第8卷‧第7期,
198007
, pp. 646-660
赤背條鼠之生殖週期
- 作者:
周文豪; 林俊義
- 作者服務機構:
私立東海大學生物系
- 中文摘要:
自一九七八年元月到一九七九年三月之十五個月研究期間,於東海大學及其附近共採集赤背
條鼠(Apodemus agrarius Pallas)374隻。由其生殖變數顯示,雌鼠在四月到一月間有懷孕現象
,以四月到九月間為生殖鼎盛期;而雄鼠則全年皆可生殖。赤背條鼠的生殖和日照時數、氣溫及
雨量有密切的關係。
由53隻懷孕雌鼠之胚胎數,可計算其每胎生產3.8±0.7隻(2~5隻)幼鼠,且由黃體數知
其排卵率為4.9±1.4。排卵率和每胎生產隻數的差額顯示出生前死亡率達21.5%,包括20.4%
的?床前死亡率和1.1%的?床後死亡率。每胎生產隻數以生殖季開始為最高。初產者之每胎生
產隻數(3.9±0.7)與複產者(3.8±0.8)並無顯著的差別(p>0.05)。大部份雌鼠可生產2胎,只
有十二月一隻懷孕的雌鼠同時具有二組胎痕,被認為可以生產3胎以上者。由此推測雌鼠在生產
第二胎以後死亡率高。
雌雄比例為45:55%,無異於1:1之比,但在五月到九月(生殖鼎盛期)間以外之雌雄比
例,顯然雄多於雌(131:99;p<0.05),推測在非生殖鼎盛期時雌鼠之死亡率較高,族?更替一
年一次。
由高的死亡率、快速的族?更替,以及高的生殖率顯示,赤背條鼠之生殖傾向於r-策略。a
- 英文摘要:
A total of 374 specimens of Apodemusagrarius Pallas, including 172 females and 202males, were examined monthly for reproductiveparameters from January, 1978 to March, 1979.Pregnant females were found from April toJanuary, but the period of high reproductiveactivity lasted only from April through Septmber.Mean testis weights of males were high fromMarch through September with a sharp declinein October. However, 30-40% of adult malesin monthly samples for October through Feb-ruary had functional testes with enlarged seminalvesicles, indicating the potential for breedingthroughout the year. The annual reproductivepattern is closely correlated with daylength,temperature and rainfall, suggesting that repro-ductive activity is strongly influenced by one ormore of these factors. The mean litter size based on embryo countsof 53 pregnancies was 3.8±0.7 with a rangefrom 2 to 5, and the mean ovulation rate basedon corpora lutea counts was 4.9±1.4. Thedifference between litter size and ovulation rateindicated that the prenatal mortality was 21.5%including 20.4% pre-implantation mortality and1.1% post-implantation mortality. The littersize was higher in the beginning of breedingseason (Apr.-May: 4.3±0.7, June-July: 4.0±0.4,Aug.-Sep.: 3.6±0.8, Oct.-Nov.: 3.5±0.7, Dec.-Jan.: 3.8±0.8 respectively). The primiparouslitter size (3.9±0.7) was not significantly different(p>0.05) from the multiparous (3.8±0.8). Mostof the females were found to have 2 litters,except one pregnant female which had 2 differentsets of placental scars. This evidence indicateshigh mortality of females after their secondpregnancy. The sex ratio (55% males: 45% females)based on 363 trapped animals was not signifi-cantly different from a 1:1 ratio. Other than themain breeding season, however, males appearedgreater in number than females (131:99; P<0.05),suggesting that sexes show different mortalityduring that period. The high mortality within the first year oflife along with evidence of high reproductiverate indicates that this species may be stronglyr-selected.
- 中文關鍵字:
--
- 英文關鍵字:
--