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Petipas RH, Antoch AA, Eaker AA, Kehlet-Delgado H, Friesen ML. Back to the future: Using herbarium specimens to isolate nodule-associated bacteria. Ecol Evol 2024; 14:e11719. [PMID: 39011130 PMCID: PMC11246978 DOI: 10.1002/ece3.11719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 06/14/2024] [Accepted: 06/21/2024] [Indexed: 07/17/2024] Open
Abstract
Herbarium specimens are increasingly being used as sources of information to understand the ecology and evolution of plants and their associated microbes. Most studies have used specimens as a source of genetic material using culture-independent approaches. We demonstrate that herbarium specimens can also be used to culture nodule-associated bacteria, opening the possibility of using specimens to understand plant-microbe interactions at new spatiotemporal scales. We used historic and contemporary nodules of a common legume, Medicago lupulina, to create a culture collection. We were able to recover historic bacteria in 15 genera from three specimens (collected in 1950, 2004, and 2015). This work is the first of its kind to isolate historic bacteria from herbarium specimens. Future work should include inoculating plants with historic strains to see if they produce nodules and if they affect plant phenotype and fitness. Although we were unable to recover any Ensifer, the main symbiont of Medicago lupulina, we recovered some other potential nodulating species, as well as many putative growth-promoting bacteria.
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Affiliation(s)
- Renee H Petipas
- Department of Plant Pathology Washington State University Pullman Washington USA
| | - Amanda A Antoch
- Department of Plant Pathology Washington State University Pullman Washington USA
- Department of Microbiology University of Washington Seattle Washington USA
| | - Ashton A Eaker
- Department of Plant Pathology Washington State University Pullman Washington USA
| | - Hanna Kehlet-Delgado
- Department of Plant Pathology Washington State University Pullman Washington USA
| | - Maren L Friesen
- Department of Plant Pathology Washington State University Pullman Washington USA
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Zhang F, Long R, Ma Z, Xiao H, Xu X, Liu Z, Wei C, Wang Y, Peng Y, Yang X, Shi X, Cao S, Li M, Xu M, He F, Jiang X, Zhang T, Wang Z, Li X, Yu LX, Kang J, Zhang Z, Zhou Y, Yang Q. Evolutionary genomics of climatic adaptation and resilience to climate change in alfalfa. MOLECULAR PLANT 2024; 17:867-883. [PMID: 38678365 DOI: 10.1016/j.molp.2024.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 04/09/2024] [Accepted: 04/24/2024] [Indexed: 04/29/2024]
Abstract
Given the escalating impact of climate change on agriculture and food security, gaining insights into the evolutionary dynamics of climatic adaptation and uncovering climate-adapted variation can empower the breeding of climate-resilient crops to face future climate change. Alfalfa (Medicago sativa subsp. sativa), the queen of forages, shows remarkable adaptability across diverse global environments, making it an excellent model for investigating species responses to climate change. In this study, we performed population genomic analyses using genome resequencing data from 702 accessions of 24 Medicago species to unravel alfalfa's climatic adaptation and genetic susceptibility to future climate change. We found that interspecific genetic exchange has contributed to the gene pool of alfalfa, particularly enriching defense and stress-response genes. Intersubspecific introgression between M. sativa subsp. falcata (subsp. falcata) and alfalfa not only aids alfalfa's climatic adaptation but also introduces genetic burden. A total of 1671 genes were associated with climatic adaptation, and 5.7% of them were introgressions from subsp. falcata. By integrating climate-associated variants and climate data, we identified populations that are vulnerable to future climate change, particularly in higher latitudes of the Northern Hemisphere. These findings serve as a clarion call for targeted conservation initiatives and breeding efforts. We also identified pre-adaptive populations that demonstrate heightened resilience to climate fluctuations, illuminating a pathway for future breeding strategies. Collectively, this study enhances our understanding about the local adaptation mechanisms of alfalfa and facilitates the breeding of climate-resilient alfalfa cultivars, contributing to effective agricultural strategies for facing future climate change.
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Affiliation(s)
- Fan Zhang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China; National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Ruicai Long
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhiyao Ma
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Hua Xiao
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Xiaodong Xu
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Zhongjie Liu
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Chunxue Wei
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Yiwen Wang
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Yanling Peng
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Xuanwen Yang
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Xiaoya Shi
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Shuo Cao
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China
| | - Mingna Li
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Ming Xu
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Fei He
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xueqian Jiang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Tiejun Zhang
- School of Grassland Science, Beijing Forestry University, Beijing 100083, China
| | - Zhen Wang
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
| | - Xianran Li
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99163, USA
| | - Long-Xi Yu
- U.S. Department of Agriculture-Agricultural Research Service, Plant Germplasm Introduction and Testing Research, Prosser, WA 99350, USA
| | - Junmei Kang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zhiwu Zhang
- Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99163, USA
| | - Yongfeng Zhou
- National Key Laboratory of Tropical Crop Breeding, Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Key Laboratory of Synthetic Biology, Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518000, China; National Key Laboratory of Tropical Crop Breeding, Tropical Crops Genetic Resources Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China.
| | - Qingchuan Yang
- Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
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Ahatović Hajro A, Hasanović M, Murtić S, Kalajdžić A, Pojskić N, Durmić-Pašić A. Serpentine environment prevails over geographic distribution in shaping the genetic diversity of Medicago lupulina L. Mol Genet Genomics 2024; 299:28. [PMID: 38472470 DOI: 10.1007/s00438-024-02124-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 02/03/2024] [Indexed: 03/14/2024]
Abstract
Edaphic conditions of serpentine soils, naturally rich in heavy metals, act as a strong selection pressure that shapes specific metal-tolerant ecotypes. Medicago lupulina L. (black medick) is not only a widespread plant species that prefers calcareous and dry soil types but also grows at the borders of serpentine formations. It can also be found in waste and disturbed habitats. This is a species with reported phytoremediation potential, however, there is no published data regarding the impact of the environment on the genetic distribution of this species. The aim of our research was to explore how selection pressure of serpentine soils affects genetic diversity of M. lupulina and to test heavy-metal accumulation capacity of this species. Specimens of 11 M. lupulina populations were collected from serpentine outcrops located in Central and Eastern Bosnia as well as from non-serpentine sites. Soil and plant samples were analyzed for the total contents of heavy metals using air-acetylene flame atomic absorption spectroscopy. Genetic diversity was analyzed using AFLP (Amplified Fragment Length Polymorphism) markers. Serpentine soils showed high nickel, cobalt, chromium and iron concentrations. Nickel and manganese concentrations in soil samples and plant material showed statistically significant correlation. Although plants in two populations show the ability to extract Ni, M. lupulina does not show hyperaccumulating properties. Despite severe selective pressure, genetic diversity in serpentine populations is not reduced. Analyses of intrapopulation and interpopulation genetic diversity showed significant genetic differentiation among populations which is not related to their geographic distance. Population from non-metalliferous soil showed clear separation from all other populations. Diversity data suggest that serpentine populations maintain genetic diversity by undetected mechanisms and that edaphic factors rather than geography influence genetic structure analyzed M. lupulina populations.
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Affiliation(s)
- Anesa Ahatović Hajro
- Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina.
| | - Mujo Hasanović
- Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina
| | - Senad Murtić
- Faculty of Agriculture and Food Sciences, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina
| | - Abdurahim Kalajdžić
- Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina
| | - Naris Pojskić
- Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina
| | - Adaleta Durmić-Pašić
- Institute for Genetic Engineering and Biotechnology, University of Sarajevo, Zmaja Od Bosne 8, 71 000, Sarajevo, Bosnia and Herzegovina
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Genetic Diversity and Differentiation of Eleven Medicago Species from Campania Region Revealed by Nuclear and Chloroplast Microsatellites Markers. Genes (Basel) 2021; 13:genes13010097. [PMID: 35052437 PMCID: PMC8774365 DOI: 10.3390/genes13010097] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/23/2021] [Accepted: 12/29/2021] [Indexed: 11/17/2022] Open
Abstract
The species belonging to the genus Medicago are considered a very important genetic resource at global level both for planet’s food security and for sustainable rangelands management. The checklist of the Italian flora (2021) includes a total number of 40 Medicago species for Italy, and 27 for Campania region, with a number of doubtful records or related to species no more found in the wild. In this study, 10 Medicago species native to Campania region, and one archaeophyte (M. sativa), identified by means of morphological diagnostic characters, were analyzed in a blind test to assay the efficacy of nine microsatellite markers (five cp-SSRs and four n-SSRs). A total number of 33 individuals from 6 locations were sampled and genotyped. All markers were polymorphic, 40 alleles were obtained with n-SSRs ranging from 8–12 alleles per locus with an average of 10 alleles per marker, PIC values ranged from 0.672 to 0.847, and the most polymorphic SSR was MTIC 564. The cp-SSRs markers were highly polymorphic too; PIC values ranged from 0.644 to 0.891 with an average of 0.776, the most polymorphic cp-SSR was CCMP10. 56 alleles were obtained with cp-SSRs ranging from 7 to 17 alleles per locus with an average of 11. AMOVA analysis with n-SSR markers highlighted a great level of genetic differentiation among the 11 species, with a statistically significant fixation index (FST). UPGMA clustering and Bayesian-based population structure analysis assigned these 11 species to two main clusters, but the distribution of species within clusters was not the same for the two analyses. In conclusion, our results demonstrated that the combination of the used SSRs well distinguished the 11 Medicago species. Moreover, our results demonstrated that the use of a limited number of SSRs might be considered for further genetic studies on other Medicago species.
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Dieterich Mabin ME, Brunet J, Riday H, Lehmann L. Self-Fertilization, Inbreeding, and Yield in Alfalfa Seed Production. FRONTIERS IN PLANT SCIENCE 2021; 12:700708. [PMID: 34295346 PMCID: PMC8290836 DOI: 10.3389/fpls.2021.700708] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/04/2021] [Indexed: 06/13/2023]
Abstract
Selfing (self-pollination) is the ultimate form of inbreeding, or mating among close relatives. Selfing can create yield loss when inbreeding depression, defined as a lower survival and reproduction of inbred relative to outbred progeny, is present. To determine the impact of selfing in alfalfa (Medicago sativa L.), we quantified the selfing rate of 32 alfalfa seed production fields located in three regions, namely, the Pacific Northwest (PNW), the Central Valley of California (CEV), and the Imperial Valley of California (IMP). Selfing rates (the proportion of selfed seeds) varied between 5.3 and 30% with an average of 12.2% over the 32 seed production fields. In both the parents and their progeny, we observed an excess of heterozygotes relative to Hardy-Weinberg expectations. We detected notable levels of inbreeding in parents (0.231 ± 0.007 parental inbreeding coefficient) and progeny (0.229 ± 0.005). There were a 15% decrease in the number of seeds per stem (seed set) and a 13% decline in the number of seeds per pod in selfed relative to outcrossed stems, but negligible inbreeding depression for pods per raceme and seed weight. The number of racemes on selfed stems increased significantly in fields with greater selfing rates, supporting the presence of geitonogamous or among flower selfing. Despite the significant level of inbreeding depression, seed set did not decrease in fields with higher selfing rates, where the greater number of racemes on the selfed stems increased the seed set. The effects of the field selfing rate on the seed yield metrics were mostly indirect with direct effects of the number of racemes per stem. Available data indicate that the majority of selfing in alfalfa is pollinator-mediated, and thus, eliminating selfing in alfalfa seed production would require the selection of self-incompatible varieties, which, by eliminating inbreeding depression, would provide a 15% potential increase in seed yield and an increase in future hay yield.
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Affiliation(s)
- Molly E. Dieterich Mabin
- Vegetable Crops Research Unit, United States Department of Agriculture-Agricultural Research Service, Madison, WI, United States
| | - Johanne Brunet
- Vegetable Crops Research Unit, United States Department of Agriculture-Agricultural Research Service, Madison, WI, United States
| | - Heathcliffe Riday
- US Dairy Forage Research Center, United States Department of Agriculture-Agricultural Research Service, Madison, WI, United States
| | - Lauren Lehmann
- US Dairy Forage Research Center, United States Department of Agriculture-Agricultural Research Service, Madison, WI, United States
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Cuartas‐Hernández SE, Moreno‐Betancur DJ. Contrasting population genetic structure of two sympatric species of Anthurium(Araceae) along elevation in an Andean mountain forest. Biotropica 2020. [DOI: 10.1111/btp.12775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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7
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Böckelmann J, Tremetsberger K, Šumberová K, Kohl G, Grausgruber H, Bernhardt K. Genetic variation in an ephemeral mudflat species: The role of the soil seed bank and dispersal in river and secondary anthropogenic habitats. Ecol Evol 2020; 10:3620-3635. [PMID: 32313622 PMCID: PMC7160169 DOI: 10.1002/ece3.6109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 11/05/2019] [Accepted: 01/20/2020] [Indexed: 01/27/2023] Open
Abstract
Many ephemeral mudflat species, which rely on a soil seed bank to build up the next generation, are endangered in their natural habitat due to the widespread regulation of rivers. The aim of the present study was to elucidate the role of the soil seed bank and dispersal for the maintenance of genetic diversity in populations of near-natural river habitats and anthropogenic habitats created by traditional fish farming practices using Cyperus fuscus as a model. Using microsatellite markers, we found no difference in genetic diversity levels between soil seed bank and above-ground population and only moderate differentiation between the two fractions. One possible interpretation is the difference in short-term selection during germination under specific conditions (glasshouse versus field) resulting in an ecological filtering of genotypes out of the reservoir in the soil. River populations harbored significantly more genetic diversity than populations from the anthropogenic pond types. We suggest that altered levels and patterns of dispersal together with stronger selection pressures and historical bottlenecks in anthropogenic habitats are responsible for the observed reduction in genetic diversity. Dispersal is also supposed to largely prohibit genetic structure across Europe, although there is a gradient in private allelic richness from southern Europe (high values) to northern, especially north-western, Europe (low values), which probably relates to postglacial expansion out of southern and/or eastern refugia.
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Affiliation(s)
- Jörg Böckelmann
- Department of Integrative Biology and Biodiversity ResearchInstitute of BotanyUniversity of Natural Resources and Life SciencesViennaAustria
- Present address:
Division of Tropical Ecology and Animal BiodiversityDepartment of Botany and Biodiversity ResearchUniversity of ViennaViennaAustria
| | - Karin Tremetsberger
- Department of Integrative Biology and Biodiversity ResearchInstitute of BotanyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Kateřina Šumberová
- Department of Vegetation EcologyInstitute of BotanyThe Czech Academy of SciencesBrnoCzech Republic
| | - Gudrun Kohl
- Department of Integrative Biology and Biodiversity ResearchInstitute of BotanyUniversity of Natural Resources and Life SciencesViennaAustria
- Present address:
Division of Microbial EcologyDepartment of Microbiology and Ecosystem ScienceUniversity of ViennaViennaAustria
| | - Heinrich Grausgruber
- Division of Plant BreedingDepartment of Crop SciencesUniversity of Natural Resources and Life SciencesViennaAustria
| | - Karl‐Georg Bernhardt
- Department of Integrative Biology and Biodiversity ResearchInstitute of BotanyUniversity of Natural Resources and Life SciencesViennaAustria
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Batstone RT, Peters MAE, Simonsen AK, Stinchcombe JR, Frederickson ME. Environmental variation impacts trait expression and selection in the legume-rhizobium symbiosis. AMERICAN JOURNAL OF BOTANY 2020; 107:195-208. [PMID: 32064599 DOI: 10.1002/ajb2.1432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 11/04/2019] [Indexed: 05/22/2023]
Abstract
PREMISE The ecological outcomes of mutualism are well known to shift across abiotic or biotic environments, but few studies have addressed how different environments impact evolutionary responses, including the intensity of selection on and the expression of genetic variance in key mutualism-related traits. METHODS We planted 30 maternal lines of the legume Medicago lupulina in four field common gardens and compared our measures of selection on and genetic variance in nodulation, a key trait reflecting legume investment in the symbiosis, with those from a previous greenhouse experiment using the same 30 M. lupulina lines. RESULTS We found that both the mean and genetic variance for nodulation were much greater in the greenhouse than in the field and that the form of selection on nodulation significantly differed across environments. We also found significant genotype-by-environment (G × E) effects for fitness-related traits that were generated by differences in the rank order of plant lines among environments. CONCLUSIONS Overall, our results suggest that the expression of genotypic variation and selection on nodulation differ across environments. In the field, significant rank-order changes for plant fitness potentially help maintain genetic variation in natural populations, even in the face of directional or stabilizing selection.
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Affiliation(s)
- Rebecca T Batstone
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Carl Woese Institute for Genomic Biology, University of Illinois at Champaign-Urbana, Urbana, IL, 61801, USA
| | - Madeline A E Peters
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Anna K Simonsen
- Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Koffler Scientific Reserve, University of Toronto, King, ON, L7B 1K5, Canada
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
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Nagel R, Durka W, Bossdorf O, Bucharova A. Rapid evolution in native plants cultivated for ecological restoration: not a general pattern. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:551-558. [PMID: 30120869 DOI: 10.1111/plb.12901] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
The growing number of restoration projects worldwide increases the demand for seed material of native species. To meet this demand, seeds are often produced through large-scale cultivation on specialised farms, using wild-collected seeds as the original sources. However, during cultivation, plants experience novel environmental conditions compared to those in natural populations, and there is a danger that the plants in cultivation are subject to unintended selection and lose their adaptation to natural habitats. Although the propagation methods are usually designed to maintain as much natural genetic diversity as possible, the effectiveness of these measures have never been tested. We obtained seed of five common grassland species from one of the largest native seed producers in Germany. For each species, the seeds were from multiple generations of seed production. We used AFLP markers and a common garden experiment to test for genetic and phenotypic changes during cultivation of these plants. The molecular markers detected significant evolutionary changes in three out of the five species and we found significant phenotypic changes in two species. The only species that showed substantial genetic and phenotypic changes was the short-lived and predominantly selfing Medicago lupulina, while in the other, mostly perennial and outcrossing species, the observed changes were mostly minor. Agricultural propagation of native seed material for restoration can cause evolutionary changes, at least in some species. We recommend caution, particularly in selfing and short-lived species, where evolution may be more rapid and effects may thus be more severe.
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Affiliation(s)
- R Nagel
- Plant Evolutionary Ecology, Institute of Evolution & Ecology, University of Tübingen, Tübingen, Germany
| | - W Durka
- Department of Community Ecology, Helmholtz Centre for Environmental Research-UFZ, Halle, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - O Bossdorf
- Plant Evolutionary Ecology, Institute of Evolution & Ecology, University of Tübingen, Tübingen, Germany
| | - A Bucharova
- Plant Evolutionary Ecology, Institute of Evolution & Ecology, University of Tübingen, Tübingen, Germany
- Nature Conservation and landscape Ecology, University of Freiburg, Freiburg, Germany
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Harrison TL, Wood CW, Heath KD, Stinchcombe JR. Geographically structured genetic variation in the
Medicago lupulina
–
Ensifer
mutualism. Evolution 2017; 71:1787-1801. [DOI: 10.1111/evo.13268] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/08/2017] [Accepted: 04/15/2017] [Indexed: 12/30/2022]
Affiliation(s)
- Tia L. Harrison
- Department of Ecology and Evolutionary BiologyUniversity of Toronto 25 Willcocks Street Toronto Ontario Canada M5S 3B2
| | - Corlett W. Wood
- Department of Ecology and Evolutionary BiologyUniversity of Toronto 25 Willcocks Street Toronto Ontario Canada M5S 3B2
| | - Katy D. Heath
- Department of Plant BiologyUniversity of Illinois 505 S. Goodwin Avenue Urbana Illinois 61801
| | - John R. Stinchcombe
- Department of Ecology and Evolutionary BiologyUniversity of Toronto 25 Willcocks Street Toronto Ontario Canada M5S 3B2
- Centre for Genome Evolution and FunctionUniversity of Toronto 25 Willcocks Street Toronto Ontario Canada M5S 3B2
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Harrison TL, Wood CW, Borges IL, Stinchcombe JR. No evidence for adaptation to local rhizobial mutualists in the legume Medicago lupulina. Ecol Evol 2017; 7:4367-4376. [PMID: 28649348 PMCID: PMC5478075 DOI: 10.1002/ece3.3012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 03/15/2017] [Accepted: 03/27/2017] [Indexed: 12/31/2022] Open
Abstract
Local adaptation is a common but not ubiquitous feature of species interactions, and understanding the circumstances under which it evolves illuminates the factors that influence adaptive population divergence. Antagonistic species interactions dominate the local adaptation literature relative to mutualistic ones, preventing an overall assessment of adaptation within interspecific interactions. Here, we tested whether the legume Medicago lupulina is adapted to the locally abundant species of mutualistic nitrogen-fixing rhizobial bacteria that vary in frequency across its eastern North American range. We reciprocally inoculated northern and southern M. lupulina genotypes with the northern (Ensifer medicae) or southern bacterium (E. meliloti) in a greenhouse experiment. Despite producing different numbers of root nodules (the structures in which the plants house the bacteria), neither northern nor southern plants produced more seeds, flowered earlier, or were more likely to flower when inoculated with their local rhizobia. We then used a pre-existing dataset to perform a genome scan for loci that showed elevated differentiation between field-collected plants that hosted different bacteria. None of the loci we identified belonged to the well-characterized suite of legume-rhizobia symbiosis genes, suggesting that the rhizobia do not drive genetic divergence between M. lupulina populations. Our results demonstrate that symbiont local adaptation has not evolved in this mutualism despite large-scale geographic variation in the identity of the interacting species.
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Affiliation(s)
- Tia L. Harrison
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Corlett W. Wood
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Isabela L. Borges
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - John R. Stinchcombe
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
- Centre for Genome Evolution and FunctionUniversity of TorontoTorontoONCanada
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Population genetic structure and demographic history of Medicago ruthenica (Fabaceae) on the Qinghai-Tibetan Plateau based on nuclear ITS and chloroplast markers. BIOCHEM SYST ECOL 2016. [DOI: 10.1016/j.bse.2016.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Yang L, Chen J, Hu W, Yang T, Zhang Y, Yukiyoshi T, Zhou Y, Wang Y. Population Genetic Structure of Glycyrrhiza inflata B. (Fabaceae) Is Shaped by Habitat Fragmentation, Water Resources and Biological Characteristics. PLoS One 2016; 11:e0164129. [PMID: 27711241 PMCID: PMC5053598 DOI: 10.1371/journal.pone.0164129] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 09/20/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Habitat fragmentation, water resources and biological characteristics are important factors that shape the genetic structure and geographical distribution of desert plants. Analysis of the relationships between these factors and population genetic variation should help to determine the evolutionary potential and conservation strategies for genetic resources for desert plant populations. As a traditional Chinese herb, Glycyrrhiza inflata B. (Fabaceae) is restricted to the fragmented desert habitat in China and has undergone a dramatic decline due to long-term over-excavation. Determining the genetic structure of the G. inflata population and identifying a core collection could help with the development of strategies to conserve this species. RESULTS We investigated the genetic variation of 25 G. inflata populations based on microsatellite markers. A high level of population genetic divergence (FST = 0.257), population bottlenecks, reduced gene flow and moderate genetic variation (HE = 0.383) were detected. The genetic distances between the populations significantly correlated with the geographical distances, and this suggests that habitat fragmentation has driven a special genetic structure of G. inflata in China through isolation by distance. STRUCTURE analysis showed that G. inflata populations were structured into three clusters and that the populations belonged to multiple water systems, which suggests that water resources were related to the genetic structure of G. inflata. In addition, the biological characteristics of the perennial species G. inflata, such as its long-lived seeds, asexual reproduction, and oasis ecology, may be related to its resistance to habitat fragmentation. A core collection of G. inflata, that included 57 accessions was further identified, which captured the main allelic diversity of G. inflata. CONCLUSIONS Recent habitat fragmentation has accelerated genetic divergence. The population genetic structure of G. inflata has been shaped by habitat fragmentation, water resources and biological characteristics. This genetic information and core collection will facilitate the conservation of wild germplasm and breeding of this Chinese medicinal plant.
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Affiliation(s)
- Lulu Yang
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, P.R. China
- University of the Chinese Academy of Sciences, Beijing, P.R. China
| | - Jianjun Chen
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, P.R. China
| | - Weiming Hu
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, P.R. China
- University of the Chinese Academy of Sciences, Beijing, P.R. China
| | - Tianshun Yang
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, P.R. China
| | - Yanjun Zhang
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, P.R. China
| | | | | | - Ying Wang
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, P.R. China
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Basbag M, Aydin A, Sakiroglu M. Evaluating Agronomic Performance and Investigating Molecular Structure of Drought and Heat Tolerant Wild Alfalfa (Medicago sativa L.) Collection from the Southeastern Turkey. Biochem Genet 2016; 55:63-76. [PMID: 27567621 DOI: 10.1007/s10528-016-9772-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/24/2016] [Indexed: 10/21/2022]
Abstract
Drought is a major stress factor for agricultural production including alfalfa production. One way to counterbalance the yield losses is the introgression of drought tolerant germplasm into breeding programs. As an effort to exploit such germplasm, 16 individual plants were selected from the Southeastern Turkey from their natural habitat and clonally propagated in field trials with an ultimate goal to use the germplasm as parents for releasing a synthetic cultivar. Forage yield and forage quality traits were evaluated and molecular genetic diversity among genotypes were determined using inter simple sequence repeat markers. Genotypes showed a variation from growth habit to yield and quality traits indicating sufficient phenotypic variation for diverse breeding efforts (for grazing or harvesting) and long term selection schemes. A large amount of genetic variation was observed even with a limited number of marker and genotypes. However, no pattern of spatial genetic structure was observed for the scale of the study when genetic variation is linked to the geographic origin. We conclude that ex situ natural variation provides a wealth of germplasm that could be incorporated into breeding programs aiming to improve drought tolerance. We also suggest an extensive collection of seeds/plant tissue from unique plants with desirable traits rather than putting more efforts to create a spatial germplasm sampling efforts in narrow regions.
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Affiliation(s)
- Mehmet Basbag
- Department of Field Crops, Faculty of Agriculture, Dicle University, 21280, Diyarbakir, Turkey
| | - Ali Aydin
- Department of Field Crops, Faculty of Agriculture and Natural Sciences, Recep Tayyip Erdogan University, 53300, Rize, Turkey
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Simonsen AK, Stinchcombe JR. Standing genetic variation in host preference for mutualist microbial symbionts. Proc Biol Sci 2015; 281:rspb.2014.2036. [PMID: 25355477 DOI: 10.1098/rspb.2014.2036] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Many models of mutualisms show that mutualisms are unstable if hosts lack mechanisms enabling preferential associations with mutualistic symbiotic partners over exploitative partners. Despite the theoretical importance of mutualism-stabilizing mechanisms, we have little empirical evidence to infer their evolutionary dynamics in response to exploitation by non-beneficial partners. Using a model mutualism-the interaction between legumes and nitrogen-fixing soil symbionts-we tested for quantitative genetic variation in plant responses to mutualistic and exploitative symbiotic rhizobia in controlled greenhouse conditions. We found significant broad-sense heritability in a legume host's preferential association with mutualistic over exploitative symbionts and selection to reduce frequency of associations with exploitative partners. We failed to detect evidence that selection will favour the loss of mutualism-stabilizing mechanisms in the absence of exploitation, as we found no evidence for a fitness cost to the host trait or indirect selection on genetically correlated traits. Our results show that genetic variation in the ability to preferentially reduce associations with an exploitative partner exists within mutualisms and is under selection, indicating that micro-evolutionary responses in mutualism-stabilizing traits in the face of rapidly evolving mutualistic and exploitative symbiotic bacteria can occur in natural host populations.
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Affiliation(s)
- Anna K Simonsen
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Canada M5S 3B2
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology & Centre for the Analysis of Genome Evolution and Function, University of Toronto, 25 Willcocks Street, Toronto, Canada M5S 3B2
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Simonsen AK, Chow T, Stinchcombe JR. Reduced plant competition among kin can be explained by Jensen's inequality. Ecol Evol 2014; 4:4454-66. [PMID: 25512842 PMCID: PMC4264895 DOI: 10.1002/ece3.1312] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/10/2014] [Accepted: 10/13/2014] [Indexed: 11/18/2022] Open
Abstract
Plants often compete with closely related individuals due to limited dispersal, leading to two commonly invoked predictions on competitive outcomes. Kin selection, from evolutionary theory, predicts that competition between relatives will likely be weaker. The niche partitioning hypothesis, from ecological theory, predicts that competition between close relatives will likely be stronger. We tested for evidence consistent with either of these predictions by growing an annual legume in kin and nonkin groups in the greenhouse. We grew plant groups in treatments of symbiotic nitrogen fixing bacteria differing in strain identity and composition to determine if differences in the microbial environment can facilitate or obscure plant competition patterns consistent with kin selection or niche partitioning. Nonkin groups had lower fitness than expected, based on fitness estimates of the same genotypes grown among kin. Higher fitness among kin groups was observed in mixtures of N-fixing bacteria strains compared to single inoculations of bacteria strains present in the soil, which increased fitness differences between kin and nonkin groups. Lower fitness in nonkin groups was likely caused by increased competitive asymmetry in nonkin groups due to genetic differences in plant size combined with saturating relationships with plant size and fitness- i.e. Jensen's inequality. Our study suggests that microbial soil symbionts alter competitive dynamics among kin and nonkin. Our study also suggests that kin groups can have higher fitness, as predicted by kin selection theory, through a commonly heritable trait (plant size), without requiring kin recognition mechanisms.
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Affiliation(s)
- Anna K Simonsen
- Department of Ecology and Evolutionary Biology, University of Toronto Toronto, Ontario, Canada
| | - Theresa Chow
- Department of Ecology and Evolutionary Biology, University of Toronto Toronto, Ontario, Canada
| | - John R Stinchcombe
- Department of Ecology and Evolutionary Biology & Centre for the Analysis of Genome Evolution and Function, University of Toronto Toronto, Ontario, Canada
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Zitouna N, Marghali S, Gharbi M, Chennaoui-Kourda H, Haddioui A, Trifi-Farah N. Mediterranean Hedysarum phylogeny by transferable microsatellites from Medicago. BIOCHEM SYST ECOL 2013. [DOI: 10.1016/j.bse.2013.03.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dick CA, Herman JA, O’Dell RE, Lopez-Villalobos A, Eckert C, Whittall JB. Cryptic genetic subdivision in the San Benito evening primrose (Camissonia benitensis). CONSERV GENET 2013. [DOI: 10.1007/s10592-013-0533-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fourquin C, del Cerro C, Victoria FC, Vialette-Guiraud A, de Oliveira AC, Ferrándiz C. A change in SHATTERPROOF protein lies at the origin of a fruit morphological novelty and a new strategy for seed dispersal in medicago genus. PLANT PHYSIOLOGY 2013; 162:907-17. [PMID: 23640757 PMCID: PMC3668079 DOI: 10.1104/pp.113.217570] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Angiosperms are the most diverse and numerous group of plants, and it is generally accepted that this evolutionary success owes in part to the diversity found in fruits, key for protecting the developing seeds and ensuring seed dispersal. Although studies on the molecular basis of morphological innovations are few, they all illustrate the central role played by transcription factors acting as developmental regulators. Here, we show that a small change in the protein sequence of a MADS-box transcription factor correlates with the origin of a highly modified fruit morphology and the change in seed dispersal strategies that occurred in Medicago, a genus belonging to the large legume family. This protein sequence modification alters the functional properties of the protein, affecting the affinities for other protein partners involved in high-order complexes. Our work illustrates that variation in coding regions can generate evolutionary novelties not based on gene duplication/subfunctionalization but by interactions in complex networks, contributing also to the current debate on the relative importance of changes in regulatory or coding regions of master regulators in generating morphological novelties.
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Pérez F, León C, Muñoz T. How variable is delayed selfing in a fluctuating pollinator environment? A comparison between a delayed selfing and a pollinator-dependent Schizanthus species of the high Andes. Evol Ecol 2012. [DOI: 10.1007/s10682-012-9612-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Zhang S, Zhao C, Lamb EG. Cotyledon damage affects seed number through final plant size in the annual grassland species Medicago lupulina. ANNALS OF BOTANY 2011; 107:437-42. [PMID: 21196450 PMCID: PMC3043934 DOI: 10.1093/aob/mcq259] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 11/09/2010] [Accepted: 11/22/2010] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS The effects of cotyledon damage on seedling growth and survival are relatively well established, but little is known about the effects on aspects of plant fitness such as seed number and size. Here the direct and indirect mechanisms linking cotyledon damage and plant fitness in the annual species Medicago lupulina are examined. METHODS Growth and reproductive traits, including mature plant size, time to first flowering, flower number, seed number and individual seed mass were monitored in M. lupulina plants when zero, one or two cotyledons were removed at 7 d old. Structural equation modelling (SEM) was used to examine the mechanisms linking cotyledon damage to seed number and seed mass. KEY RESULTS Cotyledon damage reduced seed number but not individual seed mass. The primary mechanism was a reduction in plant biomass with cotyledon damage that in turn reduced seed number primarily through a reduction in flower numbers. Although cotyledon damage delayed flower initiation, it had little effect on seed number. Individual seed mass was not affected by cotyledon removal, but there was a trade-off between seed number and seed mass. CONCLUSIONS It is shown how a network of indirect mechanisms link damage to cotyledons and fitness in M. lupulina. Cotyledon damage had strong direct effects on both plant size and flowering phenology, but an analysis of the causal relationships among plant traits and fitness components showed that a reduction in plant size associated with cotyledon damage was an important mechanism influencing fitness.
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Affiliation(s)
- Shiting Zhang
- Institute of Ecology, Key Laboratory of Arid and Grassland Agroecology of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Chuan Zhao
- Institute of Ecology, Key Laboratory of Arid and Grassland Agroecology of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - Eric G. Lamb
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada
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Wang Y, Guo J, Zhao G. Chloroplast microsatellite diversity of Clintonia udensis (Liliaceae) populations in East Asia. BIOCHEM SYST ECOL 2011. [DOI: 10.1016/j.bse.2010.12.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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He T, Lamont BB, Krauss SL, Enright NJ. Genetic connectivity and inter-population seed dispersal of Banksia hookeriana at the landscape scale. ANNALS OF BOTANY 2010; 106:457-466. [PMID: 20647226 PMCID: PMC2924833 DOI: 10.1093/aob/mcq140] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 03/02/2010] [Accepted: 06/01/2010] [Indexed: 05/28/2023]
Abstract
BACKGROUND AND AIMS Landscape genetics combines approaches from population genetics and landscape ecology, increasing the scope for conceptual advances in biology. Banksia hookeriana comprises clusters of individuals located on dune crests (geographical populations) physically separated by uninhabitable swales, with local extinctions common through frequent fire and/or severe drought. METHODS A landscape genetics approach was used to explore landscape-scale genetic connectivity and structure among geographical populations of B. hookeriana on 18 physically separated dunes located within a heterogeneous landscape of 3 x 5 km. These geographical populations were separated by approx. 0.1 to >1 km of unsuitable intervening swale habitat. Using 11 highly variable microsatellite loci, we utilized a Bayesian approach to identify genetic discontinuities within and between these geographical populations. Population allocation tests were then used to detect inter-dune seed dispersal inferred from assignment of individuals to a source population other than that from which they were collected. KEY RESULTS For the modal number of genetically distinct clusters (n = 17 genetic populations), two coincided with the geographical (dune) populations, eight spanned two to four geographical populations, and the remaining seven were spread among various parts of the sampled dunes, so that most geographical populations were spatially defined mosaics of individuals (subpopulations) belonging to two or more genetic populations. We inferred 25 inter-dune immigrants among the 582 individuals assessed, with an average distance between sink and source dunes of 1.1 km, and a maximum of 3.3 km. CONCLUSIONS The results show that genetic structure in an apparently strongly spatially structured landscape is not solely dependent on landscape structure, and that many physically defined geographical populations were genetic mosaics. More strikingly, there were physically separated individuals and groups of individuals that were part of the same genetically defined populations. We attribute this mismatch between spatially and genetically defined population structure to the varying closeness of the dunes and the ability of seeds to disperse long distances.
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Affiliation(s)
- Tianhua He
- Centre for Ecosystem Diversity and Dynamics, Department of Environment and Agriculture, Curtin University, Perth, WA 6845, Australia.
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