福山試驗林食蟹獴(Herpestes urva)之社會結構

Abstract

獴科動物的社會結構從獨居到群居，有許多類型；但是被歸類為獨居性的獴也可能展現許多複雜的社會行為。本研究利用捕捉標放及無線電追蹤，收集被認為屬於獨居性的食蟹獴族群組成與空間分布資料，並配合微衛星體基因座分子技術分析分子遺傳資料，檢視福山試驗林內食蟹獴的社會結構，包括個體間遺傳相似度與活動範圍分布的關係、播遷模式及食蟹獴配對系統。 自2008年4月至2009年9月共捕獲22隻食蟹獴 (10雄12雌) 51次，所有個體皆掛有發報器。扣除定位點數不足的個體，19隻食蟹獴有效定位點從16點至80點不等，活動範圍面積介於5.01公頃至80.51公頃，平均44.77 ± 19.04公頃，性別間及年齡間都沒有顯著差異。同一時期追蹤的食蟹獴活動範圍，在雄性間、雌性間及異性間活動範圍都會有重疊，從0 %至96.4 %。 以11組微衛星基因座分析23份食蟹獴組織樣本(包括一隻非本研究捕獲的死亡個體之組織)，每個基因座的對偶基因數為2至6個，平均為3.27個，HＯ為0.565 ± 0.283，HE為0.513 ± 0.221，與1997年食蟹獴樣本的遺傳多型性類似，但遺傳結構有分化的趨勢。FIS值為-0.063，顯示福山食蟹獴沒有偏離逢機配對之預期。兩兩個體配對的遺傳相似度從-0.472至0.338，平均為-0.026，雄性兩兩配對與雌性兩兩配對之平均遺傳相似度沒有差異，顯示福山食蟹獴的播遷模式沒有性別上的偏差。根據遺傳分析個體間關係的結果配合野外觀察資料推論出5組親子組合，其中兩組有相同的父親不同的母親，推論食蟹獴的配對系統為一雄多雌。 比較有親屬關係的個體與沒有親屬關係個體間活動範圍重疊度沒有顯著差異；而雄性間及雌性成體間遺傳相似度越近時活動範圍及核心區域重疊度會越小，推測可能是為了降低和有關係個體的競爭或交配機會。在研究期間所紀錄一起活動的2隻個體多為繁殖對或親子對，但有1組2隻一起活動的是沒有關係的非成體，推論一起行動的原因可能為共同禦敵，顯示福山食蟹獴除了生殖和育幼外，還會出現其他不同程度的互動行為，並非完全獨居的動物。

Social structures of different mongoose species of Family Herpestidae vary greatly from being solitary to social. Some solitary mongooses have been observed to have complex social interaction than expected. To understand the social structure of the crab-eating mongoose (Herpestes urva), which was categorized as a solitary mongoose, I conducted mark-recpture, radio-tracking and genetic analysis using microsatellite markers to examine spatial distribution and relatedness of individuals, dispersal pattern of male and females, and mating system of the species. From April 2008 to September 2009, I captured 22 crab-eating mongoose (10 males and 12 females), and all of them were fitted with transmitters. The number of location fixes recorded for 19 mongooses ranged from 16 to 80. Average home range size was 44.77 ± 19.04 ha (range: 5.01 - 80.51 ha). Home range overlaps could be found in male, female and inter-sexual pairs, and the degree of home range overlaps varied from 0 % to 96.4 %. Genetic analysis based on 11 microsatellites loci showed that mean number of alleles per locus was 3.27 (range: 2 – 6) and the average observed and expected heterozygosity was 0.565 ± 0.283 and 0.513 ± 0.221, respectively. Genetic diversity of population in 1997 and 2008, though not significantly different, showed trend of genetic differentiation. Genetic data also indicated no in-breeding in the Fushan population (FIS = -0.063). Mean pairwise relatedness was -0.026 (range: -0.472 to 0.338) and no significant difference was found between that of male pairs and female pairs, which suggested no sex-biased dispersal. Parent-offspring analysis suggested potential polygynous mating system. The Mantel test indicated a significantly negative relationship between relatedness of male pairs and overlaps of their home ranges, and between that of adult female pairs, which suggested that crab-eating mongooses may avoid resource competition and mating with individuals that are closely related. The crab-eating mongooses were mostly solitarily or active in either breeding or parent-offspring pairs. However, one pair of unrelated subadults which were found to move together, perhaps as a anti-predator strategy, suggested that the crab-eating mongoose may have more complex social interaction than expected of a solitary animal.