生物因局部性適應而造成族群間的分化，是演化生物學中的重要議題。而瘧疾對生物在不同海拔高度族群的選汰壓力差異，正提供了廣分布種免疫相關基因產生局部性適應的機會。本研究以廣泛分布於台灣低至高海拔闊葉林緣的繡眼畫眉(Alcippe morrisonia morrisonia)為模式，探討分布於低(200-400公尺)、中(1000-1250公尺)、高(1940-2200公尺)海拔族群的主要組織相容性複合體基因(major histocompatibility complex, MHC)是否受到不同程度禽瘧疾的選汰壓力而產生局部性適應。本研究以毛細管電泳-單股構形多型性(CE-SSCP, capillary electrophoresis-single strand conformation polymorphism,)技術自繡眼畫眉分離出共28個MHC class I對偶基因。在潛在的瘧疾疫區中(中、低海拔族群)，發現MHC對偶基因Almo*05與個體染病與否有顯著關聯 (p=0.0062)：帶有MHC對偶基因Almo*05的個體感染禽瘧疾的比例顯著較未攜帶者為高(p=0.0091)，顯示對偶基因Almo*05對禽瘧疾有較佳的感受力。再者，此對偶基因頻率在非疫區的高海拔族群較中低海拔族群顯著為高(p=0.0282)；此結果顯示Almo*05在高海拔地區有選汰壓力減輕的現象，這間接支持禽瘧疾相關的MHC對偶基因頻率分布，在不同海拔高度的族群產生局部性適應現象。另以AMOVA (Analysis of Molecular Variance,分子變異分析)檢測MHC基因及五個微衛星體基因座(microsatellite loci)於不同海拔族群間的遺傳分化情形；結果顯示，微衛星體基因在不同海拔族群間呈現些微但顯著分化(FST=0.00057, p=0.04692)，但MHC基因在不同海拔族群間並無分化(FST= -0.00032, p=0.45064)。這結果表示MHC對偶基因在三個海拔高度族群間的頻率分布，比中性預期下更為平均，符合不同海拔繡眼畫眉MHC的整體多樣性可能是藉由平衡式天擇來維持的假說。綜合上述結果，本研究證明不同海拔高度間，病原天擇壓力可造成族群MHC對偶基因的局部性適應，而另一方面，不同海拔繡眼畫眉族群MHC基因多樣性可能可藉由平衡式天擇來維持。

Local adaptation leading to population differentiation is a fundamental question in evolutionary biology. Altitudinal variation in malarial pressure across altitudes provides opportunities for resistance-related genes of widespread species to adapt locally. Here I used the gray-cheeked fulvetta (Alcippe morrisonia morrisonia) populations in central Taiwan as a model to study whether divergent malarial pressure at low (200-400 m), intermediate (1000-1250 m) and high (1940-2200 m) altitudes leads to local adaptation of host’s MHC (major histocompatibility complex) genes. Twenty-eight alleles of MHC class I genes were identified using CE-SSCP (capillary electrophoresis-single strand conformation polymorphism) method in this study. In malarial endemic region (i.e. low and intermediate altitudes), MHC allele Almo* 05 was identified as a determinant factor in malarial infection (forward stepwise regression analysis, p=0.0062); significantly higher ratio of individuals carrying Almo* 05 were infected with malaria than those without the allele, indicating Almo* 05 was susceptible to malarial infection. Furthermore, Almo* 05 was of significantly higher frequency at high altitudes than at low and intermediate altitudes. My results suggested that allele frequency of specific MHC allele could be modulated by altitudinal pressure gradient of malaria. In addition, results of AMOVA (Analysis of Molecular Variance) test suggested that alleles of five microsatellite loci showed slight but significant differentiation of allelic frequency among three altitudinal populations (FST=0.00057, p=0.04692), whereas MHC alleles did not (FST= -0.00032, p=0.45064). The observation of a more even allele distribution among altitudes at MHC is concordant with the expectation of balancing selection maintaining MHC diversity. In sum, this study demonstrates that, across altitudes, specific MHC allele may adapt to divergent pathogenic selection, while balancing selection may play a key role in maintaining MHC polymorphism in the gray-cheeked fulvetta populations among different altitudes.

Altizer, S., D. Harvell, and E. Friedle. 2003. Rapid evolutionary dynamics and disease threats to biodiversity. Trends in Ecology & Evolution 18:589-596.
Arakawa, H., A. Tsuji, M. Maeda, M. Kamahori, and H. Kambara. 1997. Analysis of single-strand conformation polymorphisms by capillary electrophoresis with laser induced fluorescence detection. Journal of Pharmaceutical and Biomedical Analysis 15:1537-1544.
Beaumont, M. A. 2005. Adaptation and speciation: what can Fst tell us? Trends in Ecology & Evolution 20:435-440.
Behnke, J. M., and F. N. Wahid. 1991. Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): H-2 linked genes determine worm survival. Parasitology 103:157-164.
Bonneaud, C., J. Perez-Tris, P. Federici, O. Chastel, and G. Sorci. 2006. Major histocompatibility alleles associated with local resistance to malaria in a passerine. Evolution 60:383-389.
Burdon, J. J., and P. H. Thrall. 1999. Spatial and temporal patterns in coevolving plant and pathogen associations. The American Naturalist 153 S15–S33.
Bynum, W. F. 1999. Ronald Ross and the malaria-mosquito cycle. Parassitologia 41:49-52.
Cattani, J. A., J. S. Moir, F. D. Gibson, M. Ginny, J. Paino, W. Davidson, and M. P. Alpers. 1986. Small-area variations in the epidemiology of malaria in Madang Province. Papua New Guinea Medical Journal 29:11-17.
Chen, C. Y., S. A. Cohen, M. B. Zaleski, and B. Albini. 1992. Genetic control of streptococcus-induced hepatic granulomatous in mice. Immunogenetics 36:28-32.
de Campos-Lima, P. O., R. Gavioli, Q. J. Zhang, L. E. Wallace, R. Dolcetti, M. Rowe, A. B. Rickinson, and M. G. Masucci. 1993. HLA-A11 epitope loss isolates of Epstein-Barr virus from a highly A11+ population. Science 260:98-100.
Dieckmann, U., M. Doebeli, J. A. J. Metz, and D. Tautz 2004. Adaptive speciation. Cambrideg University press., Cambridge.
Edwards, S. V., J. Nusser, and J. Gasper. 2000. Characterization and evolution of major histocompatibility complex (Mhc) genes in non-model organisms, with examples from birds. Pages 168-207 in A. J. Baker, editor. Molecular Methods in Ecology. Blackwell Science, Oxford, UK.
Ekblom, R., S. A. Sæther, M. Grahn, P. Fiske, J. A. Kålås, and J. Höglund. 2007. Spatial pattern of MHC class II variation in the great snipe (Gallinago media). Molecular Ecology 16:1439-1451.
Epstein, P. R. 2001. Climate change and emerging infectious diseases. Microbes and Infection 3:747-754.
Excoffier, L., G. Laval, and S. Schneider. 2005. Arlequin (version 3.0): An integrated software package for population genetics data analysis. Evolutionary Bioinformatics Online 1:47-50.
Excoffier, L., P. E. Smouse, and J. M. Quattro. 1992. Analysis of Molecular Variance inferred from metric distances among DNA haplotypes: application to human mitochondrial DNA restriction data. Genetics 131:479-491.
Garrigan, D., and P. W. Hedrick. 2003. Perspective: detecting adaptive molecular polymorphism: lessons from the MHC Evolution 57:1707-1722.
Gemmell, N. J., and S. Akiyama. 1996. An efficient method for the extraction of DNA from vertebrate tissues Trends in Genetics 12:338-339.
Grant, P. R., B. R. Grant, J. N. M. Smith, I. J. Abbott, and L. K. Abbott. 1976. Darwin's Finches: Population Variation and Natural Selection. PNAS 73:257-261.
Hay, S. I., C. A. Guerra, A. J. Tatem, A. M. Noor, and R. W. Snow. 2004. The global distribution and population at risk of malaria: past, present, and future. The Lancet Infectious Diseases 4:327-336.
Hill, A. V. S., A. Jepson, M. Plebanski, and S. C. Gilbert. 1997. Genetic analysis of host–parasite coevolution in human malaria. Philosophical Transactions of the Royal Society B: Biological Sciences 352:1317-1325.
Huang, Y.-J., C. Chen, and S.-H. Li. 2004. Polymorphic tetranucleotide microsatellite loci in the Hwamei (Garrulax canorus canorus) (Timaliidae). Molecular Ecology Notes 4:170-172.
Hughes, A. L. 1999. Adaptive evolution of genes and genomes. Oxford University Press, New York.
Kawecki, T. J., and D. Ebert. 2004. Conceptual issues in local adaptation. Ecology Letters 7:1225-1241.
Kleindorfer, S., S. Lambert, and D. C. Paton. 2006. Ticks (Ixodes sp.) and blood parasites (Haemoproteus spp.) in New Holland Honeyeaters (Phylidonyris novaehollandiae): evidence for site specificity and fitness costs. Emu 106:113-118.
Kumar, S., K. Tamura, and M. Nei. 2004. MEGA3: Integrated software for Molecular Evolutionary Genetics Analysis and sequence alignment. Brief Bioinform 5:150-163.
Land, J. V. t., P. V. Putten, Zwaan, Kamping, and W. V. Delden. 1999. Latitudinal variation in wild populations of Drosophila melanogaster: heritabilities and reaction norms. Journal of Evolutionary Biology 12:222-232.
Ledig, F. T., and D. R. Korbobo. 1983. Adaptation of sugar maple populations along altitudinal gradients: photosynthesis, respiration, and specific leaf weight. American Journal of Botany 70:256-265.
Lively, C. M. 1992. Parthenogenesis in a freshwater snail: reproductive assurance versus parasitic release. Evolution 46:907-913.
Macnair, M. R. 1987. Heavy metal tolerance in plants: A model evolutionary system. Trends in Ecology & Evolution 2:354-359.
Marzal, A., F. d. Lope, C. Navarro, and A. P. Møller. 2005. Malarial parasites decrease reproductive success: an experimental study in a passerine bird. Oecologia 142:541-545.
McClelland, E. E., D. J. Penn, and W. K. Potts. 2003. Major Histocompatibility Complex Heterozygote Superiority during Coinfection. Infect. Immun. 71:2079-2086.
Meyer, D., and G. Thomson. 2001. How selection shapes variation of the human major histocompatibility complex: a review. Annals of Human Genetics 65:1-26.
Miaud, C., and J. Merilä. 2000. Local adaptation or environmental induction? Causes of population differentiation in Alpine amphibians. Biota 2:31-50.
Miller, K. M., K. H. Kaukinen, T. D. Beacham, and R. E. Withler. 2001. Geographic heterogeneity in natural selection on an MHC locus in sockeye salmon. Genetica 111:237-257.
Molineaux, L., and G. Gramiccia. 1980. The Gharki project: research on the epidemiology and control of malaria in sudan savanna of West Africa. World Health Organisation, Geneva.
Oleksyn, J., M. G. Tjoelker, and P. B. Reich. 1998. Adaptation to Changing environment in Scots pine populations across a latitudinal gradient. Silva Fennica 32:129-140.
Onori, E., and B. Grab. 1980. Indicators for the forecasting of malaria epidemics. Bulletin of World Health Organisation 58:91-98.
Palo, J. U., R. B. O'Hara, A. T. Laugen, A. Laurila, C. R. Primmer, and J. Merila. 2003. Latitudinal divergence of common frog (Rana temporaria) life history traits by natural selection: evidence from a comparison of molecular and quantitative genetic data. Molecular Ecology 12:1963-1978.
Prugnolle, F., A. Manica, M. Charpentier, J. F. Guégan, V. Guernier, and F. Balloux. 2005. Pathogen-driven selection and worldwide HLA class I diversity. Current Biology 15:1022-1027.
Rätti, O., R. Dufva, and R. Alatalo. 1993. Blood parasites and male fitness in the pied flycatcher. Oecologia 96:410-414.
Raymond, M., and F. Rousset. 1995. GENEPOP (Version 1.2): Population Genetics Software for Exact Tests and Ecumenicism. J Hered 86:248-249.
Rudge, D. 1999. Taking the Peppered Moth with a Grain of Salt. Biology and Philosophy 14:9-37.
Ruiz, X., D. Oro, and J. González-Solís. 1995. Incidence of a Haemoproteus lari parasitemia in a threatened gull: Larus audouinii. Ornis Fennica 72:159-164.
Rundle, H. D., and P. Nosil. 2005. Ecological speciation. Ecology Letters 8:336-352.
Seutin, G., B. N. White, and P. T. Boag. 1991. Preservation of avian blood and tissue samples for DNA analysis. Canadian journal of zoology 69:82-90.
Sokal, R. R., and F. J. Rohlf 1995. Biometry: the principles and practice of statistics in biological research. W. H. Freeman and Company, New York.
Van Oosterhout, C., D. A. Joyce, S. M. Cummings, J. Blais, N. J. Barson, I. W. Ramnarine, R. S. Mohammed, N. Persad, and J. Cable. 2006. Balancing selection, random genetic drift, and genetic variation at the major histocompatibility complex in two wild populations of guppies (Poecilia reticulata). Evolution 60:2562-2574.
Waldenström, J., S. Bench, D. Hasselquist, and Ö. Östman. 2004. A nested polymerase chain reaction method vary efficient in detecting Plasmodium and Haemoproteus infections from avian blood. Journal of Parasitology 90:191-194.
Warner, R. E. 1968. The role of introduced disease in the extinction of the endemic Hawaiian avifauna. The Condor 70:101-120.
Wegner, K. M., T. B. H. Reusch, and M. Kalbe. 2003. Multiple parasites are driving major histocompatibility complex polymorphism in the wild. Journal of Evolutionary Biology 16:224-232.
Westerdahl, H., B. Hansson, S. Bensch, and D. Hasselquist. 2004. Between-year variation of MHC allele frequencies in great reed warblers: selection or drift? Journal of Evolutionary Biology 17:485-492.
Westerdahl, H., J. Waldenström, B. Hansson, D. Hasselquist, T. von Schantz, and S. Bensch. 2005. Associations between malaria and MHC genes in a migratory songbird. Proceedings of the Royal Society B: Biological Sciences 272:1511-1518.
Williams, G. C. 1966. Adaptation and natural selection. Princeton University press, Princeton.
Wiwanitkit, V. 2006. Correlation between prevalence of malaria and altitude, a study in a rural endemic area of Thailand. Haema 9:56-58.
Woodworth, B. L., C. T. Atkinson, D. A. LaPointe, P. J. Hart, C. S. Spiegel, E. J. Tweed, C. Henneman, J. LeBrun, T. Denette, R. DeMots, K. L. Kozar, D. Triglia, D. Lease, A. Gregor, T. Smith, and D. Duffy. 2005. Host population persistence in the face of introduced vector-borne diseases: Hawaii amakihi and avian malaria. PNAS 102:1531-1536.
Yeung, C., H. Yi-Jiun, and L. Shou-Hsien. 2004. Development of polymorphic microsatellite markers for the Steere's Liocichla (Liocichla steerii). Molecular Ecology Notes 4:420-422.
Yuhki, N., and S. J. O'Brien. 1990. DNA variation of the mammalian major histocompatibility complex reflects genomic diversity and population history. PNAS 87:836-840.