메뉴 건너뛰기




Volumn 185, Issue 1, 2010, Pages 332-342

Tree endurance on the Tibetan Plateau marks the world's highest known tree line of the Last Glacial Maximum

Author keywords

Glacial refugia; High mountain areas; Juniperus tibetica complex; Orographic leading edge; Orographic rear edge; Tibetan Plateau

Indexed keywords

ADAPTATION; CHLOROPLAST; CONIFEROUS TREE; GENE FLOW; INTERPOPULATION VARIATION; LAST GLACIAL MAXIMUM; OROGRAPHY; PHYLOGEOGRAPHY; RANGE SIZE; REFUGIUM; TOPOGRAPHIC EFFECT; TREELINE;

EID: 71249110645     PISSN: 0028646X     EISSN: 14698137     Source Type: Journal    
DOI: 10.1111/j.1469-8137.2009.03007.x     Document Type: Article
Times cited : (142)

References (74)
  • 2
    • 71249093281 scopus 로고    scopus 로고
    • Taxonomic affinity of rushforth's Bhutan juniper and Juniperus indica using SNP's from nrDNA and cp trnC-trnD, terpenoids and RAPD data
    • Adams RP, Morris JA, Schwarzbach AE. 2008. Taxonomic affinity of rushforth's Bhutan juniper and Juniperus indica using SNP's from nrDNA and cp trnC-trnD, terpenoids and RAPD data. Phytologia 90 : 233 245.
    • (2008) Phytologia , vol.90 , pp. 233-245
    • Adams, R.P.1    Morris, J.A.2    Schwarzbach, A.E.3
  • 3
    • 33747333661 scopus 로고    scopus 로고
    • Modelling plateau peoples: The early human use of the world's high plateaux
    • Aldenderfer M. 2006. Modelling plateau peoples: the early human use of the world's high plateaux. World Archaeology 38 : 357 370.
    • (2006) World Archaeology , vol.38 , pp. 357-370
    • Aldenderfer, M.1
  • 6
    • 33645049319 scopus 로고    scopus 로고
    • Contrasting effects of long distance seed dispersal on genetic diversity during range expansion
    • Bialozyt R, Ziegenhagen B, Petit RJ. 2006. Contrasting effects of long distance seed dispersal on genetic diversity during range expansion. Journal of Evolutionary Biology 19 : 12 20.
    • (2006) Journal of Evolutionary Biology , vol.19 , pp. 12-20
    • Bialozyt, R.1    Ziegenhagen, B.2    Petit, R.J.3
  • 8
    • 33746838018 scopus 로고    scopus 로고
    • General climatic controls and topoclimatic variations in Central and High Asia
    • Bohner J. 2006. General climatic controls and topoclimatic variations in Central and High Asia. Boreas 35 : 279 295.
    • (2006) Boreas , vol.35 , pp. 279-295
    • Bohner, J.1
  • 9
    • 0033771358 scopus 로고    scopus 로고
    • TCS. A computer program to estimate gene genealogies
    • Clement M, Posada D, Crandall KA. 2000. TCS. A computer program to estimate gene genealogies. Molecular Ecology 9 : 1657 1659.
    • (2000) Molecular Ecology , vol.9 , pp. 1657-1659
    • Clement, M.1    Posada, D.2    Crandall, K.A.3
  • 10
    • 71249102462 scopus 로고    scopus 로고
    • CodonCode Corporation. CodonCode Corporation. Dedham, MA, USA.
    • CodonCode Corporation 2007. Codoncode Aligner [2.0]. Computer program. CodonCode Corporation Dedham, MA, USA.
    • (2007) Codoncode Aligner [2.0]. Computer Program
  • 11
    • 0035151471 scopus 로고    scopus 로고
    • Diverging trends between heterozygosity and allelic richness during postglacial colonization in the European beech
    • Comps B, Gomory D, Letouzey J, Thiebaut B, Petit RJ. 2001. Diverging trends between heterozygosity and allelic richness during postglacial colonization in the European beech. Genetics 157 : 389 397.
    • (2001) Genetics , vol.157 , pp. 389-397
    • Comps, B.1    Gomory, D.2    Letouzey, J.3    Thiebaut, B.4    Petit, R.J.5
  • 12
    • 0027285731 scopus 로고
    • Empirical tests of some predictions from coalescent theory with applications to intraspecific phylogeny reconstruction
    • Crandall KA, Templeton AR. 1993. Empirical tests of some predictions from coalescent theory with applications to intraspecific phylogeny reconstruction. Genetics 134 : 959 969.
    • (1993) Genetics , vol.134 , pp. 959-969
    • Crandall, K.A.1    Templeton, A.R.2
  • 13
    • 0001547109 scopus 로고
    • Inheritance of chloroplast and mitochondrial genomes in pedunculate oak investigated with an efficient PCR method
    • Dumolin S, Demesure B, Petit RJ. 1995. Inheritance of chloroplast and mitochondrial genomes in pedunculate oak investigated with an efficient PCR method. Theoretical and Applied Genetics 91 : 1253 1256.
    • (1995) Theoretical and Applied Genetics , vol.91 , pp. 1253-1256
    • Dumolin, S.1    Demesure, B.2    Petit, R.J.3
  • 15
    • 0242541692 scopus 로고    scopus 로고
    • On the problem of possible last-glacial forest-refuge areas within the deep valleys of Eastern Tibet
    • Frenzel B, Bräuning A, Adamczyk S. 2003. On the problem of possible last-glacial forest-refuge areas within the deep valleys of Eastern Tibet. Erdkunde 57 : 182 198.
    • (2003) Erdkunde , vol.57 , pp. 182-198
    • Frenzel, B.1    Bräuning, A.2    Adamczyk, S.3
  • 16
    • 0030821992 scopus 로고    scopus 로고
    • Statistical tests of neutrality of mutations against population growth, hitchhiking and background selection
    • Fu YX. 1997. Statistical tests of neutrality of mutations against population growth, hitchhiking and background selection. Genetics 147 : 915 925.
    • (1997) Genetics , vol.147 , pp. 915-925
    • Fu, Y.X.1
  • 18
    • 33750208632 scopus 로고    scopus 로고
    • Contrasting patterns of historical colonization in white oaks (Quercus spp.) in California and Europe
    • Grivet D, Deguilloux MF, Petit RJ, Sork VL. 2006. Contrasting patterns of historical colonization in white oaks (Quercus spp.) in California and Europe. Molecular Ecology 15 : 4085 4093.
    • (2006) Molecular Ecology , vol.15 , pp. 4085-4093
    • Grivet, D.1    Deguilloux, M.F.2    Petit, R.J.3    Sork, V.L.4
  • 19
    • 18444385410 scopus 로고    scopus 로고
    • Conserving biodiversity under climate change: The rear edge matters
    • Hampe A, Petit RJ. 2005. Conserving biodiversity under climate change: the rear edge matters. Ecology Letters 8 : 461 467.
    • (2005) Ecology Letters , vol.8 , pp. 461-467
    • Hampe, A.1    Petit, R.J.2
  • 20
    • 37249092468 scopus 로고    scopus 로고
    • Ever deeper phylogeographies: Trees retain the genetic imprint of Tertiary plate tectonics
    • Hampe A, Petit RJ. 2007. Ever deeper phylogeographies: trees retain the genetic imprint of Tertiary plate tectonics. Molecular Ecology 16 : 5113 5114.
    • (2007) Molecular Ecology , vol.16 , pp. 5113-5114
    • Hampe, A.1    Petit, R.J.2
  • 22
    • 0002446735 scopus 로고
    • Postglacial distribution and species substructure: Lessons from pollen, insects and hybrid zones
    • Lees, D.R. Edwards, D. eds. London, UK. Academic
    • Hewitt GM. 1993. Postglacial distribution and species substructure: lessons from pollen, insects and hybrid zones. In : Lees DR, Edwards D, eds. Evolutionary patterns and processes. Linnean Society symposium series 14. London, UK : Academic, 97 123.
    • (1993) Evolutionary Patterns and Processes. Linnean Society Symposium Series 14. , pp. 97-123
    • Hewitt, G.M.1
  • 23
    • 0029860602 scopus 로고    scopus 로고
    • Some genetic consequences of ice ages, and their role in divergence and speciation
    • Hewitt GM. 1996. Some genetic consequences of ice ages, and their role in divergence and speciation. Biological Journal of the Linnean Society 58 : 247 276.
    • (1996) Biological Journal of the Linnean Society , vol.58 , pp. 247-276
    • Hewitt, G.M.1
  • 25
    • 0034702196 scopus 로고    scopus 로고
    • The genetic legacy of the Quaternary ice ages
    • Hewitt G. 2000. The genetic legacy of the Quaternary ice ages. Nature 405 : 907 913.
    • (2000) Nature , vol.405 , pp. 907-913
    • Hewitt, G.1
  • 27
    • 0001935493 scopus 로고
    • Gene genealogies and the coalescent process
    • Futuyma, D. Antonovics, J. eds. Oxford, UK. Oxford University Press
    • Hudson RR. 1990. Gene genealogies and the coalescent process. In : Futuyma D, Antonovics J, eds. Oxford surveys in evolutionary biology. Oxford, UK : Oxford University Press, 1 44.
    • (1990) Oxford Surveys in Evolutionary Biology , pp. 1-44
    • Hudson, R.R.1
  • 28
    • 0034849408 scopus 로고    scopus 로고
    • MRBAYES: Bayesian inference of phylogenetic trees
    • Huelsenbeck JP, Ronquist F. 2001. MRBAYES: Bayesian inference of phylogenetic trees. Bioinformatics 17 : 754 755.
    • (2001) Bioinformatics , vol.17 , pp. 754-755
    • Huelsenbeck, J.P.1    Ronquist, F.2
  • 30
    • 0141613140 scopus 로고    scopus 로고
    • Postglacial population growth of Cunninghamia konishii (Cupressaceae) inferred from phylogeographical and mismatch analysis of chloroplast DNA variation
    • Hwang SY, Lin TP, Ma CS, Lin CL, Chung JD, Yang JC. 2003. Postglacial population growth of Cunninghamia konishii (Cupressaceae) inferred from phylogeographical and mismatch analysis of chloroplast DNA variation. Molecular Ecology 12 : 2689 2695.
    • (2003) Molecular Ecology , vol.12 , pp. 2689-2695
    • Hwang, S.Y.1    Lin, T.P.2    Ma, C.S.3    Lin, C.L.4    Chung, J.D.5    Yang, J.C.6
  • 31
    • 85047679528 scopus 로고    scopus 로고
    • Spatial patterns of genetic variation generated by different forms of dispersal during range expansion
    • Ibrahim KM, Nichols RA, Hewitt GM. 1996. Spatial patterns of genetic variation generated by different forms of dispersal during range expansion. Heredity 77 : 282 291.
    • (1996) Heredity , vol.77 , pp. 282-291
    • Ibrahim, K.M.1    Nichols, R.A.2    Hewitt, G.M.3
  • 33
    • 33846818565 scopus 로고    scopus 로고
    • Holocene paleosols and colluvial sediments in Northeast Tibet (Qinghai Province, China): Properties, dating and paleoenvironmental implications
    • Kaiser K, Schoch WH, Miehe G. 2007. Holocene paleosols and colluvial sediments in Northeast Tibet (Qinghai Province, China): Properties, dating and paleoenvironmental implications. CATENA 69 : 91 102.
    • (2007) CATENA , vol.69 , pp. 91-102
    • Kaiser, K.1    Schoch, W.H.2    Miehe, G.3
  • 34
    • 67349113792 scopus 로고    scopus 로고
    • Charcoal and fossil wood from palaeosols, sediments and artificial structures indicating Late Holocene woodland decline in southern Tibet (China)
    • Kaiser K, Opgenoorth L, Schoch WH, Miehe G. 2009. Charcoal and fossil wood from palaeosols, sediments and artificial structures indicating Late Holocene woodland decline in southern Tibet (China). Quaternary Science Reviews 28 : 1539 1554.
    • (2009) Quaternary Science Reviews , vol.28 , pp. 1539-1554
    • Kaiser, K.1    Opgenoorth, L.2    Schoch, W.H.3    Miehe, G.4
  • 35
    • 0031747902 scopus 로고    scopus 로고
    • Paternal inheritance of chloroplast and mitochondrial DNA in interspecific hybrids of Chamaecyparis spp
    • Kondo T, Tsumura Y, Kawahara T, Okamura M. 1998. Paternal inheritance of chloroplast and mitochondrial DNA in interspecific hybrids of Chamaecyparis spp. Breeding Science 48 : 177 179.
    • (1998) Breeding Science , vol.48 , pp. 177-179
    • Kondo, T.1    Tsumura, Y.2    Kawahara, T.3    Okamura, M.4
  • 38
    • 3543035788 scopus 로고    scopus 로고
    • Geographic patterns of (genetic, morphologic, linguistic) variation: How barriers can be detected by using Monmonier's algorithm
    • Manni F, Guerard E, Heyer E. 2004. Geographic patterns of (genetic, morphologic, linguistic) variation: how barriers can be detected by using Monmonier's algorithm. Human Biology 76 : 173 190.
    • (2004) Human Biology , vol.76 , pp. 173-190
    • Manni, F.1    Guerard, E.2    Heyer, E.3
  • 39
    • 34748842004 scopus 로고    scopus 로고
    • Mitochondrial and chloroplast phylogeography of Picea crassifolia Kom. (Pinaceae) in the Qinghai-Tibetan Plateau and adjacent highlands
    • Meng LH, Yang R, Abbott RJ, Miehe G, Hu TH, Liu JQ. 2007. Mitochondrial and chloroplast phylogeography of Picea crassifolia Kom. (Pinaceae) in the Qinghai-Tibetan Plateau and adjacent highlands. Molecular Ecology 16 : 4128 4137.
    • (2007) Molecular Ecology , vol.16 , pp. 4128-4137
    • Meng, L.H.1    Yang, R.2    Abbott, R.J.3    Miehe, G.4    Hu, T.H.5    Liu, J.Q.6
  • 40
    • 33751225101 scopus 로고    scopus 로고
    • Palaeoecological and experimental evidence of former forests and woodlands in the treeless desert pastures of Southern Tibet (Lhasa, AR Xizang, China)
    • Miehe G, Miehe S, Schlutz F, Kaiser K, Duo L. 2006. Palaeoecological and experimental evidence of former forests and woodlands in the treeless desert pastures of Southern Tibet (Lhasa, AR Xizang, China). Palaeogeography Palaeoclimatology Palaeoecology 242 : 54 67.
    • (2006) Palaeogeography Palaeoclimatology Palaeoecology , vol.242 , pp. 54-67
    • Miehe, G.1    Miehe, S.2    Schlutz, F.3    Kaiser, K.4    Duo, L.5
  • 42
    • 36649020140 scopus 로고    scopus 로고
    • An inventory of forest relicts in the pastures of Southern Tibet (Xizang AR, China)
    • Miehe G, Miehe S, Will M, Opgenoorth L, Duo L, Dorgeh T, Liu JQ. 2008. An inventory of forest relicts in the pastures of Southern Tibet (Xizang AR, China). Plant Ecology 194 : 157 177.
    • (2008) Plant Ecology , vol.194 , pp. 157-177
    • Miehe, G.1    Miehe, S.2    Will, M.3    Opgenoorth, L.4    Duo, L.5    Dorgeh, T.6    Liu, J.Q.7
  • 43
    • 0030042907 scopus 로고    scopus 로고
    • The hows and whys of cytoplasmic inheritance in seed plants
    • Mogensen HL. 1996. The hows and whys of cytoplasmic inheritance in seed plants. American Journal of Botany 83 : 383 404.
    • (1996) American Journal of Botany , vol.83 , pp. 383-404
    • Mogensen, H.L.1
  • 44
    • 22944482184 scopus 로고    scopus 로고
    • SeqState - Primer design and sequence statistics for phylogenetic DNA data sets
    • Müller K. 2005. SeqState - primer design and sequence statistics for phylogenetic DNA data sets. Applied Bioinformatics 4 : 65 69.
    • (2005) Applied Bioinformatics , vol.4 , pp. 65-69
    • Müller, K.1
  • 48
  • 50
    • 0031856979 scopus 로고    scopus 로고
    • Identifying populations for conservation on the basis of genetic markers
    • Petit RJ, El Mousadik A, Pons O. 1998. Identifying populations for conservation on the basis of genetic markers. Conservation Biology 12 : 844 855.
    • (1998) Conservation Biology , vol.12 , pp. 844-855
    • Petit, R.J.1    El Mousadik, A.2    Pons, O.3
  • 53
    • 0029159581 scopus 로고
    • Estimation, variance and optimal sampling of gene diversity.1. Haploid locus
    • Pons O, Petit RJ. 1995. Estimation, variance and optimal sampling of gene diversity.1. Haploid locus. Theoretical and Applied Genetics 90 : 462 470.
    • (1995) Theoretical and Applied Genetics , vol.90 , pp. 462-470
    • Pons, O.1    Petit, R.J.2
  • 54
    • 0029914065 scopus 로고    scopus 로고
    • Measuring and testing genetic differentiation with ordered versus unordered alleles
    • Pons O, Petit RJ. 1996. Measuring and testing genetic differentiation with ordered versus unordered alleles. Genetics 144 : 1237 1245.
    • (1996) Genetics , vol.144 , pp. 1237-1245
    • Pons, O.1    Petit, R.J.2
  • 55
    • 0034496201 scopus 로고    scopus 로고
    • Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa
    • Prentice IC, Jolly D. 2000. Mid-Holocene and glacial-maximum vegetation geography of the northern continents and Africa. Journal of Biogeography 27 : 507 519.
    • (2000) Journal of Biogeography , vol.27 , pp. 507-519
    • Prentice, I.C.1    Jolly, D.2
  • 56
    • 51449110361 scopus 로고    scopus 로고
    • Phylogeographic insights into cryptic glacial refugia
    • Provan J, Bennett KD. 2008. Phylogeographic insights into cryptic glacial refugia. Trends in Ecology & Evolution 23 : 564 571.
    • (2008) Trends in Ecology & Evolution , vol.23 , pp. 564-571
    • Provan, J.1    Bennett, K.D.2
  • 57
    • 37549010737 scopus 로고    scopus 로고
    • Evidence for cryptic northern refugia among high- and temperate-latitude species in Beringia - A response to Stewart and Dalen (2008)
    • Pruett CL, Winker K. 2008. Evidence for cryptic northern refugia among high- and temperate-latitude species in Beringia - a response to Stewart and Dalen (2008). Climatic Change 86 : 23 27.
    • (2008) Climatic Change , vol.86 , pp. 23-27
    • Pruett, C.L.1    Winker, K.2
  • 58
    • 0026548159 scopus 로고
    • Population growth makes waves in the distribution of pairwise genetic differences
    • Rogers AR, Harpending H. 1992. Population growth makes waves in the distribution of pairwise genetic differences. Molecular Biology and Evolution 9 : 552 569.
    • (1992) Molecular Biology and Evolution , vol.9 , pp. 552-569
    • Rogers, A.R.1    Harpending, H.2
  • 59
    • 0041386108 scopus 로고    scopus 로고
    • MrBayes 3: Bayesian phylogenetic inference under mixed models
    • Ronquist F, Huelsenbeck JP. 2003. MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19 : 1572 1574.
    • (2003) Bioinformatics , vol.19 , pp. 1572-1574
    • Ronquist, F.1    Huelsenbeck, J.P.2
  • 60
    • 0347513220 scopus 로고    scopus 로고
    • DnaSP, DNA polymorphism analyses by the coalescent and other methods
    • Rozas J, Sanchez-DelBarrio JC, Messeguer X, Rozas R. 2003. DnaSP, DNA polymorphism analyses by the coalescent and other methods. Bioinformatics 19 : 2496 2497.
    • (2003) Bioinformatics , vol.19 , pp. 2496-2497
    • Rozas, J.1    Sanchez-Delbarrio, J.C.2    Messeguer, X.3    Rozas, R.4
  • 64
    • 35448987767 scopus 로고    scopus 로고
    • Fire and ice: Volcanic and glacial impacts on the phylogeography of the New Zealand forest fern Asplenium hookerianum
    • Shepherd LD, Perrie LR, Brownsey PJ. 2007. Fire and ice: volcanic and glacial impacts on the phylogeography of the New Zealand forest fern Asplenium hookerianum. Molecular Ecology 16 : 4536 4549.
    • (2007) Molecular Ecology , vol.16 , pp. 4536-4549
    • Shepherd, L.D.1    Perrie, L.R.2    Brownsey, P.J.3
  • 65
    • 0034350427 scopus 로고    scopus 로고
    • Gaps as characters in sequence-based phylogenetic analyses
    • Simmons MP, Ochoterena H. 2000. Gaps as characters in sequence-based phylogenetic analyses. Systematic Biology 49 : 369 381.
    • (2000) Systematic Biology , vol.49 , pp. 369-381
    • Simmons, M.P.1    Ochoterena, H.2
  • 66
    • 0035500901 scopus 로고    scopus 로고
    • Cryptic northern refugia and the origins of the modern biota
    • Stewart JR, Lister AM. 2001. Cryptic northern refugia and the origins of the modern biota. Trends in Ecology & Evolution 16 : 608 613.
    • (2001) Trends in Ecology & Evolution , vol.16 , pp. 608-613
    • Stewart, J.R.1    Lister, A.M.2
  • 69
    • 34547781750 scopus 로고    scopus 로고
    • MEGA4: Molecular evolutionary genetics analysis (MEGA) software version 4.0
    • Tamura K, Dudley J, Nei M, Kumar S. 2007. MEGA4: molecular evolutionary genetics analysis (MEGA) software version 4.0. Molecular Biology and Evolution 24 : 1596 1599.
    • (2007) Molecular Biology and Evolution , vol.24 , pp. 1596-1599
    • Tamura, K.1    Dudley, J.2    Nei, M.3    Kumar, S.4
  • 70
    • 0010150730 scopus 로고    scopus 로고
    • Late Cenozoic vegetational history and climatic characteristics of Qinghai-Xizang Plateau
    • Tang LY, Shen CM. 1996. Late Cenozoic vegetational history and climatic characteristics of Qinghai-Xizang Plateau. Acta Micropalaeontologica Sinica 13 : 321 337.
    • (1996) Acta Micropalaeontologica Sinica , vol.13 , pp. 321-337
    • Tang, L.Y.1    Shen, C.M.2
  • 71
    • 0027968068 scopus 로고
    • Clustal-W - Improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice
    • Thompson JD, Higgins DG, Gibson TJ. 1994. Clustal-W - improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Research 22 : 4673 4680.
    • (1994) Nucleic Acids Research , vol.22 , pp. 4673-4680
    • Thompson, J.D.1    Higgins, D.G.2    Gibson, T.J.3
  • 72
    • 9244229069 scopus 로고    scopus 로고
    • Trees or no trees? the environments of central and eastern Europe during the Last Glaciation
    • Willis KJ, van Andel TH. 2004. Trees or no trees? The environments of central and eastern Europe during the Last Glaciation. Quaternary Science Reviews 23 : 2369 2387.
    • (2004) Quaternary Science Reviews , vol.23 , pp. 2369-2387
    • Willis, K.J.1    Van Andel, T.H.2
  • 73
    • 0034105589 scopus 로고    scopus 로고
    • The full-glacial forests of central and southeastern Europe
    • Willis KJ, Rudner E, Sumegi P. 2000. The full-glacial forests of central and southeastern Europe. Quaternary Research 53 : 203 213.
    • (2000) Quaternary Research , vol.53 , pp. 203-213
    • Willis, K.J.1    Rudner, E.2    Sumegi, P.3
  • 74
    • 33644878518 scopus 로고    scopus 로고
    • Phylogeography of the Qinghai-Tibetan Plateau endemic Juniperus przewalskii (Cupressaceae) inferred from chloroplast DNA sequence variation
    • DOI 10.1111/j.1365-294X.2005.02677.x
    • Zhang Q, Chiang TY, George M, Liu JQ, Abbott RJ. 2005. Phylogeography of the Qinghai-Tibetan Plateau endemic Juniperus przewalskii (Cupressaceae) inferred from chloroplast DNA sequence variation. Molecular Ecology 14 : 3513 3524. (Pubitemid 43919953)
    • (2005) Molecular Ecology , vol.14 , Issue.11 , pp. 3513-3524
    • Zhang, Q.1    Chiang, T.Y.2    George, M.3    Liu, J.Q.4    Abbott, R.J.5


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.