东方田鼠两亚种幼体生长特征参数的比较

在相同驯养条件下同步测定东方田鼠(Microtus fortis)指名亚种和长江亚种幼体的生长特征参数。两亚种初生幼体表型特征无明显差异。采用Von Bertalanffy生长模型对两亚种幼体的体重、体长和尾长,以Logistic生长方程对后足长生长过程进行拟合与描述。指名亚种雄体渐近体重、体长和尾长均大于或显著大于长江亚种,雌体前者小于后者;两亚种在17~20 d体重均已产生性二型分化,长江亚种两性个体渐近体重、体长和尾长差值大于指名亚种。两亚种雌体体重、体长、尾长和后足生长速率均相应地大于雄体,体重生长曲线拐点出现时间、瞬时生长率曲线拐点出现时间较体长、尾长和后足长明显迟缓。两亚种两性个体的后足长生长速率要大于其体重、体长和尾长。结果表明,(1)雌体较雄体早熟;(2)雄性体重指名亚种大于长江亚种,雌体相反,指名亚种性二型现象较长江亚种明显;(3)后足长较体重、体长和尾长较早地达到成熟时的大小;(4)两亚种幼体性二型分化时间早于其性成熟过程。

Comparison on the Postnatal Growth Parameter of Microtus fortis calamorum and M.f.Fortis

The postnatal growth of Microtus fortis fortis and M.f.calamorum born during the same period and raised in the identically artificial conditions were measured.There were no significant differences in body weight(BW),body length(BL),tail length(TL) and hind foot length(HFL) between M.f.fortis' and M.f.calamorum's natal pups.Von Bertalanffy equation was well fitted with growth data of BW,BL and TL,and Logistic equation with those of HFL.The male's asymptotic BW,BL and TL of M.f.fortis were larger than those of M.f.calamorum, which of female were in the opposite situation.The sexual dimorphism of the two subspecies both occurred at day 17-20,and the differences between the asymptotic BW, BL and TL for M.f.fortis were larger than those for M.f.calamorum.The growth rate (k) of the four phenotypic characteristics of female were larger than that of male,respectively,and the inflexion of growth curve and instantaneous growth rate curve of BW occurred late than those of BL,TL and HFL.The growth rate of HFL for female and male of the two subspecies's were larger than that of BW,BL,and TL.The results showed that:(1) female matured early than male relatively;(2) the male body size of M.f.fortis were obviously larger than that of M.f.calamorum,on the contrary,which of female of the latter larger than that of the former,and the sexual dimorphism of M.f.fortis are more obvious than that of M.f.calamorum;(3) HFL approached early to the size of the matured voles than BW,BL and TL;(4) The initial dimorphism of body weight for the two subspecies occurred before the sexual maturation process.