並列タイトル等個体数が増加し，分布が拡大しているエゾシカ個体群における遺伝的な空間構造に関する研究：個体群管理と関連させて
一般注記Since the 1980s, the sika deer (Cervus nippon) population of Hokkaido, Japan, has grown,resulting in range expansion and overabundance, which led to the damage of agriculturalland, forests, and natural vegetation, in addition to increased number of traffic collisions. Themanagement and control of the deer population are critical for ecosystem management.Studies on spatial genetic structure of the deer population provide valuable information aboutconservation and management policies.To assess the effects of this range expansion on the spatial genetic structure of the population,I compared subpopulation structures during two different periods (1991-1996, and2008-2010), using mitochondrial DNA (D-loop) and microsatellite (9 loci). The number ofgene-based subpopulations decreased across the 15-year period; specifically from four tothree subpopulations based on mtDNA, and from two to one subpopulation based onmicrosatellite DNA. The fusion of the two northern subpopulations caused the change to themtDNA-based structure, which might be explained by the dispersal of females from higherto lower density subpopulation. In comparison, the reason for the change in the microsatelliteDNA-based structure was unclear, because no significant genetic differentiation wasobserved between the two study periods. A stable mtDNA-based structure was maintainedin the north and central area separated by a west-to-east boundary, while a north-to-southboundary in eastern Hokkaido maintained stability in the eastern subpopulation versus allother subpopulation.To answer whether genetic differentiation occurs associated with migratory partitioning(migratory and philopatry), I analyzed mtDNA and microsatellite DNA genetic features offemale sika deer that were radio-tracked by Igota et al. (2004). The two clusters (cluster mt1and mt2) that were detected based on mtDNA analyses showed highly significant geneticdifferentiation. However, these clusters did not perfectly match migratory habits (migrants and non-migrants). Cluster mt1 consisted of migrants and non-migrants, while only migrants were found in cluster mt2. Similarly, individuals belonging to the two clusters (cluster ms1 and ms2) that were detected based on microsatellite DNA analyses did not perfectly match migratory habits. Cluster ms1 consisted of migrants and non-migrants, while only migrants were found in cluster ms2. Individuals belonging to both of cluster mt1 and ms1 were seven, while individuals belonging to both of cluster mt2 and ms2 were 13. The seven were migrants that moved toward the north from their wintering site in summer, while 10 of the 13 were non-migrants that did not leave their wintering site in summer. The seven and 10 individuals were distinctive about both mtDNA and microsatellite DNA features, and they showed the same migratory habit. These results indicate that there were genetically distinctive group associated with migratory habits in a sika deer population in Hokkaido.In Hokkaido, the Conservation and Management Plan for Sika deer (CMPS) has been encouraging hunters to target female sika deer in areas of high population density, because the removal of adult females with high reproductive value represents the most efficient strategy of controlling abundant populations. The management units (MUs) of CMPS are defined as western and eastern subpopulations, differing from the subpopulation structure identified in this study. These MUs may not demographically work well, because female-biased hunting effort in mtDNA-based subpopulation 2000mtE would not impact the neighboring subpopulation 2000mtN. Since the dispersal of females between 2000mtE and 2000mtN was limited, the 2000mtN population size would continue to increase, despite the successful control of the 2000mtE. Therefore, the management units should be revised based on an mtDNA-based structure identified in this study.
(主査) 教授 齋藤 隆, 教授 佐藤 冬樹, 准教授 内海 俊介, 准教授 岸田 治, 研究主幹 宇野 裕之 （地方独立行政法人北海道立総合研究機構）
環境科学院（生物圏科学専攻）
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受理日（W3CDTF）2015-02-03T05:25:05+09:00
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