關渡草澤地小麝鼩 (鼩形目：尖鼠科) 的婚配制度

Abstract

鼩鼱是各類棲地中常見的小型哺乳動物，然而對於鼩鼱的婚配制度至今所知不多，研究亞熱帶或熱帶地區鼩鼱婚配制度的文獻更是缺乏。本實驗藉由監測小麝鼩繁殖季時個體的空間分佈，配合微衛星體基因座的資料探討小麝鼩婚配制度；我測試前人提出「生活於亞熱帶地區、有季節性變動棲地的鼩鼱，婚配制度應為一夫一妻制」之假說。本實驗於2006年在關渡自然保護區的草澤地中以捉放法進行小麝鼩(Crocidura shantungensis)族群以及個體活動範圍的監測。我自兩種同屬鼩鼱(C. russula與C. suaveolens)的微衛星體基因座中篩選出8組適用於小麝鼩的引子進行族群個體親子源鑑定；同時分析在同一胎的子代中是否呈現多重父系血緣。實驗結果顯示居留於樣區的雄性小麝鼩活動範圍較雌性大，且傾向與多隻雌性重疊；反之雌性小麝鼩則較具領域性，這樣的空間分佈模式被歸類為「一夫一妻一夫多妻」婚配制度的指標之ㄧ。而分子遺傳的結果則發現雌、雄小麝鼩在單一生殖季中會與一隻以上的異性交配，且雌性在同一胎可與一隻以上的雄性交配，符合一般所認為的亂交制。本研究推翻了前人提出一夫一妻的假說。我認為關渡地區小麝鼩的族群特性如：族群密度以及性別比，亦可能是塑成其婚配制度的原因。

The knowledge on the mating systems of shrews is insufficient, especially for species living in the sub-tropic or tropic regions. Previous studies have hypothesized that the mating systems of Crocidurae should be monogamous in sub-tropical/tropical regions with seasonal climate and resource availability. I tested the hypothesis by investigating the spatial organization and genetic relatedness of Crocidura shantungensis in GuanDu salt marsh during the reproductive season. The population dynamic and spatial organizations of shrews were monitored with the capture-mark-recapture method in 2006. Eight microsatellite primers cross-species amplified from C. russula and C. suaveolens were used to perform parentage analyses of population and examine multiple paternity within litters. The results showed that the home range sizes of males were generally larger than those of females. Males also tended to overlap with multiple females, while females were territorial. The spatial organizations of 40 resident shrews suggested that the social mating system of C. shantungensis was likely facultative monogamy or effective polygyny. On the other hand, parentage analyses of population members and multiple paternity within litters showed both females and males mated multiply. Our results rejected the hypothesized model. Population characteristics, such as population density and sex ratio may have contributed to the mating system of C. shantungensis in GuanDu.