摘要
通过比较法对实验室内布氏田鼠 (Microtusbrandti)幼仔生长发育与光周期关系的研究表明 ,尽管出生和断乳时的窝仔数及断乳时窝仔存活率不受光周期的影响 (t test,P >0 0 5 ) ,每种光周期条件下出生和断乳时雌雄比例差异不显著 (Chi square检验 ,P >0 0 5 ) ,不同光周期间雄性比例无明显差异 (百分数的检验 ,P >0 0 5 ) ,但是 ,随着幼仔的生长 ,出生并饲养在长光照周期 (LD ,14L∶10D)下的个体体重、体长和肥满度显著大于短光照周期 (SD ,10L∶14D)下的幼体 ,尤在出生 9或 14天以后的各阶段 (t test,P <0 0 5 )。在 6 0日龄时 ,LD雄鼠的睾丸、附睾及储精囊成熟指数显著高于SD鼠 (t test,睾丸 ,t =3 30 9,df =14,P <0 0 1;附睾 ,t=3 6 2 2 ,df =14,P <0 0 1;储精囊 ,t=3 379,df =14,P <0 0 1)。但LD组的皮毛厚度和绒毛长度显著低于SD组 (t test,皮毛厚度t=- 5 185 ,df =14,P <0 0 1;绒毛长度t=- 2 415 ,df =14,P <0 0 5 )。作者认为体重、肥满度和性腺成熟指数 (GSI)高的LD鼠较SD鼠更适应于繁殖期的繁殖生存 ;而生长发育缓慢 ,皮毛厚度、绒毛长度高的SD鼠更能适应越冬生存。在自然环境中 ,光周期可能被布氏田鼠作为季节环境变化的信号 ,使其在形态和生殖方面提前作好准备 ,采取不同的策略以适?
Most of small mammals, including Brandt's in temperate zone, voles (Microtus brandti), reproduce and rear offspring during seasons with mild environmental conditions and abundant food. It is assumed that animals bearing offspring during the breeding season increase their reproductive fitness and that reproduction at other periods results in fewer surviving progeny and possible energy crises for the parents. It, so that, is important that the environmental cues employed by animals to forecast the optimal breeding season are termed the proximate factors or cues of seasonal breeding. Photoperiod is the most common environmental factor used by north temperate mammals for timing reproduction. Brandt's voles' puberty and somatic growth are delayed by as many as 20 weeks in offspring late compared with early in the natural breeding season. The present study was the first measurement of some somatic and reproductive traits by comparing Brandt's voles pups born and housed in long (LD:14L∶10D) versus short (SD:10L∶14D) day photoperiod from birth to 28 days age or in 60 days age (The parents of LD and SD pups respectively housed exceeded 4 weeks in long and short day photoperiod after pairing). The goal was to determine whether photoperiod affect rate of growth and development of Brandt's voles offspring. The results showed that photoperiod had no significant effect on the litter size at birth( t =1 21, df =18, P >0 05),the litter size at weaning (t=1 43,df=18,P>0 05) and the mean survival rate of pups per litter at weaning (t=1 38, df=18,P>0 05). Compared with SD pups, however, it is during eye opening period (postnatal day 10～14) or after eye opening (exceeded postnatal day 14) that LD offspring matured more rapidly with respect to body weight ( W ), body length ( L ) and relative fatness ( K wl =W/L ) with the development of pups. Additionally, gonad somatic index (GSI'=sin -1 w\-g/w×100%, W g: gonad weight, W : body weight), including paired testes index (GSI t'), paired epididymal index(GSI e') and seminal vesicle index (GSI v'), were greater for LD 60 day age male pups than those for SD group( t test, GSI t', t=3 309,df=14,P <0 01;GSI e', t=3 622,df=14,P <0 01;GSI v', t=3 379, df=14, P <0 01). In contrast, the pelage depth and under hair length of 60 day age SD offspring were thicker or longer than those of LD ones( t test, t=-5 185,df=14,P<0 01; t=-2 415,df=14,P<0 05, respectively). The present study indicated that several traits of vole pups were influenced by postnatel photoperiod or dam's photoperiod history. The results suggest that photoperiod or day length induce the seasonal changes of growth and development of Brandt's voles pups, and likely facilitates adaptation of voles to seasonally varying environmental condition.
出处
《动物学报》
SCIE
CAS
CSCD
北大核心
2001年第2期150-157,共8页
ACTA ZOOLOGICA SINICA
基金
国家自然科学基金资助项目!(No .3 9470 117)&&
关键词
布氏田鼠
光周期
体重
体长
肥满度
性腺发育
皮毛
幼鼠
Brandt's voles (Microtus brandti), Photoperiod, Body weight, Body length,Relative fatness, Gonad development, Pelage
