151
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Boumans L, Hogner S, Brittain J, Johnsen A. Ecological speciation by temporal isolation in a population of the stonefly Leuctra hippopus (Plecoptera, Leuctridae). Ecol Evol 2017; 7:1635-1649. [PMID: 28261472 PMCID: PMC5330929 DOI: 10.1002/ece3.2638] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/19/2016] [Accepted: 11/05/2016] [Indexed: 11/08/2022] Open
Abstract
Stream dwelling invertebrates are ideal candidates for the study of ecological speciation as they are often adapted to particular environmental conditions within a stream and inhabit only certain reaches of a drainage basin, separated by unsuitable habitat. We studied an atypical population of the stonefly Leuctra hippopus at a site in central Norway, the Isterfoss rapids, in relation to three nearby and two remote conspecific populations. Adults of this population emerge about a month earlier than those of nearby populations, live on large boulders emerging from the rapids, and are short-lived. This population also has distinct morphological features and was studied earlier during the period 1975-1990. We reassessed morphological distinctness with new measurements and added several analyses of genetic distinctness based on mitochondrial and nuclear sequence markers, as well as AFLP fingerprinting and SNPs mined from RAD sequences. The Isterfoss population is shown to be most closely related to its geographical neighbors, yet clearly morphologically and genetically distinct and homogeneous. We conclude that this population is in the process of sympatric speciation, with temporal isolation being the most important direct barrier to gene flow. The shift in reproductive season results from the particular temperature and water level regime in the Isterfoss rapids. The distinct adult body shape and loss of flight are hypothesized to be an adaptation to the unusual habitat. Ecological diversification on small spatial and temporal scales is one of the likely causes of the high diversity of aquatic insects.
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Affiliation(s)
- Louis Boumans
- Natural History Museum University of Oslo Oslo Norway
| | - Silje Hogner
- Natural History Museum University of Oslo Oslo Norway
| | - John Brittain
- Natural History Museum University of Oslo Oslo Norway
| | - Arild Johnsen
- Natural History Museum University of Oslo Oslo Norway
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152
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Hua X, Bromham L. Darwinism for the Genomic Age: Connecting Mutation to Diversification. Front Genet 2017; 8:12. [PMID: 28224003 PMCID: PMC5293951 DOI: 10.3389/fgene.2017.00012] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 01/19/2017] [Indexed: 12/30/2022] Open
Abstract
A growing body of evidence suggests that rates of diversification of biological lineages are correlated with differences in genome-wide mutation rate. Given that most research into differential patterns of diversification rate have focused on species traits or ecological parameters, a connection to the biochemical processes of genome change is an unexpected observation. While the empirical evidence for a significant association between mutation rate and diversification rate is mounting, there has been less effort in explaining the factors that mediate this connection between genetic change and species richness. Here we draw together empirical studies and theoretical concepts that may help to build links in the explanatory chain that connects mutation to diversification. First we consider the way that mutation rates vary between species. We then explore how differences in mutation rates have flow-through effects to the rate at which populations acquire substitutions, which in turn influences the speed at which populations become reproductively isolated from each other due to the acquisition of genomic incompatibilities. Since diversification rate is commonly measured from phylogenetic analyses, we propose a conceptual approach for relating events of reproductive isolation to bifurcations on molecular phylogenies. As we examine each of these relationships, we consider theoretical models that might shine a light on the observed association between rate of molecular evolution and diversification rate, and critically evaluate the empirical evidence for these links, focusing on phylogenetic comparative studies. Finally, we ask whether we are getting closer to a real understanding of the way that the processes of molecular evolution connect to the observable patterns of diversification.
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Affiliation(s)
- Xia Hua
- Centre for Macroevolution and Macroecology, Research School of Biology, Australian National University, Canberra ACT, Australia
| | - Lindell Bromham
- Centre for Macroevolution and Macroecology, Research School of Biology, Australian National University, Canberra ACT, Australia
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153
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Stewart KA, Hudson CM, Lougheed SC. Can alternative mating tactics facilitate introgression across a hybrid zone by circumventing female choice? J Evol Biol 2016; 30:412-421. [DOI: 10.1111/jeb.13017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 11/12/2016] [Accepted: 11/14/2016] [Indexed: 01/30/2023]
Affiliation(s)
- K. A. Stewart
- College of Environmental Science and Engineering; Tongji University; Shanghai China
| | - C. M. Hudson
- School of Life and Environmental Sciences; University of Sydney; Sydney NSW Australia
| | - S. C. Lougheed
- Department of Biology; Queen's University; Kingston ON Canada
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154
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Berner D, Ammann M, Spencer E, Rüegg A, Lüscher D, Moser D. Sexual isolation promotes divergence between parapatric lake and stream stickleback. J Evol Biol 2016; 30:401-411. [PMID: 27862535 DOI: 10.1111/jeb.13016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 11/07/2016] [Indexed: 12/26/2022]
Abstract
Speciation can be initiated by adaptive divergence between populations in ecologically different habitats, but how sexually based reproductive barriers contribute to this process is less well understood. We here test for sexual isolation between ecotypes of threespine stickleback fish residing in adjacent lake and stream habitats in the Lake Constance basin, Central Europe. Mating trials exposing females to pairings of territorial lake and stream males in outdoor mesocosms allowing for natural reproductive behaviour reveal that mating occurs preferentially between partners of the same ecotype. Compared to random mating, this sexual barrier reduces gene flow between the ecotypes by some 36%. This relatively modest strength of sexual isolation is surprising because comparing the males between the two ecotypes shows striking differentiation in traits generally considered relevant to reproductive behaviour (body size, breeding coloration, nest size). Analysing size differences among the individuals in the mating trials further indicates that assortative mating is not related to ecotype differences in body size. Overall, we demonstrate that sexually based reproductive isolation promotes divergence in lake-stream stickleback along with other known reproductive barriers, but we also caution against inferring strong sexual isolation from the observation of strong population divergence in sexually relevant traits.
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Affiliation(s)
- D Berner
- Zoological Institute, University of Basel, Basel, Switzerland
| | - M Ammann
- Zoological Institute, University of Basel, Basel, Switzerland
| | - E Spencer
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | - A Rüegg
- Zoological Institute, University of Basel, Basel, Switzerland
| | - D Lüscher
- Zoological Institute, University of Basel, Basel, Switzerland
| | - D Moser
- Zoological Institute, University of Basel, Basel, Switzerland
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155
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Lackey ACR, Boughman JW. Evolution of reproductive isolation in stickleback fish. Evolution 2016; 71:357-372. [PMID: 27901265 DOI: 10.1111/evo.13114] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 10/15/2016] [Accepted: 10/24/2016] [Indexed: 12/21/2022]
Abstract
To understand how new species form and what causes their collapse, we examined how reproductive isolation evolves during the speciation process, considering species pairs with little to extensive divergence, including a recently collapsed pair. We estimated many reproductive barriers in each of five sets of stickleback fish species pairs using our own data and decades of previous work. We found that the types of barriers important early in the speciation process differ from those important late. Two premating barriers-habitat and sexual isolation-evolve early in divergence and remain two of the strongest barriers throughout speciation. Premating isolation evolves before postmating isolation, and extrinsic isolation is far stronger than intrinsic. Completing speciation, however, may require postmating intrinsic incompatibilities. Reverse speciation in one species pair was characterized by significant loss of sexual isolation. We present estimates of barrier strengths before and after collapse of a species pair; such detail regarding the loss of isolation has never before been documented. Additionally, despite significant asymmetries in individual barriers, which can limit speciation, total isolation was essentially symmetric between species. Our study provides important insight into the order of barrier evolution and the relative importance of isolating barriers during speciation and tests fundamental predictions of ecological speciation.
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Affiliation(s)
- Alycia C R Lackey
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan.,Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, East Lansing, Michigan.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan.,Department of Biological Sciences, Watershed Studies Institute, Murray State University, 2112 Biology Building, Murray, State University, Murray, Kentucky, 42071
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan.,Ecology, Evolutionary Biology, and Behavior Program, Michigan State University, East Lansing, Michigan.,BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, Michigan
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156
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Willis CG, Donohue K. The evolution of intrinsic reproductive isolation in the genus
Cakile
(Brassicaceae). J Evol Biol 2016; 30:361-376. [DOI: 10.1111/jeb.13011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 10/21/2016] [Accepted: 11/04/2016] [Indexed: 11/29/2022]
Affiliation(s)
- C. G. Willis
- Department of Biology Duke University Durham NC USA
| | - K. Donohue
- Department of Biology Duke University Durham NC USA
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157
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Jacobsen MW, Smedegaard L, Sørensen SR, Pujolar JM, Munk P, Jónsson B, Magnussen E, Hansen MM. Assessing pre- and post-zygotic barriers between North Atlantic eels (Anguilla anguilla and A. rostrata). Heredity (Edinb) 2016; 118:266-275. [PMID: 27827390 DOI: 10.1038/hdy.2016.96] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/13/2016] [Accepted: 08/22/2016] [Indexed: 12/21/2022] Open
Abstract
Elucidating barriers to gene flow is important for understanding the dynamics of speciation. Here we investigate pre- and post-zygotic mechanisms acting between the two hybridizing species of Atlantic eels: Anguilla anguilla and A. rostrata. Temporally varying hybridization was examined by analyzing 85 species-diagnostic single-nucleotide polymorphisms (SNPs; FST ⩾0.95) in eel larvae sampled in the spawning region in the Sargasso Sea in 2007 (N=92) and 2014 (N=460). We further investigated whether genotypes at these SNPs were nonrandomly distributed in post-F1 hybrids, indicating selection. Finally, we sequenced the mitochondrial ATP6 and nuclear ATP5c1 genes in 19 hybrids, identified using SNP and restriction site associated DNA (RAD) sequencing data, to test a previously proposed hypothesis of cytonuclear incompatibility leading to adenosine triphosphate (ATP) synthase dysfunction and selection against hybrids. No F1 hybrids but only later backcrosses were observed in the Sargasso Sea in 2007 and 2014. This suggests that interbreeding between the two species only occurs in some years, possibly controlled by environmental conditions at the spawning grounds, or that interbreeding has diminished through time as a result of a declining number of spawners. Moreover, potential selection was found at the nuclear and the cytonuclear levels. Nonetheless, one glass eel individual showed a mismatch, involving an American ATP6 haplotype and European ATP5c1 alleles. This contradicted the presence of cytonuclear incompatibility but may be explained by that (1) cytonuclear incompatibility is incomplete, (2) selection acts at a later life stage or (3) other genes are important for protein function. In total, the study demonstrates the utility of genomic data when examining pre- and post-zyotic barriers in natural hybrids.
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Affiliation(s)
- M W Jacobsen
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - L Smedegaard
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - S R Sørensen
- National Institute of Aquatic Resources, Charlottenlund, Denmark
| | - J M Pujolar
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - P Munk
- National Institute of Aquatic Resources, Charlottenlund, Denmark
| | - B Jónsson
- Northwest Iceland Nature Research Centre, Saudárkrókur, Iceland
| | - E Magnussen
- Faculty of Science and Technology, University of the Faroe Islands, Torshavn, Faroe Islands
| | - M M Hansen
- Department of Bioscience, Aarhus University, Aarhus, Denmark
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158
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Henrich T, Kalbe M. The role of prezygotic isolation mechanisms in the divergence of two parasite species. BMC Evol Biol 2016; 16:245. [PMID: 27829374 PMCID: PMC5103353 DOI: 10.1186/s12862-016-0799-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 10/14/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The formation of reproductive barriers in diverging lineages is a prerequisite to complete speciation according to the biological species concept. In parasites with complex life cycles, speciation may be driven by adaptation to different intermediate hosts, yet diverging lineages can still share the same definitive host where reproduction takes place. In these cases, prezygotic isolation mechanisms should evolve very early and be particularly strong, preventing costly unfavourable matings. In this study, we investigated the importance of prezygotic barriers to reproduction in two cestode species that diverged 20-25mya and show an extraordinary degree of specificity to different intermediate hosts. Both species share the same definitive hosts and hybridize in the laboratory. Yet, natural hybrids have so far not been detected. METHODS We used a combination of different experiments to investigate the role of prezygotic barriers to reproduction in the speciation of these parasites. First, we investigated whether hybridization is possible under natural conditions by exposing lab-reared herring gulls (Larus argentatus, the definitive hosts) to both parasites of either sympatric or allopatric combinations. In a second experiment, we tested whether the parasites prefer conspecifics over parasites from a different species in dichotomous mate choice trials. RESULTS Our results show that the two species hybridize under natural conditions with parasites originating either from sympatric or allopatric populations producing hybrid offspring. Surprisingly, the mate choice experiment indicated that both parasite species prefer mates of the different species to conspecifics. CONCLUSIONS Neither fundamental constraints against hybridization in a natural host nor assortative mate choice sufficiently explain the persistent segregation of the two tapeworm species in nature. Hence, postzygotic ecological selection against hybrids is presumably the more important driving force limiting gene flow between the two parasite sister species.
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Affiliation(s)
- Tina Henrich
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary, Biology, August-Thienemann-Strasse 2, 24306, Plön, Germany.
| | - Martin Kalbe
- Department of Evolutionary Ecology, Max Planck Institute for Evolutionary, Biology, August-Thienemann-Strasse 2, 24306, Plön, Germany.
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159
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Gould BA, Chen Y, Lowry DB. Pooled ecotype sequencing reveals candidate genetic mechanisms for adaptive differentiation and reproductive isolation. Mol Ecol 2016; 26:163-177. [DOI: 10.1111/mec.13881] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/22/2016] [Accepted: 08/29/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Billie A. Gould
- Department of Plant Biology; Michigan State University; Plant Biology Laboratories; 612 Wilson Road Room 166 East Lansing MI 48824 USA
| | - Yani Chen
- Department of Plant Biology; Michigan State University; Plant Biology Laboratories; 612 Wilson Road Room 166 East Lansing MI 48824 USA
| | - David B. Lowry
- Department of Plant Biology; Michigan State University; Plant Biology Laboratories; 612 Wilson Road Room 166 East Lansing MI 48824 USA
- Program in Ecology, Evolutionary Biology and Behavior; Michigan State University; Giltner Hall 293 Farm Ln Rm 103 East Lansing MI 48824 USA
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160
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Hipperson H, Dunning LT, Baker WJ, Butlin RK, Hutton I, Papadopulos AST, Smadja CM, Wilson TC, Devaux C, Savolainen V. Ecological speciation in sympatric palms: 2. Pre- and post-zygotic isolation. J Evol Biol 2016; 29:2143-2156. [PMID: 27374779 PMCID: PMC5096058 DOI: 10.1111/jeb.12933] [Citation(s) in RCA: 21] [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: 03/26/2016] [Revised: 06/27/2016] [Accepted: 06/30/2016] [Indexed: 01/22/2023]
Abstract
We evaluated reproductive isolation in two species of palms (Howea) that have evolved sympatrically on Lord Howe Island (LHI, Australia). We estimated the strength of some pre- and post-zygotic mechanisms in maintaining current species boundaries. We found that flowering time displacement between species is consistent across in and ex situ common gardens and is thus partly genetically determined. On LHI, pre-zygotic isolation due solely to flowering displacement was 97% for Howea belmoreana and 80% for H. forsteriana; this asymmetry results from H. forsteriana flowering earlier than H. belmoreana and being protandrous. As expected, only a few hybrids (here confirmed by genotyping) at both juvenile and adult stages could be detected in two sites on LHI, in which the two species grow intermingled (the Far Flats) or adjacently (Transit Hill). Yet, the distribution of hybrids was different between sites. At Transit Hill, we found no hybrid adult trees, but 13.5% of younger palms examined there were of late hybrid classes. In contrast, we found four hybrid adult trees, mostly of late hybrid classes, and only one juvenile F1 hybrid in the Far Flats. This pattern indicates that selection acts against hybrids between the juvenile and adult stages. An in situ reciprocal seed transplant between volcanic and calcareous soils also shows that early fitness components (up to 36 months) were affected by species and soil. These results are indicative of divergent selection in reproductive isolation, although it does not solely explain the current distribution of the two species on LHI.
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Affiliation(s)
- H Hipperson
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK
| | - L T Dunning
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK
| | - W J Baker
- Royal Botanic Gardens, Kew, Richmond, UK
| | - R K Butlin
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
- Sven Lovén Centre for Marine Sciences, Tjärnö, University of Gothenburg, Stromstäd, Sweden
| | - I Hutton
- Lord Howe Island Museum, Lord Howe Island, NSW, Australia
| | - A S T Papadopulos
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK
- Royal Botanic Gardens, Kew, Richmond, UK
| | - C M Smadja
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK
| | - T C Wilson
- Royal Botanic Gardens and Domain Trust, Sydney, NSW, Australia
| | | | - V Savolainen
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, UK.
- Royal Botanic Gardens, Kew, Richmond, UK.
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161
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Baek YS, Royer SM, Broz AK, Covey PA, López-Casado G, Nuñez R, Kear PJ, Bonierbale M, Orillo M, van der Knaap E, Stack SM, McClure B, Chetelat RT, Bedinger PA. Interspecific reproductive barriers between sympatric populations of wild tomato species (Solanum section Lycopersicon). AMERICAN JOURNAL OF BOTANY 2016; 103:1964-1978. [PMID: 27864262 DOI: 10.3732/ajb.1600356] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/21/2016] [Indexed: 05/09/2023]
Abstract
PREMISE OF THE STUDY Interspecific reproductive barriers (IRBs) often prevent hybridization between closely related species in sympatry. In the tomato clade (Solanum section Lycopersicon), interspecific interactions between natural sympatric populations have not been evaluated previously. In this study, we assessed IRBs between members of the tomato clade from nine sympatric sites in Peru. METHODS Coflowering was assessed at sympatric sites in Peru. Using previously collected seeds from sympatric sites in Peru, we evaluated premating prezygotic (floral morphology), postmating prezygotic (pollen-tube growth), and postzygotic barriers (fruit and seed development) between sympatric species in common gardens. Pollen-tube growth and seed development were examined in reciprocal crosses between sympatric species. KEY RESULTS We confirmed coflowering of sympatric species at five sites in Peru. We found three types of postmating prezygotic IRBs during pollen-pistil interactions: (1) unilateral pollen-tube rejection between pistils of self-incompatible species and pollen of self-compatible species; (2) potential conspecific pollen precedence in a cross between two self-incompatible species; and (3) failure of pollen tubes to target ovules. In addition, we found strong postzygotic IRBs that prevented normal seed development in 11 interspecific crosses, resulting in seed-like structures containing globular embryos and aborted endosperm and, in some cases, overgrown endothelium. Viable seed and F1 hybrid plants were recovered from three of 19 interspecific crosses. CONCLUSIONS We have identified diverse prezygotic and postzygotic IRBs that would prevent hybridization between sympatric wild tomato species, but interspecific hybridization is possible in a few cases.
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Affiliation(s)
- You Soon Baek
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Suzanne M Royer
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Paul A Covey
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Gloria López-Casado
- Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA
| | - Reynaldo Nuñez
- Department of Horticulture and Crop Science, Ohio State University, Wooster, Ohio 44691, USA
| | - Philip J Kear
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Merideth Bonierbale
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Matilde Orillo
- Quality and Nutrition Laboratory, Centro Internacional de la Papa, Perú Postal 1558, Lima, Peru
| | - Esther van der Knaap
- Department of Horticulture and Crop Science, Ohio State University, Wooster, Ohio 44691, USA
- Department of Horticulture, University of Georgia, Athens, Georgia 30602, USA
| | - Stephen M Stack
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
| | - Bruce McClure
- Department of Biochemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Roger T Chetelat
- Department of Plant Sciences, University of California Davis, Davis, California 95616, USA
| | - Patricia A Bedinger
- Department of Biology, Colorado State University, Fort Collins, Colorado 80523-1878, USA
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162
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Barnard‐Kubow KB, So N, Galloway LF. Cytonuclear incompatibility contributes to the early stages of speciation. Evolution 2016; 70:2752-2766. [DOI: 10.1111/evo.13075] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 09/08/2016] [Accepted: 09/17/2016] [Indexed: 12/20/2022]
Affiliation(s)
| | - Nina So
- Department of Biology University of Virginia Charlottesville Virginia 22904
- Current Address: Doctoral Program in Neurobiology and Behavior Columbia University New York NY 10027
| | - Laura F. Galloway
- Department of Biology University of Virginia Charlottesville Virginia 22904
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163
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Bertel C, Hülber K, Frajman B, Schönswetter P. No evidence of intrinsic reproductive isolation between two reciprocally non-monophyletic, ecologically differentiated mountain plants at an early stage of speciation. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9867-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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164
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Esposito F, Jacquemyn H, Waud M, Tyteca D. Mycorrhizal Fungal Diversity and Community Composition in Two Closely Related Platanthera (Orchidaceae) Species. PLoS One 2016; 11:e0164108. [PMID: 27695108 PMCID: PMC5047478 DOI: 10.1371/journal.pone.0164108] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/20/2016] [Indexed: 01/17/2023] Open
Abstract
While it is generally acknowledged that orchid species rely on mycorrhizal fungi for completion of their life cycle, little is yet known about how mycorrhizal fungal diversity and community composition vary within and between closely related orchid taxa. In this study, we used 454 amplicon pyrosequencing to investigate variation in mycorrhizal communities between pure (allopatric) and mixed (sympatric) populations of two closely related Platanthera species (Platanthera bifolia and P. chlorantha) and putative hybrids. Consistent with previous research, the two species primarily associated primarily with members of the Ceratobasidiaceae and, to a lesser extent, with members of the Sebacinales and Tulasnellaceae. In addition, a large number of ectomycorrhizal fungi belonging to various families were observed. Although a considerable number of mycorrhizal fungi were common to both species, the fungal communities were significantly different between the two species. Individuals with intermediate morphology showed communities similar to P. bifolia, confirming previous results based on the genetic architecture and fragrance composition that putative hybrids essentially belonged to one of the parental species (P. bifolia). Differences in mycorrhizal communities between species were smaller in mixed populations than between pure populations, suggesting that variation in mycorrhizal communities was largely controlled by local environmental conditions. The small differences in mycorrhizal communities in mixed populations suggests that mycorrhizal fungi are most likely not directly involved in maintaining species boundaries between the two Platanthera species. However, seed germination experiments are needed to unambiguously assess the contribution of mycorrhizal divergence to reproductive isolation.
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Affiliation(s)
- Fabiana Esposito
- Earth and Life Institute, Biodiversity Research Centre, Université catholique de Louvain, Croix du Sud 4-5 (L7.07.04), B-1348 Louvain-la-Neuve, Belgium
| | - Hans Jacquemyn
- Department of Biology, Plant Conservation and Population Biology, KULeuven, B-3001, Leuven, Belgium
| | - Michael Waud
- Department of Biology, Plant Conservation and Population Biology, KULeuven, B-3001, Leuven, Belgium
| | - Daniel Tyteca
- Earth and Life Institute, Biodiversity Research Centre, Université catholique de Louvain, Croix du Sud 4-5 (L7.07.04), B-1348 Louvain-la-Neuve, Belgium
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165
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Yardeni G, Tessler N, Imbert E, Sapir Y. Reproductive isolation between populations of Iris atropurpurea is associated with ecological differentiation. ANNALS OF BOTANY 2016; 118:971-982. [PMID: 27436798 PMCID: PMC5055820 DOI: 10.1093/aob/mcw139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 05/13/2016] [Accepted: 05/23/2016] [Indexed: 05/28/2023]
Abstract
Background and Aims Speciation is often described as a continuous dynamic process, expressed by different magnitudes of reproductive isolation (RI) among groups in different levels of divergence. Studying intraspecific partial RI can shed light on mechanisms underlying processes of population divergence. Intraspecific divergence can be driven by spatially stochastic accumulation of genetic differences following reduced gene flow, resulting in increased RI with increased geographical distance, or by local adaptation, resulting in increased RI with environmental difference. Methods We tested for RI as a function of both geographical distance and ecological differentiation in Iris atropurpurea, an endemic Israeli coastal plant. We crossed plants in the Netanya Iris Reserve population with plants from 14 populations across the species' full distribution, and calculated RI and reproductive success based on fruit set, seed set and fraction of seed viability. Key Results We found that total RI was not significantly associated with geographical distance, but significantly increased with ecological distance. Similarly, reproductive success of the crosses, estimated while controlling for the dependency of each component on the previous stage, significantly reduced with increased ecological distance. Conclusions Our results indicate that the rise of post-pollination reproductive barriers in I. atropurpurea is more affected by ecological differentiation between populations than by geographical distance, supporting the hypothesis that ecological differentiation is predominant over isolation by distance and by reduced gene flow in this species. These findings also affect conservation management, such as genetic rescue, in the highly fragmented and endangered I. atropurpurea.
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Affiliation(s)
- Gil Yardeni
- The Botanical Garden, Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Naama Tessler
- Department of Biology, University of Haifa, Oranim, Tivon, Israel
| | - Eric Imbert
- Institut des Sciences de l’Evolution CNRS, IRD, University Montpellier 2, Montpellier, France
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166
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Díaz Infante S, Lara C, Arizmendi MDC, Eguiarte LE, Ornelas JF. Reproductive ecology and isolation of Psittacanthus calyculatus and P. auriculatus mistletoes (Loranthaceae). PeerJ 2016; 4:e2491. [PMID: 27703848 PMCID: PMC5045876 DOI: 10.7717/peerj.2491] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/25/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Relationships between floral biology and pollinator behavior are important to understanding species diversity of hemiparasitic Psittacanthus mistletoes (c. 120 species). We aimed to investigate trait divergence linked to pollinator attraction and reproductive isolation (RI) in two hummingbird-pollinated and bird-dispersed Psittacanthus species with range overlap. METHODS We investigated the phylogenetic relationships, floral biology, pollinator assemblages, seed dispersers and host usage, and the breeding system and female reproductive success of two sympatric populations of P. calyculatus and P. auriculatus, and one allopatric population of P. calyculatus. Flowers in sympatry were also reciprocally pollinated to assess a post-mating component of RI. RESULTS Hummingbird assemblages differed between calyculatus populations, while allopatric plants of calyculatus opened more but smaller flowers with longer lifespans and produced less nectar than those in sympatry. Bayesian-based phylogenetic analysis indicated monophyly for calyculatus populations (i.e. both populations belong to the same species). In sympatry, calyculatus plants opened more and larger flowers with longer lifespans and produced same nectar volume than those of auriculatus; populations shared pollinators but seed dispersers and host usage differed between species. Nectar standing crops differed between sympatric populations, with lower visitation in calyculatus. Hand pollination experiments indicated a predominant outcrossing breeding system, with fruit set after interspecific pollination two times higher from calyculatus to auriculatus than in the opposite direction. CONCLUSIONS Given the low genetic differentiation between calyculatus populations, observed trait divergence could have resulted from changes regarding the local communities of pollinators and, therefore, expected divergence for peripheral, allopatric populations. Using RI estimates, there were fewer heterospecific matings than expected by chance in P. calyculatus (RI4A = 0.629) as compared to P. auriculatus (RI4A = 0.20). When considering other factors of ecological isolation that affect co-occurrence, the RI4C values indicate that isolation by hummingbird pollinators was less effective (0.20) than isolation by host tree species and seed dispersers (0.80 and 0.60, respectively), suggesting that host usage is the most important ecological isolation factor between the two species. Accordingly, the absolute and relative cumulative strength values indicated that the host tree species' barrier is currently contributing the most to maintaining these species in sympatry.
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Affiliation(s)
- Sergio Díaz Infante
- Laboratorio de Ecología, UBIPRO, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla de Baz, Estado de México, Mexico
| | - Carlos Lara
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico
| | - María del Coro Arizmendi
- Laboratorio de Ecología, UBIPRO, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla de Baz, Estado de México, Mexico
| | - Luis E. Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, Distrito Federal, Mexico
| | - Juan Francisco Ornelas
- Departamento de Biología Evolutiva, Instituto de Ecología, A.C., Xalapa, Veracruz, Mexico
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167
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Tong ZY, Huang SQ. Pre- and post-pollination interaction between six co-flowering Pedicularis species via heterospecific pollen transfer. THE NEW PHYTOLOGIST 2016; 211:1452-1461. [PMID: 27174497 DOI: 10.1111/nph.14005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/06/2016] [Indexed: 06/05/2023]
Abstract
It remains unclear how related co-flowering species with shared pollinators minimize reproductive interference, given that the degree of interspecific pollen flow and its consequences are little known in natural communities. Differences in pollen size in six Pedicularis species with different style lengths permit us to measure heterospecific pollen transfer (HPT) between species pairs in sympatry. The role of pollen-pistil interactions in mitigating the effects of HPT was examined. Field observations over 2 yr showed that bumblebee pollinators visiting one species rarely moved to another. Heterospecific pollen (HP) comprised < 10% of total stigmatic pollen loads for each species over 2 yr, and was not related to conspecific pollen deposition. Species with longer styles generally received more HP per stigma. The pollen tube study showed that pollen from short-styled species could not grow the full length of the style of long-styled species. Pollen from long-styled species could grow through the short style of P. densispica, but P. densispica rarely received HP in nature. Flower constancy is a key pre-pollination barrier to HPT between co-flowering Pedicularis species. Post-pollination pollen-pistil interactions may further mitigate the effects of HPT because HP transferred to long styles could generally be effectively filtered.
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Affiliation(s)
- Ze-Yu Tong
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Shuang-Quan Huang
- Institute of Evolution and Ecology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China
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168
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Larcombe MJ, Costa E Silva J, Tilyard P, Gore P, Potts BM. On the persistence of reproductive barriers in Eucalyptus: the bridging of mechanical barriers to zygote formation by F1 hybrids is counteracted by intrinsic post-zygotic incompatibilities. ANNALS OF BOTANY 2016; 118:431-44. [PMID: 27401540 PMCID: PMC4998977 DOI: 10.1093/aob/mcw115] [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: 02/24/2016] [Accepted: 05/04/2016] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS Many previous studies conclude that pre-zygotic barriers such as mechanical isolation account for most reproductive isolation between pairs of taxa. However, the inheritance and persistence of barriers such as these after the first generation of hybridization is rarely quantified, even though it is a vital consideration in understanding gene flow potential. There is an asymmetrical pre-zygotic mechanical barrier to hybridization between Eucalyptus nitens and Eucalyptus globulus, which completely prevents small-flowered E. nitens pollen from mating with large E. globulus flowers, while the reverse cross is possible. We aimed to determine the relative importance of pre- and post-zygotic barriers in preventing gene flow following secondary contact between E. nitens and E. globulus, including the inheritance of barriers in advanced-generation hybrids. METHODS Experimental crossing was used to produce outcrossed E. nitens, E. globulus and their F1, F2, BCg and BCn hybrids. The strength and inheritance of a suite of pre- and post-zygotic barriers were assessed, including 20-year survival, growth and reproductive capacity. KEY RESULTS The mechanical barrier to hybridization was lost or greatly reduced in the F1 hybrid. In contrast, intrinsic post-zygotic barriers were strong and persistent. Line-cross analysis indicated that the outbreeding depression in the hybrids was best explained by epistatic loss. CONCLUSIONS The removal of strong mechanical barriers between E. nitens and E. globulus allows F1 hybrids to act as a bridge for bi-directional gene flow between these species. However, strong and persistent post-zygotic barriers exist, meaning that wherever F1 hybridization does occur, intrinsic post-zygotic barriers will be responsible for most reproductive isolation in this system. This potential transient nature of mechanical barriers to zygote formation due to additive inheritance in hybrids appears under-appreciated, and highlights the often important role that intrinsic post-mating barriers play in maintaining species boundaries at zones of secondary contact.
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Affiliation(s)
- Matthew J Larcombe
- Department of Botany, University of Otago, PO Box 56, Dunedin 9011, New Zealand
| | - João Costa E Silva
- Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
| | - Paul Tilyard
- School of Biological Sciences, and ARC Centre for Forest Value, 10 University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
| | - Peter Gore
- seedEnergy Pty Ltd, 2 Derwent Avenue, Margate, Tasmania 7054, Australia
| | - Brad M Potts
- School of Biological Sciences, and ARC Centre for Forest Value, 10 University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
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169
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Vallejo-Marín M, Hiscock SJ. Hybridization and hybrid speciation under global change. THE NEW PHYTOLOGIST 2016; 211:1170-87. [PMID: 27214560 DOI: 10.1111/nph.14004] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/07/2016] [Indexed: 05/24/2023]
Abstract
Contents 1170 I. 1170 II. 1172 III. 1175 IV. 1180 V. 1183 1184 References 1184 SUMMARY: An unintended consequence of global change is an increase in opportunities for hybridization among previously isolated lineages. Here we illustrate how global change can facilitate the breakdown of reproductive barriers and the formation of hybrids, drawing on the flora of the British Isles for insight. Although global change may ameliorate some of the barriers preventing hybrid establishment, for example by providing new ecological niches for hybrids, it will have limited effects on environment-independent post-zygotic barriers. For example, genic incompatibilities and differences in chromosome numbers and structure within hybrid genomes are unlikely to be affected by global change. We thus speculate that global change will have a larger effect on eroding pre-zygotic barriers (eco-geographical isolation and phenology) than post-zygotic barriers, shifting the relative importance of these two classes of reproductive barriers from what is usually seen in naturally produced hybrids where pre-zygotic barriers are the largest contributors to reproductive isolation. Although the long-term fate of neo-hybrids is still to be determined, the massive impact of global change on the dynamics and distribution of biodiversity generates an unprecedented opportunity to study large numbers of unpredicted, and often replicated, hybridization 'experiments', allowing us to peer into the birth and death of evolutionary lineages.
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Affiliation(s)
- Mario Vallejo-Marín
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK
| | - Simon J Hiscock
- University of Oxford Botanic Garden, Rose Lane, Oxford, OX1 4AZ, UK
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170
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Keller B, de Vos JM, Schmidt‐Lebuhn AN, Thomson JD, Conti E. Both morph- and species-dependent asymmetries affect reproductive barriers between heterostylous species. Ecol Evol 2016; 6:6223-44. [PMID: 27648239 PMCID: PMC5016645 DOI: 10.1002/ece3.2293] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 12/13/2022] Open
Abstract
The interaction between floral traits and reproductive isolation is crucial to explaining the extraordinary diversity of angiosperms. Heterostyly, a complex floral polymorphism that optimizes outcrossing, evolved repeatedly and has been shown to accelerate diversification in primroses, yet its potential influence on isolating mechanisms remains unexplored. Furthermore, the relative contribution of pre- versus postmating barriers to reproductive isolation is still debated. No experimental study has yet evaluated the possible effects of heterostyly on pre- and postmating reproductive mechanisms. We quantify multiple reproductive barriers between the heterostylous Primula elatior (oxlip) and P. vulgaris (primrose), which readily hybridize when co-occurring, and test whether traits of heterostyly contribute to reproductive barriers in unique ways. We find that premating isolation is key for both species, while postmating isolation is considerable only for P. vulgaris; ecogeographic isolation is crucial for both species, while phenological, seed developmental, and hybrid sterility barriers are also important in P. vulgaris, implicating sympatrically higher gene flow into P. elatior. We document for the first time that, in addition to the aforementioned species-dependent asymmetries, morph-dependent asymmetries affect reproductive barriers between heterostylous species. Indeed, the interspecific decrease of reciprocity between high sexual organs of complementary floral morphs limits interspecific pollen transfer from anthers of short-styled flowers to stigmas of long-styled flowers, while higher reciprocity between low sexual organs favors introgression over isolation from anthers of long-styled flowers to stigmas of short-styled flowers. Finally, intramorph incompatibility persists across species boundaries, but is weakened in long-styled flowers of P. elatior, opening a possible backdoor to gene flow through intramorph pollen transfer between species. Therefore, patterns of gene flow across species boundaries are likely affected by floral morph composition of adjacent populations. To summarize, our study highlights the general importance of premating isolation and newly illustrates that both morph- and species-dependent asymmetries shape boundaries between heterostylous species.
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Affiliation(s)
- Barbara Keller
- Department of Systematic and Evolutionary BotanyUniversity of ZürichZollikerstrasse 1078008ZürichSwitzerland
| | - Jurriaan M. de Vos
- Department of Ecology and Evolutionary BiologyBrown University80 Waterman StreetBox G‐WProvidenceRhode Island02912USA
- Present address: Comparative Plant and Fungal Biology DepartmentRoyal Botanic GardensKewRichmondSurreyTW9 3AE UK
| | | | - James D. Thomson
- Ecology and Evolutionary Biology DepartmentUniversity of Toronto25 Harbord St.TorontoOntarioM5S 3G5Canada
| | - Elena Conti
- Department of Systematic and Evolutionary BotanyUniversity of ZürichZollikerstrasse 1078008ZürichSwitzerland
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171
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Delmore KE, Kenyon HL, Germain RR, Irwin DE. Phenotypic divergence during speciation is inversely associated with differences in seasonal migration. Proc Biol Sci 2016; 282:rspb.2015.1921. [PMID: 26559951 DOI: 10.1098/rspb.2015.1921] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Differences in seasonal migration might promote reproductive isolation and differentiation by causing populations in migratory divides to arrive on the breeding grounds at different times and/or produce hybrids that take inferior migratory routes. We examined this question by quantifying divergence in song, colour, and morphology between sister pairs of North American migratory birds. We predicted that apparent rates of phenotypic differentiation would differ between pairs that do and do not form migratory divides. Consistent with this prediction, results from mixed effects models and Ornstein-Uhlenbeck models of evolution showed different rates of divergence between these groups; surprisingly, differentiation was greater among non-divide pairs. We interpret this finding as a result of variable rates of population blending and fusion between partially diverged forms. Ancient pairs of populations that subsequently fused are now observed as a single form, whereas those that did not fuse are observable as pairs and included in our study. We propose that fusion of two populations is more likely to occur when they have similar migratory routes and little other phenotypic differentiation that would cause reproductive isolation. By contrast, pairs with migratory divides are more likely to remain reproductively isolated, even when differing little in other phenotypic traits. These findings suggest that migratory differences may be one among several isolating barriers that prevent divergent populations from fusing and thereby increase the likelihood that they will continue differentiating as distinct species.
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Affiliation(s)
- Kira E Delmore
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T1Z4
| | - Haley L Kenyon
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T1Z4
| | - Ryan R Germain
- Department of Forest and Conservation Sciences, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia, Canada V6T1Z4
| | - Darren E Irwin
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, Canada V6T1Z4
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172
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Ferris KG, Barnett LL, Blackman BK, Willis JH. The genetic architecture of local adaptation and reproductive isolation in sympatry within the Mimulus guttatus species complex. Mol Ecol 2016; 26:208-224. [PMID: 27439150 DOI: 10.1111/mec.13763] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 06/30/2016] [Accepted: 07/05/2016] [Indexed: 01/05/2023]
Abstract
The genetic architecture of local adaptation has been of central interest to evolutionary biologists since the modern synthesis. In addition to classic theory on the effect size of adaptive mutations by Fisher, Kimura and Orr, recent theory addresses the genetic architecture of local adaptation in the face of ongoing gene flow. This theory predicts that with substantial gene flow between populations local adaptation should proceed primarily through mutations of large effect or tightly linked clusters of smaller effect loci. In this study, we investigate the genetic architecture of divergence in flowering time, mating system-related traits, and leaf shape between Mimulus laciniatus and a sympatric population of its close relative M. guttatus. These three traits are probably involved in M. laciniatus' adaptation to a dry, exposed granite outcrop environment. Flowering time and mating system differences are also reproductive isolating barriers making them 'magic traits'. Phenotypic hybrids in this population provide evidence of recent gene flow. Using next-generation sequencing, we generate dense SNP markers across the genome and map quantitative trait loci (QTLs) involved in flowering time, flower size and leaf shape. We find that interspecific divergence in all three traits is due to few QTL of large effect including a highly pleiotropic QTL on chromosome 8. This QTL region contains the pleiotropic candidate gene TCP4 and is involved in ecologically important phenotypes in other Mimulus species. Our results are consistent with theory, indicating that local adaptation and reproductive isolation with gene flow should be due to few loci with large and pleiotropic effects.
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Affiliation(s)
- Kathleen G Ferris
- Department of Biology, Duke University, 125 Science Drive, Durham, NC, 27705, USA
| | - Laryssa L Barnett
- Department of Biology, Duke University, 125 Science Drive, Durham, NC, 27705, USA
| | - Benjamin K Blackman
- Department of Biology, University of Virginia, 485 McCormick Road, Charlottesville, VA, 22904, USA
| | - John H Willis
- Department of Biology, Duke University, 125 Science Drive, Durham, NC, 27705, USA
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173
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A hybridisation barrier between two evolutionary lineages of Barbarea vulgaris (Brassicaceae) that differ in biotic resistances. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9858-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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174
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Ostevik KL, Andrew RL, Otto SP, Rieseberg LH. Multiple reproductive barriers separate recently diverged sunflower ecotypes. Evolution 2016; 70:2322-2335. [PMID: 27479368 DOI: 10.1111/evo.13027] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 06/12/2016] [Accepted: 06/27/2016] [Indexed: 01/17/2023]
Abstract
Measuring reproductive barriers between groups of organisms is an effective way to determine the traits and mechanisms that impede gene flow. However, to understand the ecological and evolutionary factors that drive speciation, it is important to distinguish between the barriers that arise early in the speciation process and those that arise after speciation is largely complete. In this article, we comprehensively test for reproductive isolation between recently diverged (<10,000 years bp) dune and nondune ecotypes of the prairie sunflower, Helianthus petiolaris. We find reproductive barriers acting at multiple stages of hybridization, including premating, postmating-prezygotic, and postzygotic barriers, despite the recent divergence. Barriers include extrinsic selection against immigrants and hybrids, a shift in pollinator assemblage, and postpollination assortative mating. Together, these data suggest that multiple barriers can be important for reducing gene flow in the earliest stages of speciation.
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Affiliation(s)
- Katherine L Ostevik
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Rose L Andrew
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Sarah P Otto
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Biology, Indiana University, Bloomington, Indiana
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175
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Walter GM, Wilkinson MJ, James ME, Richards TJ, Aguirre JD, Ortiz‐Barrientos D. Diversification across a heterogeneous landscape. Evolution 2016; 70:1979-92. [DOI: 10.1111/evo.13009] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 07/05/2016] [Indexed: 12/11/2022]
Affiliation(s)
- Greg M. Walter
- School of Biological Sciences University of Queensland St. Lucia QLD 4072 Australia
| | - Melanie J. Wilkinson
- School of Biological Sciences University of Queensland St. Lucia QLD 4072 Australia
| | - Maddie E. James
- School of Biological Sciences University of Queensland St. Lucia QLD 4072 Australia
| | - Thomas J. Richards
- School of Biological Sciences University of Queensland St. Lucia QLD 4072 Australia
| | - J. David Aguirre
- School of Biological Sciences University of Queensland St. Lucia QLD 4072 Australia
- Institute of Natural and Mathematical Sciences Massey University Auckland 0745 New Zealand
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176
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Pegoraro L, Cafasso D, Rinaldi R, Cozzolino S, Scopece G. Habitat preference and flowering-time variation contribute to reproductive isolation between diploid and autotetraploid Anacamptis pyramidalis. J Evol Biol 2016; 29:2070-2082. [PMID: 27369842 DOI: 10.1111/jeb.12930] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 06/22/2016] [Accepted: 06/27/2016] [Indexed: 11/29/2022]
Abstract
Tetraploid lineages are typically reproductively isolated from their diploid ancestors by post-zygotic isolation via triploid sterility. Nevertheless, polyploids often also exhibit ecological divergence that could contribute to reproductive isolation from diploid ancestors. In this study, we disentangled the contribution of different forms of reproductive isolation between sympatric diploid and autotetraploid individuals of the food-deceptive orchid Anacamptis pyramidalis by quantifying the strength of seven reproductive barriers: three prepollination, one post-pollination prezygotic and three post-zygotic. The overall reproductive isolation between the two cytotypes was found very high, with a preponderant contribution of two prepollination barriers, that is phenological and microhabitat differences. Although the contribution of post-zygotic isolation (triploid sterility) is confirmed in our study, these results highlight that prepollination isolation, not necessarily involving pollinator preference, can represent a strong component of reproductive isolation between different cytotypes. Thus, in the context of polyploidy as quantum speciation, that generates reproductive isolation via triploid sterility, ecological divergence can strengthen the reproductive isolation between cytotypes, reducing the waste of gametes in low fitness interploidy crosses and thus favouring the initial establishment of the polyploid lineage. Under this light, speciation by polyploidy involves ecological processes and should not be strictly considered as a nonecological form of speciation.
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Affiliation(s)
- L Pegoraro
- Department of Biology, University of Padua, Padua, Italy
| | - D Cafasso
- Department of Biology, University Federico II of Naples, Naples, Italy
| | - R Rinaldi
- Department of Biology, University Federico II of Naples, Naples, Italy
| | - S Cozzolino
- Department of Biology, University Federico II of Naples, Naples, Italy
| | - G Scopece
- Department of Biology, University Federico II of Naples, Naples, Italy.
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177
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Moyers BT, Rieseberg LH. Remarkable life history polymorphism may be evolving under divergent selection in the silverleaf sunflower. Mol Ecol 2016; 25:3817-30. [DOI: 10.1111/mec.13723] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 06/01/2016] [Accepted: 06/02/2016] [Indexed: 01/27/2023]
Affiliation(s)
- Brook T. Moyers
- Department of Botany; University of British Columbia; 3529-6270 University Blvd Vancouver British Columbia Canada V6T 1Z4
| | - Loren H. Rieseberg
- Department of Botany; University of British Columbia; 3529-6270 University Blvd Vancouver British Columbia Canada V6T 1Z4
- Department of Biology; Indiana University; 1001 E 3rd St Bloomington IN 47405 USA
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178
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Kuligowska K, Lütken H, Müller R. Towards development of new ornamental plants: status and progress in wide hybridization. PLANTA 2016; 244:1-17. [PMID: 26969022 DOI: 10.1007/s00425-016-2493-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 02/19/2016] [Indexed: 05/21/2023]
Abstract
The present review provides insights into the key findings of the hybridization process, crucial factors affecting the adaptation of new technologies within wide hybridization of ornamental plants and presents perspectives of further development of this strategy. Wide hybridization is one of the oldest breeding techniques that contributed enormously to the development of modern plant cultivars. Within ornamental breeding, it represents the main source of genetic variation. During the long history of wide hybridization, a number of methods were implemented allowing the evolution from a conventional breeding tool into a modern methodology. Nowadays, the research on model plants and crop species increases our understanding of reproductive isolation among distant species and partly explains the background of the traditional approaches previously used for overcoming hybridization barriers. Characterization of parental plants and hybrids is performed using molecular and cytological techniques that strongly facilitate breeding processes. Molecular markers and sequencing technologies are used for the assessment of genetic relationships among plants, as the genetic distance is typically depicted as one of the most important factors influencing cross-compatibility in hybridization processes. Furthermore, molecular marker systems are frequently applied for verification of hybrid state of the progeny. The flow cytometry and genomic in situ hybridization are used in the assessment of hybridization partners and characterization of hybrid progeny in relation to genome stabilization as well as genome recombination and introgression. In the future, new research and technologies are likely to provide more detailed information about genes and pathways responsible for interspecific reproductive isolation. Ultimately, this knowledge will enable development of strategies for obtaining compatible lines for hybrid production. Recent development in sequencing technologies and availability of sequence data will also facilitate creation of new molecular markers that will advance marker-assisted selection in hybridization process.
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Affiliation(s)
- Katarzyna Kuligowska
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Højbakkegård Allé 9-13, 2630, Tåstrup, Denmark.
| | - Henrik Lütken
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Højbakkegård Allé 9-13, 2630, Tåstrup, Denmark
| | - Renate Müller
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Højbakkegård Allé 9-13, 2630, Tåstrup, Denmark
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179
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Stanton K, Valentin CM, Wijnen ME, Stutstman S, Palacios JJ, Cooley AM. Absence of postmating barriers between a selfing vs. outcrossing Chilean Mimulus species pair. AMERICAN JOURNAL OF BOTANY 2016; 103:1030-1040. [PMID: 27283023 DOI: 10.3732/ajb.1600079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 05/10/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Reproductive isolation between sympatric species pairs may be maintained by both pre- and postmating barriers. Here we evaluate potential barriers to mating between the outcrossing Mimulus luteus and its more highly selfing sympatric congener, M. cupreus, two members of the South American luteus complex of Mimulus. METHODS Seed set was compared following autonomous self-pollination, manual pollination, conspecific outcrossing, and sympatric and allopatric hybridization, for laboratory-maintained inbred lines and wild-collected accessions. Survival and reproductive fitness of hybrids relative to parental species were examined across environments that differed with respect to temperature and soil nutrients, two factors that vary across the ranges of M. luteus and M. cupreus. KEY RESULTS Mimulus luteus was minimally capable of autonomous self-fertilization, consistent with reliance on an animal pollinator, whereas M. cupreus was a successful selfer across all tested accessions. Postmating barriers to hybridization are negligible, in both low- and high-stress environments, across multiple sympatric and allopatric populations. CONCLUSION As in the North American M. guttatus-M. nasutus species pair, postmating barriers contribute little to isolation between M. luteus and M. cupreus. This result reinforces the importance of premating barriers, specifically species differences in reliance on, and accessibility to, animal pollinators. A unique aspect of the M. luteus-M. cupreus pair is the recent gain of red floral anthocyanin pigmentation in M. cupreus. On the basis of species differences in vegetative anthocyanin production, a facultative stress-protective response, we propose a potential stress-protective role for the constitutive floral anthocyanins of M. cupreus.
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Affiliation(s)
- Kimmy Stanton
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Celine M Valentin
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Marijke E Wijnen
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | - Sage Stutstman
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
| | | | - Arielle M Cooley
- Whitman College Biology Department, Walla Walla, Washington 99362 USA
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180
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Tonosaki K, Osabe K, Kawanabe T, Fujimoto R. The importance of reproductive barriers and the effect of allopolyploidization on crop breeding. BREEDING SCIENCE 2016; 66:333-49. [PMID: 27436943 PMCID: PMC4902455 DOI: 10.1270/jsbbs.15114] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 01/25/2016] [Indexed: 05/04/2023]
Abstract
Inter-specific hybrids are a useful source for increasing genetic diversity. Some reproductive barriers before and/or after fertilization prevent production of hybrid plants by inter-specific crossing. Therefore, techniques to overcome the reproductive barrier have been developed, and have contributed to hybridization breeding. In recent studies, identification of molecules involved in plant reproduction has been studied to understand the mechanisms of reproductive barriers. Revealing the molecular mechanisms of reproductive barriers may allow us to overcome reproductive barriers in inter-specific crossing, and to efficiently produce inter-specific hybrids in cross-combinations that cannot be produced through artificial techniques. Inter-specific hybrid plants can potentially serve as an elite material for plant breeding, produced through the merging of genomes of parental species by allopolyploidization. Allopolyploidization provides some benefits, such as heterosis, increased genetic diversity and phenotypic variability, which are caused by dynamic changes of the genome and epigenome. Understanding of allopolyploidization mechanisms is important for practical utilization of inter-specific hybrids as a breeding material. This review discusses the importance of reproductive barriers and the effect of allopolyploidization in crop breeding programs.
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Affiliation(s)
- Kaoru Tonosaki
- Kihara Institute for Biological Research, Yokohama City University,
641-12 Maioka, Totsuka, Yokohama, Kanagawa 244-0813,
Japan
- Corresponding author (e-mail: )
| | - Kenji Osabe
- Okinawa Institute of Science and Technology,
1919-1 Tancha, Onna-son, Kunigami, Okinawa 904-0495,
Japan
| | - Takahiro Kawanabe
- Graduate School of Agricultural Science, Kobe University,
Rokkodai, Nada-ku, Kobe 657-8501,
Japan
| | - Ryo Fujimoto
- Graduate School of Agricultural Science, Kobe University,
Rokkodai, Nada-ku, Kobe 657-8501,
Japan
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181
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Richards TJ, Ortiz-Barrientos D. Immigrant inviability produces a strong barrier to gene flow between parapatric ecotypes of Senecio lautus. Evolution 2016; 70:1239-48. [PMID: 27159252 DOI: 10.1111/evo.12936] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 02/07/2016] [Accepted: 04/12/2016] [Indexed: 01/16/2023]
Abstract
Speciation proceeds when gene exchange is prevented between populations. Determining the different barriers preventing gene flow can therefore give insights into the factors driving and maintaining species boundaries. These reproductive barriers may result from intrinsic genetic incompatibilities between populations, from extrinsic environmental differences between populations, or a combination of both mechanisms. We investigated the potential barriers to gene exchange between three adjacent ecotypes of an Australian wildflower to determine the strength of individual barriers and the degree of overall isolation between populations. We found almost complete isolation between the three populations mainly due to premating extrinsic barriers. Intrinsic genetic barriers were weak and variable among populations. There were asymmetries in some intrinsic barriers due to the origin of cytoplasm in hybrids. Overall, these results suggest that reproductive isolation between these three populations is almost complete despite the absence of geographic barriers, and that the main drivers of this isolation are ecologically based, consistent with the mechanisms underlying ecological speciation.
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Affiliation(s)
- Thomas J Richards
- School of Biological Sciences St. Lucia, University of Queensland, QLD, Australia.
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182
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Pease JB, Guerrero RF, Sherman NA, Hahn MW, Moyle LC. Molecular mechanisms of postmating prezygotic reproductive isolation uncovered by transcriptome analysis. Mol Ecol 2016; 25:2592-608. [DOI: 10.1111/mec.13679] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 12/22/2022]
Affiliation(s)
- James B. Pease
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Rafael F. Guerrero
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Natasha A. Sherman
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Matthew W. Hahn
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
- School of Informatics and Computing Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Leonie C. Moyle
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
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183
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Byers KJRP, Xu S, Schlüter PM. Molecular mechanisms of adaptation and speciation: why do we need an integrative approach? Mol Ecol 2016; 26:277-290. [DOI: 10.1111/mec.13678] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/18/2016] [Accepted: 04/21/2016] [Indexed: 01/06/2023]
Affiliation(s)
- Kelsey J. R. P. Byers
- Department of Systematic and Evolutionary Botany; University of Zurich; Zollikerstrasse 107 CH-8008 Zurich Switzerland
| | - Shuqing Xu
- Max Planck Institute for Chemical Ecology; Hans-Knöll-Straße 8 D-07745 Jena Germany
| | - Philipp M. Schlüter
- Department of Systematic and Evolutionary Botany; University of Zurich; Zollikerstrasse 107 CH-8008 Zurich Switzerland
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184
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Kenney AM, Sweigart AL. Reproductive isolation and introgression between sympatric
Mimulus
species. Mol Ecol 2016; 25:2499-517. [DOI: 10.1111/mec.13630] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/18/2016] [Accepted: 03/22/2016] [Indexed: 01/19/2023]
Affiliation(s)
- Amanda M. Kenney
- Department of Genetics University of Georgia Athens GA 30602 USA
- Department of Biological Sciences St. Edward's University Austin TX 78704 USA
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185
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Záveská E, Fér T, Šída O, Marhold K, Leong-Škorničková J. Hybridization among distantly related species: Examples from the polyploid genus Curcuma (Zingiberaceae). Mol Phylogenet Evol 2016; 100:303-321. [PMID: 27090448 DOI: 10.1016/j.ympev.2016.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 04/08/2016] [Accepted: 04/12/2016] [Indexed: 01/17/2023]
Abstract
Discerning relationships among species evolved by reticulate and/or polyploid evolution is not an easy task, although it is widely discussed. The economically important genus Curcuma (ca. 120 spp.; Zingiberaceae), broadly distributed in tropical SE Asia, is a particularly interesting example of a group of palaeopolyploid origin whose evolution is driven mainly by hybridization and polyploidization. Although a phylogeny and a new infrageneric classification of Curcuma, based on commonly used molecular markers (ITS and cpDNA), have recently been proposed, significant evolutionary questions remain unresolved. We applied a multilocus approach and a combination of modern analytical methods to this genus to distinguish causes of gene tree incongruence and to identify hybrids and their parental species. Five independent regions of nuclear DNA (DCS, GAPDH, GLOBOSA3, LEAFY, ITS) and four non-coding cpDNA regions (trnL-trnF, trnT-trnL, psbA-trnH and matK), analysed as a single locus, were employed to construct a species tree and hybrid species trees using (*)BEAST and STEM-hy. Detection of hybridogenous species in the dataset was also conducted using the posterior predictive checking approach as implemented in JML. The resulting species tree outlines the relationships among major evolutionary lineages within Curcuma, which were previously unresolved or which conflicted depending upon whether they were based on ITS or cpDNA markers. Moreover, by using the additional markers in tests of plausible topologies of hybrid species trees for C. vamana, C. candida, C. roscoeana and C. myanmarensis suggested by previous molecular and morphological evidence, we found strong evidence that all the species except C. candida are of subgeneric hybrid origin.
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Affiliation(s)
- Eliška Záveská
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic.
| | - Tomáš Fér
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
| | - Otakar Šída
- Department of Botany, National Museum in Prague, Prague, Czech Republic
| | - Karol Marhold
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic; Institute of Botany, Slovak Academy of Sciences, Bratislava, Slovak Republic
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186
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Barker MS, Arrigo N, Baniaga AE, Li Z, Levin DA. On the relative abundance of autopolyploids and allopolyploids. THE NEW PHYTOLOGIST 2016; 210:391-8. [PMID: 26439879 DOI: 10.1111/nph.13698] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Michael S Barker
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Nils Arrigo
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
- Department of Ecology and Evolution, University of Lausanne, CH-1015, Lausanne, Switzerland
| | - Anthony E Baniaga
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Zheng Li
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Donald A Levin
- Section of Integrative Biology, University of Texas, Austin, TX, 78713, USA
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187
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Campbell DR, Jürgens A, Johnson SD. Reproductive isolation between Zaluzianskya species: the influence of volatiles and flower orientation on hawkmoth foraging choices. THE NEW PHYTOLOGIST 2016; 210:333-342. [PMID: 26536281 DOI: 10.1111/nph.13746] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
Floral trait differences between related species may play a key role in reproductive isolation imposed by pollinators. Volatile emissions can influence pollinator choice, but how they act in combination with traits such as flower orientation is rarely studied. We compared flower-opening patterns, morphology, colour, orientation and volatile emissions for two closely related species of Zaluzianskya and their natural hybrids. Hawkmoth pollinators were tested for preference between flowers of the two species, and between flowers with manipulations of volatiles or orientation. Flowers of Z. natalensis and Z. microsiphon open at night and day, respectively, but they overlap during early evening, when hawkmoths showed a strong preference for Z. natalensis. The species have similar flower size and colour, but Z. natalensis emits more floral volatiles in the evening and presents flowers vertically face-up as opposed to horizontally in Z. microsiphon, whereas natural hybrids are intermediate. Adding methyl benzoate and linalool to flowers of Z. microsiphon did not increase hawkmoth attraction, but re-orientation of flowers to face vertically increased attraction when scent cues were present, whereas re-orientation of Z. natalensis flowers to face horizontally decreased attraction. This study highlights the importance of flower orientation in imposing reproductive isolation.
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Affiliation(s)
- Diane R Campbell
- Department of Ecology & Evolutionary Biology, University of California, Irvine, CA, 92697, USA
| | - Andreas Jürgens
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
- Plant Chemical Ecology, Technische Universität Darmstadt, Schnittspahnstrasse 4, 64287, Darmstadt, Germany
| | - Steven D Johnson
- School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
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188
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A subunit of the oligosaccharyltransferase complex is required for interspecific gametophyte recognition in Arabidopsis. Nat Commun 2016; 7:10826. [PMID: 26964640 PMCID: PMC4792959 DOI: 10.1038/ncomms10826] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 01/21/2016] [Indexed: 12/11/2022] Open
Abstract
Species-specific gamete recognition is a key premise to ensure reproductive success and the maintenance of species boundaries. During plant pollen tube (PT) reception, gametophyte interactions likely allow the species-specific recognition of signals from the PT (male gametophyte) by the embryo sac (female gametophyte), resulting in PT rupture, sperm release, and double fertilization. This process is impaired in interspecific crosses between Arabidopsis thaliana and related species, leading to PT overgrowth and a failure to deliver the sperm cells. Here we show that ARTUMES (ARU) specifically regulates the recognition of interspecific PTs in A. thaliana. ARU, identified in a genome-wide association study (GWAS), exclusively influences interspecific--but not intraspecific--gametophyte interactions. ARU encodes the OST3/6 subunit of the oligosaccharyltransferase complex conferring protein N-glycosylation. Our results suggest that glycosylation patterns of cell surface proteins may represent an important mechanism of gametophyte recognition and thus speciation.
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189
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Senerchia N, Felber F, North B, Sarr A, Guadagnuolo R, Parisod C. Differential introgression and reorganization of retrotransposons in hybrid zones between wild wheats. Mol Ecol 2016; 25:2518-28. [DOI: 10.1111/mec.13515] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/24/2015] [Accepted: 11/30/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Natacha Senerchia
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - François Felber
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
- Musée et Jardins Botaniques Cantonaux; 1007 Lausanne Switzerland
| | - Béatrice North
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Anouk Sarr
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Roberto Guadagnuolo
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
| | - Christian Parisod
- Laboratory of Evolutionary Botany; Institute of Biology; University of Neuchâtel; 2000 Neuchâtel Switzerland
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190
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Ingley SJ, Johnson JB. Divergent natural selection promotes immigrant inviability at early and late stages of evolutionary divergence. Evolution 2016; 70:600-16. [DOI: 10.1111/evo.12872] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/21/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Spencer J. Ingley
- Evolutionary Ecology Laboratories, Department of Biology; Brigham Young University; Provo Utah 84602
| | - Jerald B. Johnson
- Evolutionary Ecology Laboratories, Department of Biology; Brigham Young University; Provo Utah 84602
- Monte L. Bean Life Science Museum; Brigham Young University; Provo Utah 84602
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191
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Strong reproductive isolation despite occasional hybridization between a widely distributed and a narrow endemic Rhododendron species. Sci Rep 2016; 6:19146. [PMID: 26751844 PMCID: PMC4707479 DOI: 10.1038/srep19146] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/07/2015] [Indexed: 12/29/2022] Open
Abstract
Reproductive isolation (RI) plays an important role for speciation, but assessing reproductive barriers at all life-cycle stages remains challenging. In plants, most studies addressing the topic have been focusing on herbs with short generation times. The present study attempted to quantify several reproductive barriers between a hybridizing species pair of long-lived woody rhododendrons. Consistent with findings of previous studies, pre-zygotic reproductive barriers contributed more to total RI than post-zygotic reproductive barriers. Especially in the more widespread species geographic isolation was an important barrier, and pollinator constancy contributed exceptionally to RI in both species. Additionally to strong pre-zygotic reproductive barriers, post-zygotic reproductive barriers were considerable, and had asymmetric tendencies favoring one of the species as maternal parent. Overall, despite occasional hybridization, the present study provides evidence for strong RI between R. cyanocarpum and R. delavayi.
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192
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Senerchia N, Felber F, Parisod C. Genome reorganization in F1 hybrids uncovers the role of retrotransposons in reproductive isolation. Proc Biol Sci 2015; 282:20142874. [PMID: 25716787 DOI: 10.1098/rspb.2014.2874] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Interspecific hybridization leads to new interactions among divergent genomes, revealing the nature of genetic incompatibilities having accumulated during and after the origin of species. Conflicts associated with misregulation of transposable elements (TEs) in hybrids expectedly result in their activation and genome-wide changes that may be key to species boundaries. Repetitive genomes of wild wheats have diverged under differential dynamics of specific long terminal repeat retrotransposons (LTR-RTs), offering unparalleled opportunities to address the underpinnings of plant genome reorganization by selfish sequences. Using reciprocal F1 hybrids between three Aegilops species, restructuring and epigenetic repatterning was assessed at random and LTR-RT sequences with amplified fragment length polymorphism and sequence-specific amplified polymorphisms as well as their methylation-sensitive counterparts, respectively. Asymmetrical reorganization of LTR-RT families predicted to cause conflicting interactions matched differential survival of F1 hybrids. Consistent with the genome shock model, increasing divergence of merged LTR-RTs yielded higher levels of changes in corresponding genome fractions and lead to repeated reorganization of LTR-RT sequences in F1 hybrids. Such non-random reorganization of hybrid genomes is coherent with the necessary repression of incompatible TE loci in support of hybrid viability and indicates that TE-driven genomic conflicts may represent an overlooked factor supporting reproductive isolation.
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Affiliation(s)
- Natacha Senerchia
- Laboratory of Evolutionary Botany, Institute of Biology, University of Neuchâtel, Rue Emile Argand 11, Neuchâtel 2000, Switzerland
| | - François Felber
- Laboratory of Evolutionary Botany, Institute of Biology, University of Neuchâtel, Rue Emile Argand 11, Neuchâtel 2000, Switzerland Musée et Jardins Botaniques Cantonaux, Lausanne 1007, Switzerland
| | - Christian Parisod
- Laboratory of Evolutionary Botany, Institute of Biology, University of Neuchâtel, Rue Emile Argand 11, Neuchâtel 2000, Switzerland
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193
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Johnson MA, Price DK, Price JP, Stacy EA. Postzygotic barriers isolate sympatric species of Cyrtandra (Gesneriaceae) in Hawaiian montane forest understories. AMERICAN JOURNAL OF BOTANY 2015; 102:1870-1882. [PMID: 26542848 DOI: 10.3732/ajb.1500288] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/02/2015] [Indexed: 06/05/2023]
Abstract
PREMISE OF THE STUDY Recent reviews of reproductive isolation (RI) in plants propose that boundaries between closely related species are maintained predominantly through prezygotic mechanisms. However, few experimental studies have explored how boundaries are maintained in long-lived species. Hawaiian Cyrtandra presents an intriguing challenge to our understanding of RI, as it comprises 60 shrub or small tree species that are almost exclusively restricted to wet forests, where sympatry of multiple species is common. METHODS We assessed the relative strengths of pre- and postzygotic barriers among four species of Cyrtandra occurring at the extremes of the main Hawaiian Island's natural island-age gradient, Kaua'i (4.7 Myr) and Hawai'i Island (0.6 Myr), to contrast the strengths and stages of reproductive isolation among species at different stages of divergence. KEY RESULTS A combination of F1 seed germination, F1 seedling survival, and F1 seedling growth isolated (61-91%) three of the species from sympatric relatives. In contrast, the fourth species was isolated (59%) from its sympatric relative through phenological differences alone. Significant postzygotic barriers in between-island crosses were also observed in one species. CONCLUSIONS Results suggest that boundaries between sympatric Cyrtandra species in Hawaii are maintained predominantly through postzygotic barriers. Observations from between-island crosses indicate that postzygotic barriers can arise in allopatry, which may be important in the initial divergence of populations. Future studies of RI in Cyrtandra should include a broader range of species to determine if postzygotic isolating barriers are foremost in the maintenance of species boundaries in this large genus.
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Affiliation(s)
- Melissa A Johnson
- Tropical Conservation Biology and Environmental Science Graduate Program, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720
| | - Donald K Price
- Tropical Conservation Biology and Environmental Science Graduate Program, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720 Department of Biology, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720
| | - Jonathan P Price
- Tropical Conservation Biology and Environmental Science Graduate Program, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720 Department of Geography, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720
| | - Elizabeth A Stacy
- Tropical Conservation Biology and Environmental Science Graduate Program, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720 Department of Biology, University of Hawai'i at Hilo, 200 W. Kawili Street, Hilo, Hawai'i 96720
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194
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Gray DA, Gutierrez NJ, Chen TL, Gonzalez C, Weissman DB, Cole JA. Species divergence in field crickets: genetics, song, ecomorphology, and pre- and postzygotic isolation. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12668] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- David A. Gray
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Nicholas J. Gutierrez
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Tom L. Chen
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - Christopher Gonzalez
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
| | - David B. Weissman
- Department of Entomology; California Academy of Sciences; San Francisco CA 94118 USA
| | - Jeffrey A. Cole
- Department of Biology; California State University Northridge; Northridge CA 91330-8303 USA
- Department of Biology; Pasadena City College; Pasadena CA 91106 USA
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195
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Pinheiro F, Cafasso D, Cozzolino S, Scopece G. Transitions between self-compatibility and self-incompatibility and the evolution of reproductive isolation in the large and diverse tropical genus Dendrobium (Orchidaceae). ANNALS OF BOTANY 2015; 116:457-67. [PMID: 25953040 PMCID: PMC4549954 DOI: 10.1093/aob/mcv057] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/30/2015] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS The evolution of interspecific reproductive barriers is crucial to understanding species evolution. This study examines the contribution of transitions between self-compatibility (SC) and self-incompatibility (SI) and genetic divergence in the evolution of reproductive barriers in Dendrobium, one of the largest orchid genera. Specifically, it investigates the evolution of pre- and postzygotic isolation and the effects of transitions between compatibility states on interspecific reproductive isolation within the genus. METHODS The role of SC and SI changes in reproductive compatibility among species was examined using fruit set and seed viability data available in the literature from 86 species and ∼2500 hand pollinations. The evolution of SC and SI in Dendrobium species was investigated within a phylogenetic framework using internal transcribed spacer sequences available in GenBank. KEY RESULTS Based on data from crossing experiments, estimations of genetic distance and the results of a literature survey, it was found that changes in SC and SI significantly influenced the compatibility between species in interspecific crosses. The number of fruits produced was significantly higher in crosses in which self-incompatible species acted as pollen donor for self-compatible species, following the SI × SC rule. Maximum likelihood and Bayesian tests did not reject transitions from SI to SC and from SC to SI across the Dendrobium phylogeny. In addition, postzygotic isolation (embryo mortality) was found to evolve gradually with genetic divergence, in agreement with previous results observed for other plant species, including orchids. CONCLUSIONS Transitions between SC and SI and the gradual accumulation of genetic incompatibilities affecting postzygotic isolation are important mechanisms preventing gene flow among Dendrobium species, and may constitute important evolutionary processes contributing to the high levels of species diversity in this tropical orchid group.
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Affiliation(s)
- Fabio Pinheiro
- Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista, 13506-900, Rio Claro, SP, Brazil,
| | - Donata Cafasso
- Università degli Studi di Napoli Federico II, Department of Biology, via Cinthia, I-80126, Naples, Italy and
| | - Salvatore Cozzolino
- Università degli Studi di Napoli Federico II, Department of Biology, via Cinthia, I-80126, Naples, Italy and
| | - Giovanni Scopece
- Università degli Studi di Napoli Federico II, Department of Biology, via Cinthia, I-80126, Naples, Italy and Institute for Plant Protection, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, 10, I-50019, Sesto Fiorentino (FI), Italy
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196
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Baack E, Melo MC, Rieseberg LH, Ortiz-Barrientos D. The origins of reproductive isolation in plants. THE NEW PHYTOLOGIST 2015; 207:968-84. [PMID: 25944305 DOI: 10.1111/nph.13424] [Citation(s) in RCA: 187] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 03/16/2015] [Indexed: 05/23/2023]
Abstract
Reproductive isolation in plants occurs through multiple barriers that restrict gene flow between populations, but their origins remain uncertain. Work in the past decade has shown that postpollination barriers, such as the failure to form hybrid seeds or sterility of hybrid offspring, are often less strong than prepollination barriers. Evidence implicates multiple evolutionary forces in the origins of reproductive barriers, including mutation, stochastic processes and natural selection. Although adaptation to different environments is a common element of reproductive isolation, genomic conflicts also play a role, including female meiotic drive. The genetic basis of some reproductive barriers, particularly flower colour influencing pollinator behaviour, is well understood in some species, but the genetic changes underlying many other barriers, especially pollen-stylar interactions, are largely unknown. Postpollination barriers appear to accumulate at a faster rate in annuals compared with perennials, due in part to chromosomal rearrangements. Chromosomal changes can be important isolating barriers in themselves but may also reduce the recombination of genes contributing to isolation. Important questions for the next decade include identifying the evolutionary forces responsible for chromosomal rearrangements, determining how often prezygotic barriers arise due to selection against hybrids, and establishing the relative importance of genomic conflicts in speciation.
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Affiliation(s)
- Eric Baack
- Department of Biology, Luther College, Decorah, IA, 52101, USA
| | - Maria Clara Melo
- School of Biological Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Loren H Rieseberg
- Department of Botany, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
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197
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Austen EJ, Weis AE. What drives selection on flowering time? An experimental manipulation of the inherent correlation between genotype and environment. Evolution 2015; 69:2018-33. [DOI: 10.1111/evo.12709] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 06/09/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Emily J. Austen
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto Ontario Canada M5S 3B2
- Department of Biology; Mount Allison University; Sackville New Brunswick Canada E4L 1E2
| | - Arthur E. Weis
- Department of Ecology and Evolutionary Biology; University of Toronto; Toronto Ontario Canada M5S 3B2
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198
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Qvarnström A, Ålund M, McFarlane SE, Sirkiä PM. Climate adaptation and speciation: particular focus on reproductive barriers in Ficedula flycatchers. Evol Appl 2015; 9:119-34. [PMID: 27087843 PMCID: PMC4780377 DOI: 10.1111/eva.12276] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 05/14/2015] [Indexed: 01/19/2023] Open
Abstract
Climate adaptation is surprisingly rarely reported as a cause for the build‐up of reproductive isolation between diverging populations. In this review, we summarize evidence for effects of climate adaptation on pre‐ and postzygotic isolation between emerging species with a particular focus on pied (Ficedula hypoleuca) and collared (Ficedula albicollis) flycatchers as a model for research on speciation. Effects of climate adaptation on prezygotic isolation or extrinsic selection against hybrids have been documented in several taxa, but the combined action of climate adaptation and sexual selection is particularly well explored in Ficedula flycatchers. There is a general lack of evidence for divergent climate adaptation causing intrinsic postzygotic isolation. However, we argue that the profound effects of divergence in climate adaptation on the whole biochemical machinery of organisms and hence many underlying genes should increase the likelihood of genetic incompatibilities arising as side effects. Fast temperature‐dependent co‐evolution between mitochondrial and nuclear genomes may be particularly likely to lead to hybrid sterility. Thus, how climate adaptation relates to reproductive isolation is best explored in relation to fast‐evolving barriers to gene flow, while more research on later stages of divergence is needed to achieve a complete understanding of climate‐driven speciation.
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Affiliation(s)
- Anna Qvarnström
- Animal Ecology/Department of Ecology and Genetics Uppsala University Uppsala Sweden
| | - Murielle Ålund
- Animal Ecology/Department of Ecology and Genetics Uppsala University Uppsala Sweden
| | - S Eryn McFarlane
- Animal Ecology/Department of Ecology and Genetics Uppsala University Uppsala Sweden
| | - Päivi M Sirkiä
- Animal Ecology/Department of Ecology and Genetics Uppsala University Uppsala Sweden; Finnish Museum of Natural History Zoology Unit University of Helsinki Helsinki Finland
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199
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Abstract
Understanding how seed size is regulated in angiosperms is a key goal for plant science as seed size is an important component of overall seed yield. Angiosperm seeds comprise three clearly defined components, i.e. the embryo, endosperm and seed coat, with each having a distinct genetic composition which exerts different influences on seed development. Complex cross-talk and integration of signals from these different regions of the seed together determine its final size. The present review considers some of the major regulators of seed size, with a particular emphasis on the role of the seed coat in modulating endosperm proliferation and cellularization. The innermost layer of the seed coat, the endothelium, synthesizes flavonoids which are held to provide a defensive function against microbes, act as feeding deterrents, provide UV protection and to have a role in seed dormancy. A growing body of data suggests that flavonoids may also play a fundamental role in regulating communication between the seed coat and the endosperm. In the present review, we discuss how this may be achieved in the light of the fact that several flavonoids are known to be potent auxin transport regulators.
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200
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Twyford AD, Friedman J. Adaptive divergence in the monkey flower Mimulus guttatus is maintained by a chromosomal inversion. Evolution 2015; 69:1476-1486. [PMID: 25879251 PMCID: PMC5029580 DOI: 10.1111/evo.12663] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 04/01/2015] [Indexed: 12/15/2022]
Abstract
Organisms exhibit an incredible diversity of life history strategies as adaptive responses to environmental variation. The establishment of novel life history strategies involves multilocus polymorphisms, which will be challenging to establish in the face of gene flow and recombination. Theory predicts that adaptive allelic combinations may be maintained and spread if they occur in genomic regions of reduced recombination, such as chromosomal inversion polymorphisms, yet empirical support for this prediction is lacking. Here, we use genomic data to investigate the evolution of divergent adaptive ecotypes of the yellow monkey flower Mimulus guttatus. We show that a large chromosomal inversion polymorphism is the major region of divergence between geographically widespread annual and perennial ecotypes. In contrast, ∼40,000 single nucleotide polymorphisms in collinear regions of the genome show no signal of life history, revealing genomic patterns of diversity have been shaped by localized homogenizing gene flow and large-scale Pleistocene range expansion. Our results provide evidence for an inversion capturing and protecting loci involved in local adaptation, while also explaining how adaptive divergence can occur with gene flow.
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Affiliation(s)
- Alex D Twyford
- Ashworth Laboratories, Institute of Evolutionary Biology, The University of Edinburgh, Charlotte Auerbach Road, Edinburgh, EH9 3FL, United Kingdom.,Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244
| | - Jannice Friedman
- Department of Biology, Syracuse University, 107 College Place, Syracuse, New York, 13244
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