnology, National Pingtung University of Science and Technology, Pingtung, 912, Taiwan.
| | - Chang-Hung Chou
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
- Research Center for Biodiversity, China Medical University, Taichung, 404, Taiwan.
| | - Hao-Ven Wang
- Department of Life Science, National Cheng Kung University, Tainan, 701, Taiwan.
| | - Ya-Zhu Ko
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
| | - Tzen-Yuh Chiang
- Department of Life Science, National Cheng Kung University, Tainan, 701, Taiwan.
| | - Yu-Chung Chiang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
- Department of Biomedical Science and Environment Biology, Kaohsiung Medical University, Kaohsiung, 807, Taiwan.
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Dyer RJ. Is there such a thing as landscape genetics? Mol Ecol 2015; 24:3518-28. [DOI: 10.1111/mec.13249] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 01/13/2023]
Affiliation(s)
- Rodney J. Dyer
- Department of Biology & Center for Environmental Studies; Virginia Commonwealth University; 1000 West Cary Street Richmond VA 23284-2012 USA
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15
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Guo YY, Luo YB, Liu ZJ, Wang XQ. Reticulate evolution and sea-level fluctuations together drove species diversification of slipper orchids (Paphiopedilum) in South-East Asia. Mol Ecol 2015; 24:2838-55. [PMID: 25847454 DOI: 10.1111/mec.13189] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 03/29/2015] [Accepted: 03/31/2015] [Indexed: 01/19/2023]
Abstract
South-East Asia covers four of the world's biodiversity hotspots, showing high species diversity and endemism. Owing to the successive expansion and contraction of distribution and the fragmentation by geographical barriers, the tropical flora greatly diversified in this region during the Tertiary, but the evolutionary tempo and mode of species diversity remain poorly investigated. Paphiopedilum, the largest genus of slipper orchids comprising nearly 100 species, is mainly distributed in South-East Asia, providing an ideal system for exploring how plant species diversity was shaped in this region. Here, we investigated the evolutionary history of this genus with eight cpDNA regions and four low-copy nuclear genes. Discordance between gene trees and network analysis indicates that reticulate evolution occurred in the genus. Ancestral area reconstruction suggests that vicariance and long-distance dispersal together led to its current distribution. Diversification rate variation was detected and strongly correlated with the species diversity in subg. Paphiopedilum (~80 species). The shift of speciation rate in subg. Paphiopedilum was coincident with sea-level fluctuations in the late Cenozoic, which could have provided ecological opportunities for speciation and created bridges or barriers for gene flow. Moreover, some other factors (e.g. sympatric distribution, incomplete reproductive barriers and clonal propagation) might also be advantageous for the formation and reproduction of hybrid species. In conclusion, our study suggests that the interplay of reticulate evolution and sea-level fluctuations has promoted the diversification of the genus Paphiopedilum and sheds light into the evolution of Orchidaceae and the historical processes of plant species diversification in South-East Asia.
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Affiliation(s)
- Yan-Yan Guo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, 100093, China.,Shenzhen Key Laboratory for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, No. 889, Wangtong Road, Shenzhen, 518114, China.,Center for Biotechnology and BioMedicine, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China
| | - Yi-Bo Luo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, 100093, China
| | - Zhong-Jian Liu
- Shenzhen Key Laboratory for Orchid Conservation and Utilization, The National Orchid Conservation Center of China and The Orchid Conservation and Research Center of Shenzhen, No. 889, Wangtong Road, Shenzhen, 518114, China
| | - Xiao-Quan Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, 100093, China
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Tsai CC, Wu PY, Kuo CC, Huang MC, Yu SK, Hsu TW, Chiang TY, Chiang YC. Analysis of microsatellites in the vulnerable orchid Gastrodia flavilabella: the development of microsatellite markers, and cross-species amplification in Gastrodia. BOTANICAL STUDIES 2014; 55:72. [PMID: 28510952 PMCID: PMC5430336 DOI: 10.1186/s40529-014-0072-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/29/2014] [Indexed: 05/28/2023]
Abstract
BACKGROUND Gastrodia flabilabella is a mycoheterotrophic orchid that obtains carbohydrates and nutrients from its symbiotic mycorrhizal fungi. The species is an endemic and vulnerable species enlisted in the "A Preliminary Red List of Taiwanese Vascular Plants" according to the IUCN Red List Categories and Criteria Version 3.1. G. flabilabella dwells the underground of broadleaf and coniferous forest with richness litter. Based on herbarium records, this species is distributed in central Taiwan. Twenty eight microsatellite loci were developed in G. flabilabella and were tested for cross-species amplification in additional taxa of G. confusoides, G. elata, and G. javanica. We estimated the genetic variation that is valuable for conservation management and the development of the molecular identification system for G. elata, a traditional Chinese medicine herb. RESULTS Microsatellite primer sets were developed from G. flabilabella using the modified AFLP and magnetic bead enrichment method. In total, 257 microsatellite loci were obtained from a magnetic bead enrichment SSR library. Of the 28 microsatellite loci, 16 were polymorphic, in which the number of alleles ranged from 2 to 15, with the observed heterozygosity ranging from 0.02 to 1.00. In total, 15, 13, and 7 of the loci were found to be interspecifically amplifiable to G. confusoides, G. elata, and G. javanica, respectively. CONCLUSIONS Amplifiable and transferable microsatellite loci are potentially useful for future studies in investigating intraspecific genetic variation, reconstructing phylogeographic patterns among closely related species, and establishing the standard operating system of molecular identification in Gastrodia.
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Affiliation(s)
- Chi-Chu Tsai
- Crop Improvement Division, Kaohsiung District Agricultural Research and Extension Station, Pingtung, 908 Taiwan
| | - Pei-Yin Wu
- Department of Life Science, National Cheng Kung University, Tainan, 701 Taiwan
| | - Chia-Chi Kuo
- Department of Nursing, Meiho University, Pingtung, 912 Taiwan
| | - Min-Chun Huang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan
| | - Sheng-Kun Yu
- Taiwan Society of Plant Systematics, Kaohsiung, 804 Taiwan
| | - Tsai-Wen Hsu
- Endemic Species Research Institute, Nantou, 552 Taiwan
| | - Tzen-Yuh Chiang
- Department of Life Science, National Cheng Kung University, Tainan, 701 Taiwan
| | - Yu-Chung Chiang
- Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan
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